Find research datasets worth reusing

opencc-zeroDec 2021View details →

Investigating the morphological and genetic divergence of arctic char (Salvelinus alpinus) populations in lakes of arctic Alaska

Polymorphism facilitates coexistence of divergent morphs (e.g., phenotypes) of the same species by minimizing intraspecific competition, especially when resources are limiting. Arctic char (Salvelinus sp.) are a Holarctic fish often forming morphologically, and sometimes genetically, divergent morphs. In this study, we assessed the morphological and genetic diversity and divergence of 263 individuals from seven populations of arctic char with varying length-frequency distributions across two distinct groups of lakes in northern Alaska. Despite close geographic proximity, each lake group occurs on landscapes with different glacial ages and surface water connectivity, and thus were likely colonized by fishes at different times. Across lakes, a continuum of physical (e.g., lake area, maximum depth) and biological characteristics (e.g., primary productivity, fish density) exists, likely contributing to characteristics of present-day char populations. Although some lakes exhibit bimodal size distributions, using model-based clustering of morphometric traits corrected for allometry, we did not detect morphological differences within and across char populations. Genomic analyses using 15,934 SNPs obtained from genotyping-by-sequencing demonstrated differences among lake groups related to historical biogeography, but within lake groups and within individual lakes, genetic differentiation was not related to total body length. We used PERMANOVA to identify environmental and biological factors related to observed char size structure. Significant predictors included water transparency (i.e., a primary productivity proxy), char density (fish·ha-1), and lake group. Larger char occurred in lakes with greater primary production and lower char densities, suggesting less intraspecific competition and resource limitation. Thus, char populations in more productive and connected lakes may prove more stable to environmental changes, relative to food-limited and closed lakes, if lake productivity increases concomitantly. Our findings provide some of the first descriptions of genomic characteristics of char populations in arctic Alaska, and offer important consideration for the persistence of these populations for subsistence and conservation.

opencc-by-4.0Jan 2022View details →

Data and R codes from: Exploring the effect of 195 years-old locks on species movement: Landscape genetics of painted turtles in the Rideau Canal, Canada

Aquatic systems have been extensively altered by human structures (e.g., construction of dams/canals) and these have major impacts on the connectivity of wildlife populations through the loss and isolation of suitable habitats. Habitat loss and isolation affect gene flow and influence the persistence of populations in time and space by restricting movements. Isolation can result in higher inbreeding, lower genetic diversity, and greater genetic structure, which may render populations more vulnerable to environmental changes, and thus to extinction. Given the ubiquity and the persistence of dams and canals in space and time, it is crucial to understand their effects on the population genetics of aquatic species. Here, we documented the genetic diversity and structure of painted turtle (Chrysemys picta) populations in the Rideau Canal, Ontario, Canada. More specifically, we used 13 microsatellites to evaluate the influence of locks on genetic variation in 822 painted turtles from 22 sites evenly distributed along the 202-km canal. Overall, we found low, but significant, genetic differentiation suggesting that some dispersal is occurring throughout the canal. In addition, we showed that locks contribute to the genetic differentiation observed in the system. Clustering analysis revealed two distinct genetic groups whose boundary is associated with a series of six locks. Our results illustrate how artificial waterways, such as canal systems, can influence population genetic structure. We highlight the importance of adopting management plans that can mitigate the impacts of human infrastructure and preserve gene flow across the landscape to maintain viable populations.

opencc-by-4.0Jan 2022View details →

Coloc summary results for "Dissection of multiple sclerosis genetics identifies B and CD4+ T cells as driver cell subsets"

Text files containing coloc results between MS GWAS loci and CD4 T and B cell cis-eQTLs from DICE. These results accompany the paper "Dissection of multiple sclerosis genetics identifies B and CD4+ T cells as driver cell subsets"

opencc-zeroDec 2016View details →

Data from: Genetic diversity and divergence in the fountain darter (Etheostoma fonticola): implications for conservation of an endangered species

The endangered fountain darter Etheostoma fonticola is found only in the Comal and San Marcos rivers in the Guadalupe River basin in central Texas, USA. Comal River fountain darters were believed to be extir- pated following a severe drought in the 1950s and were reintroduced in the early 1970s using 457 darters from the San Marcos River. In this study we used 23 microsatellite loci to describe and evaluate the genetic diversity, population structure and effective population size (Ne) of fountain darters. We also evaluated the genetic effect of the Comal River reintroduction and the influence of low-head dams (dams) on dispersal in both rivers. Bayesian analysis of individual genotypes and Analysis of Molecular Variation supported two distinct populations concordant with the two rivers. Estimates of Ne were much smaller (<10 %) than census size (Nc) in both rivers but did not indicate the populations are at risk of an immediate and rapid loss of genetic diversity. Coalescent-based estimates of the genetically effective number of founders (Nf) for the Comal River averaged about 49 darters and, together with the indices of genetic diversity and the bottleneck test (heterozygosity excess) results, were consistent with a founder event following the reintroduction in the Comal River. Finally, our results regarding the influence of dams on fountain darter dispersal were equivocal and did not support a conclusion. We recommend this issue be examined further as part of the fountain darter recovery program.

Data from: Population genetics and independently replicated evolution of predator-associated burst speed ecophenotypy in mosquitofish

Many species show replicated ecophenotypy due to recurring patterns of natural selection. Based on the presence or absence of pursuit predators, at least 17 species of fish repeatedly differentiated in body shape in a manner that increases burst swimming speed and the likelihood of predator escape. The predator-associated burst speed (PABS) ecophenotype is characterized by a small head and trunk and enlarged caudal region. Mechanisms promoting replicated phenotype-environment association include selection (without evolution), a single instance of adaptive evolution followed by biased habitat occupation, repeated instances of local adaptation, or adaptive phenotypic plasticity. Common garden rearing of mosquitofish, Gambusia affinis, demonstrated a likely heritable basis for PABS phenotypy, but it is unknown whether populations are otherwise genetically distinct or whether replicated ecophenotypy represents a single or replicated instances of adaptation. To genetically characterize the populations and test hypotheses of single or multiple adaptations, we characterized variation in 12 polymorphic DNA microsatellites in the previously studied G. affinis populations. Populations were genetically distinct by multilocus analysis, exhibited high allelic diversity, and were heterozygote deficient, which effects were attributed to G. affinis's shoaling nature and habitat patchiness. Genetic and phenotypic distances among populations were correlated for non-PABS but not PABS morphology. Multilocus analysis demonstrated ecophenotype polyphyly and scattered multivariate genetic structure which support only the replicated-adaptation model. As all of the diverse tests performed demonstrated lack of congruence between patterns of molecular genetic and PABS differentiation, it is likely that divergent natural selection drove multiple instances of adaptive evolution.Many species show replicated ecophenotypy due to recurring patterns of natural selection. Based on the presence or absence of pursuit predators, at least 17 species of fish repeatedly differentiated in body shape in a manner that increases burst swimming speed and the likelihood of predator escape. The predator-associated burst speed (PABS) ecophenotype is characterized by a small head and trunk and enlarged caudal region. Mechanisms promoting replicated phenotype-environment association include selection (without evolution), a single instance of adaptive evolution followed by biased habitat occupation, repeated instances of local adaptation, or adaptive phenotypic plasticity. Common garden rearing of mosquitofish, Gambusia affinis, demonstrated a likely heritable basis for PABS phenotypy, but it is unknown whether populations are otherwise genetically distinct or whether replicated ecophenotypy represents a single or replicated instances of adaptation. To genetically characterize the populations and test hypotheses of single or multiple adaptations, we characterized variation in 12 polymorphic DNA microsatellites in the previously studied G. affinis populations. Populations were genetically distinct by multilocus analysis, exhibited high allelic diversity, and were heterozygote deficient, which effects were attributed to G. affinis's shoaling nature and habitat patchiness. Genetic and phenotypic distances among populations were correlated for non-PABS but not PABS morphology. Multilocus analysis demonstrated ecophenotype polyphyly and scattered multivariate genetic structure which support only the replicated-adaptation model. As all of the diverse tests performed demonstrated lack of congruence between patterns of molecular genetic and PABS differentiation, it is likely that divergent natural selection drove multiple instances of adaptive evolution.

Role of individual dispersal in genetic resilience in fluctuating populations of the gray-sided vole Myodes rufocanus

Population densities of the grey-sided vole Myodes rufocanus fluctuate greatly within and across years in Japan. Here, to investigate the role of individual dispersal in maintaining population genetic diversity, we examined how genetic diversity varied during fluctuations in density by analyzing eight microsatellite loci in voles sampled three times per year for 5 years, using two fixed trapping grids (approximately 0.5 ha each). At each trapping session, all captured voles at each trapping grid were removed. The STRUCTURE program was used to analyze serially collected samples to examine how population crashes were related to temporal variability, based on local-scale genetic compositions in each population. In total, 461 and 527 voles were captured at each trapping grid during this study. The number of voles captured during each trapping session (i.e., vole density) varied considerably at both grids. Although patterns in fluctuations were not synchronized between grids, the peak densities were similar. At both grids, the mean allele number recorded at each trapping session was strongly, positively, and non-linearly correlated with density. STRUCTURE analyses revealed that the proportions of cluster compositions among individuals at each grid differed markedly before and after the crash phase, implying the long-distance dispersal of voles from remote areas at periods of low density. The present results suggest that, in grey-sided vole populations, genetic diversity varies with density largely at the local scale; in contrast, genetic variation in a metapopulation is well-preserved at the regional scale due to the density-dependent dispersal behaviors of individuals. By influencing the dispersal patterns of individuals, fluctuations in density affect metapopulation structure spatially and temporally, while the levels of genetic diversity are preserved in a metapopulation.

The genetic diversity of triploid Celtis pumila and its diploid relatives C. occidentalis and C. laevigata (Cannabaceae)

The genus Celtis in eastern North America shows puzzling patterns of variation. While three species are generally recognized, many authors have suggested hybridization may be blurring the boundaries among them. Suspected hybridization between C. occidentalis and C. pumila has hampered conservation planning for the latter, which is a Threatened species in Canada. Using microsatellite markers and flow cytometry, we assessed the relationship between genetic diversity, ploidy, and morphology in this group. We confirmed the presence of two diploid species, C. occidentalis and C. laevigata, and that they do hybridize where they co-occur in southern Missouri and Illinois. We found two triploid genetic groups. These groups had distinct geographic ranges, but were morphologically very similar, corresponding to C. pumila. Furthermore, the triploid groups were characterized by a small number of heterozygous multi-locus genotypes. A single genotype dominated populations across Ontario, Michigan, Ohio and Pennsylvania, indicating apomictic reproduction is common in these groups. While the triploid clusters were distinct from each other, they did have strong associations with sympatric diploid species, and also with the western triploid species C. reticulata. The triploid Celtis pumila demonstrates remarkable phenotypic plasticity, with the same genotype variously presenting as dwarf shrubs in xeric, exposed sites, and subcanopy tree in mesic forests.

Complex genetic patterns and distribution limits mediated by native congeners of the worldwide invasive red‐eared slider turtle

Non-native (invasive) species offer a unique opportunity to study the geographic distribution and range limits of species, wherein the evolutionary change driven by interspecific interactions between native and non-native closely related species is a key component. The red-eared slider turtle, Trachemys scripta elegans (TSE), has been introduced and successfully established worldwide. It can coexist with its native congeners T. cataspila, T. venusta and T. taylori in Mexico. We performed comprehensive fieldwork, executed a battery of genetic analyses and applied a novel species distribution modeling approach to evaluate their historical lineage relationships and contemporary population genetic patterns. Our findings support the historical common ancestry between native TSE and non-native (TSEalien), while also highlighting the genetic differentiation of the exotic lineage. Genetic patterns are associated with their range size/endemism gradient, the microendemic T. taylori showed significant reduced genetic diversity and high differentiation, whereas TSEalien showed the highest diversity and signals of population size expansion. Counter to our expectations, lower naturally occurring distribution overlap and little admixture patterns were found between TSE and its congeners, exhibiting reduced gene flow and clear genetic separation across neighboring species despite having zones of contact. We demonstrate that these native Trachemys species have distinct climatic niche suitability, likely preventing establishment of and displacement by the TSEalien. Moreover, we found major niche overlap between TSEalien and native species worldwide, supporting our prediction that sites with closer ecological optima to the invasive species have higher establishment risk than those that are closer to the niche-center of the native species.

opencc-by-4.0Mar 2022View details →

Genetic and epigenetic differentiation across intertidal gradients in the foundation plant Spartina alterniflora

This record contains supplementary information for the article "Genetic and epigenetic differentiation across intertidal gradients in the foundation plant Spartina alterniflora". It contains the barcodes (barcodes.txt), the reference contigs (contigs.fasta.gz), the annotation of the reference contigs (mergedAnnot.csv.gz), the SNPs (snps.vcf.gz), the methylation data (methylation.txt.gz), and the experimental design (design.txt). All data are unfiltered. All reads are available on SRA (PRJNA798549). Note that the barcode sequences and the control nucleotide were already removed from the demultiplexed files (hence, for each sample, reads are also split into "watson" and "crick" based on the control nucleotide).

Global flyway evolution in red knots Calidris canutus and genetic evidence for a Nearctic refugium

Present-day ecology and population structure are the legacies of past climate and habitat perturbations, and this is particularly true for species that are widely distributed at high latitudes. The red knot, Calidris canutus, is an arctic-breeding, long-distance migratory shorebird with six recognized subspecies defined by differences in morphology, migration behavior, and annual-cycle phenology, in a global distribution thought to have arisen just since the Last Glacial Maximum (LGM). We used nextRAD sequencing of 10,881 single-nucleotide polymorphisms (SNPs) to assess the neutral genetic structure and phylogeographic history of 172 red knots representing all known global breeding populations. Using population genetics approaches, including model-based scenario-testing in an approximate Bayesian computation (ABC) framework, we infer that red knots derive from two main lineages that diverged ca. 34,000 years ago, and thus most likely persisted at the LGM in both Palearctic and Nearctic refugia, followed by at least two instances of secondary contact and admixture. Within two Beringian subspecies (C. c. roselaari and rogersi), we detected previously unknown genetic structure among sub-populations sharing a migratory flyway, reflecting additional complexity in the phylogeographic history of the region. Conversely, we found very weak genetic differentiation between two Nearctic populations (rufa and islandica) with clearly divergent migratory phenotypes and little or no apparent contact throughout the annual cycle. Together, these results suggest that relative gene flow among migratory populations reflects a complex interplay of historical, geographical, and ecological factors.

Dataset for: Rio de Janeiro and other paleodrainages evidenced by the genetic structure of an Atlantic Forest catfish

Aim: The disjunct distributions of freshwater organisms along coastal drainages are usually explained by paleodrainages formed during sea-level retreats that connected currently isolated basins, or by river capture from tectonic adjustments between adjoining watersheds. We evaluate the relative importance of these events on the genetic variation of freshwater fishes inhabiting the Serra do Mar in eastern Brazil, a region with steep mountains and pronounced bays. Location: Coastal river drainages in southeastern Brazil. Taxon: Catfishes of the Trichomycterus alternatus group. Methods: We tested the effects of paleolandscape connections (GIS-reconstructed paleodrainages and putative river captures) on the genetic structure (mitochondrial and nuclear markers) of T. alternatus from 15 drainages using phylogenetic reconstructions, lineage delimitation methods and analyses of molecular variance. Results: Trichomycterus alternatus is monophyletic and comprised of three main lineages: two restricted to the basin at its northernmost distribution and another broadly distributed to the south. In the latter, seven major cytb clades were geographically compatible with the eight paleodrainages, with three incongruences matching river captures previously described for the Guanabara Bay (GB). Shared haplotypes among isolated rivers flowing into GB provide the first molecular evidence of the 'Rio de Janeiro' paleoriver. Main conclusions: Dispersal via paleorivers is an important process, but it is not enough to recover the most recent dispersive events. Therefore, integrating both paleo-riverine configuration (GIS-based) and localized river captures (geological studies) is crucial to reveal the role of past geological and climatic events on the distribution of freshwater organisms. Taken together, these two factors significantly explained a high portion T. alternatus genetic structure along coastal drainages, revealing a paleolandscape scenario that may have been used by other freshwater Atlantic Forest taxa.

opencc-by-4.0Feb 2023View details →

The genetic consequences of captive breeding, environmental change and human exploitation in the endangered peninsular pronghorn

Binned microsatelite data of the peninsular pronghorn subspecies (Antilocapra americana peninsularis). Data is organized in by year manner. Each population correspond to the year samples were collected from, for example Pop_09 corresponds to samples collected from year 2009, whereas Pop_21 corresponds to the samples collected from year 2021.

Ecological traits drive genetic structuring in two open-habitat birds from the morphologically cryptic genus Elaenia (Aves: Tyrannidae)

Understanding the relative contributions of the many factors that shape population genetic structuring is a central theme in evolutionary and conservation biology. Historically, abiotic or extrinsic factors (such as geographic barriers or climatic shifts) have received greater attention than biotic or intrinsic factors (such as dispersal or migration). This focus stems in part from the logistical difficulties in taking a comparative phylogeographic approach that contrasts species that have experienced similar abiotic conditions during their evolution yet differ in the intrinsic attributes that might shape their genetic structure. To explore the effects of intratropical migration on the genetic structuring of Neotropical birds, we chose two congeneric species, the Lesser Elaenia (Elaenia chiriquensis) and the Plain-crested Elaenia (E. cristata), that are largely sympatric, and which have similar plumage, habitat preferences, and breeding phenology. Despite these many commonalities, they differ in migratory behavior: E. chiriquensis is an intratropical migratory species while E. cristata is sedentary. We used a reduced representation genomic approach to test whether migratory behavior is associated with increased gene flow and therefore lower genetic population structure. As predicted, we found notably stronger genetic structuring in the sedentary species than in the migratory ones. E. cristata comprises genetic clusters with geographic correspondence throughout its distribution, while there are no geographic groups within Brazil for E. chiriquensis. This comparison adds to the growing evidence about how intrinsic traits like migration can shape the genetic structuring of birds, and advances our understanding of the diversification patterns of the understudied, open habitat species from South America.

Genetic data and niche differences suggest that disjunct populations of Diglossa brunneiventris are not sister lineages

Disjunct distributions within a species are of great interest in systematics and biogeography. This separation can function as a barrier to gene flow when the distance among populations exceeds the dispersal capacity of individuals, and depending on the duration of the barrier, it may eventually lead to speciation. Here we describe patterns of geographic differentiation of two disjunct populations of Diglossa brunneiventris separated by approximately 1000 km along the Andes. Diglossa brunneiventris vuilleumieri is isolated in northern Colombia, while Diglossa brunneiventris brunneiventris has a seemingly continuous distribution across Peru, Bolivia, and Chile. We sequenced mitochondrial and nuclear DNA of the two Diglossa brunneiventris subspecies to evaluate whether they form a monophyletic clade, while including the other three species within the carbonaria complex (D. gloriosa, D. humeralis and D. carbonaria). We also constructed ecological niche models for each Diglossa brunneiventris subspecies to compare their climatic niches. We found that when using all available molecular data, the two D. brunneiventris subspecies are not sister lineages. In fact, each subspecies is more closely related to other species in the carbonaria complex. Our niche modeling analyses showed that the subspecies are occupying almost entirely different climatic niches. An additional, and not expected result was that the carbonaria complex might encompass more cryptic species than previously considered. We suggest reevaluating the taxonomic status of these brunneiventris populations, especially the northern subspecies, given its highly restricted range and potential threatened status.

Leg length and bristle density both necessary for water surface locomotion are genetically correlated in water striders

Access to hitherto unexploited ecological opportunities is associated with phenotypic evolution and often results in significant lineage diversification. Yet, our understanding of the mechanisms underlying such adaptive traits remains limited. Water striders have been able to exploit the water-air interface, primarily facilitated by changes in the density of hydrophobic bristles and a significant increase in leg length. These two traits are functionally correlated and are both necessary for generating efficient locomotion on the water surface. Whether bristle density and leg length have any cellular or developmental genetic mechanisms in common is unknown. Here, we combine comparative genomics and transcriptomics with functional RNAi assays to examine the developmental genetic and cellular mechanisms underlying the patterning of the bristles and the legs in Gerris buenoi and Mesovelia mulsanti, two species of water striders. We found that two gene duplication events in the genes beadex and taxi led to a functional expansion of the paralogs to affect bristle density and leg length. We also identified genes for which no function in bristle development has been previously described in other insects. Interestingly, most of these genes play a dual role in regulating bristle development and leg length. In addition, these genes play a role in regulating cell division. This result suggests that cell division may be a common mechanism through which these genes can simultaneously regulate leg length and bristle density. We propose that pleiotropy, by which gene function affects the development of multiple traits, may play a prominent role in facilitating access to unexploited ecological opportunities and species diversification.

opencc-zeroDec 2021View details →

Environmental differences explain subtle yet detectable genetic structure in a widespread pollinator

Background The environment is a strong driver of genetic structure in many natural populations, yet often neglected in population genetic studies. This may be a particular problem in vagile species, where subtle structure cannot be explained by limitations to dispersal. Consequently, these species might falsely be considered quasi-panmictic and hence potentially mismanaged. A species this might apply to, is the buff-tailed bumble bee (Bombus terrestris), an economically important and widespread pollinator, which is considered to be quasi-panmictic at mainland continental scales. Here we aimed to (i) quantify genetic structure in 21+ populations of the buff-tailed bumble bee, sampled throughout two Eastern European countries, and (ii) analyse the degree to which structure is explained by environmental differences, habitat permeability and geographic distance. Using 12 microsatellite loci, we characterised populations of this species with Fst analyses, complemented by discriminant analysis of principal components and Bayesian clustering approaches. We then applied generalized dissimilarity modelling to simultaneously assess the informativeness of geographic distance, habitat permeability and environmental differences among populations in explaining divergence. Results Genetic structure of the buff-tailed bumble bee quantified by means of Fst was subtle and not detected by Bayesian clustering. Discriminant analysis of principal components suggested insignificant but still noticeable structure that slightly exceeded estimates obtained through Fst analyses. As expected, geographic distance and habitat permeability were not informative in explaining the spatial pattern of genetic divergence. Yet, environmental variables related to temperature, vegetation and topography were highly informative, explaining between 33 and 39% of the genetic variation observed. Conclusions In contrast to previous studies reporting quasi-panmixia in continental populations of this species, we demonstrated the presence of subtle population structure related to environmental heterogeneity. Environmental data proved to be highly useful in unravelling the drivers of genetic structure in this vagile and opportunistic species. We highlight the potential of including these data to obtain a better understanding of population structure and the processes driving it in species considered to be quasi-panmictic.

Data from: Demography predicts genetic effective size in a desert stream fish community

Demographic data collected during long-term diversity monitoring and short-term ecological surveys were used to calculate summary statistics to compare with estimates of genetic effective size for nine species occurring in the Gila River, New Mexico, USA. Diversity survey data collected by New Mexico Department of Game and Fish from 1988 to 2010 were converted to presence/absence data to create detection histories for each of the nine focal species. Simple occupancy models of detection histories implemented using program PRESENCE were used to estimate the annual probability of sites becoming extirpated. A second data source from affiliated short-term ecological studies provided numbers of individuals captured and area sampled and was used to estimate mean density of adult individuals across sample sites. These data were also used to calculated an index of commonness that incorporates both relative abundance and study wide occupancy. Microsatellite genotypes from a previous study and Dryad submission were used to estimate effective number of breeders and genetic effective size (estimates included in this submission) for each species and contemporary migration rates. Migration rates were estimated using the Bayesian assignment model implemented in program BIMr. Outputs from all independent model runs and code to process output files are included with this data submission.

Genetic modifiers of Huntington's disease differentially influence motor and cognitive domains

Genome-wide association studies (GWAS) of Huntington's disease (HD) have identified six DNA maintenance gene loci (among others) as modifiers and implicated a two step-mechanism of pathogenesis: somatic instability of the causative HTT CAG repeat with subsequent triggering of neuronal damage. The largest studies have been limited to HD individuals with a rater-estimated age at motor onset. To capitalize on the wealth of phenotypic data in several large HD natural history studies, we have performed algorithmic prediction using common motor and cognitive measures to predict age at other disease landmarks as additional phenotypes for GWAS. Combined with imputation using the Trans-Omics for Precision Medicine reference panel, predictions using integrated measures provided objective landmark phenotypes with greater power to detect most modifier loci. Importantly, substantial differences in the relative modifier signal across loci, highlighted by comparing common modifiers at MSH3 and FAN1, revealed that individual modifier effects can act preferentially in the motor or cognitive domains. Individual components of the DNA maintenance modifier mechanisms may therefore act differentially on the neuronal circuits underlying the corresponding clinical measures. In addition, we identified new modifier effects at the PMS1 and PMS2 loci and implicated a potential new locus on chromosome 7. These findings indicate that broadened discovery and characterization of HD genetic modifiers based on additional quantitative or qualitative phenotypes offers not only the promise of in-human validated therapeutic targets, but also a route to dissecting the mechanisms and cell types involved in both the somatic instability and toxicity components of HD pathogenesis.

Data from: Limited evidence of a genetic basis for sex determination in the common creek chub, Semotilus atromaculatus

Sexual reproduction is almost universal in vertebrates of the animal kingdom; therefore, each species which use it must have a mechanism for designating sex as male or female. Fish especially have a wide range of sex determining systems. In the present study, we aimed to identify a genetic basis for sex determination in the common creek chub (Semotilus atromaculatus) using genotyping-by-sequencing data. No sex-associated markers were found by RADSex or a GWAS using GEMMA, however, our Weir and Cockerham locus-specific FST analysis and discriminant analysis of principal components revealed some genetic differentiation between the sexes at several loci. While no explicit sex determination mechanism has been yet discovered in creek chub, these loci are potential candidates for future studies. Incompatible systems are thought to increase reproductive isolation but interspecific hybridization is common among groups such as cyprinid minnows; thus, studies such as ours can provide insight into hybridization and evolutionary diversification of this clade. We also highlight technical challenges involved in studying sex determination in species with extremely variable mechanisms.