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675 results for “Introgression”
Pre-introduction introgression contributes to parallel differentiation and contrasting hybridisation outcomes between invasive and native marine mussels
<p class="CxSpFirst">Non-native species experience novel selection pressures in introduced environments and may interbreed with native lineages. Species introductions therefore provide opportunities to investigate repeated patterns of adaptation and introgression across replicated contact zones. Here, we investigate genetic parallelism between multiple introduced populations of the invasive marine mussel, <i>Mytilus galloprovincialis</i>, in the absence (South Africa and California) and presence of hybridisation with a native congener (<i>Mytilus planulatus</i> in Batemans Bay and Sydney Harbour, Australia). Repeatability in post-introduction differentiation from native-range populations varied between genetically distinct Atlantic and Mediterranean lineages, with Atlantic-derived introductions displaying high differentiation (<i>maxFST</i>>0.4) and parallelism at outlier loci. Identification of long non-coding RNA transcripts (lncRNA) additionally allowed us to clarify that parallel responses are largely limited to protein-coding loci, with lncRNAs likely evolving under evolutionary constraints. Comparisons of independent hybrid zones revealed differential introgression most strongly in Batemans Bay, with an excess of <i>M. galloprovincialis</i> ancestry and resistance to introgression at loci differentiating parental lineages (<i>M. planulatus</i> and Atlantic <i>M. galloprovincialis</i>)<i>. </i>Additionally, contigs putatively introgressed with divergent alleles from a closely related species, <i>Mytilus edulis, </i>showed stronger introgression asymmetries compared to genome-wide trends and also diverged in parallel in both Atlantic-derived introductions. These results suggest that divergent demographic histories experienced by introduced lineages, including pre-introduction introgression, influences contemporary admixture dynamics. Our findings build on previous investigations reporting contributions of historical introgression to intrinsic reproductive architectures shared between marine lineages and illustrate that interspecific introgression history can shape differentiation between colonising populations and their hybridisation with native congeners.</p>
Pigmentation Genes Show Evidence of Repeated Divergence and Multiple Bouts of Introgression in Setophaga Warblers
<p>Species radiations have long served as model systems in evolutionary biology. However, it has only recently become possible to study the genetic bases of the traits responsible for diversification, and only in a small number of model systems. Here we use genomes of 36 species of North, Central, and South American warblers to highlight the role of pigmentation genes—involved in melanin and carotenoid processing—in the diversification of this group. We show that <i>agouti signaling protein</i> (<i>ASIP</i>) and <i>beta-carotene oxygenase 2</i> (<i>BCO2</i>) are predictably divergent between species that differ in the distribution of melanin and carotenoid in their plumages, respectively. Among species, sequence variation at <i>ASIP</i> broadly mirrors the species' phylogenetic history, consistent with repeated, independent mutations generating melanin-based variation. In contrast, <i>BCO2</i> variation is highly discordant from the species tree, with evidence of cross-lineage introgression among species like the yellow warbler (<i>Setophaga petechia</i>) and magnolia warbler (<i>S. magnolia</i>) with extensive carotenoid-based coloration. We also detect introgression of a small part of the <i>BCO2</i> coding region (<3 kb) in <i>S. discolor</i> and <i>S. vitellina, </i>including an amino acid substitution that is unique to warblers but otherwise highly conserved across birds. Lateral transfer of carotenoid-processing genes has been documented in arthropods, but introgression of <i>BCO2</i> as demonstrated here—presumably adaptive—represents the first example of carotenoid gene transfer among vertebrates. These contrasting genomic patterns show that both independent evolution in a common set of genes and past gene flow have fueled plumage diversification in this colorful avian radiation.</p>
The legacy of recurrent introgression during the radiation of hares
Hybridization may often be an important source of adaptive variation, but the extent and long-term impacts of introgression have seldom been evaluated in the phylogenetic context of a radiation. Hares (<i>Lepus</i>) represent a widespread mammalian radiation of 32 extant species characterized by striking ecological adaptations and recurrent admixture. To understand the relevance of introgressive hybridization during the diversification of <i>Lepus</i>, we analyzed whole exome sequences (61.7 Mb) from 15 species of hares (1- 4 individuals per species), spanning the global distribution of the genus, and two outgroups. We used a coalescent framework to infer species relationships and divergence times, despite extensive genealogical discordance. We found high levels of allele sharing among species and show that this reflects extensive incomplete lineage sorting and temporally layered hybridization. Our results revealed recurrent introgression at all stages along the <i>Lepus</i> radiation, including recent gene flow between extant species since the last glacial maximum, but also pervasive ancient introgression occurring since near the origin of the hare lineages. We show that ancient hybridization between northern hemisphere species has resulted in shared variation of potential adaptive relevance to highly seasonal environments, including genes involved in circadian rhythm regulation, pigmentation, and thermoregulation. Our results illustrate how the genetic legacy of ancestral hybridization may persist across a radiation, leaving a long-lasting signature of shared genetic variation that may contribute to adaptation within and among species.
Interspecific introgression reveals a role of male genital morphology during the evolution of reproductive isolation in Drosophila
Rapid divergence in genital structures among nascent species has been posited to be an early-evolving cause of reproductive isolation, although evidence supporting this idea as a widespread phenomenon remains mixed. Using a collection of interspecific introgression lines between two Drosophila species that diverged ~240,000 years ago, we tested the hypothesis that even modest divergence in genital morphology can result in substantial fitness losses. We studied the reproductive consequences of variation in the male epandrial posterior lobes between Drosophila mauritiana and D. sechellia and found that divergence in posterior lobe morphology has significant fitness costs on several pre-fertilization and post-copulatory reproductive measures. Males with divergent posterior lobe morphology also significantly reduced the life span of their mates. Interestingly, one of the consequences of genital divergence was decreased oviposition and fertilization, which suggests that a sensory bias for posterior lobe morphology could exist in females, and thus posterior lobe morphology may be the target of cryptic female choice in these species. Our results provide evidence that divergence in genitalia can in fact give rise to substantial reproductive isolation early during species divergence, and they also reveal novel reproductive functions of the external male genitalia in Drosophila.
Tracking invasions of a destructive defoliator, the gypsy moth (Erebidae: Lymantria dispar): population structure, origin of intercepted specimens, and Asian introgression into North America
Genetic data can help elucidate the dynamics of biological invasions, which are fueled by the constant expansion of international trade. The introduction of European gypsy moth (<i>Lymantria dispar dispar</i>) into North America is a classic example of human-aided invasion that has caused tremendous damage to North American temperate forests. Recently, the even more destructive Asian gypsy moth (mainly <i>L. d. asiatica</i> and <i>L. d. japonica</i>) has been intercepted in North America, mostly transported by cargo ships. To track invasion pathways, we developed a diagnostic panel of 60 DNA loci (55 nuclear and 5 mitochondrial) to characterize worldwide genetic differentiation within <i>L. dispar</i> and its sister species <i>L. umbrosa</i>. Hierarchical analyses supported strong differentiation and recovered five geographic groups that correspond to 1) North America, 2) Europe plus North Africa and Middle East, 3) the Urals, Central Asia, and Russian Siberia, 4) continental East Asia, and 5) the Japanese islands. Interestingly, <i>L. umbrosa</i> was grouped with <i>L. d. japonica</i>, and the introduced North American population exhibits remarkable distinctiveness from contemporary European counterparts. Each geographic group, with the exception of North America, shows additional lower-level structures when analyzed individually, which provided the basis for inference of the origin of invasive specimens. Two assignment approaches consistently identified a coastal area of continental East Asia as the major source for Asian invasion during 2014–2015, with Japan being another source. By analyzing simulation and laboratory crosses, we further provided evidence for the occurrence of natural Asian-North American hybrids in the Pacific Northwest, raising concerns for introgression of Asian alleles that may accelerate range expansion of gypsy moth in North America. Our study demonstrates how genetic data contribute to bio-surveillance of invasive species with results that can inform regulatory management and reduce the frequency of trade-associated invasions.
Data from: Limited hatchery introgression into wild brook trout (Salvelinus fontinalis) populations despite reoccurring stocking
Due to increased anthropogenic pressures on many fish populations, supplementing wild populations with captive-raised individuals has become an increasingly common management practice. Stocking programs can be controversial due to uncertainty about the long-term fitness effects of genetic introgression on wild populations. In particular, introgression between hatchery and wild individuals can cause declines in wild population fitness, resiliency, and adaptive potential, and contribute to local population extirpation. However, low survival and fitness of captive-raised individuals can minimize the long-term genetic consequences of stocking in wild populations, and to date the prevalence of introgression in actively stocked ecosystems has not been rigorously evaluated. We quantified the extent of introgression in 30 populations of wild brook trout (Salvelinus fontinalis) in a Pennsylvania watershed, and examined the correlation between introgression and 11 environmental covariates. Genetic assignment tests were used to determine the origin (wild vs. captive-raised) for 1742 wild-caught and 300 hatchery brook trout. To avoid assignment biases, individuals were assigned to two simulated populations that represented the average allele frequencies in wild and hatchery groups. Fish with intermediate probabilities of wild ancestry were classified as introgressed, with threshold values determined through simulation. Even with reoccurring stocking at most sites, over 93% of wild-caught individuals probabilistically assigned to wild origin, and only 6% of wild-caught fish assigned to introgressed. Models examining environmental drivers of introgression explained less than 3% of the among-population variability, and all estimated effects were highly uncertain. This was not surprising given overall low introgression observed in this study. Our results suggest that introgression of hatchery-derived genotypes can occur at low rates, even in actively stocked ecosystems and across a range of habitats. However, a cautious approach to stocking may still be warranted, as the potential effects of stocking on wild population fitness and the mechanisms limiting introgression are not known.
Data from: Hare pseudo-reference genome from: the genomic impact of historical hybridization with massive mitochondrial DNA introgression
<p><b>Background:</b> The extent to which selection determines interspecific patterns of genetic exchanges enlightens the role of adaptation in evolution and speciation. Often reported extensive interspecific introgression could be selection-driven, but also result from demographic processes, especially in cases of invasive species replacements, which can promote introgression at their front. Because invasion and selective sweeps similarly mold variation, population genetics evidence for selection can only be gathered in an explicit demographic framework. The Iberian hare, <i>Lepus granatensis</i>, displays in its northern range extensive mitochondrial DNA introgression from <i>L. timidus</i>, an arctic/boreal species that it replaced locally after the last glacial maximum. We use whole-genome sequencing to infer geographic and genomic patterns of nuclear introgression and fit a neutral model of species replacement with hybridization, allowing us to evaluate how selection influenced introgression genome-wide, including for mtDNA.</p> <p><b>Results:</b> Although the average nuclear and mtDNA introgression patterns are strongly contrasted, they fit a single neutral model of post-glacial invasive replacement of <i>timidus</i> by <i>granatensis</i>. Outliers of elevated introgression include several genes related to immunity, spermatogenesis, and mitochondrial metabolism. Introgression is reduced on the X-chromosome and in low recombining regions.</p> <p><b>Conclusion:</b> General nuclear and mtDNA patterns of introgression can be explained by purely demographic processes. Hybrid incompatibilities and interplay between selection and recombination locally modulate levels of nuclear introgression. Selection promoted introgression of some genes involved in conflicts, either interspecific (parasites) or possibly cytonuclear. In the latter case, nuclear introgression could mitigate the potential negative effects of alien mtDNA on mitochondrial metabolism and male-specific traits.</p>
Data from: A new species and introgression in eastern Asian hemlocks (Pinaceae: Tsuga)
Species delimitation in Pinaceae is often challenged by limited morphological differentiation and introgression. In Tsuga (hemlocks), species delimitation has been most challenging among northeastern Asian taxa, where the species are weakly marked morphologically and range in number from three to five in previous studies. Two low-copy nuclear four-coumarase-ligase (4CL) genes andmorphology strongly support a clade of the Japanese endemic T. diversifolia and T. sieboldii from Japan and Ulleung island (Ulleungdo) in Korea. This clade is here referred to as the oceanic hemlocks. 4CL strongly supports a sister-group relationship of the widespread northeastern Asian T. chinensis and eastern North American T. caroliniana. In contrast, chloroplast genomes, which are markedly reduced in Tsuga and relatives, strongly support Japanese T. sieboldii as sister to T. chinensis and moderately support T. caroliniana as sister to a clade of T. diversifolia and hemlocks fromUlleungdo. These divergent topologies suggest chloroplast capture of T. chinensis by Japanese T. sieboldii. Ulleungdo hemlocks are distinct from other northeastern Asian species in leaf and cone morphology and phenologically in common-garden observations. We therefore describe these hemlocks as a new species, T. ulleungensis.
Data from: A complex pattern of post-divergence expansion, contraction, introgression and asynchronous responses to Pleistocene climate changes in two Dipelta sister species from western China
The well-known vicariance and dispersal models dominate in understanding the allopatric pattern for related species and presume the simultaneous occurrence of speciation and biogeographic events. However, the formation of allopatry may postdate the species divergence. We examined this hypothesis using DNA sequence data from 3 chloroplast fragments and 5 nuclear loci of Dipelta floribunda and D. yunnanensis, two shrub species with the circum Sichuan Basin distribution, combining the climatic niche modeling approach. The best-fit model supported by the approximate Bayesian computation (ABC) analysis indicated that, D. floribunda and D. yunnanensis diverged during the mid-Pleistocene period, consistent with the largest glacial period in the Qinghai-Tibet Plateau (QTP). The historically inter-specific gene flow was identified but seemed to have ceased after the last interglacial period (LIG), when the range of D. floribunda moved northward from the south of the Sichuan Basin. Further, populations of D. floribunda had expanded obviously in the north of the Sichuan Basin after the last glacial maximum (LGM). Relatively, the range of D. yunnanensis expanded before the LGM, reduced during the post-LGM especially in the north of the Sichuan Basin, reflecting the asynchronous responses of related species to the contemporary climate changes. Our results suggested that complex topography should be considered in understanding the distributional patterns even for closely related species and their demographic responses.
Data from: Origins of the Greenland shark (Somniosus microcephalus): impacts of ice-olation and introgression
Herein, we use genetic data from 277 sleeper sharks to perform coalescent-based modeling to test the hypothesis of early Quaternary emergence of the Greenland shark (Somniosus microcephalus) from ancestral sleeper sharks in the Canadian Arctic-Subarctic region. Our results show that morphologically cryptic somniosids S. microcephalus and Somniosus pacificus can be genetically distinguished using combined mitochondrial and nuclear DNA markers. Our data confirm the presence of genetically admixed individuals in the Canadian Arctic and sub-Arctic, and temperate Eastern Atlantic regions, suggesting introgressive hybridization upon secondary contact following the initial species divergence. Conservative substitution rates fitted to an Isolation with Migration (IM) model indicate a likely species divergence time of 2.34 Ma, using the mitochondrial sequence DNA, which in conjunction with the geographic distribution of admixtures and Pacific signatures likely indicates speciation associated with processes other than the closing of the Isthmus of Panama. This time span coincides with further planetary cooling in the early Quaternary period followed by the onset of oscillating glacial-interglacial cycles. We propose that the initial S. microcephalus–S. pacificus split, and subsequent hybridization events, were likely associated with the onset of Pleistocene glacial oscillations, whereby fluctuating sea levels constrained connectivity among Arctic oceanic basins, Arctic marginal seas, and the North Atlantic Ocean. Our data demonstrates support for the evolutionary consequences of oscillatory vicariance via transient oceanic isolation with subsequent secondary contact associated with fluctuating sea levels throughout the Quaternary period—which may serve as a model for the origins of Arctic marine fauna on a broad taxonomic scale.
Data from: Leap-frog dispersal and mitochondrial introgression: phylogenomics and biogeography of Limnonectes fanged frogs in the Lesser Sundas Archipelago of Wallacea
Aim: The Lesser Sunda Islands are situated between the Sunda and Sahul Shelves, with a linear arrangement that has functioned as a two-way filter for taxa dispersing between the Asian and Australo-Papuan biogeographic realms. Distributional patterns of many terrestrial vertebrates suggest a stepping-stone model of island colonization. Here we investigate the timing and sequence of island colonization in Asian-origin fanged frogs from the volcanic Sunda Arc islands with the goal of testing the stepping-stone model of island colonization. Location: The Indonesian islands of Java, Lombok, Sumbawa, Flores, and Lembata. Taxon: Limnonectes dammermani and L. kadarsani (Family: Dicroglossidae) Methods: Mitochondrial DNA was sequenced from 153 frogs to identify major lineages and to select samples for an exon-capture experiment. We designed probes to capture sequence data from 974 exonic loci (1,235,981 bp) from 48 frogs including the outgroup species, L. microdiscus. The resulting data were analyzed using phylogenetic, population genetic, and biogeographical model testing methods. Results: The mtDNA phylogeny finds L. kadarsani paraphyletic with respect to L. dammermani, with a pectinate topology consistent with the stepping-stone model. Phylogenomic analyses of 974 exons recovered the two species as monophyletic sister taxa that diverged ~7.6 Ma with no detectable contemporary gene flow, suggesting introgression of the L. dammermani mitochondrion into L. kadarsani on Lombok resulting from an isolated ancient hybridization event ~4 Ma. Within L. kadarsani, the Lombok lineage diverged first while the Sumbawa and Lembata lineages are nested within a Flores assemblage composed of two parapatrically distributed lineages meeting in central Flores. Biogeographical model comparison found strict stepping-stone dispersal to be less likely than models involving leap-frog dispersal events. Main conclusions: These results suggest that the currently accepted stepping-stone model of island colonization might not best explain the current patterns of diversity in the archipelago. The high degree of genetic structure, large divergence times, and absent or low levels of migration between lineages suggests that L. kadarsani represents five distinct species.
Data from: Late Pleistocene range expansion of North American topminnows accompanied by admixture and introgression.
Aim: We used genome-scale sampling to assess the phylogeography of a group of topminnows in the Fundulus notatus species complex. Two of the species have undergone extensive range expansions resulting in broadly overlapping distributions, and sympatry within drainages has provided opportunities for hybridization and introgression. We assess the timing and pattern of range expansion in the context of late-Pleistocene-Holocene drainage events, and evaluate the evidence for introgressive hybridization between species. Location: Central and southern United States including drainages of the Gulf of Mexico Coastal Plain and portions of the Mississippi River drainage in and around the Central Highlands. Taxon: Topminnows, Genus Fundulus, subgenus Zygonectes - Fundulus notatus, Fundulus olivaceus, Fundulus euryzonus Methods: We sampled members of the F. notatus species complex throughout their respective ranges, including numerous drainage systems where species co-occur. We collected genome-wide Single Nucleotide Polymorphisms (SNPs) using the Genotype by Sequencing (GBS) method, and subjected data to population genetic analyses to infer the population histories of both species, including explicit tests for admixture and introgression. The methods employed included STRUCTURE, Principle Coordinates Analysis, TreeMix and Approximate Bayesian Computation. Results: Genetic data are presented for 749 individuals sampled from 14 F. notatus, 20 F. olivaceus, and two F. euryzonus populations. Members of the species complex differed in phylogeographic structure, with F. notatus exhibiting geographic clusters corresponding to Pleistocene coastal drainages, and F. olivaceus comparatively lacking in phylogeographic structure. Evidence for interspecific introgression varied by drainage. Main Conclusions: Populations of F. notatus and F. olivaceus exhibited contrasting patterns of lineage diversity among coastal drainages, indicating inter-specific differences in their Pleistocene southern refugia. Phylogeographic patterns in both species indicated that range expansions into the northern limits of contemporary distributions coincided with and continued subsequent to the Last Glacial Maximum. There was evidence of introgression between species in some, but not all drainages where the species co-occur, in a pattern that is correlated with previous estimates of hybridization rates.
Data from: Introgression between divergent corn borer species in a region of sympatry: implications on the evolution and adaptation of pest arthropods
The Asian corn borer, Ostrinia furnacalis, and European corn borer, O. nubilalis (Lepidoptera: Crambidae), cause damage to cultivated maize in spatially distinct geographies, and have evolved divergent hydrocarbons as the basis of sexual communication. The Yili area of Xinjiang Uyghur Autonomous Region in China represents the only known region where O. furnacalis has invaded a native O. nubilalis range, and these two corn borer species have made secondary contact. Genetic differentiation was estimated between Ostrinia larvae collected from maize plants at 11 locations in Xinjiang Province, and genotyped using high throughput SNP and microsatellite markers. Maternal lineages were assessed by direct sequencing of mitochondrial cytochrome c oxidase subunit I and II haplotypes, and a high degree of genotypic diversity was demonstrated between lineages based on SNP genotypes. Furthermore, historical introgression was predicted among SNP genotypes only at sympatric locations in the Yili area, whereas in Xinjiang populations wherein only O. furnacalis haplotypes were detected no analogous introgressed genotypes were predicted. Our detection of putative hybrids and historical evidence of introgression defines Yili area as a hybrid zone between the species in normal ecological interactions, and furthermore might indicate that adaptive traits could spread even between seemingly divergent species through horizontal transmission. Results of this study indicate there may be a continuum in the degree of reproductive isolation between Ostrinia species, and that the elegance of distinct and complete speciation based on modifications to the pheromone communication might need to be reconsidered.
Data from: Inferring phylogeny and introgression using RADseq data: an example from flowering plants (Pedicularis: Orobanchaceae)
Phylogenetic relationships among recently diverged species are often difficult to resolve due to insufficient phylogenetic signal in available markers and/or conflict among gene trees. Here we explore the use of reduced-representation genome sequencing, specifically in the form of restriction-site associated DNA (RAD), for phylogenetic inference and the detection of ancestral hybridization in non-model organisms. As a case study, we investigate Pedicularis section Cyathophora, a systematically recalcitrant clade of flowering plants in the broomrape family (Orobanchaceae). Two methods of phylogenetic inference, maximum likelihood and Bayesian concordance, were applied to data sets that included as many as 40,000 RAD loci. Both methods yielded similar topologies that included two major clades: a "rex-thamnophila" clade, composed of two species and several subspecies with relatively low floral diversity, and geographically widespread distributions at lower elevations, and a "superba" clade, composed of three species characterized by relatively high floral diversity and isolated geographic distributions at higher elevations. Levels of molecular divergence between subspecies in the rex-thamnophila clade are similar to those between species in the superba clade. Using Patterson's D-statistic test, including a novel extension of the method that enables finer-grained resolution of introgression among multiple candidate taxa by removing the effect of their shared ancestry, we detect significant introgression among nearly all taxa in the rex-thamnophila clade, but not between clades or among taxa within the superba clade. These results suggest an important role for geographic isolation in the emergence of species barriers, by facilitating local adaptation and differentiation in the absence of homogenizing gene flow.
Data from: Mapping reduced introgression loci to the X chromosome of the hybridizing field crickets, Gryllus firmus and G. pennsylvanicus
The genomic architecture of barriers to gene exchange during the speciation process is poorly understood. The genomic islands model suggests that loci associated with barriers to gene exchange prevent introgression of nearby genomic regions via linkage disequilibrium. But few analyses of the actual genomic location of non-introgressing loci in closely related species exist. In a previous study Maroja et al. showed that in the hybridizing field crickets, Gryllus firmus and G. pennsylvanicus, 50 non-introgressing loci are localized on two autosomal regions and the X chromosome, but they were not able to map the loci along the X chromosome because they used a male informative cross. Here, we localize the introgressing and non-introgressing loci on the X chromosome and reveal that all X-linked non-introgressing loci are restricted to a 50-cM region with 10 of these loci mapped to a single location. We discuss the implications of this finding to speciation.
Data from: Genome-specific histories of divergence and introgression between an allopolyploid unisexual salamander lineage and two ancestral sexual species
Quantifying introgression between sexual species and polyploid lineages traditionally thought to be asexual is an important step in understanding what drives the longevity of putatively asexual groups. Here, we capitalize on three recent innovations—ultraconserved element (UCE) sequencing, bioinformatic techniques for identifying genome-specific variation in polyploids, and model-based methods for evaluating historical gene flow—to measure the extent and tempo of introgression over the evolutionary history of an allopolyploid lineage of all-female salamanders and two ancestral sexual species. Our analyses support a scenario in which the genomes sampled in unisexual salamanders last shared a common ancestor with genomes in their parental species ~3.4 million years ago, followed by a period of divergence between homologous genomes. Recently, secondary introgression has occurred at different times with each sexual species during the last 500,000 years. Sustained introgression of sexual genomes into the unisexual lineage is the defining characteristic of their reproductive mode, but this study provides the first evidence that unisexual genomes have undergone long periods of divergence without introgression. Unlike other sperm-dependent taxa in which introgression is rare, the alternating periods of divergence and introgression between unisexual salamanders and their sexual relatives could explain why these salamanders are among the oldest described unisexual animals.
Multiple decades of stocking has resulted in limited hatchery introgression in wild brook trout (Salvelinus fontinalis) populations of Nova Scotia
<p>Many populations of freshwater fishes are threatened with losses, and increasingly, the release of hatchery individuals is one strategy being implemented to support wild populations. However, stocking of hatchery individuals may pose long-term threats to wild populations, particularly if genetic interactions occur between wild and hatchery individuals. One highly prized sport fish that has been heavily stocked throughout its range is the brook trout (Salvelinus fontinalis). In Nova Scotia, Canada, hatchery brook trout have been stocked since the early 1900s, and despite continued stocking efforts, populations have suffered declines in recent decades. Before this study, the genetic structure of brook trout populations in the province was unknown; however, given the potential negative consequences associated with hatchery stocking, it is possible that hatchery programs have adversely affected the genetic integrity of wild populations. To assess the influence of hatchery supplementation on wild populations, we genotyped wild brook trout from 12 river systems and hatchery brook trout from two major hatcheries using 100 microsatellite loci. Genetic analyses of wild trout revealed extensive population genetic structure among and within river systems and significant isolation-by-distance. Hatchery stocks were genetically distinct from wild populations, and most populations showed limited to no evidence of hatchery introgression (<5% hatchery ancestry). Only a single location had a substantial number of hatchery-derived trout and was located in the only river where a local strain is used for supplementation. The amount of hatchery stocking within a watershed did not influence the level of hatchery introgression. Neutral genetic structure of wild populations was influenced by geography with some influence of climate and stocking indices. Overall, our study suggests that long-term stocking has not significantly affected the genetic integrity of wild trout populations, highlighting the variable outcomes of stocking and the need to evaluate the consequences on a case-by-case basis</p>
Assembled RADseq Data: "Historical introgression among the American live oaks and the comparative nature of tests for introgression"
<p>Assembled sequence data for Eaton et al. (2015) "Historical introgression among the American live oaks and the comparative nature of tests for introgression". The unassembled sequence data are available on NCBI SRA. </p> <p>Data sets were assembled using pyrad v.2.13 as described in notebook 1 from the study.</p>
Data from: Hybridization and adaptive introgression in a marine invasive species in native habitats
<p><span>Hybridization</span> <span>of distinct populations or species is an important evolutionary driving force. For invasive species, hybridization can enhance their competitive advantage in the non-native range as a source of adaptive novelty by introgression of selectively favoured alleles. </span><span>W</span><span>e use </span><span>single-nucleotide polymorphism arrays (SNP-chips) to assess genetic diversity and population structure in the invasive ctenophore <em>Mnemiopsis</em> <em>leidyi</em> </span><span>in native habitats along the USA east coast. H</span><span>ybrids are present at the distribution border of the two lineages. However, our data suggests selection against hybrids in stable habitats, while hybrids are selected for in fluctuating environments. H</span><span>ybrid populations thriving in extreme and unstable environments of the native range, such as the Chesapeake Bay, could accelerate the invasion success if translocated. For <em>M. leidyi</em>, this is especially relevant as low salinity currently limits its invasion range in western Eurasia. </span><span>Hybridization status is thus important but currently disregarded to determine high-risk areas for ballast water exchange.</span></p>
Ancient introgression in mouse lemurs (Microcebus:Cheirogaleidae) explains 20 years of phylogenetic uncertainty
<p>Mouse lemurs (genus <em>Microcebus</em>) are a clade of approximately 26 named species of small, nocturnal primates endemic to Madagascar. The genus radiated one and ten million years ago and is morphologically cryptic, with most species having been named within the past 20 years largely based on phylogenetic analysis of short fragments of mitochondrial data. More recent work has been focused on revisiting species designations with autosomal nuclear data using more sophisticated statistical approaches. The order of speciation events in <em>Microcebus </em>remains contentious, particularly with regard to the placement of the <em>M. ravelobensis </em>clade. We investigated support for previous phylogenetic hypotheses based on available whole-genome assemblies from six species and an outgroup. We recovered over 4,000 one-to-one orthologs from these assemblies and used concatenation and coalescent species tree methods to<em> </em>evaluate if differences between previous studies were due to methodological differences or to limitations from too few loci. Observed gene tree discordance was high with patterns inconsistent with incomplete lineage sorting alone. Therefore, we estimated phylogenetic networks to investigate ancient introgression events that may explain observed gene tree distributions and previous phylogenetic conflicts. A network model, invoking some role for introgressive hybridization in the early evolution of <em>Microcebus</em>, better characterizes phylogenetic relationships than does any binary species tree. Our results provide insights into the biogeographic history of a threatened and diverse group of primates while also highlighting an important role for phylogenetic network methods in resolving cases of phylogenetic uncertainty.</p>
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.