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The role of human activities in island biogeography is highlighted under the background of global changes, and humans interfere with the island biodiversity by introducing alien species, occupying natural habitats, and planting forests or crops. China’s islands are receiving increasing human interferences in different forms and intensities and provide natural laboratories for the study on island biogeography under varying human interference. The five inhabited islands with intermediate human interference in Miaodao Archipelago served as the study area. The island and site scales were employed to delineate the plant diversities, and influencing factors were collected by adequately considering the intermediate human interference, and three aspects of factors, i.e., natural, human, and ecological factors, were obtained. Then, the spatial sensitivities of island plant diversities to the factors were identified and quantified. The results indicated that the species richness on the five islands was intermediate compared with the remaining islands in the same archipelago and those in the other regions of China. Different island groups in the same archipelago shared the common characteristics in species composition and each island group had its own feature under the specific human interference. The island area, isolation, and population presented the highest influencing degrees on plant diversity spatial pattern from the perspective of island scale, while the slope, artificial landscape area, and soil available phosphorus exerted the highest influence degrees at site scale. Human activities with intermediate intensity exert positive effects on plant diversity at island scale through species introduction but negative effects at site scale through occupying the natural habitats. [ABSTRACT FROM AUTHOR]

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]

Little is known of how Neotropical freshwater ecosystems will respond to future climate scenarios. In Neotropical rainforests, a substantial fraction of the freshwater available to the aquatic fauna is found within phytotelmata, plant-held waters that form aquatic islands in a terrestrial matrix. We hypothesized that phytotelmata in close proximity have higher resilience capacity to severe drought than the isolated ones, under the assumption that immigration from nearby sources promotes faster recovery. We used rainshelters to emulate an extreme drought (67 days without rainfall) in tank-forming bromeliads arranged in patches of 1, 3 or 6 plants in a primary forest of French Guiana. Habitat size was a stronger determinant of invertebrate species richness and biomass per bromeliad than patch size. Larger bromeliad patches attenuated the adverse effect of drought on the biomass of predators, probably because short-range migration within dense patches allowed individuals to find moist refuges. However, the recovery of aquatic communities and ecosystem functions was mostly supported by in situ resistance, and a rescue effect of immigration was weak. Whilst environmental management plans tend to focus on dense networks of connected water bodies, our study shows that efforts should not omit the isolated ones. [ABSTRACT FROM AUTHOR]

Summary: Among flowering plants, self‐compatibility, longer lifespan, and generalized pollination syndrome are each thought to increase the lifetime odds of finding a mate, particularly in isolated locales. An accumulated body of evidence supports the role of breeding system in island colonization, but less is known about the impact of other traits and their interactions during establishment.We employ a global dataset of 3222 flowering plant species from 169 families to estimate the effects of traits on the probability of island occurrence. Our analyses additionally account for taxonomic group membership and assess the role of island arrival opportunity.Self‐compatibility is strongly associated with island colonization. A longer lifespan and generalized pollination syndrome are also associated with increased island colonization, although this is influenced by their interaction with breeding system. The probability of island colonization is highly dependent on taxonomically conserved unmeasured traits and arrival opportunity. As expected, mate limitation appears to increase with dispersal distance, although many other factors are at play.We find that arrival opportunity and breeding system are the primary drivers of island colonization relative to other life‐history traits we account for here, lending additional support for the positive role of uniparental reproduction in establishment following long‐distance dispersal. [ABSTRACT FROM AUTHOR]

Since the inception of the field of evolution, mimicry has yielded insights into foundational evolutionary processes, including adaptive peak shifts, speciation, and the emergence and maintenance of phenotypic polymorphisms. 1,2,3 In recent years, the coevolutionary processes generating mimicry have gained increasing attention from researchers. Despite significant advances in understanding Batesian and Müllerian mimicry in Lepidopteran systems, few other mimetic systems have received similar detailed research. Here, we present a Batesian mimicry complex involving flightless, armored Pachyrhynchus weevils and their winged Doliops longhorn beetle mimics and examine their coevolutionary patterns within the Philippine archipelagos. Pachyrhynchus weevils are primarily found in the Philippines, where distinct species radiations have occurred on different islands, each with unique color patterns serving as a warning to predators. This defensive trait and mimicry between unrelated species were first described by Wallace in 1889. Notably, the distantly related longhorn beetle Doliops , despite being soft-bodied and ostensibly palatable, mimics the heavily armored, flightless Pachyrhynchus. To address mimicry in this system, we reconstructed the phylogeny of Doliops using a probe set consisting of 38,000 ultraconserved elements. Our study examines the following questions central to understanding the Pachyrhynchus-Doliops mimicry system: (1) to what extent are coevolutionary interactions conserved (i.e., lineage-constrained) and (2) are the codiversification patterns primarily driven by biotic or abiotic factors? 4,5,6 To assess color mimicry and cospeciation, we examined the evolution of nanostructure-based warning colors and the effect of island biogeography on cospeciation. Our findings demonstrate the beetle's ability to repeatedly evolve multiple solutions to similar evolutionary challenges, evolving similar color patterns using different types of photonic crystals with varying degrees of order. We revealed that the observed pattern of cospeciation is driven mainly by abiotic factors from their biogeographic history. Unlike the patterns of coevolution seen between angiosperms and insect lineages, 7 most ecological interactions do not persist longer than a few million years, leading to patterns of modularity rather than ecological nestedness. 4,6,7 [Display omitted] • Coevolutionary interactions arise from community assembly events, not host tracking • Structural colors in model and mimetic systems use different nano-level mechanisms • We resolved the phylogeny of Doliops using a design of more than 30,000 UCE loci To what extent are coevolutionary interactions conserved (i.e., lineage-constrained)? Are codiversification patterns primarily driven by biotic or abiotic factors? Van Dam et al. examine these questions using a beetle mimicry system and find that abiotic factors from their biogeographic history primarily influence their pattern of cospeciation. [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]

Since its coinage ca. 1850 AD by Philip Barker Webb, the biogeographical region of Macaronesia, consisting of the North Atlantic volcanic archipelagos of the Azores, Madeira with the tiny Selvagens, the Canaries and Cabo Verde, and for some authors different continental coastal strips, has been under dispute. Herein, after a brief introduction on the terminology and purpose of regionalism, we recover the origins of the Macaronesia name, concept and geographical adscription, as well as its biogeographical implications and how different authors have positioned themselves, using distinct terrestrial or marine floristic and/or faunistic taxa distributions and relationships for accepting or rejecting the existence of this biogeographical region. Four main issues related to Macaronesia are thoroughly discussed: (i) its independence from the Mediterranean phytogeographical region; (ii) discrepancies according to different taxa analysed; (iii) its geographical limits and the role of the continental enclave(s), and, (iv) the validity of the phytogeographical region level. We conclude that Macaronesia has its own identity and a sound phytogeographical foundation, and that this is mainly based on three different floristic components that are shared by the Macaronesian core (Madeira and the Canaries) and the outermost archipelagos (Azores and Cabo Verde). These floristic components are: (i) the Palaeotropical‐Tethyan Geoflora, formerly much more widely distributed in Europe and North Africa and currently restricted to the three northern archipelagos (the Azores, Madeira and the Canaries); (ii) the African Rand Flora, still extant in the coastal margins of Africa and Arabia, and present in the southern archipelagos (Madeira, the Canaries and Cabo Verde), and (iii) the Macaronesian neoendemic floristic component, represented in all the archipelagos, a result of allopatric diversification promoted by isolation of Mediterranean ancestors that manage to colonize Central Macaronesia and, from there, the outer archipelagos. Finally, a differentiating floristic component recently colonized the different archipelagos from the nearest continental coast, providing them with different biogeographic flavours. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the patterns of stream diatom beta diversity in islands versus continents across scales, to relate community similarities with spatial and environmental distances and to investigate the role of island characteristics in shaping insular diatom beta diversity. Location: Africa, America, Europe and the Pacific. Time Period: Present. Major Taxa Studied: Stream diatoms. Methods: We compared diatom beta diversity between islands and continents at large scales (within biogeographic regions) in two study regions (America and Europe) and at small scales (within islands/equivalent areas in continents) in three regions (Africa, America and Europe) partitioning beta diversity into turnover and nestedness components. We used a partial Mantel test and distance–decay curves to assess how diatom beta diversity on islands and continents is affected by spatial and environmental distances. Finally, using island data from all four regions, we evaluated the relationship between island beta diversity and island latitude, area, age and isolation using linear models. Results: At large scales, mean dissimilarities were higher on islands than in continents in Europe but lower in America. At smaller scales, the differences varied mostly depending on island isolation. Beta diversity was mainly caused by species turnover. Partial Mantel test and distance–decay curves revealed that spatial and environmental distances shaped diatom beta diversity at large, but not at small scales. Moreover, diatom beta diversity on islands was affected by island latitude, age and isolation, but not by island area. Main Conclusions: Diatom beta diversity on islands versus continents and its responses to spatial and environmental factors are scale and region dependent. Incomplete colonisation, evolutionary processes and environmental filtering likely contribute to insular beta diversity, which further varies with island latitude, age and isolation. This study sheds new light on beta diversity of microorganisms on islands and suggests that beta diversity should be explicitly considered in island biogeographical research. [ABSTRACT FROM AUTHOR]

Island ecosystems have emerged as vital model systems for evolutionary and speciation studies due to their unique environmental conditions and biodiversity. This study investigates the population divergence, hybridization dynamics, and evolutionary history of hybridizing golden‐backed and red‐backed Dinopium flameback woodpeckers on the island of Sri Lanka, providing insights into speciation processes within an island biogeographic context. Utilizing genomic analysis based on next‐generation sequencing, we revealed that the Dinopium hybrid zone on this island is a complex three‐way hybrid zone involving three genetically distinct populations: two cryptic populations of golden‐backed D. benghalense in the north and one island‐endemic red‐backed population of D. psarodes in the south of Sri Lanka. Our findings indicate asymmetric introgressive hybridization, where alleles from the southern D. psarodes introgress into the northern D. benghalense genome while phenotype remains adapted to their respective northern arid and southern wet habitats. The discovery of two genetically distinct but phenotypically similar D. benghalense populations in northern Sri Lanka highlights the process of cryptic population differentiation within island ecosystems. These populations trace their ancestry back to a common ancestor, similar to the Indian form D. b. tehminae, which colonized Sri Lanka from mainland India during the late Pleistocene. Subsequent divergence within the island, driven by selection, isolation by distance, and genetic drift, led to the current three populations. Our findings provide evidence of cryptic diversification and within‐island population divergence, highlighting the complexity of hybridization and speciation processes. These findings further emphasize the intricate nature of evolutionary dynamics in island ecosystems. [ABSTRACT FROM AUTHOR]

Interactions between plants and insects have long fascinated scientists. While some plants rely on insects for pollination and seed dispersal, insects rely on plants for food or as a habitat. Despite extensive research investigating pair‐wise species interactions, few studies have characterized plant and insect communities simultaneously, making it unclear if diverse plant communities are generally associated with diverse insect communities. This work aims to better understand the historical and evolutionary relationships between plant and insect phylogenetic diversity (PD) on islands. We hypothesized that phylogenetically diverse plant communities (i.e., high PD) support diverse insect communities, with the relationship varying with island isolation, area, age, and latitude. Species lists for plants and insects were compiled from the published literature, and plant PD was calculated using ´standardized mean pairwise distance´ (SES.MPD) and ´standardized mean nearest taxon distance´ (SES.MNTD). For insects, PD was estimated using the number of genera, families, and orders. We found that plant diversity in evolutionary recent times (SES.MNTD) is associated with recent insect diversity (number of genera), but no relationship was found between plant and insect diversity across whole phylogenies (plant SES.MPD vs. number of insect families). Distant islands generally support high PD of plants (high SES.MPD and SES.MNTD) and insects (low number of genera). Plant and insect PD was generally high on small islands, except for plant SES.MPD revealing no relationship with island size. Insect PD was somewhat higher on young islands (low number of families), whereas there was no relationship between island age and plant PD. Plant SES.MPD was higher on high latitude islands, yet we did not find significant relationships between the latitude and the metrics of insect PD or plant SES.MNTD. These findings suggest that protecting high plant PD may also help conserve high insect PD, with a focus on small and distant islands as potential hotspots of phylogenetic diversity across multiple taxa. [ABSTRACT FROM AUTHOR]

Understanding factors that influence the viability of populations is central to conservation biology. Small and isolated populations have elevated risk of extinction due to demographic and genetic stochasticity. The Apostle Islands National Lakeshore features a genetically unique and culturally important population of archipelagic black bears (Makwa; Ursus americanus). While dispersal is central to population viability, previous studies of this population did not sample the adjacent mainland black bear population on the Red Cliff Reservation (Gaa-miskwaabikaang). Therefore, we lack robust estimates of dispersal, gene flow and overall connectivity among the islands and with the mainland population. In partnership with Red Cliff Band of Lake Superior Chippewa and the National Park Service, we non-invasively collected black bear hair, and used 17 microsatellite markers to genotype 141 black bears. We then estimated genetic diversity, population structure, dispersal, and conducted a pedigree network analysis to identify areas of the archipelago important for connectivity and reproduction. We found evidence of a well-connected archipelagic bear population structured into five clusters and characterized by moderate dispersal between islands and mainland. We found that three of the islands are disproportionately important for genetically connecting the archipelago, but the islands were nevertheless reliant upon the mainland for gene flow and genetic diversity. The high connectivity between islands and the mainland demonstrates a potential metapopulation dynamic, where islands may serve as a reservoir of individuals for the mainland and the mainland supplying individuals likely important for maintaining genetic diversity of island populations. Given the importance of island–mainland connectivity, future tribal and federal collaboration will be important to maintain a genetically and demographically viable population of black bears. [ABSTRACT FROM AUTHOR]

Microbial community dynamics on sinking particles control the amount of carbon that reaches the deep ocean and the length of time that carbon is stored, with potentially profound impacts on Earths climate. A mechanistic understanding of the controls on sinking particle distributions has been hindered by limited depth- and time-resolved sampling and methods that cannot distinguish individual particles. Here, we analyze microbial communities on nearly 400 individual sinking particles in conjunction with more conventional composite particle samples to determine how particle colonization and community assembly might control carbon sequestration in the deep ocean. We observed community succession with corresponding changes in microbial metabolic potential on the larger sinking particles transporting a significant fraction of carbon to the deep sea. Microbial community richness decreased as particles aged and sank; however, richness increased with particle size and the attenuation of carbon export. This suggests that the theory of island biogeography applies to sinking marine particles. Changes in POC flux attenuation with time and microbial community composition with depth were reproduced in a mechanistic ecosystem model that reflected a range of POC labilities and microbial growth rates. Our results highlight microbial community dynamics and processes on individual sinking particles, the isolation of which is necessary to improve mechanistic models of ocean carbon uptake.

We tested the hypothesis that, for land snails, long-distance dispersal across oceans is primarily via aerial dispersal (i.e. wind- or bird-mediated), which likely favors so-called micromolluscs through immigrant selection for small (aerially buoyant) body size. Immigrant selection is a filtering process favoring phenotypes conferring greater capacities for long-distance dispersal. We also tested predictions of E. O. Wilson’s taxon cycle, which hypothesizes that descendant species of island colonists are subject to a series of ecological and evolutionary dynamics, resulting over time in progressively more ecologically specialized island endemics with more limited dispersal capacity. We tested predictions of immigrant selection on aerial dispersal and the taxon cycle in native Pacific Island land snails of the Samoan Islands, Mariana Islands, and Lord Howe Island and neighboring small islands using geographic range, shell size, microhabitat, and elevation data compiled from primary and secondary literature. Single-archipelago endemic species found on multiple islands within an archipelago had significantly larger shell sizes than widespread species found in multiple archipelagos and single-island endemic species. Single-archipelago endemic and single-island endemic species were associated with vegetation and ground/rock microhabitats, respectively, whereas widespread species were more likely to be microhabitat generalists. Single-island endemic species were more likely to occur at high-elevation habitats, while widespread species were more likely to be confined to low-elevation habitats. Consistent with predictions of the taxon cycle and immigrant selection on aerial dispersal, Pacific Island land snails endemic to single islands or archipelagos (i.e. those assumed to be later in the taxon cycle) are more likely to have larger body size (archipelago endemics) and to occupy higher elevations (i.e. island interiors; island endemics) in more specialized microhabitats (all endemics).

ABSTRACT Aim Location Taxon Methods Results Main Conclusion We assessed the influence of island isolation on the composition of insular bird assemblages with a particular focus on species traits associated with dispersal. To do so, we tested whether ecomorphological metrics of dispersal ability, namely hand‐wing index and Kipp's distance, increase with increasing island isolation.Global.Birds.We integrated global datasets of island characteristics with distribution and ecomorphological trait information of birds; our final dataset comprised information for 2034 native, resident and terrestrial species inhabiting 2399 islands. Species restricted to islands were removed to avoid potentially confounding effects of speciation, such as the evolution of flightlessness or poor flight on islands. Using the generalised additive models, we tested for the relationship between hand‐wing index or Kipp's distance and island isolation, accounting for the effects of island area and spatial autocorrelation. We performed the analyses separately for (i) continental and oceanic islands and (ii) for all terrestrial birds and for passerine birds only.Hand‐wing index and Kipp's distance were positively related to island isolation on oceanic islands, that is bird communities on more isolated oceanic islands were composed of species with wings that had a higher aspect ratio and were more elongated. However, this relationship did not hold for continental islands. We found these patterns to be consistent for all terrestrial birds as well as for passerine birds only.Our study provides strong evidence that island isolation influences the trait composition of island bird assemblages at a global scale. Our results highlight the variation of dispersal‐related ecomorphological traits among bird assemblages on islands, suggesting that these traits play an important role in mediating the influence of island isolation on community assembly processes on islands. [ABSTRACT FROM AUTHOR]

The influence of fragmentation per se on biodiversity is hotly debated, with evidence of negative, neutral, or even positive effects after controlling for habitat amount. Principles from this debate are often used to inform biodiversity conservation in remnant habitat fragments but are rarely considered in a restoration context. Habitat restoration is essential to work alongside conservation and reverse biodiversity declines. Although restored habitats vary along a similar fragmentation gradient to remnant patches, the importance of different processes likely varies. Communities in remnant patches are largely determined by existing populations, while communities in restored patches are shaped by colonization from nearby populations. We illustrate how fragmentation per se can have variable outcomes for biodiversity depending on whether habitat is conserved or restored. The fragmentation debate, in its current form, has limited application for restoration ecology, and we emphasize the need for ecologists and conservationists to consider the directionality of the fragmentation process. [ABSTRACT FROM AUTHOR]

Multiple‐island endemics (MIE) are considered ideal natural subjects to study patterns of island colonization that involve recent population‐level genetic processes. Kleinia neriifolia is a Canarian MIE widespread across the archipelago, which exhibits a close phylogenetic relationship with species in northwest Africa and at the other side of the Sahara Desert. Here, we used target sequencing with plastid skimming (Hyb‐Seq), a dense population‐level sampling of K. neriifolia, and representatives of its African–southern Arabian relatives to infer phylogenetic relationships and divergence times at the species and population levels. Using population genetic techniques and machine learning (convolutional neural networks [CNNs]), we reconstructed phylogeographic relationships and patterns of genetic admixture based on a multilocus SNP nuclear dataset. Phylogenomic analysis based on the nuclear dataset identifies the northwestern African Kleinia anteuphorbium as the sister species of K. neriifolia, with divergence starting in the early Pliocene. Divergence from its sister clade, comprising species from the Horn of Africa and southern Arabia, is dated to the arid Messinian period, lending support to the climatic vicariance origin of the Rand Flora. Phylogeographic model testing with CNNs supports an initial colonization of the central island of Tenerife followed by eastward and westward migration across the archipelago, which resulted in the observed east/west phylogeographic split. Subsequent population extinctions linked to aridification events, and recolonization from Tenerife, are proposed to explain the patterns of genetic admixture in the eastern Canary Islands. We demonstrate that CNNs based on SNPs can be used to discriminate among complex scenarios of island migration and colonization. [ABSTRACT FROM AUTHOR]

In the Anthropocene, the ranges of introduced species are expanding, while extinction‐prone species are contracting. Introductions and extinctions are caused by how species respond to human impacts, but it is unknown why the ranges of some species expand and some contract. Here, we test whether this opposite response of human impact is due to introduced and extinction‐prone species falling at opposite ends of geographic, evolutionary, or ecological trait continua. We constructed a database of native range maps, traits, phylogenetic relationships, and the introduction and extinction‐prone status of squamate reptiles with ranges native to the Western Hemisphere. Across > 3000 snake and lizard species (88% of known native squamates), 142 had been introduced elsewhere and 483 were extinction‐prone (i.e. vulnerable, endangered, critically endangered, extinct in the wild, extinct). To explain variation in status, we first tested if the same human‐impacted regions in the Americas contained the native ranges of species of either status. Second, we tested for phylogenetic signal in species status. Finally, we tested the explanatory power of multiple trait continua. The native ranges of introduced and extinction‐prone reptiles were clustered in island regions with high human impact versus mainland regions with lower human impact. Phylogenetic signal was weak for status, but introduced and extinction‐prone species were clustered in different clades. All geographic and ecological traits that explained each status supported the opposite ends hypothesis. Introduced species had larger, edgier ranges, while extinction‐prone species had smaller, simpler ranges. Introduced species were mostly herbivorous/omnivorous, while extinction‐prone species were mostly carnivorous. Introduced species produced larger clutches, while extinction‐prone species had smaller body sizes. In the Anthropocene, the native ranges of introduced and extinction‐prone species are in the same human‐impacted regions where trait continua, having opposite effects, determine whether species ranges expand or contract in the continuing face of global change. [ABSTRACT FROM AUTHOR]

Island ecosystems are particularly susceptible to the impacts of invasive species. Many rare and endangered species that are endemic to islands are negatively affected by invasions. Past studies have shown that the establishment of non‐native species on islands is related to native plant richness, habitat heterogeneity, island age, human activity, and climate. However, it is unclear whether the factors promoting establishment (i.e. the formation of self‐sustaining populations) also promote subsequent invasion (i.e. spread and negative impacts). Using data from 4308 non‐native plant species across 46 islands and archipelagos globally, we examined which biogeographic characteristics influence established and invasive plant richness using generalized linear models nested within piecewise structural equation models. Our results indicate that anthropogenic land use (i.e. human modification) is strongly associated with establishment but not invasion, that climate (maximum monthly temperature) is strongly associated with invasion but not establishment, and that habitat heterogeneity (represented by maximum elevation and island area) is strongly associated with both establishment and invasion. Island isolation explains native plant richness well, but is not associated with established and invasive plant richness, likely due to anthropogenic introductions. We conclude that anthropogenic land use on islands is likely to be a proxy for the number of introductions (i.e. propagule pressure), which is more important for establishment than invasion. Conversely, islands with more diverse habitats and favorable (warm) climate conditions are likely to contain more available niche space (i.e. 'vacant niches') which create opportunities for both establishment and invasion. By evaluating multiple stages of the invasion process, we differentiate between the biogeographic characteristics that influence plant establishment (which does not necessarily lead to ecological impacts) versus those that influence subsequent plant invasion (which does lead to negative impacts). [ABSTRACT FROM AUTHOR]

The island biogeography theory predicts that species richness in islands and island-like systems is the ultimate result of island isolation and area. Species with high dispersal capabilities are predicted to be less affected by these factors because of their capacity to move more efficiently between islands or habitats, and here we test this idea in bats, the only mammals capable of flight. We conducted mist net and acoustic surveys across 21 islands in the San Juan Archipelago (Washington State, United States) and adjacent northwest mainland to: (i) investigate the effects of island area, distance from mainland, and habitat on bat diversity; and (ii) evaluate whether differences in morphological (body mass, forearm length, wing loading) and ecological (dietary niche breadth, foraging guild) traits among species influence their prevalence across islands. We found that island size strongly influenced patterns of species richness, with larger islands having a greater number of bat species. However, neither island distance from mainland nor any measure of habitat availability was a significant predictor of species richness at the scale of this study. Additionally, we found that dietary niche breadth, as opposed to any morphological trait, best predicted the prevalence of species across the islands. Our results suggest that species with more specialized diets may be more vulnerable to habitat fragmentation, and provide insight into how geographic and ecological factors affect the diversity of insular bat communities, adding to growing knowledge about the role of species traits as mediators of their responses to large-scale landscape structure. [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]

In anthropogenic islands as urban parks, the fern species richness and composition may be determined ecologically by the quality of habitat, including area greenness, or biogeographically by area size. As the development of the theory of island biogeography also includes man-made parks, it is feasible to test whether area-species relationship applies in these urban parks, and is more pronouncedly evident compared to another ecological factor, such as NDVI. Total species number and composition of 8 urban parks in a kecamatan (subdistrict) in Tegal Regency were collected and arranged in clustering methods to understand the similarity between parks. The similarity analysis result is important for the management of the parks in Slawi. The species richness data is subsequently tested using Pearson correlation and regression against NDVI and area sizes. The relation between NDVI and species richness is nonsignificant (p=0.058), while area size and species richness is significant (p=0.003). This signifies that the urban fern species richness is determined by area as biogeographical factor, compared to NDVI as ecological factor. This result is important for the purpose of designing and managing urban parks as evidently size is important in the effort of attracting native biodiversity into urban parks and in turn enhancing the well-being of urban population. [ABSTRACT FROM AUTHOR]

Aim: A nested pattern (nestedness) in species composition is a frequent signature of insular communities. However, it remains unclear whether the drivers of nestedness are consistent across multiple island systems. Here, we investigated the pattern and drivers of taxonomic, functional and phylogenetic nestedness in terrestrial mammal assemblages from 10 distinct island systems (archipelagos). Location: Global. Time period: Contemporary. Major taxa studied: Terrestrial mammals. Methods: We compiled occurrence data and species traits of terrestrial mammals from 228 islands in 10 distinct island assemblages. We assembled a dataset of island biogeographic characteristics for each of these islands, including island area, isolation index and maximum elevation. For all 10 assemblages, we first tested for significant patterns of taxonomic, functional and phylogenetic nestedness. We then examined the associations between nestedness, island biogeographic characteristics and species traits. Results: We detected significant patterns of taxonomic, functional or phylogenetic nestedness in mammal assemblages from all 10 archipelagos. Biogeographic characteristics of islands affecting the rate of extinction in island species, namely, island area and elevation, were significantly associated with the degree of nestedness in these assemblages. Traits associated with the extinction probability of a species, such as litter size, further drove the nested pattern in some assemblages. Main conclusions: All analyses pointed to selective extinction as a main mechanism shaping the observed nested patterns in island mammal assemblages. From a conservation point of view, different management strategies should be implemented for mammal assemblages in these island systems by identifying the drivers of species extinction rates specific to each island system and species occurring on these islands. [ABSTRACT FROM AUTHOR]

Aim: Wallacea is a global biodiversity hotspot and Sulawesi is the largest island in this region, notable for a high proportion of endemic species. The Wakatobi archipelago, off the southeastern peninsular arm of Sulawesi, is home to several endemic bird species. Although islands are known to influence the morphology of their resident species, competitive interactions also exert strong influences on morphology. Here, we consider the contributions of both islands and competitors on two morphological traits of two bird species in a small passerine guild found on the Wakatobi islands. Location: Wakatobi archipelago, Sulawesi Tenggara, Indonesia. Taxon: Wakatobi White‐eye (Zosterops flavissimus) and Wakatobi Sunbird (Cinnyris infrenatus). Methods: Working with morphological measures (from netting studies), population density metrics (from transect surveys) and fundamental data from islands (area, distance from mainland and elevation), we investigated (by means of multiple linear regression) which terms best explained variation in the body size and bill size of two small passerine birds endemic to the Wakatobi islands. Results: Both island metrics and competitor presence/density were useful in describing the variation in body size of both bird species. However, only competitor presence/density was useful in describing variation in bill size of the birds. The best models describing variation in these traits included terms representing both interspecific and intraspecific competition. Main Conclusions: Our findings indicate that simple island metrics may be useful in predicting some of the variation in some functional traits of island species. However, in this example, simple island metrics were insufficient to explain the full variation in body size of endemic birds across the Wakatobi archipelago and were of no use in predicting the variation in their bill size. As bill morphology frequently dictates diet and feeding niche, it is a trait which may determine population divergence and speciation. If simple island metrics fail to describe such diversification, it is surely important to capture that information in other ways. [ABSTRACT FROM AUTHOR]

Aim: Island biological communities are considered to comprise non‐random assemblages from surrounding source pools, but whether they converge towards predictable structural properties remains unclear. Here, we (i) test whether insular communities of land snails converge towards similar functional and/or taxonomic properties and (ii) evaluate whether island functional diversity is determined by island biogeographical characteristics such as area and distance to the pool as well as human‐related variables. Location: Sixty‐six continental Aegean islands. Taxon: Land snails. Methods: We compiled a database of two morphological traits with functional significance (shell height and width) for 163 island species and 1529 species from the major species pools. We quantified inter‐specific morphological dissimilarity between pairs of islands (turnover), using a modified index of the mean nearest taxon distance. We tested for functional and taxonomic convergence using null models and assessing whether overall mean turnover among islands and pairwise island‐by‐island turnover were lower than expected by chance. We performed multiple regression analyses to test whether functional diversity metrics scale with island biogeographical characteristics and human‐related variables. Results: Our analyses provide strong evidence that communities of land snails across the Aegean islands converge towards non‐random functional properties and taxonomic structure. At the island level, a wide range of different shell shapes is observed, indicating greater functional richness than expected by chance. Regression analyses showed that island area is the only efficient predictor of functional diversity, indicating that available ecological/resource space is of central importance in driving the assembly of different shell shapes. Main Conclusions: Our findings, consistent with previous studies of other taxa from oceanic islands, highlight that island species communities are not randomly assembled and display convergence in their functional and taxonomic composition. Integrating functional diversity metrics within biogeographic analyses has the potential to further our understanding of island biodiversity patterns. [ABSTRACT FROM AUTHOR]

Aim: The distribution of birds among islands is thought to be regulated by island physical geography (i.e. island area, isolation and latitude). In contrast, work on continents indicates that bird diversity is often regulated by plant diversity. Consequently, the (statistical) direct and indirect effects of physical geography on island bird distribution are poorly understood. We investigated the relative roles of physical geography and vegetation in determining island bird diversity in the South West Pacific at two taxonomic scales of resolution: total bird diversity and bird diversity within functional guilds. Location: Eleven archipelagos in the South West Pacific. Taxon: Land birds. Methods: We created a dataset characterising total and functional guild diversity for land birds and seed plants (i.e. Spermatophytes) among archipelagos. We then used mediation analysis to disentangle the direct and indirect (i.e. mediated) effects of physical geography and vegetation on bird diversity. Results: On a broad taxonomic scale, total bird diversity was directly determined by total plant diversity, not the area, isolation or latitude of islands. On a fine taxonomic scale results differed between functional guilds. The diversity of herbivorous and frugivorous birds was directly determined by physical geography rather than plant total and trait diversity. Woody and herbaceous plant species diversity mediated the effect of physical geography on forest‐dwelling, above ground nesting and ground nesting bird diversity. Granivorous, nectarivorous and grassland‐dwelling bird diversities were unrelated to both physical geography and herbaceous plant diversity. Main Conclusions: Physical geography and vegetation can have both direct and indirect effects on island bird diversity. Furthermore, relationships between physical geography, vegetation and bird diversity can vary markedly among functional guilds. [ABSTRACT FROM AUTHOR]

The island syndrome is a widespread biological phenomenon that describes a suite of morphological, behavioural, demographic and life‐history changes associated with island dwelling. These similar evolutionary responses among disparate groups of animals and plants represent a remarkable case of convergent evolution. Among animals, birds are a highly suitable group to study the island syndrome; they are a comparatively data‐rich taxon, are frequent island colonisers, and sometimes display extreme adaptations such as the loss of flight. However, the avian island syndrome literature is fragmented, and multiple components are rarely considered together even though many are inextricably linked. We reviewed multi‐species comparative studies, single‐species or population‐level studies and anecdotal accounts, to summarise and assess the support for individual components of the island syndrome for birds, and to identify suites of traits that should be considered together. The weight of evidence for island syndrome patterns in morphology is substantial, but is more partial or even anecdotal for various aspects of behaviour, life history and physiology. Full validation of the island syndrome in birds will require the less‐studied components to be treated in a comparative framework, and for covarying components to be examined in an integrated way. An improved description of the scope of the syndrome will pave the way to understanding its drivers. [ABSTRACT FROM AUTHOR]

The Japanese Archipelago consists of four major islands and numerous small islands. The Goto Islands are located near Kyushu, a major island in the Japanese Archipelago. We have previously reported that the population of the Japanese Genji firefly, Nipponoluciola cruciata, inhabiting the Goto Islands displays a unique flashing pattern that is used for pre-mating communication between males and females, indicating the possibility of genetic isolation of the Goto Islands population from neighbouring N. cruciata populations. In this study, we aimed to elucidate the gene flow between the Goto Islands N. cruciata population and its neighbouring island populations by molecular phylogenetic analyses based on the mitochondrial DNA regions of cytochrome c oxidase subunit II and ND5, also coupled to genome-wide analysis of nuclear DNA single nucleotide polymorphisms. Our results suggested that the Goto Islands N. cruciata population is genetically isolated from other populations of this species. Nuclear DNA-based population analyses indicated gene flow between the populations inhabiting the Kyushu and Iki Islands, situated at a distance approximately equal to that between the Goto and Kyushu Islands. Therefore, the genetic isolation of the Goto Islands N. cruciata population is largely affected by flashing pattern behaviour, underlining an ongoing speciation process. [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]

Unraveling the phylogeographic histories of species remains a key endeavor for comprehending the evolutionary processes contributing to the rich biodiversity and high endemism found in East Asia. In this study, we explored the phylogeographic patterns and demographic histories of three endemic fishfly and dobsonfly species (Neochauliodes formosanus, Protohermes costalis, and Neoneuromus orientalis) belonging to the holometabolan order Megaloptera. These species, which share a broad and largely overlapping distribution, were analyzed using comprehensive mitogenomic data. Our findings revealed a consistent influence of vicariance on the population isolation of Neoc. formosanus and P. costalis between Hainan, Taiwan, and the East Asian mainland during the early Pleistocene, potentially hindering subsequent colonization of the later diverged Neon. orientalis to these islands. Additionally, we unveiled the dual function of the major mountain ranges in East Asia, serving both as barriers and conduits, in shaping the population structure of all three species. Notably, we demonstrated that these co-distributed species originated from Southwest, Southern, and eastern Central China, respectively, then subsequently migrated along multi-directional routes, leading to their sympatric distribution on the East Asian mainland. Furthermore, our results highlighted the significance of Pleistocene land bridges along the eastern coast of East Asia in facilitating the dispersal of mountain-dwelling insects with low dispersal ability. Overall, this study provides novel insight into the synergistic impact of Pleistocene geological and climatic events in shaping the diversity and distribution of aquatic insects in East Asia. [ABSTRACT FROM AUTHOR]

ABSTRACT Terrestrial bird populations on small, species depauperate islands often experience selection for generalist foraging traits via ecological release; however, it is unclear how island conditions may uniquely influence other life‐history characteristics of small‐island birds, such as the unusually high rates of molt‐breeding overlap exhibited on the island of Grenada. To explore this question, we collected data on the life cycles and diets of 10 commonly occurring Grenadian bird species to assess the degree of generalist foraging and evaluate how seasonal patterns in diet niche breadth and diet overlap among species relates to the high rates of molt‐breeding overlap. We evaluated three hypotheses explaining drivers of molt‐breeding overlap (constraints on molt rate, unpredictable food abundance, and limited duration of food abundance), and suggest that widespread overlap in small‐island tropical communities may be the result of generalist foraging adaptations and restricted time periods of sufficient invertebrate availability for successful breeding and molt to occur. We found that these species typically exhibited low breeding period seasonality followed by synchronized peaks in molt intensity and molt‐breeding overlap during peak rainfall and high invertebrate abundance. There was also greater diet overlap and wider niche widths of invertebrate resources in the wet season when molt‐breeding overlap occurred, and greater niche partitioning of invertebrate items among species in the dry season suggesting that competitive interactions for invertebrates were stronger in the dry season. Birds also shared more plant food sources in the dry season when invertebrate abundance is low, though seasonal differences in plant diet diversity and niche width varied by species. These results provide evidence that scarce invertebrate resources and competition likely limit productivity and molt/self‐maintenance in these island‐adapted, species‐depauperate communities, and drive high rates of molt‐breeding overlap, a relatively uncommon life‐history strategy.

Abstract: Background: The question of which ecological and evolutionary processes structure the distribution of biodiversity has intrigued scientists for centuries, and historically, inferences have been gained predominantly by studying animals and plants. Although substantial progress has been made towards understanding the multitude of factors that shape host‐associated microbial communities (i.e., microbiomes), it remains largely unknown whether large‐scale geographical patterns in diversity observed for macroorganisms also apply for their microbiomes and whether microbiomes are shaped by the same processes that appear key for determining biogeographical patterns in their hosts. The geographical distribution of microbiome diversity: We discuss challenges and potential approaches for studying microbiome biogeography, with the goal of inspiring future lines of research that can stimulate the development of new ecological and evolutionary theory in the microbiome field. The theory and examples presented here focus specifically on bacterial microbiomes, and we give an overview of host‐associated bacterial microbiome research beginning to examine some of the classic biodiversity patterns central to the fields of ecology and evolution. Potential impacts of microbiome variation for host ecology and evolution: Microbiome diversity patterns are particularly important to consider because microbes are crucial for many aspects of the biology of their hosts. We discuss how more comprehensive knowledge of the geographical variation of microbiome diversity at the host individual and population levels might be crucial for understanding host ecology and evolution.

Abstract The equilibrium theorem provided a fundamental framework for understanding species’ distributions and movement in fragmented ecosystems. Wetland-dependent avian species are model organisms to test insular predictions within protected area networks because their mobility allows surveillance of isolated patches without landscape barriers. We hypothesized size and isolation would influence functional connectivity of sanctuaries by GPS-marked wintering mallards (Anas platyrhynchos) within a mesocosm protected sanctuary area network. We evaluated functional connectivity and sanctuary use, measured by movements between sanctuaries, using a multistate modeling framework. Proximity drove connectivity, underscoring that patch isolation—not size—influenced connectivity, even for an avian species with no ascertainable landscape resistance or barriers. We also found that sanctuary use increased overwintering survival by reducing harvest mortality. Our test of equilibrium theory predictions demonstrated that isolation of protected sanctuary areas supersedes their size in determining functional connectivity for mallards and access to these areas may have direct fitness consequences. Our findings could refine land acquisition, restoration, and management practices with equal or greater emphasis on adjacency in protected area network design, especially for wetland-dependent migratory gamebirds.

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]

Oceanic archipelagos provide striking examples of lineages that have radiated over pronounced ecological gradients. Accompanying this diversification, lineages have evolved adaptations allowing survival in extreme environments. Here, we investigate the genomic basis of ecological adaptation in Canary Island Descurainia (Brassicaceae), an island relative of Arabidopsis. The seven endemic species have diversified in situ along an elevational and ecological gradient, from low‐elevation scrub to high‐elevation sub‐alpine desert. We first generated a reference genome for Descurainia millefolia, phylogenetic analysis of which placed it as sister to D. sophioides. Ninety‐six gene families were found to be specific to D. millefolia and a further 1087 and 1469 gene families have expanded or contracted in size, respectively, along the D. millefolia branch. We then employed genome re‐sequencing to sample 14 genomes across the seven species of Canary Island Descurainia and an outgroup. Phylogenomic analyses were consistent with previous reconstructions of Canary Island Descurainia in resolving low‐ and high‐elevation clades. Using the branch‐site dN/dS method, we detected positive selection for 275 genes on the branch separating the low‐ and high‐elevation species and these positively selected genes (PSGs) were significantly enriched for functions related to reproduction and stress tolerance. Comparing PSGs to those in analyses of adaptation to elevation and/or latitude in other Brassicaceae, we found little evidence of widespread convergence and gene reuse, except for two examples, one of which was a significant overlap between Descurainia and Draba nivalis, a species restricted to high latitudes. The study of Canary Island Descurainia suggests that the transition to high‐elevation environments such as that found in the high mountains of the Canary Islands involves selection on genes related to reproduction and stress tolerance but that repeated evolution across different lineages that have evolved into similar habitats is limited, indicating substantially different molecular trajectories to adaptation. [ABSTRACT FROM AUTHOR]

Ireland and Britain are two islands located at Europe's westernmost edge, both of which act as the final breeding outposts for many bird species within their European ranges. Despite their similar geographic locations and geological histories, Ireland and Britain host different breeding avifauna assemblages. Diversity profiles, which can serve as more robust alternatives to classic diversity indices, were employed in this study to explore disparities in the two islands' breeding avifauna assemblages. Variations in assemblages were explored, along with their potential drivers, through analyses at three levels: island‐scale breeding bird assemblage compositions, island‐scale diversity profiles considering 49 common breeding species, and habitat‐specific diversity profiles considering assemblages in east/central Irish farmland and East Anglian farmland. Analysis of the two islands' breeding avifauna assemblages revealed that the Irish assemblage is a complete subset of the British assemblage. Analyses of Irish and British assemblages at both an island scale and a habitat scale revealed patterns linking land use to trends within the two islands' avifauna assemblages. Irish assemblages contained greater proportions of insectivorous farmland species by abundance, while British assemblages contained greater proportions of seed‐eating farmland species; both trends appeared to be related to structural differences in agricultural land use on the two islands. The British and East Anglian assemblages exhibited higher diversity across all analyses, which appeared to be driven by the assemblages' higher relative abundances of species that were most genetically distinct. This study highlights the ability of diversity profiles to impart more information than classic diversity indices by incorporating species similarity data. [ABSTRACT FROM AUTHOR]

Aim: Investigating the extent of insular invasions by non‐native species (i.e., the number of islands they occupy) is central to island conservation. However, interrelationships among plant life history traits, naturalization histories, and island characteristics in determining island occupancy by non‐native plant species are poorly understood. We investigated whether island occupancy by different non‐native plant species declines in relation to their year of first naturalization and whether periods of first naturalization differ among growth forms, dispersal modes, and biogeographic origins. Then, we asked if non‐native plants that naturalized more recently occur more frequently on islands that are large, less isolated, and close to urban areas. We contrasted trends across growth forms, dispersal modes, and biogeographic origins. Location: 264 offshore islands in northern Aotearoa New Zealand. Taxa: Vascular plant species. Methods: We combined field surveys and published data for 767 non‐native plant species on the islands. We categorized each species according to its growth form (n = 3), dispersal mode (n = 4) and biogeographic origin (n = 5) and identified its year of first naturalization in Aotearoa New Zealand. We tested our hypotheses using ANCOVA and generalized linear models (GLMs). Results: There were similar declines in island occupancy in relation to the year of first naturalization in Aotearoa New Zealand across all trait and biogeographic origin categories. First naturalization times of herbaceous species, those with unspecialized dispersal modes, and those originating from Eurasia and the Mediterranean basin were disproportionately earlier than other categories. Non‐native plants with more recent first naturalization occur more frequently on large islands close to urban areas, but not on less isolated ones. Relationships with island characteristics did not differ among trait and biogeographic origin categories. Main Conclusions: Overall, time of first naturalization was more important than trait and biogeographic origin categories in explaining non‐native plant invasion patterns on islands. Since there were similar relationships between island occupancy and the year of first naturalization in Aotearoa New Zealand for all categories, management bodies should focus on non‐native plant species of trait and biogeographic origin categories that have naturalized recently (e.g., woody species from other regions within Oceania), and on large islands close to urban areas. Introduction and naturalization histories provide essential context for interpreting the role of plant traits and biogeographic origin in understanding plant invasions on islands. [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]

Islands are crucial evolutionary hotspots, providing unique opportunities for differentiation of novel biodiversity and long-term segregation of endemic species. Islands are also fragile ecosystems, where biodiversity is more exposed to environmental and anthropogenic pressures than on continents. The Ponza grayling, Hipparchia sbordonii , is an endemic butterfly species that is currently found only in two tiny islands of the Pontine archipelago, off the coast of Italy, occupying an area smaller than 10 km2. It has been classified as Endangered (IUCN) because of the extremely limited area of occurrence, population fragmentation, and the recent demographic decline. Thanks to a combination of different assemblers of long and short genomic reads, bulk transcriptome RNAseq, and synteny analysis with phylogenetically close butterflies, we produced a highly contiguous, chromosome-scale annotated reference genome for the Ponza grayling, including 28 autosomes and the Z sexual chromosomes. The final assembly spanned 388.61 Gb with a contig N50 of 14.5 Mb and a BUSCO completeness score of 98.5%. Synteny analysis using four other butterfly species revealed high collinearity with Hipparchia semele and highlighted 10 intrachromosomal inversions longer than 10 kb, of which two appeared on the lineage leading to H. sbordonii. Our results show that a chromosome-scale reference genome is attainable also when chromatin conformation data may be impractical or present specific technical challenges. The high-quality genomic resource for H. sbordonii opens up new opportunities for the accurate assessment of genetic diversity and genetic load and for the investigations of the genomic novelties characterizing the evolutionary path of this endemic island species. [ABSTRACT FROM AUTHOR]

Aims: Predictable and consistent differences between island and mainland organisms arising from biased colonization/establishment are known as insular assembly rules. Baker's rule is a long‐standing assembly rule predicting that the incidence of dioecy among early island colonizers should be lower than that of the mainland source pool. While Baker's rule is an established pattern of island floras, whether it results from trait correlation or factors other than insularity remains poorly understood. Here, I investigated the relative roles of insularity, climate, and dioecy‐correlated traits in regulating the incidence of dioecy across islands. Location: Southwest Pacific. Methods: I amassed a data set of 485 plant species distributed across eight archipelagos surrounding New Zealand. Trait correlation was estimated using an association rule algorithm. I then used a null model and undirected network models to test for Baker's rule and to disentangle the relative roles of insularity, climate, and dioecy‐correlated traits in filtering dioecy among undifferentiated island colonizers. Results: Some archipelagos conformed to Baker's rule, but the incidence of dioecy was not directly linked to insularity. Instead, it was directly regulated by dioecy‐related traits, that is, fleshy‐fruitedness and woody habit, which in turn were primarily driven by climate. Conclusions: Island assembly rules can result from trait correlation. While results were partially consistent with predictions by Baker's rules, this resulted from dioecy‐related traits being largely excluded from island colonization/establishment because of climatic factors, not insularity. Geographic variation in this plant breeding system can be determined endogenously, rather than by being filtered directly by the characteristics of islands per se. [ABSTRACT FROM AUTHOR]

Plant invasions threaten the biodiversity of islands, causing serious impacts on their ecosystems. To investigate the distribution patterns of invasive alien plants on subtropical islands, the environmental determinants of species richness, and the growth forms of invasive alien plants, this study analyzed the composition and origin of invasive alien plants on 77 islands in Fujian. The similarity in the distribution of invasive alien plants between islands was assessed using the UPGMA. Moreover, feature selection, best-subset regression, and variance decomposition were performed using 19 environmental variables characterizing climate, anthropogenic disturbance, and landscape/geography, as well as the species richness and growth forms of invasive alien plants. Through the analysis, the main environmental factors affecting the species richness and growth forms of invasive alien plants on the Fujian islands were identified. The results showed 142 species of invasive alien plants in 38 families and 102 genera on 77 islands in Fujian. Annual herbs constituted the most representative growth form of invasive alien plants and tropical America was the main origin of invasive alien plants. The distribution of invasive alien plants across the 77 islands in Fujian showed a high degree of similarity, suggesting a nested pattern in their distribution. The proportions of building and farmland area (BFA), island area (A), and maximum elevation (ME) were the main driving factors of species richness and growth forms for invasive alien plants. In particular, BFA played a key role in driving plant invasion. The results of this study can help establish an early warning mechanism for invasive alien plants and better implement island ecological management, which are important for the protection of subtropical island ecosystems. [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]

In depressional freshwater wetlands, habitat size, hydrology, and fish predation are considered key controls on invertebrate assemblages. However, the relative importance of each of these factors is difficult to isolate because the factors are frequently correlated. We assessed controls exerted by habitat size, hydrology, and fish occurrence in a set of 10 Carolina bay wetlands where these factors were largely independent. Invertebrate assemblages were sampled seasonally for six years. Using Joint Species Distribution Modeling of presence/absence and relative abundance data, < 6% of the variance in overall invertebrate assemblages was explained by the combined effects of size, hydrology, and fish occurrence: hydrology explained the most. However, when assessing responses of individual taxa, 32% were responsive, again primarily to variation in hydrology. Habitat size was minimally important. Fish occurrence affected only a handful of taxa, but some of those were key ecologically (abundant consumers). Most taxa responded to only one of the three environmental factors; effect sizes for responses ranged from 2 to 15.6% of total variance explained. Overall, the influences of habitat size, hydrology, and fish occurrence were less important to invertebrates in Carolina bay wetlands than we had presumed, given the prominence of these controls in the wetland invertebrate literature. [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]

Simple Summary: This study investigates the species–area relationship of amphibians on the Zhoushan Archipelago using eDNA metabarcoding. By analyzing amphibian species diversity on the Zhoushan Archipelago, the eDNA metabarcoding detected eight amphibian species on the islands and nine species in the mainland areas. Findings reveal that the amphibian species diversity is positively related to the island area. In comparison with the traditional line transect method, eDNA metabarcoding detected more amphibian species. eDNA showcases enormous potential in detecting amphibian species. The species–area relationship is important for understanding species diversity patterns at spatial scales, but few studies have examined the relationship using environmental DNA (eDNA) techniques. We investigated amphibian diversity on 21 islands of the Zhoushan Archipelago and nearby mainland areas in China using the combination of eDNA metabarcoding and the traditional line transect method (TLTM) and identified the species–area relationship for amphibians on the islands. The mean detection probability of eDNA is 0.54, while the mean detection probability of TLTM is 0.24. The eDNA metabarcoding detected eight amphibian species on the islands and nine species in the mainland areas, compared with seven species on the islands and nine species in the mainland areas that were identified by TLTM. Amphibian richness on the islands increased with island area and habitat diversity. The species–area relationship for amphibians in the archipelago was formulated as the power function (S = 0.47A0.21) or exponential function (S = 2.59 + 2.41 (logA)). Our results suggested that eDNA metabarcoding is more sensitive for the detection of amphibian species. The combined use of eDNA metabarcoding and the traditional line transect method may optimize the survey results for amphibians. [ABSTRACT FROM AUTHOR]

Beta diversity patterns are essential for understanding how biological communities are structured. Geographical and environmental factors, as well as species dispersal ability, are important drivers of beta diversity, but their relative importance may vary across spatial scales. In this study, we evaluate whether beta diversity changes across geographical scales and analyse how different drivers affect turnover patterns of native seed plants in an oceanic archipelago, the Azores (Portugal). Using a 500 × 500 m resolution grid, we selected cells that are covered by one of the following habitats: native forest, naturalized vegetation and seminatural pastures. We calculated species turnover at three spatial scales: 1) between islands, 2) between cells within each island, and finally 3) between cells of each of the habitats of interest in each island. We then calculated the contribution of dispersal syndromes (endozoochory, epizoochory, hydrochory and anemochory) to turnover at each of the scales. Lastly, we assessed the relationship between geographical and climatic distances and habitat type with turnover. Turnover was higher at the smallest spatial scale, particularly in seminatural pastures, and decreased with increasing spatial scales, a pattern potentially associated with the historical fragmentation and current patchy distribution of native forest and seminatural habitats in the Azores. Dispersal syndromes and habitat type had a negligible effect on turnover at all scales. Geographical distance had a positive effect on turnover at all scales, increasing its importance with scale. The relationship between turnover and climatic distance was only significant at the intermediate and small scales in specific islands and habitats. Therefore, scale plays an important role at determining the effect of the drivers of turnover, in particular geographical and climatic distance. These results highlight the need to carefully select the scale of analysis when studying turnover patterns, as well as identifying the potential drivers associated with each spatial scale. [ABSTRACT FROM AUTHOR]