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The armed conflict between Ukraine and Russia that began in late February 2022 has far-reaching environmental consequences, especially regarding water resources and management. Here we analysed the multifaceted impacts of the military actions on freshwater resources and water infrastructure during the first three months of the conflict. We identified the nature of the impacts, the kind of pressures imposed on the water sector and the negative consequences for the availability and quality of freshwater resources for the civilian population. Our results showed that many water infrastructures such as dams at reservoirs, water supply and treatment systems and subsurface mines have been impacted or are at risk from military actions. Continuation of the conflict will have multiple negative sustainability implications not only in Ukraine but also on a global scale, hampering achievement of clean water and sanitation, conservation and sustainable use of water resources, and energy and food security.

The finding that adaptive evolution can often be substantial enough to alter ecological dynamics challenges traditional views of community ecology that ignore evolution. Here, we propose that evolution might commonly alter both local and regional processes of community assembly. We show how adaptation can substantially affect community assembly and that these effects depend on regional (metacommunity) factors, including environmental heterogeneity and its spatial structure. In particular, early colonists can often arrive from a nearby community, adapt to local conditions, and subsequently alter the establishment or abundance of late-arriving species, often producing an evolutionary priority effect. We also discuss how interaction type and relative rates of colonization, evolution, and community interactions determine divergent community outcomes. We describe new conceptual approaches that provide insights into these dynamics and statistical methods that can better evaluate their importance. Overall, we demonstrate that accounting for adaptation during community assembly opens up novel ways for making progress on fundamental questions in community ecology.

ispartof: LIMNOLOGY AND OCEANOGRAPHY status: Published online

The beta diversity among lakes is affected by natural environmental sorting, dispersal constraints, and anthropogenic disturbances. We hypothesized that fish beta diversity would increase towards lower latitudes and be higher in less disturbed lakes at within-region scale, but environmental disturbances could affect these patterns due to community homogenization or heterogenization (e.g., gain of exotic species) among lakes. We used generalized dissimilarity modeling to assess the relative importance of geographic distance, climate, and environmental heterogeneity on fish beta diversity across Denmark, Belgium/The Netherlands, and Spain. We also tested whether differences in beta diversity changed between lake types (e.g., clear vs. turbid lakes and lakes with vs. without exotics fish) within-region and across latitude. Beta diversity increased from Denmark to Spain and geographic distance and climate variability were the main drivers of community change across latitude, but the rate of change varied between lake types. At the within-region scale, factors such as turbidity, lake size, and presence of exotics had varying impacts on beta diversity (i.e., increasing, decreasing, or no effect) across the three regions. Our findings suggest that understanding the effects of environmental disturbances on beta diversity requires consideration of both biogeographic and local factors.

Zooplankton plays a pivotal role in lentic water bodies, linking planktonic primary producers to higher trophic levels and being a cornerstone of the planktonic food web of ponds and lakes. Because of its ease of culture, large size, rich ecology, abundance in northern temperate lakes where limnology is rooted, and the ability to work with clones, Daphnia has, in the last centuries grown to become a key model system in ecology, evolution, and ecotoxicology. Consequently, a vast majority of freshwater zooplankton ecology focuses on the role of Daphnia. While generating essential insights, this has also deviated attention from the broad ecological impact of other zooplankton. Here, we emphasize how other zooplankton taxa have an important impact in nature - often in qualitatively different ways than Daphnia. We illustrate this point by focusing on two key zooplankton functions (herbivory and stoichiometry) and suggest research to capitalize on the success story of mechanistic ecological, eco-evolutionary, and genomic Daphnia work to develop a richer set of model organisms. We currently have the tools to do so and integrating mechanistic insights in multispecies settings would foster a better understanding of the rich diversity and ecology of freshwater zooplankton.

Biotic interactions are suggested to be key factors structuring bacterioplankton community assembly but are rarely included in metacommunity studies. Eutrophication of ponds and lakes provides a useful opportunity to evaluate how bacterioplankton assembly is affected by specific environmental conditions, especially also by biotic interactions with other trophic levels such as phytoplankton and zooplankton. Here, we evaluated the importance of deterministic and stochastic processes on bacterioplankton community assembly in 35 shallow ponds along a eutrophication gradient in Belgium and assessed the direct and indirect effects of phytoplankton and zooplankton community variation on bacterioplankton assembly through a path analysis and network analysis. Environmental filtering by abiotic factors (suspended matter concentration and pH) explained the largest part of the bacterioplankton community variation. Phytoplankton community structure affected bacterioplankton structure through its effect on variation in chlorophyll-a and suspended matter concentration. Bacterioplankton communities were also spatially structured through pH. Overall, our results indicate that environmental variation is a key component driving bacterioplankton assembly along a eutrophication gradient and that indirect biotic interactions can also be important in explaining bacterioplankton community composition. Furthermore, eutrophication led to divergence in community structure and more eutrophic ponds had a higher diversity of bacteria.

Changes in the species richness of (meta-)communities emerge from changes in the relative species abundance distribution (SAD), the total density of individuals, and the amount of spatial aggregation of individuals from the same species. Yet, how human disturbance affects these underlying diversity components at different spatial scales and how this interacts with important species traits, like dispersal capacity, remains poorly understood. Using data of carabid beetle communities along a highly replicated urbanization gradient, we reveal that species richness in urban sites was reduced due to a decline in individual density as well as changes in the SAD at both small and large spatial scales. Changes in these components of species richness were linked to differential responses of groups of species that differ in dispersal capacity. The individual density effect on species richness was due to a drastic 90% reduction of low-dispersive individuals in more urban sites. Conversely, the decrease in species richness due to changes in the SAD at large (i.e. loss of species from the regional pool) and small (i.e. decreased evenness) spatial scales were driven by species with intermediate and high dispersal ability, respectively. These patterns coincide with the expected responses of these dispersal-type assemblages towards human disturbance, namely: (i) loss of low-dispersive species by local extinction processes, (ii) loss of more dispersive species from the regional species pool due to decreased habitat diversity, and (iii) dominance of a few highly dispersive species resulting in a decreased evenness. Our results demonstrate that dispersal capacity plays an essential role in determining scale-dependent changes in species richness patterns. Incorporating this information improves our mechanistic insight into how environmental change affects species diversity at different spatial scales and, thus, allows us to better forecast how human disturbance will drive local and regional changes in biodiversity patterns. This article is protected by copyright. All rights reserved.

Species may cope with warming through both rapid evolutionary and plastic responses. While thermal performance curves (TPCs), reflecting thermal plasticity, are considered powerful tools to understand the impact of warming on ectotherms, their rapid evolution has been rarely studied for multiple traits. We capitalized on a 2-year experimental evolution trial in outdoor mesocosms that were kept at ambient temperatures or heated 4°C above ambient, by testing in a follow-up common-garden experiment, for rapid evolution of the TPCs for multiple key traits of the water flea Daphnia magna . The heat-selected Daphnia showed evolutionary shifts of the unimodal TPCs for survival, fecundity at first clutch and intrinsic population growth rate toward higher optimum temperatures, and a less pronounced downward curvature indicating a better ability to keep fitness high across a range of high temperatures. We detected no evolution of the linear TPCs for somatic growth, mass and development rate, and for the traits related to energy gain (ingestion rate) and costs (metabolic rate). As a result, also the relative thermal slope of energy gain versus energy costs did not vary. These results suggest the overall (rather than per capita ) top-down impact of D. magna may increase under rapid thermal evolution.

Lake Tana is the largest freshwater lake in Ethiopia and is the source of the Blue Nile. The lake shorelines and those of its tributary river, Gilgel Abay, are characterized by the occurrence of extensive papyrus swamps (Cyperus papyrus L). While such papyrus swamps are highly recognized for their outstanding ecological and economical importance, their historical and current spatial distribution and size in the Lake Tana sub basin have not yet been systematically assessed. The primary goal of this study was to estimate the spatial distribution and temporal dynamics of papyrus swamps in the Lake Tana sub basin at five-year intervals over a period of 35 years (1985-2020). Our analyses revealed that the total surface area of the papyrus swamps in the study area declined by almost 55% (from 152 km(2) to 64 km(2)) during the last 35 years. The small patches of papyrus swamps that existed in the northern and eastern parts of the study area prior to the 1990s appear to have disappeared in recent years as well. Our data suggest that the strong decline of papyrus swamps mainly resulted from the expansion of crop farming, livestock overgrazing, drainage, and biomass overharvesting, all of which are increasing over time.

Time is running out to limit further devastating losses of biodiversity and nature's contributions to humans. Addressing this crisis requires accurate predictions about which species and ecosystems are most at risk to ensure efficient use of limited conservation and management resources. We review existing biodiversity projection models and discover problematic gaps. Current models usually cannot easily be reconfigured for other species or systems, omit key biological processes, and cannot accommodate feedbacks with Earth system dynamics. To fill these gaps, we envision an adaptable, accessible, and universal biodiversity modeling platform that can project essential biodiversity variables, explore the implications of divergent socioeconomic scenarios, and compare conservation and management strategies. We design a roadmap for implementing this vision and demonstrate that building this biodiversity forecasting platform is possible and practical.

Ecological processes maintaining landscape genetic variation and metacommunity structure in natural landscapes have traditionally been studied in isolation. Their integrated study may hold important information as to what extent the effect of major ecological processes are species- or landscape-specific, resulting in a more coherent picture on the spatial organization of biodiversity. Here, we explicitly compared the relative importance of spatial and environmental drivers of both cladoceran metacommunity structure as well as landscape genetic structure of its most widespread member, the water fleaDaphnia magna, in soda pans of the Seewinkel region in Austria. The landscape of soda pans in this region is characterized by strong environmental gradients and unidirectional wind acting as a key dispersal agent among these temporary habitats. Our study shows both parallels and divergences in the relative importance of local environmental sorting and spatial connectivity in determining landscape genetic versus metacommunity structure. The metacommunity is structured primarily by the environment, while in theD. magnametapopulation, the spatial signal is predominant. The much weaker environmental signal inDaphniacan be explained by the fact that the microsatellite markers are presumably neutral and was confirmed by a per-allele analysis. An important parallel between metacommunity and landscape genetic structure is the strong signal of the prevailing wind direction in determining the spatial pattern. This suggests that for both community as well as population assembly inD. magna, wind plays an important role in determining connectivity among soda pans, thereby affecting dispersal and colonization rates influencing both local species and genetic composition.

We lack a thorough understanding of the origin and maintenance of standing genetic variation that enables rapid evolutionary responses of natural populations. Whole genome sequencing of a resurrected Daphnia population shows that standing genetic variation in over 500 genes follows an evolutionary trajectory that parallels the pronounced and rapid adaptive evolution of multiple traits in response to predator-driven natural selection and its subsequent relaxation. Genetic variation carried by only five founding individuals from the regional genotype pool is shown to suffice at enabling the observed evolution. Our results provide insight on how natural populations can acquire the genomic variation, through colonization by a few regional genotypes, that fuels rapid evolution in response to strong selection pressures. While these evolutionary responses in our study population involved hundreds of genes, we observed no evidence of genetic erosion., Standing genetic variation allows natural populations to evolve rapidly. Genome sequences of a resurrected Daphnia population show that genetic variation carried by only five founding individuals from the regional genotype pool is enough to fuel rapid evolution in response to strong selection pressures with no evidence of genetic erosion.

In metacommunity ecology, a major focus has been on combining observational and analytical approaches to identify the role of critical assembly processes, such as dispersal limitation and environmental filtering, but this work has largely ignored temporal community dynamics. Here, we develop a "virtual ecologist" approach to evaluate assembly processes by simulating metacommunities varying in three main processes: density-independent responses to abiotic conditions, density-dependent biotic interactions, and dispersal. We then calculate a number of commonly used summary statistics of community structure in space and time and use random forests to evaluate their utility for inferring the strength of these three processes. We find that (i) both spatial and temporal data are necessary to disentangle metacommunity processes based on the summary statistics we test, and including statistics that are measured through time increases the explanatory power of random forests by up to 59% compared to cases where only spatial variation is considered; (ii) the three studied processes can be distinguished with different descriptors; and (iii) each summary statistic is differently sensitive to temporal and spatial sampling effort. Including repeated observations of metacommunities over time was essential for inferring the metacommunity processes, particularly dispersal. Some of the most useful statistics include the coefficient of variation of species abundances through time and metrics that incorporate variation in the relative abundances (evenness) of species. We conclude that a combination of methods and summary statistics is probably necessary to understand the processes that underlie metacommunity assembly through space and time, but we recognize that these results will be modified when other processes or summary statistics are used. ispartof: ECOLOGY vol:103 issue:6 ispartof: location:United States status: published

Historically, many biologists assumed that evolution and ecology acted independently because evolution occurred over distances too great to influence most ecological patterns. Today, evidence indicates that evolution can operate over a range of spatial scales, including fine spatial scales. Thus, evolutionary divergence across space might frequently interact with the mechanisms that also determine spatial ecological patterns. Here, we synthesize insights from 500 eco-evolutionary studies and develop a predictive framework that seeks to understand whether and when evolution amplifies, dampens, or creates ecological patterns. We demonstrate that local adaptation can alter everything from spatial variation in population abundances to ecosystem properties. We uncover 14 mechanisms that can mediate the outcome of evolution on spatial ecological patterns. Sometimes, evolution amplifies environmental variation, especially when selection enhances resource uptake or patch selection. The local evolution of foundation or keystone species can create ecological patterns where none existed originally. However, most often, we find that evolution dampens existing environmental gradients, because local adaptation evens out fitness across environments and thus counteracts the variation in associated ecological patterns. Consequently, evolution generally smooths out the underlying heterogeneity in nature, making the world appear less ragged than it would be in the absence of evolution. We end by highlighting the future research needed to inform a fully integrated and predictive biology that accounts for eco-evolutionary interactions in both space and time.

The increased input of nutrients into biological systems has been shown to result in altered biotic interactions through changes in food availability. The aim of this study was to test for an association between phytoplankton nutrient content and epibiont variables in natural zooplankton populations. Via a field survey, we studied how a gradient in food quantity and quality impacted host population density and epibiont variables in Daphnia pulex . We found a significant decrease in epibiont prevalence and infracommunity richness, which could mainly be attributed to a changing phytoplankton N : P ratio (caused by P‐limitation). We performed a lab experiment in which we exposed Daphnia magna to different algal nutrient ratios and the epibionts detected in the field study. P‐limitation in the algae affected D. magna performance and resulted in similar trends of food quality effects in the epibiont variables. The experiment, however, also reflected subtle differences between different epibiont species.

A key challenge for ecological risk assessment of contaminants under global warming is to predict effects at higher levels of biological organisation. One approach to reach this goal is to study how contaminants and warming cause changes in body stoichiometry as these may potentially cascade through food webs. Furthermore, though contaminants typically interact with warming, how rapid adaptation to higher temperatures affects these interactions is poorly studied. Here, we examined the effects of an important contaminant (ZnO nanoparticles, nZnO) and mild warming (4 °C) on body stoichiometry (C, N, P and their ratios) of an aquatic keystone species, the water flea Daphnia magna. To evaluate whether thermal evolution impacts the effects of nZnO at higher temperatures, we compared two sets of clones from a thermal selection experiment where Daphnia were kept in outdoor mesocosms at ambient or ambient +4 °C temperatures for 2 years. Exposure to nZnO decreased key body stoichiometric ratios (C:N, C:P and a trend for N:P) while warming increased the body C:N ratio. The stoichiometric changes to nZnO and warming were mostly independent and could be partly explained by changes in the macromolecules sugars and fat. Exposure to nZnO decreased C-rich sugars contributing to a reduced %C. Warming reduced body %C due to decreased C-rich sugars and fat levels, yet warming decreased body N% even more resulting in a higher C:N ratio. The stoichiometric responses to nZnO at the higher temperature did not differ between the two sets of clones, indicating experimental thermal evolution did not change the effects of nZnO under warming. Studying the stoichiometric responses to nZnO and warming of this keystone species may provide novel insights on the toxic effects of contaminants under warming. Moreover, understanding the influence of thermal evolution on the toxicity of contaminants is important for ecological risk assessment especially in a warming world. ispartof: ECOTOXICOLOGY vol:29 issue:2 pages:175-184 ispartof: location:United States status: published

Most research on eco-evolutionary feedbacks focuses on ecological consequences of evolution in a single species. This ignores the fact that evolution in response to a shared environmental factor in multiple species involved in interactions could alter the net cumulative effect of evolution on ecology. We empirically tested whether urbanization-driven evolution in a predator (nymphs of the damselfly Ischnura elegans) and its prey (the water flea Daphnia magna) jointly shape the outcome of predation under simulated heatwaves. Both interactors show genetic trait adaptation to urbanization, particularly to higher temperatures. We cross-exposed common-garden reared damselflies and Daphnia from replicated urban and rural populations, and quantified predation rates and functional response traits. Urban damselfly nymphs showed higher encounter and predation rates than rural damselflies when exposed to rural prey, but this difference disappeared when they preyed on urban Daphnia. This represents a case of a cryptic evo-to-eco feedback, where the evolution of one species dampens the effects of the evolution of another species on their interaction strength. The effects of evolution of each single species were strong: the scenario in which only the predator or prey was adapted to urbanization resulted in a c. 250% increase in encounter rate and a c. 25% increase in predation rate, compared to the rural predator-rural prey combination. Our results provide unique evidence for eco-evolutionary feedbacks in cities, and underscore the importance of a multi-species approach in eco-evolutionary dynamics research.Onderzoek naar eco-evolutionaire terugkoppelingen focust vaak op de ecologische gevolgen van evolutie in één soort. Bijgevolg negeert men de mogelijkheid dat evolutionaire veranderingen van meerdere interagerende soorten als respons op een gedeelde omgevingsverandering met elkaar kunnen interfereren en zo het netto effect van evolutie op ecologische processen kan veranderen. We testten empirisch of door verstedelijking gedreven evolutie in een predator (larven van de waterjuffer Ischnura elegans) en zijn prooi (de watervlo Daphnia magna) de uitkomst van predatie onder gesimuleerde hittegolven beïnvloedt. Beide interactoren vertonen genetische adaptatie aan de stadsomgeving, meer specifiek de daar voorkomende hogere temperaturen. We stelden waterjuffers en watervlooien, afkomstig van gerepliceerde stedelijke en rurale populaties en opgegroeid in een gestandaardiseerde laboratoriumomgeving, bloot aan elkaar volgens een experimenteel design waarbij alle combinaties van herkomst van prooi en predator werden getest. We kwantificeerden telkens de predatiesnelheid en functionele respons-kenmerken. Stedelijke waterjufferlarven vertoonden een hogere ontmoetings- en predatiesnelheid dan larven afkomstig uit rurale gebieden wanneer ze blootgesteld werden aan rurale Daphnia, maar niet wanneer ze blootgesteld werden aan Daphnia afkomstig uit de stad. Deze bevinding wijst op een cryptische evo-naar-eco terugkoppeling, waarbij evolutie in één van de soorten het effect van evolutie van de andere soort op de sterkte van hun interactie dempt. De effecten van evolutie in elke soort apart waren sterk: de scenario's waarin enkel de predator of de prooi aangepast was aan de stadsomgeving resulteerde in een c. 250% stijging van de ontmoetingssnelheid en een c. 25% verhoging van de predatiesnelheid, in vergelijking met een situatie waarbij een rurale predator met een rurale prooi was gecombineerd. Deze resultaten leveren uniek bewijs voor een eco-evolutionaire terugkoppeling in steden en onderlijnen het belang van een multi-soorten benadering in het onderzoek naar eco-evolutionaire dynamieken.

Global freshwater biodiversity is declining dramatically, and meeting the challenges of this crisis requires bold goals and the mobilisation of substantial resources. While the reasons are varied, investments in both research and conservation of freshwater biodiversity lag far behind those in the terrestrial and marine realms. Inspired by a global consultation, we identify 15 pressing priority needs, grouped into five research areas, in an effort to support informed stewardship of freshwater biodiversity. The proposed agenda aims to advance freshwater biodiversity research globally as a critical step in improving coordinated actions towards its sustainable management and conservation. ispartof: ECOLOGY LETTERS vol:25 issue:2 pages:255-263 ispartof: location:England status: published

Predators can strongly influence prey populations through both consumptive and non-consumptive effects. Nevertheless, most studies have focused on the consumptive effects in driving evolutionary changes. By integrating experimental evolution and resurrection ecology, we tested the roles of non-consumptive and consumptive effects in driving evolution in a Daphnia magna population that experienced strong changes in fish predation pressure. All resurrected genotypes were pooled, inoculated in outdoor mesocosms, and exposed to free-fish or caged-fish treatments. Non-consumptive effects induced rapid, repeatable changes in the clonal composition and associated genotypic trait changes that were similar in magnitude and direction to those imposed by killing. Both non-consumptive and consumptive effects caused a shift towards a dominance of the high-fish period clones that can perform better under fish predation, and this may be explained by the higher intrinsic growth rate of the high-fish period clones under predation risk. The genotypic trait changes (e.g. reduced body sizes, earlier maturation, more and smaller offspring) of the Daphnia in the mesocosm experiments were in the same direction as the adaptive trait shifts observed in situ through resurrection ecology. Our results demonstrate that non-consumptive effects can induce rapid adaptive evolution and may represent an overlooked driver of eco-evolutionary dynamics.

The present study investigates the relative importance of human disturbance, local environmental and spatial factors on variations in bird community composition in natural Ethiopian wetlands with high biodiversity conservation value. We quantified bird abundances, local environmental variables and human disturbances at 63 sites distributed over ten wetlands in two subsequent years. Variation partitioning analyses were used to explore the unique and shared contributions of human disturbance, local environmental variables and spatial factors on variations in community compositions of wetland bird species. Local environmental variables explained the largest amount of compositional variation of wetland bird species. Productivity-related variables were the most important local environmental variables determining bird community composition. Human disturbance was also an important determinant for wetland bird community composition and affected the investigated communities mainly indirectly through its effect on local environmental conditions. Spatial factors only played a minor role in variations in bird community composition. Our study highlights the urgent need for integrated management approaches that consider both nature conservation targets and socio-economic development of the region for the sustainable use and effective conservation of wetland resources.

There is growing concern about the dire socioecological consequences of abrupt transitions between alternative ecosystem states in response to environmental changes. At the same time, environmental change can trigger evolutionary responses that could stabilize or destabilize ecosystem dynamics. However, we know little about how coupled ecological and evolutionary processes affect the risk of transition between alternative ecosystem states. Using shallow lakes as a model ecosystem, we investigate how trait evolution of a key species affects ecosystem resilience under environmental stress. We find that adaptive evolution of macrophytes can increase ecosystem resilience by shifting the critical threshold, which marks the transition from a clear-water state to a turbid-water state to a higher level of environmental stress. However, following the transition, adaptation to the turbid-water state can delay the ecosystem recovery back to the clear-water state. This implies that restoration could be more effective when implemented early enough after a transition occurs and before organisms adapt to the alternative state. Our findings provide new insights into how to prevent and mitigate the occurrence of regime shifts in ecosystems and highlight the need to understand ecosystem responses to environmental change in the context of coupled ecological and evolutionary processes.

There are currently few predictions about when evolutionary processes are likely to play an important role in structuring community features. Determining predictors that indicate when evolution is expected to impact ecological processes in natural landscapes can help researchers identify eco-evolutionary ���hotspots', where eco-evolutionary interactions are more likely to occur. Using data collected from a survey in freshwater cladoceran communities, landscape population genetic data and phenotypic trait data measured in a common garden, we applied a Bayesian linear model to assess whether the impact of local trait evolution in the keystone species Daphnia magna on cladoceran community trait values could be predicted by population genetic properties (within-population genetic diversity, genetic distance among populations), ecological properties (Simpson's diversity, phenotypic divergence) or environmental divergence. We found that the impact of local trait evolution varied among communities. Moreover, community diversity and phenotypic divergence were found to be better predictors of the contribution of evolution to community trait values than environmental features or genetic properties of the evolving species. Our results thus indicate the importance of ecological context for the impact of evolution on community features. Our study also demonstrates one way to detect signatures of eco-evolutionary interactions in communities inhabiting heterogeneous landscapes using survey data of contemporary ecological and evolutionary structure.

To what extent does landscape genetic structure bear the signature of arrival order of lineages during population assembly? Rapid genetic adaptation of resident populations founded by early colonists to local conditions might prevent establishment of later-arriving lineages, resulting in an evolution-mediated priority effect. This might result in a limited window of opportunity for establishment during which the resident population did not have sufficient time yet to monopolize the patch through local adaptation. The length of this window of opportunity is expected to depend on the degree to which early colonists and immigrants are preadapted to local habitat conditions. We present an intraspecific competition model of the initial transient population and evolutionary dynamics that quantifies the window of opportunity for establishment for asexual species. The model explicitly addresses the long-lasting effects of evolution-mediated priority effects by tracking lineages through time. Our results show that the difference in initial preadaptation between early colonists and late immigrants and the speed of evolution codetermine the window of opportunity for establishment. Our results also suggest that local populations should often be dominated by descendants of just a few early colonist lineages and that landscape genetic structure should often reflect the legacy of colonization history. ispartof: American Naturalist vol:198 issue:4 pages:E95-E110 ispartof: location:United States status: accepted

Current analyses of metacommunity data largely focus on global attributes across the entire metacommunity, such as mean alpha, beta, and gamma diversity, as well as the partitioning of compositional variation into single estimates of contributions of space and environmental effects and, more recently, possible contributions of species interactions. However, this view neglects the fact that different species and sites in the landscape can vary widely in how they contribute to these metacommunity-wide attributes. We argue for a new conceptual framework with matched analytics with the goals of studying the complex and interactive relations between process and pattern in metacommunities that is focused on the variation among species and among sites which we call the ‘internal structure’ of the metacommunity. To demonstrate how the internal structure could be studied, we create synthetic data using a process-based colonization-extinction metacommunity model. We then use Joint Species Distribution Models to estimate how the contributions of space, environment and biotic interactions driving metacommunity assembly differ among species and sites. We find that this approach to the internal structure of metacommunities provides useful information about the distinct ways that different species and different sites contribute to metacommunity structure. Although it has limitations, our work points at a more general approach to understand how other possible complexities might affect internal structure and might thus be incorporated into a more cohesive metacommunity theory.

Many organisms that live in inland standing waters produce dormant life stages that can accumulate in propagule banks to survive temporarily unfavourable periods. These egg banks have important effects on the ecology of populations and communities in terms of phenology, population densities, the probability of extinction, species diversity and habitat connectivity in time and space. They also have important consequences for the evolutionary versatility of populations. Although diapause and dormant egg banks in freshwater zooplankton have been studied for several decades, little is known about the quantitative contribution of egg production and hatching to yearly egg bank budgets and their seasonality in natural ponds and lakes. Here we quantified inter- and intra-annual variation in hatching and dormant egg production in the water flea Daphnia magna in two natural shallow ponds in Flanders (Belgium) using high-intensity sampling and in situ measurements. Hatching started in spring and occurred in several bouts (April–July), accumulating to a yearly average total of 3.5 × 10 3 hatchlings m −2. Dormant egg production occurred in one-to-three bouts mainly during late spring and summer (May–August), resulting in a total yearly production ranging from 1.2 × 10 4 up to 17.3 × 10 4 ephippia m −2. In both years, there was an average surplus of 3.14 × 10 4 and 15.24 × 10 4 ephippia produced m −2 for ponds OM2 and OM3, respectively, contributing to the accumulation of the persistent egg bank. We discuss the ecological and evolutionary consequences of both the high number of ephippia that are produced and the high number of hatchlings at the start of each growing season.

© 2018 Association for the Sciences of Limnology and Oceanography How grazer selectivity regulates the primary producer community is a core topic in ecology. Yet, the role of zooplankton grazing selection on phytoplankton dynamics is poorly understood. Few studies have compared the effect of grazers with contrasting selectivity on mixed phytoplankton prey, and none over multiple phytoplankton generations. We tested the hypothesis that a selectively grazing copepod (Eudiaptomus gracilis) would facilitate the dominance of a toxic cyanobacterium (Microcystis aeruginosa) by grazing on a competing eukaryotic microalga (Cryptomonas pyrenoidifera), while a generalist cladoceran (Daphnia magna) would have no effect on the dominance of cyanobacteria in 4-d laboratory cocultures. Experiments started with a ninefold initial dominance of Cryptomonas over Microcystis by biomass. Each grazer type was added to cocultured phytoplankton and the abundance of phytoplankton was compared to no-grazer controls. As predicted, Daphnia had no effect on the relative abundance of its prey and the copepod facilitated Microcystis dominance, although the strength of facilitation slightly declined with time. As the copepod reduced mostly the biomass of the edible algae, it pushed the system toward the dominance of toxic prey, which likely reduced the efficiency of selective grazing on the last day. Hence, while the selective grazer promoted cyanobacterial dominance, the effect may be weaker than predicted from extrapolating grazing rates obtained from short-term (i.e., hourly) assays. Overall, predicting the role of zooplankton selectivity on phytoplankton dynamics—especially harmful algal blooms—would benefit from accounting for fluctuations in grazer effects due to shifting abundance and growth of each prey over time. ispartof: LIMNOLOGY AND OCEANOGRAPHY vol:64 issue:3 pages:1214-1227 status: published