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Understanding the distribution patterns and driving mechanisms of bamboo species diversity on islands is essential for advancing knowledge of island ecosystem processes and informing strategies for bamboo resource conservation and management. This study utilized standardized major axis regression (SMA) to assess the effects of island area and isolation on bamboo species across 30 islands in Fujian, China. Furthermore, a partial least squares structural equation model (PLS-SEM) was constructed to explore the driving mechanisms underlying bamboo species richness. This analysis incorporated six key environmental factors—island size, isolation, shape, climate, development intensity, and habitat heterogeneity—spanning a total of 12 variables. The primary findings were as follows: (1) Eight genera and twenty-nine bamboo species were identified on Fujian islands. Species richness increased significantly with island area, consistent with the theory of area effects, while isolation had no significant impact on richness. (2) Different reproductive types exhibited distinct responses to environmental conditions. This was evident in the species–area relationship slopes (z-values): SR = 2.07; monopodial = 0.94; sympodial = 0.82; and polycyclic = 0.44. These variations highlight the ecological adaptability and functional traits of different reproductive strategies within island ecosystems. (3) Among the six environmental factors, island area exerted the greatest influence on species richness, underscoring its role as the primary driver of bamboo diversity and reproductive strategies. (4) Island area and isolation also impacted species richness indirectly through their effects on development intensity. In conclusion, the bamboo species richness and reproductive types on Fujian islands are primarily shaped by island area, followed by development intensity and habitat heterogeneity. In contrast, climate, island shape, and isolation play relatively minor roles. This study provides critical insights into the interplay of island area, isolation, shape, climate, development intensity, and habitat heterogeneity in shaping bamboo diversity. The findings offer a valuable foundation for bamboo resource conservation, island ecosystem management, and sustainable development. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Aims Materials and Methods Results Discussion Conclusion The study of island species richness has gone far beyond traditional theories, as more and more studies attempt to include new predictor variables besides island area. Despite the rich bat diversity of Mediterranean islands, no studies have examined the factors influencing chiropteran species richness in such a geographic context.We used Greek islands as a model to detect drivers of bat species richness based on a broad species occurrence dataset from islands of the Aegean and Ionian Seas, which was explored using 10 potential predictor variables.Initially, we comprehensively evaluated all available data and sources for 53 Greek islands, deemed essential. This resulted in a reduced set of 28 islands. Predictors were grouped into three categories: island area, landscape diversity and island isolation. Generalised linear models were employed to identify the most significant factors explaining bat species richness in the 28 islands.Tree cover and the distance between the islands and their nearest coast (mainland or island) best performed to predict bat species richness on Greek islands.We show the important role of landscape composition and degree of isolation in influencing the distribution of bat species on islands.We highlight the importance of forest habitats and the vital role of their management and protection, especially in the insular systems of the Mediterranean basin, where the risk of forest degradation or loss due to wildfires and land use change is especially high. [ABSTRACT FROM AUTHOR]

The rise in species richness with area is one of the few ironclad ecological relationships. Yet, little is known about the spatial scaling of alternative dimensions of diversity. Here, we provide empirical evidence for a relationship between the richness of acoustic traits emanating from a landscape, or soundscape richness, and island area, which we term the SoundScape‐Area Relationship (SSAR). We show a positive relationship between the gamma soundscape richness and island area. This relationship breaks down at the smallest spatial scales, indicating a small‐island effect. Moreover, we demonstrate a positive spatial scaling of the plot‐scale alpha soundscape richness, but not the beta soundscape turnover, suggesting a direct effect of species on acoustic trait diversity. We conclude that the general scaling of biodiversity can be extended into the realm of ecoacoustics, implying soundscape metrics are sensitive to fundamental ecological patterns and useful in disentangling their complex mechanistic drivers. [ABSTRACT FROM AUTHOR]

Aim: The study of islands biotas is fundamental to understand biodiversity patterns and process, both on evolutionary and ecological time scales. This study explores the influence of biogeographic and climatic factors on island species–area relationships (ISARs) in volcanic and continental islands, aiming to detect differences in slopes and intercepts between these island origins. Methods: Data from 5049 vegetation plots on 58 Central Mediterranean Sea islands were collected from various sources. Islands were categorized as volcanic or continental based on their geological origin. area, isolation, maximum elevation, eccentricity, mean annual temperature and annual precipitation were calculated for each island. By using a moving window, we created groups of islands, and ISARs were fitted to each group using the Arrhenius power functions. Linear models and a permutation test were employed to examine how ISAR model parameters varied with the above-mentioned variables. Results: While ISAR intercept values did not differ between island origins, volcanic islands showed higher ISAR slopes than continental islands. Whereas increasing island isolation and mean annual temperature increased ISAR intercepts on continental islands groups, it decreased on volcanic ones. Increasing annual precipitation decreased ISAR intercept on continental islands groups and increased on volcanic islands groups. Increasing island isolation, eccentricity and mean annual temperature increased the ISAR slope on volcanic islands groups while increasing annual precipitation decreased it. Increasing maximum elevation increased ISAR slope on continental islands groups. Main conclusions: Our study provides evidence about the importance of island geological origin in determining the observed ISAR patterns. Biogeographic and climatic factors are pivotal in shaping species richness patterns on islands, exerting varying influences on both volcanic and continental islands. [ABSTRACT FROM AUTHOR]

Invasive alien plants (IAPs) pose a significant threat to island biodiversity and severely impact ecosystems. Understanding the species–area relationship and environmental determinants of growth forms for IAP species on subtropical islands is crucial for establishing an IAP's early warning mechanism, enhancing island ecological management, and protecting the ecosystems of Fujian and other subtropical islands. The study identified significant species–area relationships for IAPs and different life-form plants (trees, shrubs, and herbs), with slopes of 0.27, 0.16, 0.15, and 0.24, respectively. The small island effect does not apply to all species. Isolation has little effect on species richness, and the IAPs on Fujian islands do not conform to the isolation effect in island biogeography. Landscape factors are the main determinants of IAPs and different life-form species richness, with area, shape index, and perimeter–area ratio being the three primary landscape factors. These environmental factors are closely related to habitat heterogeneity. Besides landscape factors, different life forms respond differently to environmental factors. Climate drives the species richness distribution of shrubs and herbs, while trees are mainly influenced by human activities. Overall, landscape, human disturbance, and climate jointly drive the distribution of IAPs, with landscape factors being the most significant. [ABSTRACT FROM AUTHOR]

Spatial and trophic processes profoundly influence biodiversity, yet ecological theories often treat them independently. The theory of island biogeography and related theories on metacommunities predict higher species richness with increasing area across islands or habitat patches. In contrast, food-web theory explores the effects of traits and network structure on coexistence within local communities. Exploring the mechanisms by which landscape configurations interact with food-web dynamics in shaping metacommunities is important for our understanding of biodiversity. Here, we use a meta-food-web model to explore the role of landscape configuration in determining species richness and show that when habitat patches are interconnected by dispersal, more species can persist on smaller islands than predicted by classical theory. When patch sizes are spatially aggregated, this effect flattens the slope of the species–area relationship. Surprisingly, when landscapes have random patch-size distributions, the slope of the species–area relationships can even flip and become negative. This could be explained by higher biomass densities of lower trophic levels that then support species occupying higher trophic levels, which only persist on small and well-connected patches. This highlights the importance of simultaneously considering landscape configuration and local food-web dynamics to understand drivers of species–area relationships in metacommunities. This article is part of the theme issue 'Diversity-dependence of dispersal: interspecific interactions determine spatial dynamics'. [ABSTRACT FROM AUTHOR]

Simple Summary: The main assumption of the so-called theory of island biogeography is that larger islands are home to more species than smaller ones. However, species richness on an island is affected not only by its size but also by other features, such as the island's distance from the mainland or its geological age. The two Canary Islands Tenerife and La Gomera are a good model for testing the relationship between species richness and island area, as they differ considerably in size (the former has an area 5.5 times that of the latter) but are similar in location and age. They lie close to each other (less than 30 km apart) in the central-western part of the archipelago, about 300 km from the African coast. Both were formed as a result of volcanic activity some 11.5–12 million years ago. We compared the species composition and species richness of ladybird beetles on these two islands based on our field surveys and the literature data. As expected, clearly more ladybird species have been recorded on Tenerife (47 species) than on La Gomera (26 species). Being the largest of the Canary Islands, Tenerife has the richest ladybird fauna of all the islands in the archipelago, but it is also more susceptible to colonization by non-native ladybirds than the other islands: to date, ten species of non-native ladybirds have been recorded on Tenerife, compared to between three and seven on the other islands (five on La Gomera). Among the non-native ladybirds established on Tenerife (but not on any other island in the archipelago) is the harlequin ladybird (Harmonia axyridis), a highly invasive species of Asiatic origin that has spread nearly worldwide. This paper provides new data on the ladybird beetles (Coccinellidae) from two islands in the Canary archipelago: Tenerife, the largest island, and La Gomera, the second smallest. As they clearly differ in size but are similar in location and geological age, they are a suitable model for testing the species–area relationship. Our study shows that, in line with this main assumption of the theory of island biogeography, clearly more species occur on a large island (Tenerife) than on a small one (La Gomera). The field surveys documented the occurrence of 35 ladybird species on Tenerife (including 5 not previously reported from this island) and of 20 species on La Gomera (2 species new to the island). Coelopterus sp. collected on Tenerife (a single female that could not be identified to species) is the first record of this genus for the whole Canary Islands. Taking our data and previously published records into account, 47 species of Coccinellidae are known to occur on Tenerife and 26 species on La Gomera. Tenerife has by far the richest ladybird fauna of all the Canary Islands (the next in line, Gran Canaria, has 41 recorded species), but it also has the highest number of non-native ladybird species. All of the ten non-native species recorded in the Canary Islands are found on Tenerife, and for most of them, Tenerife was the island of their first appearance in the archipelago. This island, much more distant from the mainland than the other relatively large islands (Fuerteventura, Lanzarote), appears to be the main recipient of ladybirds immigrating to the Canary Islands. Tenerife can play this role probably because of its great habitat diversity and altitude variation, as well as intensive tourism and trade-related transport. [ABSTRACT FROM AUTHOR]

Island species-area relationship (ISAR) is the most documented pattern in island biogeography. Different hypotheses were advanced to explain this pattern. In this study, I selected 27 remote Tuamotu atolls in the South Pacific Ocean with complete surveys of native species richness of birds and vascular plants to test the influence of four abiotic predictors on species richness (atoll emerged area, habitat diversity, mean elevation, and number of islets). Linear regressions were used to assess the relative influence of predictors on native species richness while stepwise regression was then used to identify the best model. Atoll area was a significant predictor to explain native bird and plant species richness, attesting ISAR on the remote surveyed atolls. Stepwise model demonstrated that both habitat diversity and atoll area explained bird species richness, whereas atoll area and mean elevation were the best predictors for native plants. These results suggest that ISAR can be related to different hypotheses, depending on the taxon studied. Among hypotheses, the simple "target-area" hypothesis was a suitable framework to explain ISAR of native birds, while the "disturbance" hypothesis was relevant to support ISAR of native plants observed on the atolls. [ABSTRACT FROM AUTHOR]

Biological invasions are among the threats to global biodiversity and social sustainability, especially on islands. Identifying the threshold of area at which non-native species begin to increase abruptly is crucial for early prevention strategies. The small-island effect (SIE) was proposed to quantify the nonlinear relationship between native species richness and area but has not yet been applied to non-native species and thus to predict the key breakpoints at which established non-native species start to increase rapidly. Based on an extensive global dataset, including 769 species of non-native birds, mammals, amphibians and reptiles established on 4277 islands across 54 archipelagos, we detected a high prevalence of SIEs across 66.7% of archipelagos. Approximately 50% of islands have reached the threshold area and thus may be undergoing a rapid increase in biological invasions. SIEs were more likely to occur in those archipelagos with more non-native species introduction events, more established historical non-native species, lower habitat diversity and larger archipelago area range. Our findings may have important implications not only for targeted surveillance of biological invasions on global islands but also for predicting the responses of both non-native and native species to ongoing habitat fragmentation under sustained land-use modification and climate change. [ABSTRACT FROM AUTHOR]

The equilibrium theory of island biogeography (ETIB) is a widely applied dynamic theory proposed in the 1960s to explain why islands have coherent differences in species richness. The development of the ETIB was temporarily challenged in the 1970s by the alternative static theory of ecological impoverishment (TEI). The TEI suggests that the number of species on an island is determined by its number of habitats or niches but, with no clear evidence relating species richness to the number of niches however, the TEI has been almost dismissed as a theory in favour of the original ETIB. Here, we show that the number of climatic niches on islands is an important predictor of the species richness of plants, herpetofauna and land birds. We therefore propose a model called the niche‐based theory of island biogeography (NTIB), based on the MacroEcological Theory on the Arrangement of Life (METAL), which successfully integrates the number of niches sensu Hutchinson into ETIB. To account for greater species turnover at the beginning of colonisation, we include higher initial extinction rates. When we test our NTIB for resident land birds in the Krakatau Islands, it reveals a good correspondence with observed species richness, immigration and extinction rates. Provided the environmental regime remains unchanged, we estimate that the current species richness at equilibrium is ~45 species (range between 38.39 and 61.51). Our NTIB provides better prediction because it counts for changes in species richness with latitude, which is not considered in any theory of island biogeography. [ABSTRACT FROM AUTHOR]

Aim: The equilibrium theory of island biogeography predicts the positive species–area relationship and the negative species–isolation relationship, resulting in higher species richness on large and close islands. Unlike species richness, soundscape diversity integrates sound from various sources (e.g. biophony, geophony and anthrophony). However, how soundscape diversity varies with island area and isolation still needs to be tested. Here, we explored the island biogeography of bird soundscapes and the determinants of island attributes in shaping bird diversity and soundscape diversity. Location: Thousand Island Lake, Zhejiang, China. Taxon: Birds. Methods: We recorded avian soundscapes by audio recorders and censused bird diversity by line transects on 20 land‐bridge islands. We calculated four acoustic indices (acoustic complexity index, bioacoustic index, acoustic evenness index and acoustic entropy index) to assess acoustic richness, evenness and heterogeneity to explore the soundscape diversity of birds. We used multiple linear regressions, spatial autoregressions and piecewise structural equation models to examine the relationships between bird richness and acoustic diversity, and island attributes. Results: We found positive diversity–area relationships for avian soundscapes. Larger islands had more vocal species and higher habitat diversity, which led to an increment in the richness and unevenness of avian soundscapes on large islands. Acoustic evenness decreased with increasing isolation (distance to the mainland). Main Conclusions: Soundscapes on large islands are more diverse than those on small islands. Rich acoustic assemblages and heterogeneous habitats promote increased soundscape diversity on islands. Conversely, the lack of vocal contributors, resulting in a decrement in the communication of acoustic signals, can create a lower soundscape diversity on small and remote islands. Our study emphasizes the necessity of examining both species and habitat diversity in island biogeography for better understanding the underlying mechanisms determining biological soundscapes on islands. [ABSTRACT FROM AUTHOR]

Aim: Biodiversity on islands is commonly explained by a set of natural drivers such as area, isolation and habitat heterogeneity. However, constant human impact has led to considerable changes in island floras worldwide. This is reflected, among others, in increased numbers of non‐native species. Barrier islands are discrete land units, strongly influenced by humans and not displaying significant evolutionary dynamics. This makes them highly suitable for studying contemporary patterns of species richness and underlying processes. We aim to disentangle the effects of established natural and anthropogenic drivers on native and non‐native plant species richness at the example of 31 European barrier islands. Location: 31 North Sea barrier islands located off the Dutch, German and Danish coast. Taxon: Native and non‐native plant species (spermatophytes and ferns). Methods: Individual relationships of natural and anthropogenic drivers with native and non‐native plant species richness are analysed with generalised linear models (GLMs). We use structural equation models (SEMs) to additionally account for interrelations between drivers. Results: Island area was the strongest predictor of native and non‐native plant species richness but affected richness mostly indirectly through habitat heterogeneity (non‐native species) and island inhabitants (native species). Isolation had a slight negative effect on native and non‐native plant species numbers on islands. Main Conclusions: The richness of native and non‐native plant species on islands is associated with different drivers, that is, habitat heterogeneity and island inhabitants respectively. This might be caused by distinct underlying processes forming native and non‐native richness patterns. Area was confirmed to be the most important driver of species richness but acting primarily through other natural and anthropogenic drivers of plant species richness. We encourage considering both natural and anthropogenic drivers and their interrelatedness to explain contemporary biogeographic patterns of species richness. [ABSTRACT FROM AUTHOR]

The island species–area relationship (ISAR) describes how species richness increases with increasing area of a given island or island‐like habitat, such as freshwater lakes. While the ISAR is one of the most common phenomena observed in ecology, there is variation in both the form of the relationship and its underlying mechanisms.We compiled a global data set of benthic macroinvertebrates from 524 shallow freshwater lakes, ranging from 1 to 293,300 ha in area. We used individual‐based rarefaction to determine the degree to which ISAR was influenced by mechanisms other than passive sampling (larger islands passively sample more individuals from the regional pool and, therefore, have more species than smaller islands), which would bias results away from expected relationships between rarefied species richness (and other measures that capture relative abundances) and lake area. We also examined how climate may alter the shape of the ISARs.We found that both rarefied species richness (the number of species standardized by area or number of individuals) and a measure of evenness emphasizing common species exhibit shallow slopes in relationships with lake area, suggesting that the expected ISARs in these lakes most likely result from passive sampling. While there was considerable variation among ISARs across the investigated lakes, we found an overall positive rarefied ISAR for lakes in warm (i.e. tropical/subtropical) regions (n = 195), and in contrast, an overall negative rarefied ISAR in cool (i.e. north temperate) lakes (n = 329). This suggested that mechanisms beyond passive sampling (e.g. colonization–extinction dynamics and/or heterogeneity) were more likely to operate in warm lakes. One possible reason for this difference is that the area‐dependent intensity of fish predation, which can lead to flatter ISARs, is weaker in warmer relative to cooler lakes.Our study illustrates the importance of understanding both the pattern and potential processes underlying the ISARs of freshwater lakes in different climatic regions. Furthermore, it provides a baseline for understanding how further changes to the ecosystem (i.e. in lake area or climate) might influence biodiversity patterns. [ABSTRACT FROM AUTHOR]

Understanding how the complexities of biodiversity are maintained on islands has long been one of the central issues studied in conservation biology. With the global onset of anthropogenically driven biodiversity changes, the influence of anthropogenic activities challenges the applicability of the widely accepted Equilibrium Theory of Island Biogeography (ETIB). This study aimed to test how island area, isolation (MD: distance to the mainland, and ND: distance to the nearest island), and human activities (habitat heterogeneity, and proportion of road area relative to island area to refer to the human impact on island) separately and jointly affect the species diversity of vascular plants. The number of plant species with different growth forms (woody plants, herbs, and lianas) was calculated on 35 islands in Sanyang Wetland, which is a human-dominated wetland near the highly populated city of Wenzhou, China. We also evaluated the relative importance of these variables on the number of species using a random forest analysis. The number of species increased with increasing island area and habitat heterogeneity and decreased with increasing isolation for different growth forms. A significant, positive relationship was observed between the number of species and the proportion of road area for herbs, but not for woody plants and lianas. Habitat heterogeneity was the most important predictor for all plants, the proportion of road area was the most important predictor for herbs, and MD was the most important predictor for woody plants and lianas. These results indicate that ETIB remains relevant in the context of human disturbance, but the relative importance of ecological processes on species diversity differs significantly among plant growth forms. Therefore, we should consider plant functional groups when testing multifactorial effects on species diversity on human-dominated islands. [ABSTRACT FROM AUTHOR]

Aim: Artificial island habitats such as human‐made wetlands are emerging novel ecosystems. Understanding the drivers of diversity in such artificial systems is essential for balancing the goals of biodiversity conservation and human socio‐economic needs. Location: Telangana state, India. Methods: We surveyed water birds in a network of 57 artificial wetlands and assessed four macroecological biodiversity patterns: spatial betadiversity, temporal betadiversity, species‐abundance distributions (SADs), and the species–area relationship (SAR). We employed a mix of phenomenological and mechanistic models to examine the four macroecological patterns. We hypothesized that the wetland bird communities are primarily structured by immigration–extinction dynamics and thus that spatial and temporal betadiversity would be high, the within‐wetland SADs would exhibit a large number of rare species and a monotonically declining overall shape, and that the SAR across wetlands would be strongly increasing. Results: Spatial and temporal betadiversity were both high and mostly attributable to turnover rather than nestedness. While the pooled SAD exhibited an interior mode, the SAD for individual wetlands was generally log‐series distributed, consistent with a model in which immigration among wetlands is high. The SAR exhibited an increasing trend, with the 'small‐island effect', which reflects constraints on immigration and is often observed for true island archipelagos, being absent. Main Conclusions: We tentatively conclude that bird diversity in this network of artificial wetlands is mainly structured by immigration–extinction dynamics, although we acknowledge that some of the patterns are also consistent with niche dynamics and future research should measure relevant biotic and abiotic variables in these wetlands. We encourage future work in which our rich dataset is used to fit dynamic models that permit more‐detailed quantitative inferences about mechanisms structuring diversity in this novel ecosystem, which can ultimately also inform conservation management. [ABSTRACT FROM AUTHOR]

Aim: The small‐island effect (SIE) and nestedness are two important patterns in the fields of island biogeography and community ecology. However, to date, no study has tried to integrate the SIE and nestedness pattern. Therefore, the aim of this study was to integrate these two biogeographical patterns by proposing a new integrative hypothesis. The integrative hypothesis posits that the degree of nestedness of the large island matrix will be larger than that of the small island matrix split by the threshold of the SIE. Location: Global. Taxon: Plants, invertebrates and vertebrates. Methods: We compiled 219 global datasets with both the presence‐absence matrices and the variables of area and species richness. We also collected six island characteristics influencing the SIE and nestedness patterns, that is island type, taxonomic group, area range, the number of islands, species range and matrix fill. We applied breakpoint regressions to detect SIEs and used the metric NODF (Nestedness metric based on Overlap and Decreasing Fill) to quantify nestedness. We then employed logistic regressions and an information‐theoretic approach to determine which combination of island characteristics was important in determining whether the integrative hypothesis was supported. Results: Among the 92 datasets in which SIEs were unambiguously detected, nestedness analyses showed that in 64 cases (69.6%) the values of NODFc (nestedness among sites) for the large island matrices were larger than those of the small island matrices. Matrix fill and area range were substantially important in determining whether the integrative hypothesis was supported. By contrast, island type, taxonomic group, the number of islands and species range received considerably less support. Main Conclusions: Our study was the first to integrate the SIE and nestedness pattern. Overall, we found prevalent support for our integrative hypothesis. The integration of the SIE and nestedness provides new and interesting insights into these two biogeographical patterns. [ABSTRACT FROM AUTHOR]

Enhancing understanding of community assembly rules hinges on shared conceptualizations that operate across scales and levels of ecological organization. Knowledge of the biogeography of life‐history strategies is especially limited but crucial for building fundamental information on the relationships between trait diversity and species richness.The goals of this study were to (i) demonstrate how life histories can be classified using a previously identified triangular continuum of evolutionary trade‐offs; (ii) test whether spatial and temporal heterogeneity in species abundances is linked to life‐history strategy; (iii) compare species‐area relationships across the primary life‐history strategist groups and (iv) explore how species life‐history niche spaces are shaped by ecosystem size and landscape architecture.Fish communities were sampled in 40 lakes that varied widely in volume; 11 lakes were sampled annually for 28 or 42 years. Seventy‐one species were classified as equilibrium, periodic or opportunistic strategists, and species‐area curves were quantified and compared among strategy types.As predicted by life‐history theory, relative abundances of opportunistic strategists were extremely variable over space and time, whereas abundances of equilibrium and periodic strategists were more stable. Small lakes were often dominated by only one species, usually an opportunistic strategist. Species richness increased with ecosystem size, but larger ecosystems were increasingly inhabited by equilibrium, and then, periodic strategists. Richness of periodic species increased with ecosystem size at a faster rate compared with opportunistic species showing that colonization‐extinction points fundamentally vary by strategy. Similarly, life‐history niche space increased with ecosystem size in accord with species‐area relationships but showed saturation behaviour. Niche space became increasingly crowded in large lakes, particularly in lakes with higher hydrologic connectance.Ecosystem size mediates the assembly of communities through effects on environmental stability, hydrology and life‐history filtering. This finding provides novel insights into community assembly at multiple scales and has broad conservation applications. Because ecosystem size filters towards orthogonal and inverse life histories, conservation actions (e.g. fish stockings) that do not consider life‐history and community filtering rules will probably fail. [ABSTRACT FROM AUTHOR]

Aim: (i) To determine whether area and connectivity of temporary ponds can predict plant species diversity, and the diversity and abundance of different plant life histories; (ii) To explore whether pond connectivity with the river prior to river regulation predicts better plant diversity patterns than current pond connectivity, suggestive of possible effects of connectivity loss. Location: Eastern Carpathian Mountains, Romania, Europe. Methods: We fitted linear and generalized linear models (LM and GLM) to examine whether pond area and current distance from the Olt River predict plant species richness, Shannon diversity and relative cover of different social behaviour types and overall plant species richness and Shannon diversity. Using historical maps, we measured pond distance from the river ca. 60 years before the Olt River was regulated, and we refitted the LM and GLM models using pond area and past distance from the river as independent variables. Results: Total plant species richness increased with pond area, and it decreased with the distance from the river, but total plant Shannon diversity index was affected, positively, only by pond area. The strength of responses to pond area and connectivity of species richness, Shannon diversity and relative cover varied across the different social behaviour types. Past and current distances between ponds and riverbeds had similar effects on plant diversity, with some evidence for stronger effect of the present connectivity on specialist species Shannon diversity and a weaker effect on disturbance tolerants, generalists and competitors. Main Conclusions: Pond area and connectivity with the landscape are important predictors of the diversity of plant life history strategies, and therefore, useful tools in pond conservation. Consistent species richness and Shannon diversity responses of wetland specialists to pond area and connectivity make this life history type well suited for monitoring pond condition. [ABSTRACT FROM AUTHOR]

Aim: The small‐island effect (SIE), as an exception to the species–area relationship, has received much attention in true island systems. However, the prevalence and related patterns of the SIE have not been well evaluated in habitat island systems. Here, we aimed to identify the existence of SIE for habitat islands in fragmented landscapes and determine the key factors influencing species richness on small habitat islands. Location: Inner Mongolia Autonomous Region, China. Taxon: Vascular plants. Methods: Based on 78 grassland fragments in fragmented landscapes of the agro‐pastoral ecotone of northern China, we used piecewise regression, path analysis and null models to investigate the SIE of the species–area relationship. We then used a multi‐model selection to evaluate the impacts of four influencing factors (instability, isolation, habitat heterogeneity and surrounding productivity) on species richness (including habitat specialists and generalists) on small habitat islands within the range of SIE. Results: We found an obvious threshold of 5.1 ha in the species–area relationship, below which habitat island area had no direct and indirect effects on species richness. Small habitat islands (<5.1 ha) host a lower percentage of habitat specialists and a higher percentage of generalists. On small habitat islands, species richness was positively affected by habitat heterogeneity while negatively affected by instability and isolation. Habitat heterogeneity had the strongest effect on species richness, positively affecting specialist richness while negatively affecting generalist richness. Main Conclusions: There is an SIE in fragmented landscapes of the agro‐pastoral ecotone of northern China, which should be considered in biodiversity conservation. Habitat heterogeneity had a key role in determining the pattern of species richness, especially for small islands. Habitat specialists and generalists had different SIE‐related patterns. Our study highlights the importance of considering different ecological groups of species to improve our understanding of the SIE in fragmented habitats. [ABSTRACT FROM AUTHOR]

Current models of island biogeography treat endemic and non‐endemic species as if they were functionally equivalent, focussing primarily on species richness. Thus, the functional composition of island biotas in relation to island biogeographical variables remains largely unknown. Using plant trait data (plant height, leaf area and flower length) for 895 native species in the Canary Islands, we related functional trait distinctiveness and climate rarity for endemic and non‐endemic species and island ages. Endemics showed a link to climatically rare conditions that is consistent with island geological change through time. However, functional trait distinctiveness did not differ between endemics and non‐endemics and remained constant with island age. Thus, there is no obvious link between trait distinctiveness and occupancy of rare climates, at least for the traits measured here, suggesting that treating endemic and non‐endemic species as functionally equivalent in island biogeography is not fundamentally wrong. [ABSTRACT FROM AUTHOR]

Island floras are diverse with exceptionally high rates of endemicity, and they are also severely threatened. Invasive plants are widespread on islands, but whether islands are particularly susceptible to invasion or island species are more vulnerable to displacement, or both, remains unclear. As part of the "island plant syndrome," it has been predicted that island plants have convergently evolved conservative resource use, slow growth rates, and weak competitive abilities in response to moderate climates and the presumed absence of competition in communities with relatively low species richness. Yet, functional trait approaches have provided mixed evidence to support this prediction, and direct tests of competition as neighbour effects on plant performance are lacking. Considering the extensive environmental heterogeneity that exists within islands and among islands, it seems more likely that diverse functional strategies, spanning conservative to acquisitive, have evolved in island plants. Furthermore, assessing island plant syndrome predictions through comparisons with invasive species, which are nonrandom subsets of continental plants, is a flawed approach. Future studies that compare functional strategies of native island versus native continental plants and direct tests for competition between native and invasive island plants within the local scale at which competition occurs, and that consider non‐additivities with other simultaneous global threats, are urgently needed to conserve these biodiversity hotspots. [ABSTRACT FROM AUTHOR]

Aim: In the half‐century since publication of the Theory of Island Biology, ecologists have come to recognize the importance of predation as a decisive determinant of alternate states in many ecosystems. Island species are notorious for their vulnerability to introduced predators, yet the strength of island predator regimes has not been fully incorporated into our understanding of the forces that structure island consumer communities. Location: The Greater and Lesser Antilles. Taxon: Birds and Anolis lizards. Methods: Field surveys of sclerophyll and rainforest sites on islands ranging in size from 3.5 km2 Terre‐de‐Haut to 76,000 km2 Hispaniola. Results: Evidence gathered in the 1970s and 1980s shows that Antillean anoles live at higher densities on fewer resources, grow more slowly, reproduce later and live longer than mainland counterparts in conformity with the 'island syndrome'. Data from this period show that Antillean bird communities display density overcompensation, community saturation, size‐structured foraging guilds, low species diversity and low species packing, all traits consistent with the island syndrome and a regime of low predation and intense competition. Mainland species and communities display none of these features. Main conclusions: I propose that the island syndrome is an alternative state that distinguishes low‐predation island communities from high‐predation mainland counterparts. It follows that strong mainland predation regimes tend to prevent island species from colonizing. Conversely, invasion‐resistant, size‐structured island communities, despite low species diversity, prevent mainland species from colonizing islands. These predictions are experimentally testable with Anolis lizards and, if confirmed, could set island biogeography on a new course. [ABSTRACT FROM AUTHOR]

The beetle fauna of the California Channel Islands is here enumerated for the first time in over 120 years. We provide an annotated checklist documenting species-byisland diversity from an exhaustive literature review and analysis of a compiled dataset of 26,609 digitized specimen records to which were added over 3,000 individual specimen determinations. We report 825 unique species from 514 genera and 71 families (including 17 new family records) comprising 1,829 species-by-island records. Species totals for each island are as follows: Anacapa (74); San Clemente (197); San Miguel (138); San Nicolas (146); Santa Barbara (64); Santa Catalina (370); Santa Cruz (503); and Santa Rosa (337). This represents the largest list of species published to date for any taxonomic group of animals on the Channel Islands; despite this, we consider the checklist to be preliminary. We present evidence that both inventory and taxonomic efforts on Channel Islands beetles are far from complete. Rarefaction estimates indicate there are at least several hundred more species of beetles yet to be recorded from the islands. Despite the incomplete nature of existing records, we found that species diversity is highly correlated with island area. We report 56 species which are putatively geographically restricted (endemic) to the Channel Islands, with two additional species of questionable endemic status. We also report 52 species from the islands which do not natively occur in the southern California region. [ABSTRACT FROM AUTHOR]

The Equilibrium Theory of Island Biogeography postulates that larger and closer islands support higher biodiversity through the dynamic balance of colonization and extinction processes. The negative diversity–isolation (i.e. the distance to the mainland) relationship is derived based on the assumption that the mainland is the only source pool for island biotas. However, nearby islands could also act as species sources for focal islands via a source effect. In this study, we move a further step and hypothesize that nearby islands may reduce bird colonizers of the focal island and diminish its biodiversity, resulting in a negative target effect.To test our hypothesis, we assessed the effects of island area and isolation (metrics considering both the mainland and nearby islands) on taxonomic (i.e. species richness), functional and phylogenetic diversity of terrestrial breeding birds on 42 islands in the largest archipelago of China, the Zhoushan Archipelago. Furthermore, we compared the predictive power of the distance to the large island under a set of relative area thresholds and the relative area of nearby islands on species richness under a set of distance thresholds to explore the role of nearby islands as a source and/or target island.We found that island area had a positive effect on species richness, phylogenetic diversity and functional diversity, while the distance to the mainland had a negative effect only on species richness. Species richness on the focal island increased with increasing distance to the nearest larger island, indicating the negative target effect. Furthermore, the negative target effect depended on the area of nearby islands relative to the area of the focal island.Our finding of the negative target effect suggests islands located between the mainland and the focal island can be not only sources or stepping stones, but also colonization targets. This result demonstrates the importance of considering multiple geographical attributes of islands in island biogeographic studies, especially the characteristics related to source and/or target effects. [ABSTRACT FROM AUTHOR]

Aim: Island biogeography theory states that species richness increases with habitat diversity and decreases with isolation from source pools. However, ecological theory must incorporate effects of human activity to explain contemporary patterns of biodiversity. We contemporized island biogeography theory by conceptualizing island trajectories of how species richness changes over time with accelerating land development and economic trade, which increase extinction and immigration rates, respectively. With this contemporized theory, we then articulate and empirically assess expected relationships of native, introduced and total species richness with natural and anthropogenic metrics of habitat diversity and isolation from source pools. Location: Greater Caribbean region. Time period: Database finalized in 2020. Methods: We built a database of 1,042 native and introduced reptiles and amphibians (herps) for 840 Caribbean islands. For each island, we calculated natural and anthropogenic metrics of island habitat diversity and isolation from source pools and used linear model averaging to assess the expected relationships under the contemporized theory for 15 major herp clades. Results: Natural habitat diversity metrics exhibited positive relationships with native and introduced species richness, strengthening total species richness–area relationships across herp clades. Geographic isolation exhibited negative relationships with native and positive relationships with introduced species richness, weakening total species richness–isolation relationships. Economic area, based on developed land, and economic isolation, based on maritime trade, exhibited negative relationships with native species richness, but positive and negative relationships, respectively, with introduced species richness. Total species richness relationships with these two anthropogenic metrics were strongest in clades with many introduced species. Main conclusions: A contemporized island biogeography theory that includes the effects of land development and economic trade on species extinction and immigration explained current Caribbean herp species richness patterns. As human activity continues to accelerate, the contemporized theory we articulate here will increasingly predict island biogeography of the Anthropocene. [ABSTRACT FROM AUTHOR]

Aim: Many plants rely on interactions with frugivores for dispersal, suggesting that animal communities may affect plant occupancy and diversity. However, the contribution of these interaction‐led biotic variables on plant diversity is poorly understood, especially in archipelagic hotspots such as the Caribbean. In island ecosystems, biogeographic theories suggest that island configurations drive colonization‐extinction dynamics, while macroecology argues for the importance of climatic drivers of biodiversity. Within this context, we examine how frugivore‐driven biotic factors are associated with fruiting plant species richness in relation to abiotic (climatic and geologic) and island configuration characteristics. Location: Caribbean archipelagos. Methods: We compiled a review of the diversity and distributions of 6039 plants and 326 vertebrate frugivores across 105 islands within the Caribbean. We then identified characteristics related to plant‐frugivore interactions and assigned each species as having either abiotic (wind, water, etc.) or zoochoric (frugivory‐dependent) dispersal syndromes. We related plant richness and dispersal syndromes to the regional diversity and characteristics of frugivorous animals, abiotic environments and island configuration characteristics through stepwise multivariate regression with generalized linear models and model selection. Results: We found that 44.6% of Caribbean plants are dispersed through frugivory (endozoochory). Frugivore‐related characteristics, namely accumulated body mass of island bird assemblages, were the best predictors of the diversity of seed dispersal syndromes. To a lesser degree, reptile richness and soil variety were also considered important predictors for zoochoric plant distribution, while island areas affected abiotically‐dispersed plants. Main conclusion: We found that biotic characteristics of frugivore communities are important predictors of plant diversity in the Caribbean archipelagos. However, this may also be influenced by climate and colonization history. Given the importance of biotic metrics in explaining plant diversity, we suggest that fruit‐frugivore interactions are important components of island biogeography and that frugivorous communities should be accounted for plant biodiversity predictions and forecast models. [ABSTRACT FROM AUTHOR]

Aim: The species–area relationship (SAR) is one of the most distinctive biogeographic patterns, but global comparisons of the SARs between island and mainland are lacking for microbial taxa. Here, we explore whether the form of the SAR and the drivers of species richness, including area, environmental heterogeneity, climate and physico‐chemistry, differ between islands and similarly sized areas on mainland, referred to as continental area equivalents (CAEs). Location: Global. Taxon: Stream benthic diatoms. Methods: We generated CAEs on six continental datasets and examined the SARs of CAEs and islands (ISAR). Then, we compared CAEs and islands in terms of total richness and richness of different ecological guilds. We tested the factors contributing to richness in islands and CAEs with regressions. We used structural equation models to determine the effects of area versus environmental heterogeneity, climate and local conditions on species richness. Results: We found a non‐significant ISAR, but a significant positive SAR in CAEs. Richness in islands was related to productivity. Richness in CAEs was mainly dependent on area and climate, but not directly on environmental heterogeneity. Species richness within guilds exhibited inconsistent relationships with island isolation and area. Main conclusions: Ecological and evolutionary processes shaping diatom island biogeography do not depend on area at the worldwide scale probably due to the presence of distinct species pool across islands. Conversely, area was an important driver of diatom richness in continents, and this effect could be attributed to dispersal. Continents had greater richness than islands, but this was a consequence of differences in environmental conditions such as specific island climatic conditions. We stress the need for more island data on benthic diatoms, particularly from archipelagos, to better understand the biogeography of this most speciose group of algae. [ABSTRACT FROM AUTHOR]

The passive sampling hypothesis is one of the most important hypotheses used to explain the mechanism of species–area relationships (SAR) formation. This hypothesis has not yet been experimentally validated due to the confusion between passive sampling (a larger area may support more colonists when fully sampled) and sampling effects (more sampling effort will result in increased species richness when sampling is partial). In this study, we created an open microcosm system with homogeneous habitat, consistent total resources, and biodiversity background using Chinese paocai soup, a fermented vegetable, as a substrate. We made efforts to entirely exclude the influence of sampling effects and to exclusively obtain microorganisms from dispersal using microcosm and high‐throughput sequencing techniques. However, in this study, passive sampling based on dispersal failed to shape SAR, and community differences were predominantly caused by species replacement, with only minor contributions from richness differences. Ecological processes including extinction and competitive exclusion, as well as underlying factors like temporal scales and the small island effects, are very likely to have been involved in the studied system. To elucidate the mechanism of SAR development, future studies should design experiments to validate the involvement of dispersal independently. [ABSTRACT FROM AUTHOR]

The theory of island biogeography predicts that island size is a key predictor of community species richness. Islands can include any habitat surrounded environments that are inhospitable to the resident species. In arid environments, nurse trees act as islands in an environment uninhabitable to many plant species, and the size of the canopy controls the size of the understory plant community. We predicted that plant species richness will be affected by the area of the habitat and decrease with habitat isolation. We sampled the adult and seedling plant communities at canopy center, canopy edge, and outside canopy microhabitats. We found that species richness in both adult and seedling communities increases with increasing island area. However, richness in seedling communities was greater than in adult communities, and this effect was greatest at the canopy center microhabitat. Competition has been demonstrated to be more important in controlling species distributions near the canopy center, and stress is more important near the canopy edge. Thus, our results suggest that neutral forces, biotic interactions, and abiotic filtering act together to control species richness in these island communities. [ABSTRACT FROM AUTHOR]

Geographic isolation is a central mechanism of speciation, but perfect isolation of populations is rare. Although speciation can be hindered if gene flow is large, intermediate levels of migration can enhance speciation by introducing genetic novelty in the semi‐isolated populations or founding small communities of migrants. Here, we consider a two‐island neutral model of speciation with continuous migration and study diversity patterns as a function of the migration probability, population size, and number of genes involved in reproductive isolation (dubbed as genome size). For small genomes, low levels of migration induce speciation on the islands that otherwise would not occur. Diversity, however, drops sharply to a single species inhabiting both islands as the migration probability increases. For large genomes, sympatric speciation occurs even when the islands are strictly isolated. Then species richness per island increases with the probability of migration, but the total number of species decreases as they become cosmopolitan. For each genome size, there is an optimal migration intensity for each population size that maximizes the number of species. We discuss the observed modes of speciation induced by migration and how they increase species richness in the insular system while promoting asymmetry between the islands and hindering endemism. [ABSTRACT FROM AUTHOR]

According to the MacArthur-Wilson model of Island Biogeography, the species richness on a given island should be a function of the size of the island and its distance from the mainland. Following this, one might therefore expect that the likelihood that a small songbird species would nest on a given island in a large freshwater lake would similarly be a function of island size and distance to the mainland. We tested this by installing a single nest box on each of 37 islands in Lake Norman, North Carolina, in the fall of 2019. We hypothesized that Carolina Chickadees (Poecile carolinensis) would be more likely to nest in boxes on islands that are large and/or close to the mainland. Combining our results from 2020 and 2021, we found that neither island size, distance to the mainland, nor an interaction between the two explained the presence of breeding chickadees on islands. De acuerdo con el modelo de biogeografía de islas de MacArthur y Wilson, la riqueza de especies en una isla dada debería ser función del tamaño de la isla y su distancia a tierra firme. Siguiendo esto, uno podría esperar de manera similar que la probabilidad de que una especie pequeña de ave canora anide en una isla dada en un gran lago de agua dulce sería una función del tamaño de la isla y su distancia a tierra firme. Sometimos esta premisa a prueba, instalando una única caja-nido en cada una de 37 islas del lago Norman en North Carolina en el otoño de 2019. Hipotetizamos que los carboneros Poecile carolinensis serían más proclives a anidar en cajas-nido en islas que son grandes y/o cercanas a tierra firme. Combinando nuestros resultados de 2020 y 2021, encontramos que ni el tamaño de la isla, la distancia a tierra firme o la interacción de las 2 explicó la presencia de carboneros anidando en islas. Palabras clave: biogeografía de islas, cajas-nido, MacArthur y Wilson. [ABSTRACT FROM AUTHOR]

Although species richness can be determined by different mechanisms at different spatial scales, the role of scale in the effects of marine inputs on island biogeography has not been studied explicitly. Here, we evaluated the potential influence of island characteristics and marine inputs (seaweed wrack biomass and marine‐derived nitrogen in the soil) on plant species richness at both a local (plot) and regional (island) scale on 92 islands in British Columbia, Canada. We found that the effects of subsidies on species richness depend strongly on spatial scale. Despite detecting no effects of marine subsidies at the island scale, we found that as plot level subsidies increased, species richness decreased; plots with more marine‐derived nitrogen in the soil hosted fewer plant species. We found no effect of seaweed wrack at either scale. To identify potential mechanisms underlying the decrease in diversity, we fit a spatially explicit joint species distribution model to evaluate species level responses to marine subsidies and effects of biotic interactions among species. We found mixed evidence for competition for both light and nutrients, and cannot rule out an alternative mechanism; the observed decrease in species richness may be due to disturbances associated with animal‐mediated nutrient deposits, particularly those from North American river otters (Lontra canadensis). By evaluating the scale‐dependent effects of marine subsidies on island biogeographic patterns of plants and revealing likely mechanisms that act on community composition, we provide novel insights on the scale dependence of a fundamental ecological theory, and on the rarely examined links between marine and terrestrial ecosystems often bridged by animal vectors. [ABSTRACT FROM AUTHOR]

The presence of migratory birds on islands results in seasonal variation in species richness. These patterns and their geographical correlates within the context of island biogeography theory have not been examined. We used 21 years of bird observations on 690 islands from eBird to determine how seasonal species richness estimates vary as a function of island area, isolation and latitude. Species richness was highest on islands within the northern mid-latitudes during migration and on islands within tropical latitudes during the non-breeding season. Area defined positive, nonlinear relationships with species richness across seasons, with the steepest slopes occurring with islands greater than 1100 km2. Distance to mainland defined negative, nonlinear relationships with species richness across seasons, with the strongest slopes occurring with islands located greater than 150 km from the mainland. Species–area relationships were weakest for the most remote islands and strongest for islands at intermediate distances to the mainland. Intermediate proximity to other islands was a poor predictor of species richness. Our findings emphasize the presence of seasonally dynamic geographical relationships, the enhanced role of evolutionary processes on larger islands, the unique ecology of the world's most remote islands, and the importance of islands as stopover sites and wintering grounds for migratory bird species. [ABSTRACT FROM AUTHOR]

The influence of island dynamics and characteristics on taxonomic diversity, particularly species richness, are well studied. Yet, our knowledge on the influence of island dynamics and characteristics on other facets of diversity, namely functional and phylogenetic diversity, is limited, constraining our understanding of assembly processes on islands (e.g. biogeographic history, dispersal and environmental filtering and species interactions). Using barrier islands, a highly dynamic and so far, understudied island type, we investigate how multiple facets of vascular plant diversity (functional, phylogenetic and taxonomic diversity) are shaped by island geomorphology, modern and historic area, and habitat heterogeneity. In line with our expectation, historical dynamics in island geomorphology affected phylogenetic and taxonomic diversity via habitat heterogeneity. However, island area was the best predictor across all facets of diversity. Specifically, larger islands had higher functional and phylogenetic diversity than expected by chance while most of the smaller islands had lower diversity. The influence of area on functional diversity acted via habitat heterogeneity, with habitat heterogeneity influencing negatively functional diversity. Our results suggest that larger islands accumulate functionally and phylogenetically unique species. Further, results for functional diversity pointed towards potential area–heterogeneity trade‐offs, with these trade‐offs likely resulting from increased interspecific competition favoring a specific set of trait values (of stronger competitors), particularly on smaller islands. Together, these results demonstrate that going beyond taxonomic diversity contributes to identifying underlying processes shaping diversity–area relationships. [ABSTRACT FROM AUTHOR]

Understanding the effects of island shape and dispersal limitation on species assemblages is important for the conservation of bryophytes in fragmented landscapes. In order to explore the comparative contributions of dispersal limitation vs environmental filtering, island shape vs other island attributes to bryophyte species assemblages in fragmented landscapes, we investigated bryophyte flora and environmental variables (island shape, area, elevation, and isolation degree) of 71 islands in the Zhoushan Archipelago in the East China Sea. We used redundancy analysis, canonical correspondence analysis and generalized linear mixed models to explore comparative contributions of dispersal limitation vs environmental filtering, shape vs other explanatory variables to bryophyte species composition and species richness. Dispersal limitation independently accounted for 15% of the total variation in species composition, which was higher than environmental filtering (6.6%). When island shape was the only constraining explanatory variable, it explained 22.5% of the total species richness variation. Variance partitioning showed that island shape per se explained 3.8% of the total variation in species richness and 18.7% of the variation was confounded by island shape and other variables. Island shape combined with area and elevation was a good predictor of bryophyte species richness, independently explaining 40% of the total SR variation. Among twenty tested bryophyte categories, eighteen categories had positive relationships of their species richness with island shape irregularity, their species richness linearly increasing with island shape irregularity to varying extents. Island shape irregularity exerted a stronger effect on the species richness of acrocarpous mosses than that of pleurocarpous mosses. Therefore, dispersal limitation exerted significant effects on bryophyte species assemblages, and island shape imposed a significant and taxon-specific effect on bryophyte species richness. Our findings implied that a forest reserve with a high irregular shape is favourable for bryophyte conservation. [ABSTRACT FROM AUTHOR]

Cereus insularis (Cereeae, Cactaceae) is an insular endemic and dominant element of the vegetation of Fernando de Noronha Islands (FNI), a Neotropical archipelago 350 km from mainland Brazil. Here, we estimate the levels of genetic diversity for C. insularis and investigate its genetic relationship with the closely allied C. fernambucensis , which is widespread along the Brazilian coast. We genotyped and analysed 112 individuals for ten nuclear microsatellite markers to understand genetic connectivity between insular and mainland populations. The levels of genetic diversity for this species indicate an absence of genetic erosion. Furthermore, the expected heterozygosity in C. insularis is consistent with a long-term colonization process of FNI. We identify signatures of recent and bilateral gene flow among mainland and insular populations. We explain our results taking into consideration the biogeographic hypothesis to explain the peripatric origin of C. insularis. Overall, this is a case study suggesting that the generalizations of genetic conservation principles in oceanic islands, such as low levels of genetic diversity, are not always the case. Rather than challenge these principles, we stress that island dynamism throughout time should be an important factor in explaining levels of genetic diversity in insular species. [ABSTRACT FROM AUTHOR]

Area and environmental heterogeneity influence species richness in islands. Whether area or environmental heterogeneity is more relevant in determining species richness is a central issue in island biogeography. Several models have been proposed, addressing the issue, and they can be reconducted to three main hypotheses developed to explain the species-area relationship: (1) the area-per se hypothesis (known also as the extinction-colonisation equilibrium), (2) the random placement (passive sampling), and the (3) environmental heterogeneity (habitat diversity). In this paper, considering also the possible influence of geographic distance on island species richness, we explore the correlation between area, environmental heterogeneity, and species richness by using faunistic data of Oniscidea inhabiting the Pontine Islands, a group of five small volcanic islands and several islets in the Tyrrhenian Sea, located about 60 km from the Italian mainland. We found that the colonisation of large Pontine Islands may occur via processes independent of geographic distance which could instead be an important factor at a much smaller scale. Such processes may be driven by a combination of anthropogenic influences and natural events. Even in very small-size island systems, environmental heterogeneity mostly contributes to species richness. Environmental heterogeneity could influence the taxocenosis structure and, ultimately, the number of species of Oniscidea via direct and indirect effects, these last mediated by area which may or may not have a direct effect on species richness. [ABSTRACT FROM AUTHOR]

The Hawaiian Islands have long been seen as relatively devoid of native toxic plant species, a result of the paucity of herbivorous predators in this biogeographically isolated archipelago. This assertion has been subjective, without quantitative comparison to floras that evolved in the presence of such predators. We test this assertion by comparing the richness of toxic species in the native flora of the main Hawaiian Islands to that in the naturalized flora of these islands. That test shows the assertion to be correct: the relative abundance of toxic plant species in the naturalized Hawaiian flora is nearly ten times greater than the relative abundance of those species in the Hawaiian native flora. Of the approximately 150 toxic plant species now found in these islands, 92% are naturalized. The species richness of both native and naturalized Hawaiian plant species correlates positively with island size, as does the richness of toxic native and toxic naturalized plant species. These results, and the lack of significant residuals in species–area relationships across the main Hawaiian Islands, suggest that the relative youth of Hawai'i Island is not needed to account for native plant species richness on this island. [ABSTRACT FROM AUTHOR]

Aim: The accumulation of functional diversity in communities is poorly understood. Conveniently, the general dynamic model of island biogeography (GDM) makes predictions for how such diversity might accumulate over time. In this multiscale study of land snail communities on 10 oceanic archipelagos located in various regions of the globe, we test hypotheses of community assembly in systems where islands serve as chronosequences along island ontogeny. Location: Ten volcanic archipelagos. Time period: From 23 Ma to the present. Major taxa studied: Endemic land snails. Methods: Initially, we assembled geological island characteristics of area, isolation and ontogeny for all studied islands. We then characterized island‐scale biotic variables, including the species diversity and functional diversity of snail communities. From these data, we assessed relationships between island and snail community variables as predicted by the GDM, focusing initially on the islands of the Galápagos archipelago and thereafter with a broader analysis of 10 archipelagoes. Results: As in other studies of island assemblages, in Galápagos we find a hump‐shaped curve of species richness, with depauperate snail faunas on early‐ontogeny islands, increasing species richness on mid‐ontogeny islands and low species richness on islands in late ontogeny. We find exceptionally low functional diversity on early‐ontogeny islands that increases through mid‐ontogeny, whereas late‐ontogeny islands exhibit a range of functional diversity. The analysis including all 10 archipelagos indicates a major role of archipelago‐specific factors. In both sets of analyses, functional diversity is exceptionally low on early‐ontogeny islands, and island ontogeny is a significant predictor of morphology. Main conclusions: Consistent patterns of functional diversity across island ontogeny on all examined archipelagos indicate a common role for habitat filtering, ecological opportunity and competition in a diversity of systems, leading to predictable changes in functional diversity and average morphology through island ontogeny, whereas patterns of species richness appear subject to archipelago‐specific factors. [ABSTRACT FROM AUTHOR]

Aim: Research in island biogeography has long focused mainly on present‐day island configurations. Recently, there has been an increasing focus on islands' past histories of land connection, shape and size. Moreover, continental islands (=shelf islands) have received less attention than oceanic islands, and species inventories from extremely small islands are lacking in many datasets. We examine the effects of sea‐level rise since the Last Glacial Maximum (LGM) on bird species diversity and composition of tropical shelf islands in Southeast Asia. Location: Sundaland. Taxon: Birds. Methods: We compiled avifaunal island inventories for 94 islands using an exhaustive literature review of historic surveys of larger islands combined with our own comprehensive island surveys from both small and large islands. Using generalised least‐squares models with spatial autocorrelation, we assessed the importance of traditional biogeographical parameters including area, maximum elevation, distance from mainland and geographical isolation, along with post‐LGM effects of change in island area and duration since isolation. We also compared the species composition on similar‐sized shelf islands from two categories—recently submerged and unsubmerged—using non‐metric multidimensional scaling. Results: Post‐LGM effects on species diversity are minimal and insular diversity is instead well explained by present‐day island characteristics, such as area, distance to mainland and proportion of land surrounding an island within a 10 km radius (Cox and Snell Pseudo‐R2 = 0.803). Avifaunal diversity is similar across recently submerged and unsubmerged small shelf islands. Main conclusion: Avifaunal diversity on tropical shelf islands equilibrates rapidly after isolation, indicating that both extinction and immigration rates are high. In particular, a high immigration rate of dispersive species maintains diversity, especially on small islands. Over‐water dispersal is generally restricted to short distances among Sundaic birds. Consequently, the diversity of an island can be maintained by the presence of large or stepping‐stone islands near it. [ABSTRACT FROM AUTHOR]

Few studies that apply the theory of island biogeography have considered the functional and phylogenetic dimensions of diversity. However, the joint use of the three diversity dimensions, i.e. taxonomic, functional and phylogenetic, can help us to gain a better understanding of the mechanisms underlying ecological and evolutionary processes. Here, we compare phyllostomid bat assemblages between five land-bridge islands off the south-east coast of Brazil and compare these islands with three sites on the mainland. For this, we have estimated the three dimensions of α- and β-diversity, nestedness and community indexes based on mean trait values for the islands and the mainland. The mainland showed higher species richness and taxonomic, functional and phylogenetic diversity. In addition, only species richness and phylogenetic diversity were positively related to island area. Taxonomically and functionally, the poorest assemblages (minor islands) were subgroups of the richer assemblages (mainland and larger islands). Taken together, our results show that bat assemblages of smaller islands tend to be more sensitive to changes in species richness than those of larger islands, with the larger islands working as a 'source' of species for small islands. These results demonstrate the high conservation value of the larger islands, which has direct consequences for local population dynamics of phyllostomid bats. [ABSTRACT FROM AUTHOR]

Aims: Aeolian islands form an active volcanic archipelago. By using updated vascular plant checklists for islands and islets, we tested four hypotheses: (i) Island species–area relationship (ISAR) of alien species has lower c‐ and higher z‐values than native species, (ii) islands with active volcanoes have lower species richness than expected for native and alien species, (iii) ISAR of native species shows lower c‐ and higher z‐values than ISARs of Mediterranean land bridge archipelagos and (iv) species richness of smaller islets is independent of area. Location: Aeolian Archipelago, Mediterranean Basin. Taxon: Vascular plants, identified and named according to the Flora of Italy (Pignatti et al., 2017–2019). Methods: Checklists of native and alien plant species were obtained for eight islands and 24 islets. ISARs were fitted by the Arrhenius power function (S=c·Az) and used to test the first two hypotheses. The third hypothesis was tested by comparing ISAR of Aeolian Archipelago to those from other central and eastern Mediterranean archipelagos. The fourth hypothesis was tested by fitting models defining the presence and limit of the small‐island effect. Results: The checklists included 894 species—749 native and 145 alien. ISARs fitted well for native and alien species and resulted in typical values of c and z parameters. The first and second hypotheses were supported by model fitting. The third hypothesis was not confirmed by the comparison of the ISAR of the Aeolian Archipelago with other archipelagos. The small‐island effect predicted by the fourth hypothesis was supported using S versus LogA for both native and alien species, while for native species it was supported also using the log transformation of the Arrhenius model. Main conclusions: We reported a first comprehensive analysis of plant species richness in the unique Aeolian Archipelago, verifying typical ISARs, no peculiarity with respect to land bridge archipelagos and a somewhat unclear signal for the small‐island effect. [ABSTRACT FROM AUTHOR]

Aim: Accounting for geo‐environmental dynamics is crucial to understand community assembly across islands. Whittaker et al. (J Biogeogr, 35:977–994, 2008)'s General Dynamic Model (GDM) aims towards this goal. Yet, it does not explicitly consider that most islands belong to archipelagos. We examined how island biodiversity dynamics are influenced by the interaction of eco‐evolutionary processes acting at the archipelago level with each island's geo‐environmental dynamics. Location: Hypothetical archipelagos. Taxon: Any. Methods: We used an individual‐based model, ecologically neutral within the archipelago. Several islands emerge in succession with a typical volcanic ontogeny. We considered both mainland and inter‐island dispersal. Geographically isolated lineages diverged over time, possibly speciating. Results: We found diversity to be at dynamic equilibrium. In an archipelago, islands hosted more diversity and more endemic species, at both island and archipelago levels, than an equivalently‐sized single isolated island. This was due to an 'archipelago effect': inter‐island dispersal increased within‐island diversity through species occurrence on multiple islands; species may undergo anagenetic changes on the colonised islands, eventually speciating, thereby increasing archipelago diversity. Biodiversity dynamics of different islands may differ even on islands with identical geo‐environmental dynamics because the archipelago effect varied over time and affected each island differently ('history effect'). By accounting for these effects, we predicted detectable deviations from the GDM predictions, which are largest for remote archipelagos, with islands located close together and with an intermediate time of island emergence. In linear stepping‐stone archipelagos, we predicted higher diversity on centrally located islands. Main conclusions: Our results demonstrate that analyses of insular biodiversity data would greatly benefit from explicitly accounting for both archipelago and history effects. We suggest incorporating variables characterising the spatio‐temporal structure of the whole archipelago. We discuss possible difficulties in distinguishing between the archipelago effect and equilibrium diversity dynamics. [ABSTRACT FROM AUTHOR]

Aim: The accumulation of species through time has been proposed to have a hump‐shaped relationship on volcanic islands (highest species richness during intermediate stages of an island's lifespan). Change in topographic complexity (TC) of islands over time is assumed to follow the same relationship. However, TC can be measured in different ways and may not have the same impact across taxonomic groups. Here, we quantify TC across the Galápagos Islands and test the assumption that TC follows a predictable trajectory with island age. Subsequently, we ask whether including TC improves statistical models seeking to explain variation in species richness across islands. Location: Galápagos Archipelago, Ecuador. Taxon: Native and endemic terrestrial animals and plants. Methods: For each island, we generated eight TC indices from a 30‐m resolution digital elevation model. We tested for a relationship between each index and island age, and whether it significantly contributes to observed variation in species richness, using 11 different models for 12 taxonomic groups across the Galápagos Islands. Results: Four TC indices were significantly negatively correlated with either island age or ontogenetic age and only one index followed the hump‐shaped relationship with age. No index consistently contributed to the variation in species richness for all taxonomic groups. However, for all 12 taxonomic groups, incorporating at least one TC index in modelling species richness improved one or more models. The most common TC index improving models was standard deviation of slope, although each index improved at least five models across all taxa. Different factors predicted taxon‐specific richness, and habitat diversity was significant for all taxa. Main conclusions: Topographic complexity is an important component influencing species richness, but its impact likely differs among taxonomic groups and different scales. Therefore, future studies should incorporate broad, multi‐dimensional measures of TC to understand the biological importance of TC. [ABSTRACT FROM AUTHOR]

Aim: Islands have been the test bed of several theories in community ecology, biogeography, and evolutionary biology. Progress within these disciplines has given a more comprehensive and mechanistic understanding of the processes governing variation in species richness among islands. However, it remains unclear whether these same processes also explain variation in species and phylogenetic composition among islands. Integrating theory from ecology and biogeography, we infer the roles of dispersal, selection, and stochasticity on the composition of insular assemblages within archipelagos. We further assess the influence of source pool diversity and connectivity on the compositional uniqueness of insular assemblages. Location: Island systems worldwide. Taxon: Mammals. Methods: We compiled data on species composition of nonvolant mammals on ~200 islands in nine archipelagos distributed worldwide from the literature. We used variation partitioning to quantify the relative influence of the environment (selection) and geographic distance (dispersal) relative to a null model (stochasticity, randomness) on taxonomic and phylogenetic compositional turnover within archipelagos. We then used a linear mixed model to gain further insight into the underlying mechanisms shaping variation in assemblage composition among islands at a global scale. Specifically, we assessed the influence of source pool diversity, isolation from the source pool, and island characteristics on compositional uniqueness. Results: Our results suggest that within‐archipelago variation in the composition of insular mammal assemblages is associated with stochastic or unmeasured processes rather than abiotic selection or dispersal limitation. The diversity and proximity of the source pool, as well as some island characteristics, explained variation in phylogenetic, but not taxonomic, compositional uniqueness globally. Globally, isolated islands associated with phylogenetically diverse source pools exhibit high phylogenetic uniqueness whereas well‐connected islands associated with phylogenetically clustered source pools show the opposite trend. Phylogenetically unique assemblages also tend occur on islands with a small elevational span and low annual temperature variation. Main conclusions: Taken together, our results suggest that source pool diversity, along with the potential for colonization from those pools, has a strong influence on the composition of insular mammal assemblages worldwide. [ABSTRACT FROM AUTHOR]

The theory of island biogeography postulates that size and isolation are key drivers of biodiversity on islands. This theory has been applied not only to true (e.g. oceanic) islands but also to terrestrial island‐like systems (e.g. edaphic islands). Recently, a debate has opened as to whether terrestrial island‐like systems function like true islands. However, identifying the effect of insularity in terrestrial systems is conceptually and methodologically challenging because recognizing species source(s) and measuring isolation is not as straightforward as for true islands. We contribute to the debate by proposing an approach to contextualize the definition of insularity and to identify the role of isolation in terrestrial island‐like systems. To test this approach, we explored the relationship between insularity predictors and specialist species richness of edaphic islands in three systems in Europe (spring fens, mountaintops, and outcrops). We detected that insularity affected specialist richness of edaphic islands through island size and target effect (i.e. an emergent property of islands depending on their isolation and size). As predicted by the Theory of Island Biogeography, species richness decreased with increasing isularity. Given the comprehensiveness and ease of implementation of our approach, we encourage its extension to other island‐like systems. [ABSTRACT FROM AUTHOR]

Aim: The positive relationship between species richness and area—the species–area relationship (SAR)—is a key principle in ecology. Previous studies show large variation in the SAR across taxa collectively indicating the necessity of a taxon‐focused approach to accurately evaluate biodiversity scaling patterns. Ants are ideal for this given their global distribution and role in ecosystem functioning. Using data from insular ant communities, this study quantified and investigated various attributes of ant SARs and reviewed the SAR literature for ant faunas, world‐wide, to identify specific areas for improvement. Location: Islands around the world. Taxon: Ants (Hymenoptera: Formicidae). Methods: We aggregated data on species richness and island characteristics from previous studies on ant SARs to evaluate effects of climate, biogeographic realm, and latitude on slope values from these studies. A multimodel inference approach was used to determine the form of the different SARs, and whether there were any differences between mainland and insular SARs. We also assessed differences between mainland and insular SAR slopes and intercepts. To seek a general slope coefficient for ants, we used a mixed‐effect model. Finally, we tested for potential thresholds in the global insular SAR using piecewise regression models. Results: There was a negative relationship between SAR slopes and precipitation in both mainland and insular SARs, while SAR slopes and intercept values were higher in mainland compared to insular systems. Strong evidence of thresholds emerged in the global insular SAR. Finally, a general slope of 0.16 was observed for insular systems, which is lower than found in previous studies. Main Conclusions: A taxon‐focused approach proves to showcase unexpected patterns in the SAR. Ant diversity increases faster across area in mainland areas compared to true islands. The influences of climate and biogeographic realms on the ant SAR warrant deeper study. Our review highlights knowledge gaps in the ant SAR that also extend to other taxa, such as the effects of nonnative species on the SAR. [ABSTRACT FROM AUTHOR]

Aim: The Sino‐Japanese Floristic Region has extremely high species diversity with respect to temperate plants; however, the reasons for this diversity are poorly understood because most studies have only considered geographic isolation caused by climatic oscillations. In some plant groups, high floral trait diversity and uneven species diversity between insular systems and the continental area suggest other factors may have important roles too. The primary purpose of this study is to reveal how abiotic and biotic factors have shaped the species diversity anomaly of Heterotropa between the insular systems and the continental area. Location: The Sino‐Japanese Floristic Region. Taxon: Section Heterotropa (genus Asarum; Aristolochiaceae). Methods: Using ddRAD‐seq and chloroplast genome data, we built a time‐calibrated phylogenetic tree including 79 species. We estimated the patterns of floral traits (flowering time and floral size) evolution using macroevolutionary modelling, and tested the correlation of speciation rate with the trait evolution rates. Finally, we estimated the isolation factors of all taxa pairs and sister‐taxa pairs based on distribution range and floral traits. Results: Phylogenetic analysis indicated that Heterotropa was diverged into two clades (continental clade and insular clade) in the Miocene, and the major subclades corresponded to geographic entities. Most rate shifts accelerating floral trait's evolution occurred during the Pleistocene period. Evolution rate of floral traits showed positive correlation with the speciation rate. Large proportion of taxa in the insular clade are distributed allopatrically. Several sister pairs showed floral trait divergence with geographic overlap. Main Conclusions: The diversification of Heterotropa appears to have been triggered by geographic and climatic events, and subsequent repeated floral trait evolution with and without geographic isolation. Furthermore, the high species diversity in the insular systems would have been formed by the repeated range fragmentations and contractions. Our study demonstrates the importance of multidimensional studies to understand the diversification process of temperate plants in the Sino‐Japanese Floristic Region. [ABSTRACT FROM AUTHOR]

The island species area relationship (ISAR) is an important tool for measuring variation in species diversity in variety of insular systems, from true‐island archipelagoes to fragmented terrestrial landscapes. However, it suffers from several limitations. For example, due to the sample‐area effect, positive relationships between species and area cannot be directly interpreted as evidence for deterministic effects of area per se. Additionally, richness‐based analyses may obscure species‐level responses to area and isolation that may better inform conservation practice. Here, we use random placement models to control for variation in abundance, occupancy and richness associated with the sample‐area effect, allowing deterministic effects of area and isolation, and how they vary with species' functional traits, to be resolved using linear mixed effects models. We demonstrate the utility of this approach using a butterfly assemblage persisting on a naturally fragmented landscape of lake islands. The ISAR did not significantly deviate from random placement in relation to island area, isolation or habitat diversity, supporting stochastic assembly consistent with the sample‐area effect. Such inferences support the habitat amount hypothesis, which prioritizes preserving the maximum amount of habitat irrespective of its degree of fragmentation. However, species‐level analyses demonstrated that species' abundances were significantly lower on both smaller and more isolated islands than what is predicted by the sample‐area effect. Moreover, effects of area per se were significantly greater for smaller, less mobile and rare species. Species' occurrences also significantly deviated from predictions of the sample‐area effect in relation to island isolation. Thus, our approach illustrates that richness‐based analyses not only result in incorrect inferences on mechanisms underlying ISARs, but also obscure important effects of area per se and isolation on individual species that vary with functional traits. We therefore suggest that these effects should not be solely inferred from richness‐based analyses, but rather evaluated on a species‐by‐species basis. [ABSTRACT FROM AUTHOR]

We compared support for 3 hypotheses that might explain observed morphological variation among islands of 4 species of Caribbean land birds: ecological release from competition and predation pressure, predation pressure from 1 novel predator species (small Indian mongoose, Herpestes auropunctatus), and climate. We measured wing chord, tarsus length, bill length, and mass of Bananaquits (Coereba flaveola), Black-faced Grassquits (Tiaris bicolor), Lesser Antillean Bullfinches (Loxigilla noctis), and Common Ground Doves (Columbina passerina) in Grenada, 2015–2017, and combined these measures with data from 23 other Caribbean islands collated from academic papers and researchers, for a total sample size of 6,518 individuals. We found the strongest support for the ecological release hypothesis, but each of our hypotheses received some support, suggesting that ecological release from competition, predation pressure from mongoose, and climate may all interact to influence morphological adaptations of birds to local conditions in the Caribbean. [ABSTRACT FROM AUTHOR]