Find research datasets worth reusing

Data from: Consistent seasonal flexibility of the gut and its regions across wild populations of a winter-quiescent fish

Here, we investigated phenotypic flexibility in the size of the gastrointestinal (GI) tract across three northern populations of a winter-dormant warm-water fish, pumpkinseed sunfish (Lepomis gibbosus). The dried masses of all gut regions (stomach, pyloric caeca, intestine) were measured approximately biweekly between January and August 2021. In all populations, pumpkinseed exhibited pronounced structural flexibility in the GI tract, aligned with winter and the timing of reproduction. The dry mass of the GI increased by 1.3- to nearly 2.5-fold in the early spring. The pyloric caeca demonstrated the greatest capacity for flexibility, increasing by up to 3.7-fold prior to reproduction. In all populations, minimum dry GI mass was consistently achieved during winter and mid-summer. This capacity for gut flexibility may represent a novel mechanism for facilitating rapid adaptive responses (e.g., metabolic plasticity) to future environmental change.

Calling structural variants with confidence from short-read data in wild bird populations

Comprehensive characterisation of structural variation in natural populations has only become feasible in the last decade. To investigate the population genomic nature of structural variation (SV), reproducible and high-confidence SV callsets are first required. We created a population-scale reference of the genome-wide landscape of structural variation across 33 Nordic house sparrows (Passer domesticus) individuals. To produce a consensus callset across all samples using short-read data, we compare heuristic-based quality filtering and visual curation (Samplot/PlotCritic and Samplot-ML) approaches. We demonstrate that curation of SVs is important for reducing putative false positives and that the time invested in this step outweighs the potential costs of analysing short-read discovered SV datasets that include many potential false positives. We find that even a lenient manual curation strategy (e.g. applied by a single curator) can reduce the proportion of putative false positives by up to 80%, thus enriching the proportion of high-confidence variants. Crucially, in applying a lenient manual curation strategy with a single curator, nearly all (>99%) variants rejected as putative false positives were also classified as such by a more stringent curation strategy using three additional curators. Furthermore, variants rejected by manual curation failed to reflect the expected population structure from SNPs, whereas variants passing curation did. Combining heuristic-based quality-filtering with rapid manual curation of structural variants in short-read data can therefore become a time- and cost-effective first step for functional and population genomic studies requiring high-confidence SV callsets.

Data from: To lose is to win: long-term co-occurrence of two asexual populations realized by a dormant strategy of the inferior competitor

Asexual organisms are ubiquitous. While they are the same single species with the same ecological requirements, multiple asexual genotypes within a species are often found in a single habitat. Niche partitioning in time and space among genotypes has been proposed to explain this phenomenon. However, it is not clear whether these different genotypes co-occur in the long term. Therefore, we examined the population dynamics of two asexual Daphnia cf. pulex genotypes (JPN1 and JPN2) over nine years in a small mountain lake. These two genotypes consistently occurred in the same seasons and layers, suggesting that niche partitioning cannot explain their long-term co-occurrence. The abundance of JPN1 was typically higher in most years. However, the abundance of dormant eggs in lake sediments was at the same level between the genotypes. The laboratory experiment showed that JPN1 excluded JPN2. However, many JPN2 individuals produced the dormant eggs before JPN1 competitively excluded them from the experiment. Furthermore, the competitively inferior JPN2 produced the dormant eggs abundantly in the medium containing a crowding cue from JPN1. However, no such trend was observed for JPN1. These results showed that the competitively inferior asexual genotype could maintain the population with the competitively superior genotype for a long period of time because it had the ability to detect the increase in competitors and produce the dormant eggs each year before being competitively eliminated. Based on these results, we suggest that the variation in the genotype-specific response in dormant egg production to environmental change plays a key role in the long-term co-occurrence of different asexual genotypes in single habitats.

Population structure and connectivity among coastal and freshwater Kelp Gull (Larus dominicanus) populations from Patagonia

The genetic identification of significant evolutionary units and information on their connectivity can be used to design effective management and conservation plans. Despite having high dispersal capacity, several seabird species show population structure due to both abiotic and biotic barriers to gene flow. The Kelp Gull is the most abundant species of gull in the southern hemisphere. In Argentina it reproduces in both marine and freshwater environments, with more than 100,000 pairs following a metapopulation dynamic across 140 colonies in the Atlantic coast of Patagonia. However, little is known about the demography and connectivity of inland populations. We aim to provide information on the connectivity of the largest freshwater colonies (those from Nahuel Huapi Lake) with the closest Pacific and Atlantic populations to evaluate if these freshwater colonies are being subsidized by the larger coastal populations. We sampled three geographic regions (Nahuel Huapi Lake and the Atlantic and Pacific coasts) and employed a reduced-representation genomic approach to genotype individuals for single-nucleotide polymorphisms (SNPs). We found, using clustering and phylogenetic analyses, that there are three genetic groups, each corresponding to one of our sampled regions. Individuals from marine environments are more closely related to each other than to those from Nahuel Huapi Lake, indicating that the latter population constitutes the first freshwater Kelp Gull colony to be identified as a significant evolutionary unit in Patagonia.

Data from: using camera traps and N-mixture models to estimate population abundance: model selection really matters

Estimating the abundance or density of wildlife populations is a critical part of species conservation and management, but estimates can vary greatly in precision and accuracy according to the data collection and statistical methods, sampling and ecological variation, and sample size. N-mixture models are a common method which has been applied to a wide range of taxa for estimating population abundance from non-invasive data representing the distribution of the species. We used population estimates from an aerial survey of moose and videos from camera traps to assess the sensitivity of N-mixture models to ecological conditions, the spatial scale at which they were measured, the criteria used to define independent detections, and model choice based on the common statistical criterion of parsimony. The most parsimonious N-mixture models were considerably biased, producing implausibly large and considerably imprecise estimates of the abundance of moose. Most of the other models produced estimates of abundance that were ecologically realistic and relatively accurate. The accuracy of population estimates produced by N-mixture models were not overly sensitive to the formulation of models, the scale at which ecological conditions were measured, or the criteria used to define independent detection and by extension sample size. Our results suggest that parsimony was a poor measure of the predictive accuracy of the population estimates produced with the N-mixture model. Collecting and processing data from the aerial survey was less expensive and took less time, but data from camera traps can provide valuable information on behavior of the target species as well as insights into multiple species in the community.

Data for: Shifts in plant-invertebrate interactions between wild and ex-situ conservation populations of a critically endangered tree

Ex-situ conservation is an effective approach to prevent the extinction of endangered species. Biotic interactions (eg herbivory and pollination) are critical to ex-situ conservation success, including plant establishment, survival, and reproduction. However, shifts in biotic interactions between wild and ex-situ populations are still poorly understood. We compared herbivory and pollination characteristics between the only wild population (WP) and three ex-situ populations (LP, local population, nearby WP; NP, north population, ca. 850 km; and SP, south population, ca. 750 km) of a critically endangered tree species (Sinojackia huangmeiensis) to explore the latitudinal changes in plant-invertebrate interactions. Larvae of the Limacodidae family were the dominant herbivores in WP, LP, and NP, while the only herbivore observed in SP was a snail. Compared to WP, the leaf herbivory rate was unchanged in LP but decreased in NP and SP. Leaf defense traits (total phenols, tannins, leaf thickness, and leaf dry matter content) increased or remained unchanged in the three ex-situ populations. A pollinator (Apis cerana) of S. huangmeiensis was present in the four populations. NP and SP lacked some pollinators that were found in both WP and LP, but they shared one pollinator that was not observed in WP and LP. The pollinator visiting frequency increased in SP, while it did not change significantly in LP and NP. Synthesis and applications: Our results suggested that both herbivory and pollination of S. huangmeiensis changed in ex-situ populations, with complete or partial changes in herbivores, leaf herbivory rate, pollinators, pollinator visiting frequency, and fruit set in the two distant ex-situ populations. This work provides a unique empirical study of shifts in both antagonistic and mutualistic biotic interactions between wild and ex-situ populations. We emphasized that it is essential to integrate herbivore and pollinator management in future ex-situ conservation of plant species.

Data from: Pace and parity predict short-term persistence of small plant populations

Life history traits are used to predict asymptotic odds of extinction from dynamic conditions. Less is known about how life history traits interact with stochasticity and population structure of finite populations to predict near-term odds of extinction. Through empirically parameterized matrix population models, we study the impact of life history (reproduction, pace), stochasticity (environmental, demographic), and population history (existing, novel) on the transient population dynamics of finite populations of plant species. Among fast and slow pace and either uniform or increasing reproductive intensity or short or long reproductive lifespan, slow, semelparous species are at the greatest risk of extinction. Long reproductive lifespans buffer existing populations from extinction while the odds of extinction of novel populations decreases when reproductive effort is uniformly spread across the reproductive lifespan. Our study highlights the importance of population structure, pace, and two distinct aspects of parity for predicting near-term odds of extinction.

opencc-by-4.0Nov 2013View details →

Fig. 1. Tick species and the total monthly tick numbers collected during the 5 in Seasonal variations in ixodid tick populations on a commercial game farm in the Limpopo Province, South Africa

Fig. 1. Tick species and the total monthly tick numbers collected during the 5-year study period.

Fig. 4 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 4. Monthly variations in salinity values at Euphrates River during period study.

Fig. 5 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 5. Monthly variations in dissolved oxygen values at Euphrates River during period study.

Fig. 3 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 3. Monthly variations in pH values at Euphrates River during period study.

Fig. 2 in Diversity And Density Of Mollusca (Gastropoda And Bivalvia) Population In The Euphrates River At Al-Nasiriyah, Southern Iraq

Fig. 2. Monthly variations in water temperature values at Euphrates River during period study.

Rapid evolution of consumptive and non-consumptive predator effects on prey population densities, bioenergetics and stoichiometry

Predators can strongly influence prey populations not only through consumptive effects (CE) but also through non-consumptive effects (NCE) imposed by predation risk. Yet, the impact of NCE on bioenergetic and stoichiometric body contents of prey, traits that are shaping life histories, population and food web dynamics, is largely unknown. Moreover, the degree to which NCE can evolve and can drive evolution in prey populations is rarely studied. A 6-week outdoor mesocosm experiment with Caged-Fish (NCE) and Free-Ranging-Fish (CE and NCE) treatments was conducted to quantify and compare the effects of CE and NCE on population densities, bioenergetic and stoichiometric body contents of Daphnia magna, a keystone species in freshwater ecosystems. We tested for evolution of CE and NCE by using experimental populations consisting of D. magna clones from two periods of a resurrected natural pond population: a pre-fish period without fish and a high-fish period with high predation pressure. Both Caged-Fish and Free-Ranging-Fish treatments decreased the body size and population densities, especially in Daphnia from the high-fish period. Only the Free-Ranging-Fish treatment affected bioenergetic variables, while both the Caged-Fish and Free-Ranging-Fish treatments shaped body stoichiometry. The effects of CE and NCE were different between both periods indicating their rapid evolution in the natural resurrected population. Both the Caged-Fish and Free-Ranging-Fish treatments changed the clonal frequencies of the experimental Daphnia populations of the pre-fish as well as the high-fish period, indicating that not only CE but also NCE induced clonal sorting, hence rapid evolution during the mesocosm experiment in both periods. Our results demonstrate that CE as well as NCE have the potential to change not only the body size and population density but also the bioenergetic and stoichiometric characteristics of prey populations. Moreover, we show that these responses not only evolved in the studied resurrected population, but that CE and NCE also caused differential rapid evolution in a time frame of 6 weeks (ca. 4-6 generations). As NCE can evolve as well as can drive evolution, they may play an important role in shaping eco-evolutionary dynamics in predator-prey interactions.

Genetic insight into a polygenic trait using a novel Genome Wide Association approach in a wild amphibian population

Body size variation is central in the evolution of life history traits in amphibians, but the underlying genetic architecture of this complex trait is still largely unknown. Herein, we studied the genetic basis of body size and fecundity of the alternative morphotypes in a wild population of the Greek smooth newt (Lissotriton graecus). By combining a Genome-wide association approach with linkage disequilibrium network analysis, we were able to identify clusters of highly correlated loci thus maximizing sequence data for downstream analysis. The putatively associated variants explained 12.8% to 44.5% of the total phenotypic variation in body size and were mapped to genes with functional roles in the regulation of gene expression and cell cycle processes. Our study is the first to provide insights into the genetic basis of complex traits in newts and provides a useful tool to identify loci potentially involved in fitness related traits in small data sets from natural populations in non-model species.

Can livestock grazing dampen density dependent fluctuations in wild herbivore populations?

Conservation policy for the high mountains of Asia increasingly recognises the need to encompass large multi-use landscapes beyond the protected area network. Due to limited long-term research in this region, our understanding of even fundamental processes, such as factors regulating large mammal populations is poor. Understanding the factors that regulate animal populations, especially those generating cyclicity, is a long-standing problem in ecology. Long-term research across multiple taxa (mainly from Europe and North America) has focused on the relative roles of food and predation in generating cyclicity in population dynamics. It remains unclear how trophic interactions that are influenced by anthropogenic stressors can affect population dynamics in human-modified landscapes. We present a 10-year study to compare the effects of livestock grazing on density dependent dynamics in two populations of bharal, Pseudois nayaur, in the Himalaya. We combine this with a mechanistic understanding of whether density dependence in these two sites acts predominantly by affecting adult survival or recruitment. We compared and quantified density dependence in the bharal population by fitting Bayesian Gompertz state‐space (GSS) models. We found evidence for negative density dependence which indicates possible cyclic dynamics in the bharal population of the site (Tabo) with low livestock density. The population dynamics of this site were driven by recruited offspring – with a 2-year density dependent lag effect – rather than adult survival. In the site with high livestock density (Kibber), this density dependence was not detected. We postulate the potential role of excessive grazing by livestock in affecting offspring recruitment, thereby affecting the bharal population in Kibber. Synthesis and applications: Our results suggest that conservation action to facilitate wild herbivore population recovery, such as the development of protected areas and village reserves, needs to account for density dependent regulation. Sites with trophy hunting require continuous monitoring to understand the effects of density dependence so that appropriate hunting quotas can be formulated.

Population genetics of caribou in the Alaska-Yukon border region: implications for designation of conservation units and small herd persistence

Better knowledge of genetic relationships between the Fortymile caribou herd and its neighbors is needed for conservation decision-making in Canada. Here, we contribute the first fine-scale analysis of genetic population structure in nine contiguous caribou herds at the geographic boundaries between Barren-ground and Northern Mountain caribou, and at the Alaska-Yukon border. Using pairwise differentiation metrics, STRUCTURE, and discriminant analysis of principal components (DAPC) to analyze 15 microsatellite loci in 379 caribou, we found complex patterns of genetic differentiation. The Fortymile was the only herd assigned to more than one genetic cluster, indicative of its history as a larger herd whose range expansions and gene flow to other herds were likely important to maintaining diversity across a functioning genetic metapopulation. Some small herds (Chisana, Klaza, and White Mountains) were genetically distinct, while others (Hart River, Clear Creek, Mentasta) exhibited little differentiation from herds they occasionally overlap, including herds assigned to different conservation units (DUs). This genetic connectivity does not result from demographic connectivity, as episodic contact during rut, rather than herd switching, is the likely mechanism. Unusually, one small herd (White Mountains) maintained genetic differentiation despite rut overlap with Fortymile. Our data reveal that some herds with different ecological and behavioral attributes are demographically independent but nonetheless genetically connected. Thus, we suggest that managing caribou for an appropriate level of genetic connectivity, while also supporting herd persistence, will be essential to conserve caribou genetic diversity in the region.

Data from: Population structure and species delimitation in the Wehrle's salamander complex

Species are the fundamental unit of biodiversity studies. However, many species complexes are difficult to delimit, especially those characterized by complicated patterns of population structure. Salamanders in the family Plethodontidae often form species by slowly fragmenting across a landscape over space and time. They thus provide many examples of species complexes in which gradual Darwinian evolution has resulted in multiple units of varying degrees of differentiation, including incompletely separated lineages. Here we report on a molecular systematic investigation of woodland salamanders in the Plethodon wehrlei group, which has recently been split from two species into five. To quantify patterns of genetic variation, we collected genetic samples from 24 individuals from 20 populations, including all species and representing a carefully selected subset of previous work. From these samples, we obtained genomic data using anchored hybrid enrichment, which resulted in 319 loci averaging 1300 base pairs in length. Biallelic single nucleotide polymorphisms (SNPs) were randomly selected from 316 of these loci for some analyses. We examined patterns of genetic structure using PCA, DAPC, FEEMS, and STRUCTURE, and found that all of the recognized species formed genetic clusters; however, P. wehrlei and P. punctatus were relatively weakly differentiated, and STRUCTURE identified three separate clusters within P. jacksoni. Species trees inferred using wASTRAL, BPP, and TreeMix all recovered the same topology, with P. dixi sister to the other taxa, which included a northern clade (P. wehrlei, P. punctatus, P. pauleyi) and a southern clade (P. jacksoni, with three separate groups). TreeMix only inferred one gene flow event. We evaluated the candidate species using BPP and the genealogical divergence index (gdi). While BPP delimited all candidate species with strong support (all posterior probabilities = 1.0), the gdi only strongly supported P. dixi and P. pauleyi, both of which have only been recently described. We discuss the difficult problem of species delimitation in groups that form species via range fragmentation. We also provide a vision for future research with the aim of better testing and diagnosing the species diversity within the P. wehrlei group.

Data from: Range-wide genetic analysis of an endangered bumble bee (Bombus affinis) reveals population structure, isolation by distance, and low colony abundance

Declines in bumblebee species ranges and abundances are documented across multiple continents and have prompted the need for research to aid species recovery and conservation. The rusty patched bumblebee (Bombus affinis) is the first federally-listed bumblebee species in North America. We conducted a range-wide population genetics study of B. affinis from across all extant conservation units to inform conservation efforts. To understand the species' vulnerability and help establish recovery targets, we examined population structure, patterns of genetic diversity, and population differentiation. Additionally, we conducted site-level analysis of colony abundance to inform prioritizing areas for conservation, translocation, and other recovery actions. We find substantial evidence of population structuring along an east-to-west gradient. Putative populations show evidence of isolation by distance, high inbreeding coefficients, and a range wide male diploidy rate of ~15%. Our results suggest the Appalachians represents a genetically distinct cluster with high levels of private alleles and substantial differentiation from the rest of the extant range. Site-level analyses suggest low colony abundance estimates for B. affinis compared to similar datasets of stable, co-occurring species. These results lend genetic support to trends from observational studies suggesting B. affinis has undergone a recent decline and exhibits substantial spatial structure. The low colony abundances observed here suggest caution in overinterpreting the stability of populations even where B. affinis is reliably detected interannually. These results help delineate informed management units, provide context for the potential risks of translocation programs, and can help set clear recovery targets for this and other threatened bumblebee species.

Data from: Landscape heterogeneity drives population structure in four western bumble bee species

Bumble bees are critical pollinators in wild, agricultural, and urban ecosystems—providing the necessary ecological services for food and crop production. In western North America, mountain ranges have high bumble bee species richness. However, as climate change increases temperatures and restricts montane populations to higher elevational spaces, their ability to disperse and maintain genetic diversity decreases. This genetic isolation could lead to the extirpation of local pollinator communities and an overall loss of pollinators. We analyzed the genetic diversity of four broadly sympatric species of bumble bees across the Rocky and Cascade Mountains of western North America to assess habitat isolation's impact on population genetic structure. We expected species restricted to higher elevation habitats to display higher population structure and less genetic diversity across the landscape. We sampled approximately 150 bees per species from seven to eight sites across each species' range. We genotyped bees with an average of 10 loci and used FST and Bayesian Structure analysis to quantify population differentiation. Using isolation by distance and isolation by resistance analyses, species with both narrow and broad habitat suitability requirements showed evidence of habitat suitability restricting gene flow. Although each species showed varying degrees of genetic structure and gene flow, knowing how habitat heterogeneity drives genetic structure and isolation can help guide conservation efforts and determine focal regions for bumble bee conservation in the face of climate change.

COI and Cytb data of Lagocephalus spadiceus in eight populations

The Late Pleistocene-Holocene climate fluctuations have had a major impact on phylogeographic structure and historical dynamics of marine fishes in the marginal seas of the western Pacific Ocean. Lagocephalus spadiceus is a high-nutritional and economic-value species in the Southeast China Sea. The study was to assess the population genetic diversity and demography of L. spadiceus in the South China Sea (SCS). A sample of 300 specimens from eight geographic locations along the coast of mainland China and Hainan Island were obtained for this study. The mitochondrial cytochrome oxidase I (COI) and cytochrome b (Cyt b) gene datasets had high haplotype diversity but low nucleotide diversity. The genetic structure and phylogenetic analyses indicated that there was no significant population structure among the eight geographic locations. The low genetic diversity of L. spadiceus was associated with population expansion in the Late Pleistocene-Holocene period. This was supported by star haplotype networks, neutrality tests, unimodal mismatch distributions and Bayesian skyline plots. These findings have important reference value for the protection of genetic resources. Furthermore, the study illuminates the complex relationship between Pleistocene-Holocene temperature variability and phylogeography.