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6,771 results for “freshwater”
Data from: Adaptive phenotypic plasticity and local adaptation for temperature tolerance in freshwater zooplankton
Many organisms have geographical distributions extending from the tropics to near polar regions or can experience up to 30°C temperature variation within the lifespan of an individual. Two forms of evolutionary adaptation to such wide ranges in ambient temperatures are frequently discussed: local adaptation and phenotypic plasticity. The freshwater planktonic crustacean Daphnia magna, whose range extends from South Africa to near arctic sites, shows strong phenotypic and genotypic variation in response to temperature. In this study, we use D. magna clones from 22 populations (one clone per population) ranging from latitude 0° (Kenya) to 66° North (White Sea) to explore the contributions of phenotypic plasticity and local adaptation to high temperature tolerance. Temperature tolerance was studied as knockout time (time until immobilization, Timm) at 37°C in clones acclimatized to either 20°C or 28°C. Acclimatization to 28°C strongly increased Timm, testifying to adaptive phenotypic plasticity. At the same time, Timm significantly correlated with average high temperature at the clones' sites of origin, suggesting local adaptation. As earlier studies have found that haemoglobin expression contributes to temperature tolerance, we also quantified haemoglobin concentration in experimental animals and found that both acclimatization temperature (AccT) and temperature at the site of origin are positively correlated with haemoglobin concentration. Furthermore, Daphnia from warmer climates upregulate haemoglobin much more strongly in response to AccT, suggesting local adaptation for plasticity in haemoglobin expression. Our results show that both local adaptation and phenotypic plasticity contribute to temperature tolerance, and elucidate a possible role of haemoglobin in mediating these effects that differs along a cold–warm gradient.
Data from: Next-generation freshwater bioassessment: eDNA metabarcoding with a conserved metazoan primer reveals species-rich and reservoir-specific communities
Freshwater habitats are of high conservation value and provide a wide range of ecosystem services. Effective management requires regular monitoring. However, conventional methods based on direct observation or specimen collection are so invasive, expensive and labour-intensive that frequent monitoring is uncommon. Here, we test whether the evaluation of environmental DNA (eDNA) from water based on a simple protocol can be used for assessing biodiversity. We use universal metazoan primers for characterizing water eDNA across horizontal and vertical spatial dimensions in two reservoirs with known species diversity for two key taxa. eDNA obtained directly from 42 samples × 15 ml water (total = 630 ml) per reservoir yielded DNA signatures for more than 500 metazoan species, of which 105 could be identified to species/genus based on DNA barcodes. We show that eDNA can be used to assign each water sample to its reservoir of origin, and that eDNA outperforms conventional survey methods in single-sample richness comparisons, while revealing evidence for hundreds of unknown species that are undetected by conventional bioassessment methods. eDNA also confirms the presence of a recently discovered invasive snail species and provides evidence for the continued survival of a rare native species of goby not sighted in that habitat since 2007. eDNA thus promises to be a useful addition to the bioassessment toolbox for freshwater systems.
Data from: Cardiac plasticity influences aerobic performance and thermal tolerance in a tropical, freshwater fish at elevated temperatures
Fishes faced with novel thermal conditions often modify physiological functioning to compensate for elevated temperatures. This physiological plasticity (thermal acclimation) has been shown to improve metabolic performance and extend thermal limits in many species. Adjustments in cardiorespiratory function are often invoked as mechanisms underlying thermal plasticity because limitations in oxygen supply have been predicted to define thermal optima in fishes, however few studies have explicitly linked cardiorespiratory plasticity to metabolic compensation. Here we quantify thermal acclimation capacity in the commercially harvested Nile perch (Lates niloticus) of East Africa, and investigate mechanisms underlying observed changes. We reared juvenile Nile perch for 3 months under two temperature regimes, and then measured a series of metabolic traits (e.g., aerobic scope, AS) and critical thermal maximum (CTmax) upon acute exposure to a range of experimental temperatures. We also measured morphological traits of heart ventricles, gills, and brains to identify potential mechanisms for compensation. We found that long-term (3-months) exposure to elevated temperature induced compensation in upper thermal tolerance (CTmax) and metabolic performance (SMR, MMR and AS), and induced cardiac remodeling in Nile perch. Furthermore, variation in heart morphology influenced variations in metabolic function and thermal tolerance. These results indicate that plastic changes enacted over longer exposures lead to differences in metabolic flexibility when acutely exposed to temperature variation. Furthermore, we established functional links between cardiac plasticity, metabolic performance, and thermal tolerance, providing evidence that plasticity in cardiac capacity may be one mechanism for coping with climate change.
Data from: Gene expression plasticity evolves in response to colonization of freshwater lakes in threespine stickleback
Phenotypic plasticity is predicted to facilitate individual survival and/or evolve in response to novel environments. Plasticity that facilitates survival should both permit colonization and act as a buffer against further evolution, with contemporary and derived forms predicted to be similarly plastic for a suite of traits. On the other hand, given the importance of plasticity in maintaining internal homeostasis, derived populations that encounter greater environmental heterogeneity should evolve greater plasticity. We tested the evolutionary significance of phenotypic plasticity in coastal British Columbian postglacial populations of threespine stickleback (Gasterosteus aculeatus) that evolved under greater seasonal extremes in temperature after invading freshwater lakes from the sea. Two ancestral (contemporary marine) and two derived (contemporary freshwater) populations of stickleback were raised near their thermal tolerance extremes, 7°C and 22°C. Gene expression plasticity was estimated for more than 14 000 genes. Over five thousand genes were similarly plastic in marine and freshwater stickleback, but freshwater populations exhibited significantly more genes with plastic expression than marine populations. Furthermore, several of the loci shown to exhibit gene expression plasticity have been previously implicated in the adaptive evolution of freshwater populations, including a gene involved in mitochondrial regulation (PPARAa). Collectively, these data provide molecular evidence that highlights the importance of plasticity in colonization and adaptation to new environments.
Data from: Diatoms do radiate: evidence for a freshwater species flock
Due to the ubiquity and high dispersal capacity of unicellular eukaryotes, their often extraordinary diversity found in isolated and long-lived ecosystems such as ancient lakes is typically attributed to multiple colonization events rather than to in situ speciation. However, respective evolutionary studies are very scarce and the often high number of species flocks in ancient lakes across multicellular taxa raises the question whether unicellular species, such as diatoms, may radiate as well. Here, we use an integrative approach that includes molecular data from benthic diatom species of the genus Aneumastus endemic to ancient Lake Ohrid, fossil data obtained from the sediment record of a recent deep-drilling project and biogeographical information to test if this group, indeed, constitutes a species flock. Molecular-clock and phylogenetic analyses indicate a young monophyletic group of several endemic species. Molecular, fossil and biogeographical data strongly suggest a rapid intra-lacustrine diversification, which was possibly triggered by the emergence of novel habitats. This finding is the first evidence for a species flock in diatoms and suggests that in situ speciation is also a relevant evolutionary process for unicellular eukaryotes in isolated ecosystems.
Data from: Abundance inequality in freshwater communities has an ecological origin
The hollow-shaped species abundance distribution (SAD) and its allied rank abundance distribution (RAD)—showing that abundance is unevenly distributed among species—are some of the most studied patterns in ecology. To explain the nature of abundance inequality, I developed a novel framework identifying environmental favorability, which controls the balance between reproduction and immigration, as the ultimate source and species stress tolerance as a proximate factor. Thus, under harsh conditions, only a few tolerant species can reproduce, while some sensitive species can be present in low numbers due to chance immigration. This would lead to high abundance inequality between the two groups of species. Under benign conditions, both groups can reproduce and give rise to higher abundance equality. To test these ideas, I examined the variability in the parameters of a Poisson lognormal fit of the SAD and a square root fit of the RAD in diatom and fish communities across US streams. Indeed, as environmental favorability increased, more sensitive forms were able to establish large populations, diminishing the abundance disparity between locally common and rare species. Finally, it was demonstrated that in diatoms, the RAD belonged to the same family of relationships as those of population density with body size and regional distribution.
Data from: Parasite-induced inversion of geotaxis in a freshwater amphipod: a role for anaerobic metabolism?
Many parasites with complex life-cycles alter the phenotype of their intermediate hosts in ways that seem to favor transmission to a final host. Although there is a large literature on host manipulation, how parasites alter the phenotype of their hosts remains poorly known. The bird acanthocephalan Polymorphus minutus is known to alter geotaxis in its amphipod host, Gammarus roeseli. Here we examine the potential roles of low oxygen availability and the excretion, by the parasite, of two products from its own anaerobic metabolism (lactate and succinate) in altered geotaxis. Under hypoxia, uninfected Gammarus roeseli showed negative geotaxis and lower metabolic rate, two traits also altered by infection with P. minutus, albeit with different intensities. The injection of a mixture of lactate and succinate in uninfected amphipods mimicked the parasite-induced reversion of geotaxis, without affecting the metabolic rate. In addition, both P. minutus-infected gammarids and uninfected ones conditioned to hypoxia for two days showed elevated levels of lactate in the brain, but not in the hemolymph. Overall, our results indicate that the pathways involved in anaerobic metabolism and hypoxia-signalling might be responsible for the changes in geotaxis and metabolic rate induced by P. minutus infection. Our study emphasizes the need to consider the tight and complex connections between physiological processes and behavioural adjustments, in particular at the brain level, in the understanding of parasitic manipulation, and more broadly of behavioural changes in infected hosts.
Data from: Catchment zoning for freshwater conservation: refining plans to enhance action on the ground
1. Recent advances in freshwater conservation planning allow addressing some of the specific needs of these systems. These include spatial connectivity or propagation of threats along stream networks, essential to ensure the maintenance of ecosystem processes and the biodiversity they sustain. However, these peculiarities make conservation recommendations difficult to implement as they often require considering large areas that cannot be managed under conventional conservation schemes (e.g. strict protection). 2. To facilitate the implementation of conservation in freshwater systems, a multizoning approach with different management zones subject to different management regimes was proposed. So far, this approach has only been used in post hoc exercises where zones were allocated using expert criteria. This might undermine the cost-effectiveness of conservation recommendations, because both the allocation and extent of these zones have never been optimized using the principles of systematic planning. 3. Here, we demonstrate how to create a catchment multizone plan by using a commonly applied tool in marine and terrestrial realms. We first test the capability of Marxan with Zones to address problems in rivers by using a simulated example and then apply the findings to a real case in the Daly River catchment, northern Australia. We also demonstrate how to address common conservation planning issues, such as accounting for threats or species-specific connectivity needs in this multizone framework, and evaluate their effects on the spatial distribution and extent of different zones. 4. We found that by prioritizing the allocation of zones subject to different management regimes, we could minimize the total area in need of strict conservation by a twofold factor. This reduction can be further reduced (threefold) when considering species' connectivity needs. The integration of threats helped reduce the average threats of areas selected by a twofold factor. 5. Synthesis and applications. Catchment zoning can help refine conservation recommendations and enhance cost-effectiveness by prescribing different management regimes informed by ecological needs or distribution of threats. Reliable information on these factors is a key to ensure soundness of planning. Freely available software can be used to implement the approach we demonstrate here.
Data from: Ecological interactions and coexistence are predicted by gene expression similarity in freshwater green algae
Phenotypic variation controls the species interactions which determine whether or not species coexist. Long-standing hypotheses in ecology and evolution posit that phenotypic differentiation enables coexistence by increasing the size of niche differentiation. This hypothesis has only been tested using macroscopic traits to date, but niche differentiation, particularly of microscopic organisms, also occurs at the molecular and metabolic level. We examined how phenotypic variation that arises at the level of gene expression over evolutionary time affects phytoplankton species interactions and coexistence. We predicted that similarity in gene expression among species would decline with phylogenetic distance, and that reduced similarity in gene expression would weaken competition, increase facilitation and promote coexistence. To test this, we grew eight species of freshwater green algae in monocultures and bicultures for 46 days in a laboratory microcosm experiment. We quantified the strength of species interactions by: (i) fitting Lotka–Volterra models to time-series densities and estimating interaction coefficients, and (ii) calculating relative densities that compare species' steady-state densities in biculture to those in monoculture. We used Illumina high throughput sequencing to quantify the expression of 1253 families of homologous genes, including a set of 17 candidate genes that we hypothesized a priori to be involved in competition or facilitation. Synthesis. We found that closely related species had greater similarity in gene expression than did distantly related species, but as gene expression became more similar, species experienced weaker competition or greater facilitation, and were more likely to coexist. We identified gene functional categories that were uniquely differentially regulated in association with particular species interaction types. Contrary to common thinking in ecology and evolution, similarity in gene expression, and not differentiation, was associated with weaker competition, facilitation and coexistence.
Data from: Taxonomic challenges in freshwater fishes: a mismatch between morphology and DNA barcoding in fish of the north-eastern part of the Congo basin
This study evaluates the utility of DNA barcoding to traditional morphology-based species identifications for the fish fauna of the north-eastern Congo basin. We compared DNA sequences (COI) of 821 samples from 206 morphologically identified species. Best match, best close match and all species barcoding analyses resulted in a rather low identification success of 87.5%, 84.5% and 64.1%, respectively. The ratio 'nearest-neighbour distance/maximum intraspecific divergence' was lower than 1 for 26.1% of the samples, indicating possible taxonomic problems. In ten genera, belonging to six families, the number of species inferred from mtDNA data exceeded the number of species identified using morphological features; and in four cases indications of possible synonymy were detected. Finally, the DNA barcodes confirmed previously known identification problems within certain genera of the Clariidae, Cyprinidae and Mormyridae. Our results underscore the large number of taxonomic problems lingering in the taxonomy of the fish fauna of the Congo basin and illustrate why DNA barcodes will contribute to future efforts to compile a reliable taxonomic inventory of the Congo basin fish fauna. Therefore, the obtained barcodes were deposited in the reference barcode library of the Barcode of Life Initiative.
Data from: Assessing species boundaries using multilocus species delimitation in a morphologically conserved group of Neotropical freshwater fishes, the Poecilia sphenops species complex (Poeciliidae)
Accurately delimiting species is fundamentally important for understanding species diversity and distributions and devising effective strategies to conserve biodiversity. However, species delimitation is problematic in many taxa, including 'non-adaptive radiations' containing morphologically cryptic lineages. Fortunately, coalescent-based species delimitation methods hold promise for objectively estimating species limits in such radiations, using multilocus genetic data. Using coalescent-based approaches, we delimit species and infer evolutionary relationships in a morphologically conserved group of Central American freshwater fishes, the Poecilia sphenops species complex. Phylogenetic analyses of multiple genetic markers (sequences of two mitochondrial DNA genes and five nuclear loci) from 10/15 species and genetic lineages recognized in the group support the P. sphenops species complex as monophyletic with respect to outgroups, with eight mitochondrial 'major-lineages' diverged by ≥2% pairwise genetic distances. From general mixed Yule-coalescent models, we discovered (conservatively) 10 species within our concatenated mitochondrial DNA dataset, 9 of which were strongly supported by subsequent multilocus Bayesian species delimitation and species tree analyses. Results suggested species-level diversity is underestimated or overestimated by at least ~15% in different lineages in the complex. Nonparametric statistics and coalescent simulations indicate genealogical discordance among our gene tree results has mainly derived from interspecific hybridization in the nuclear genome. However, mitochondrial DNA show little evidence for introgression, and our species delimitation results appear robust to effects of this process. Overall, our findings support the utility of combining multiple lines of genetic evidence and broad phylogeographical sampling to discover and validate species using coalescent-based methods. Our study also highlights the importance of testing for hybridization versus incomplete lineage sorting, which aids inference of not only species limits but also evolutionary processes influencing genetic diversity.
Data from: Hidden diversity in the freshwater planktonic diatom Asterionella formosa
Many freshwater and marine algal species are described as having cosmopolitan distributions. Whether these widely distributed morphologically similar algae also share a similar gene pool remains often unclear. In the context of island biogeography theory, stronger spatial isolation deemed typical of freshwater lakes should restrict gene flow and lead to higher genetic differentiation among lakes. Using nine microsatellite loci, we investigate the genetic diversity of a widely distributed freshwater planktonic diatom, Asterionella formosa, across different lakes in Switzerland and the Netherlands. We applied a hierarchical spatial sampling design to determine the geographical scale at which populations are structured. A subset of the isolates was additionally analysed using amplified fragment length polymorphism (AFLP) markers. Our results revealed complex and unexpected population structure in A. formosa with evidence for both restricted and moderate to high gene flow at the same time. Different genetic markers (microsatellites and AFLPs) analysed with a variety of multivariate methods consistently revealed that genetic differentiation within lakes was much stronger than among lakes, indicating the presence of cryptic species within A. formosa. We conclude that the hidden diversity found in this study is expected to have implications for the further use of A. formosa in biogeographical, conservation and ecological studies. Further research using species-level phylogenetic markers is necessary to place the observed differentiation in an evolutionary context of speciation.
Data from: Phylogenetic evidence from freshwater crayfishes that cave adaptation is not an evolutionary dead-end
Caves are perceived as isolated, extreme habitats with a set of uniquely specialized biota, which long ago led to the idea that caves are 'evolutionary dead-ends.' This suggests that cave-adapted taxa may be doomed for extinction before they can diversify or transition to a more stable state. However, this hypothesis has not been explicitly tested in a phylogenetic framework with multiple independent cave-dwelling groups. Here we use the freshwater crayfish, a group with dozens of cave-dwelling species in multiple lineages, as a system to test this hypothesis. We consider historical patterns of lineage diversification and habitat transition as well as current patterns of geographic range size. We find that while cave-dwelling lineages have small relative range sizes and rarely transition back to the surface, they exhibit remarkably similar diversification patterns to those of other habitat types and appear to be able to maintain a diversity of lineages through time. This suggests that cave-adaptation is not a 'dead-end' for freshwater crayfish, which has positive implications for our understanding of biodiversity and conservation in cave habitats.
Data from: Spatial representativeness of environmental DNA metabarcoding signal for fish biodiversity assessment in a natural freshwater system
In the last few years, the study of environmental DNA (eDNA) has drawn attention for many reasons, including its advantages for monitoring and conservation purposes. So far, in aquatic environments, most of eDNA research has focused on the detection of single species using species-specific markers. Recently, species inventories based on the analysis of a single generalist marker targeting a larger taxonomic group (eDNA metabarcoding) have proven useful for bony fish and amphibian biodiversity surveys. This approach involves in situ filtering of large volumes of water followed by amplification and sequencing of a short discriminative fragment from the 12S rDNA mitochondrial gene. In this study, we went one step further by investigating the spatial representativeness (i.e. ecological reliability and signal variability in space) of eDNA metabarcoding for large-scale fish biodiversity assessment in a freshwater system including lentic and lotic environments. We tested the ability of this approach to characterize large-scale organization of fish communities along a longitudinal gradient, from a lake to the outflowing river. First, our results confirm that eDNA metabarcoding is more efficient than a single traditional sampling campaign to detect species presence, especially in rivers. Second, the species list obtained using this approach is comparable to the one obtained when cumulating all traditional sampling sessions since 1995 and 1988 for the lake and the river, respectively. In conclusion, eDNA metabarcoding gives a faithful description of local fish biodiversity in the study system, more specifically within a range of a few kilometers along the river in our study conditions, i.e. longer than a traditional fish sampling site.
Beyond pairwise interactions: multispecies character displacement in Mexican freshwater fish communities
Competition has long been recognized as a central force in shaping evolution, particularly through character displacement. Yet research on character displacement is biased as it has focused almost exclusively on pairs of interacting species, while ignoring multispecies interactions. Communities are seldom so simple that only pairs of species interact, and it is not clear if inferences from pairwise interactions are sufficient to explain patterns of phenotypes in nature. Here we test for character displacement in a natural system of freshwater fishes in western Mexico that contains up to four congeneric species of the genus Poeciliopsis. We analyzed body shape differences between populations with different numbers of competitors while accounting for confounding environmental variables. Surprisingly, we found evidence for convergent character displacement in populations of P. prolifica, P. viriosa and P. latidens. We also found that the convergence in body shape was not consistently in the same direction, meaning that when three or more competitors co-occurred, we did not find more extreme body shapes compared to when there were only two competitors. Instead, when three or more competitors co-occur, body shape was intermediate to the shape found with a pair of species or no competitor present. This intermediate shape suggests that evolution in multispecies communities likely occurs in response to several competitors, rather than to simple pairwise interactions. Overall, our results suggest that competition among multiple species is more complex than simple pairwise competitive interactions.
Data from: Submerged macrophytes mitigate direct and indirect insecticide effects in freshwater communities
Understanding how ecological interactions mitigate the impacts of perturbations such as pesticides in biological communities is an important basic and applied question for ecologists. In aquatic ecosystems, new evidence from microcosm experiments suggests that submerged macrophytes can buffer cladocerans from pulse exposures to the widely used insecticide malathion, and that mitigation increases with macrophyte density. However, whether these results scale up to more complex aquatic communities where ecological interactions such as competition can alter toxicity is unknown. Further, macrophyte abilities to mitigate different insecticide exposure scenarios (i.e. single versus repeated pulses) have never been tested. To address these gaps, we performed a factorial mesocosm experiment examining the influence of four macrophyte treatments (0, 10, 50, or 100 Elodea Canadensis shoots planted per mesocosm) crossed with three malathion exposure scenarios (no insecticide, single pulse, repeated pulses) on aquatic communities containing zooplankton, phytoplankton, periphyton, two snail species, and larval amphibians. In the absence of macrophytes, single malathion pulses caused short-term declines in cladoceran abundance followed by their rapid recovery, which precluded any indirect effects (i.e. trophic cascades). However, repeated malathion pulses caused cladoceran extinctions, resulting in persistent phytoplankton blooms and reduced abundance of one snail species. In contrast, with macrophytes present, even at low density, malathion had no effect on any taxa. We also discovered novel effects of macrophytes on the benthic food web. In the two highest macrophyte treatments, we observed trends of reduced periphyton biomass, decreased abundance of one snail species, and decreased amphibian time to and mass at metamorphosis. To our knowledge, this is the first evidence of negative submerged macrophyte effects on amphibians, a taxa of global conservation concern. Our findings suggest that facilitating macrophytes could be an important strategy for buffering freshwater communities from insecticides, though consideration of their impacts on animal species is necessary.
Data from: Phylogeography of the Australian freshwater turtle Chelodina expansa reveals complex relationships among inland and coastal bioregions
We examined range-wide mitochondrial phylogeographic structure in the riverine freshwater turtle Chelodina expansa to determine if this species exhibits deep genetic divergence between coastal and inland hydrological provinces as seen in co-distributed freshwater taxa. We sequenced two mitochondrial loci, genealogical relationships were assessed using a network approach, and relationships among biogeographic regions were tested using analyses of molecular variance. Population history was evaluated using neutrality tests, indices of demographic expansion, and mismatch analyses. Twenty one haplotypes were recovered across two mitochondrial haplogroups separated by ca 4% nucleotide divergence. The haplogroups have discrete geographic boundaries but only partially support a hypothesis of deep divergence between coastal and inland bioregions. The first haplogroup comprises populations from the inland Murray-Darling Basin and from coastal catchments south of the Mary River in southeast Queensland. The second haplogroup comprises populations from coastal catchments north of the Mary River. Cryptic phylogeographic barriers separating adjacent coastal populations are congruent with those demonstrated for other freshwater taxa and may result from the combined influences of the Conondale Range and alluvial deposits at the mouth of the Mary River. Our study demonstrates that freshwater taxa commonly display genetic differentiation within a biogeographic region where no boundaries have been recognised, highlighting the need to uncover cryptic microbiogeographic regions to aid conservation of freshwater biota.
Data from: Herbivory promotes dental disparification and macroevolutionary dynamics in grunters (Teleostei: Terapontidae), a freshwater adaptive radiation
Trophic shifts into new adaptive zones have played major (although often conflicting) roles in reshaping the evolutionary trajectories of many lineages. We analyze data on diet, tooth, and oral morphology and relate these traits to phenotypic disparification and lineage diversification rates across the ecologically diverse Terapontidae, a family of Australasian fishes. In contrast to carnivores and most omnivores, which have retained relatively simple, ancestral caniniform tooth shapes, herbivorous terapontids appear to have evolved a variety of novel tooth shapes at significantly faster rates to meet the demands of plant-based diets. The evolution of herbivory prompted major disparification, significantly expanding the terapontid adaptive phenotypic continuum into an entirely novel functional morphospace. There was minimal support for our hypothesis of faster overall rates of integrated tooth shape, spacing, and jaw biomechanical evolution in herbivorous terapontids in their entirety, compared with other trophic strategies. There was, however, considerable support for accelerated disparification within a diverse freshwater clade containing a range of specialized freshwater herbivores. While the evolutionary transition to herbivorous diets has played a central role in terapontid phenotypic diversification by pushing herbivores toward novel fitness peaks, there was little support for herbivory driving significantly higher lineage diversification compared with background rates across the family.
Data from: Past climate change drives current genetic structure of an endangered freshwater mussel species
Historical-to-recent climate change and anthropogenic disturbance affect species distributions and genetic structure. The Rio Grande watershed of the United States and Mexico encompasses ecosystems that are intensively exploited, resulting in substantial degradation of aquatic habitats. While significant anthropogenic disturbances in the Rio Grande are recent, inhospitable conditions for freshwater organisms likely existed prior to such disturbances. A combination of anthropogenic and past climate factors may contribute to current distributions of aquatic fauna in the Rio Grande basin. We used mitochondrial DNA and 18 microsatellite loci to infer evolutionary history and genetic structure of an endangered freshwater mussel, Popenaias popeii, throughout the Rio Grande drainage. We estimated spatial connectivity and gene flow across extant populations of P. popeii and used ecological niche models (ENMs) and approximate Bayesian computation (ABC) to infer its evolutionary history during the Pleistocene. structure results recovered regional and local population clusters in the Rio Grande. ENMs predicted drastic reductions in suitable habitat during the last glacial maximum. ABC analyses suggested that regional population structure likely arose in this species during the mid-to-late Pleistocene and was followed by a late Pleistocene population bottleneck in New Mexico populations. The local population structure arose relatively recently, perhaps due to anthropogenic factors. Popenaias popeii, one of the few freshwater mussel species native to the Rio Grande basin, is a case study for understanding how both geological and anthropogenic factors shape current population genetic structure. Conservation strategies for this species should account for the fragmented nature of contemporary populations.
Data from: Assessing the vulnerability of Africa's freshwater fishes to climate change: a continent-wide trait-based analysis
Climate change is a key driver of biodiversity loss across the globe, and freshwater fishes are predicted to be among the most vulnerable taxa. African freshwater ecosystems are home to one of the most unique and diverse ichthyo-faunas on the planet, and freshwater fish species provide essential livelihoods for millions of people living in riparian communities across the continent. Although nearly one sixth of African freshwater fishes have been designated as endangered or vulnerable to extinction by the IUCN Red List assessment, the effects of climate change on these species have not been explored on a continent-wide scale. In this study, we present the first trait-based climate change vulnerability assessment (CCVA) comprising the majority (85%) of Africa's currently described freshwater fishes. We assembled data relating to three dimensions of vulnerability including sensitivity, adaptive capacity, and exposure. In addition, we developed an index of 'conservation value' based on traditional conservation metrics including extinction risk, endemism, and provision of ecosystem services. We found that almost 40% of African freshwater fishes are vulnerable to climate change, mostly owing to the many species with highly specialized habitat and life-history requirements, and because of the numerous anthropogenic stressors they face. High proportions of species within the Nothobranchiidae and Cichlidae families were found to be vulnerable. Regions with high frequencies of vulnerable species included the African rift valley lakes, the Congo River drainage, and the coastal rivers of West Africa. Several important data deficiencies were identified relating to species' population sizes, genetic variability, and life history traits, and constitute priority research areas for the future. In addition, we highlighted some cases where traditional conservation approaches overlook species and regions that are predicted to be threatened by climate change.
ScienceDex guides
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These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.