Hybridization drives genetic erosion in sympatric desert fishes of western North America

Chafin, Tyler K.; Douglas, Michael E.; Martin, Bradley T.

doi:10.1038/s41437-019-0259-2

Cited by 37 publications

(54 citation statements)

References 78 publications

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“…Introgressed populations are another management conundrum (Allendorf, Leary, Spruell, & Wenburg, 2001) (Allendorf et al 2001) that often have negative consequences for conservation 504 efforts (Rhymer & Simberloff, 1996). However, recent insights from genomic data suggest hybridization is much more common than previously thought (Bangs, Douglas, Brunner, & 506 Douglas, 2020), and in fact reticulation is an important evolutionary process (Chafin, Douglas, Martin, & Douglas, 2019). In our data set, one population, Amargosa Canyon (AMC), appears to 508 be of hybrid origin.…”

Section: Hybridization and Subspecies 502mentioning

confidence: 78%

“…Finally, genomic tools have demonstrated the previously unknown hybrid status of 618 Amargosa Canyon SPD. Hybridization has been commonplace among desert fishes (Bangs, Douglas, Mussmann, & Douglas, 2018) and has served as a mechanism of speciation (Gerber, 620 Tibbets, & Dowling, 2001), but can also erode species boundaries (Chafin, Douglas, Martin, & Douglas, 2019). Additionally, anthropogenic climate change has induced hybridization among 622 divergent species (Canestrelli et al, 2017;Muhlfeld et al, 2014), and thus represents a post-Pleistocene evolutionary mechanism inherent to western North America (Woodhouse, Meko, 624 MacDonald, Stahle, & Cook, 2010).…”

Section: Oasis Valley)mentioning

confidence: 99%

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Defining Relictual Biodiversity: Conservation Units in Speckled Dace (Cyprinidae:Rhinichthys osculus) of the Greater Death Valley Ecosystem

Mussmann

Douglas

Oakey

2020

Preprint

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22The tips in the tree of life serve as foci for conservation and management, yet clear delimitations are masked by inherent variance at the species-population interface. Analyses using thousands of 24 nuclear loci can potentially sort inconsistencies, yet standard categories applied to this parsing are themselves potentially conflicting and/or subjective [e.g., DPS (distinct population 26 segments); DUs (Diagnosable Units-Canada); MUs (management units); SSP (subspecies); Evolutionarily Significant Units (ESUs)]. One potential solution for consistent categorization is 28 to create a comparative framework by accumulating statistical results from independent studies and evaluating congruence among data sets. Our study illustrates this approach in speckled dace 30 (Cyprinidae: Rhinichthys osculus) endemic to two basins (Owens and Amargosa) in the Death Valley ecosystem (DVE). These fish persist in the Mojave Desert as isolated Pleistocene-relicts 32 and are of conservation concern, but lack formal taxonomic descriptions/designations. Doubledigest RAD (ddRAD) methods identified 14,355 SNP loci across 10 populations (N=140). 34Species delimitation analyses [multispecies coalescent (MSC) and unsupervised machine learning (UML)] delineated four putative ESUs. F ST outlier loci (N=106) were juxtaposed to 36 uncover the potential for localized adaptations. We detected one hybrid population that resulted from upstream reconnection of habitat following contemporary pluvial periods, whereas 38 remaining populations represent relics of ancient tectonism within geographically-isolated springs and groundwater-fed streams. Our study offers three salient conclusions: A blueprint for 40 a multi-faceted delimitation of conservation units; a proposed mechanism by which criteria for intraspecific biodiversity can be potentially standardized; and a strong argument for the proactive 42 management of critically-endangered DVE fishes.3

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Section: Hybridization and Subspecies 502mentioning

confidence: 78%

Section: Oasis Valley)mentioning

confidence: 99%

Defining Relictual Biodiversity: Conservation Units in Speckled Dace (Cyprinidae:Rhinichthys osculus) of the Greater Death Valley Ecosystem

Mussmann

Douglas

Oakey

2020

Preprint

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“…On the other hand, T. ornata and T. carolina are separated by greater genetic distances than are the southeastern taxa (Martin et al, 2013), which may suggest the presence of intrinsic genetic incompatibilities (Abbott et al, 2013;Barton, 2001) and is consistent with the lack of hybrids beyond the F 1 generation. Furthermore, the low frequency of F 1 hybrids observed in the Illinois ON × EA population may have resulted from recent degradation of the prairiegrassland habitat (Manning, 2001;Mussmann et al, 2017), which subsequently initiated increased heterospecific contact or otherwise disturbed reproductive boundaries by altering the fitness consequences of hybridization (Chafin, Douglas, Martin, & Douglas, 2019;Grabenstein & Taylor, 2018…”

Section: Regional and Taxon-specific Perspectivesmentioning

confidence: 99%

“…Alternatively, rapid environmental change could simply outpace the selective filtering of maladaptive variants, with a subsequent decrease in fitness (Kokko et al, 2017). This would be particularly evident when effective population sizes are already depressed following a population bottleneck (Chafin et al, 2019). Here, extreme rates of change may also link with a genetic swamping effect (i.e., replacement of local genotypes by hybrids; Todesco et al, 2016).…”

Section: Functional Genomic Architecture In the Southeastern Hybridmentioning

confidence: 99%

Contrasting signatures of introgression in North American box turtle (Terrapene spp.) contact zones

et al. 2020

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Hybridization occurs differentially across the genome in a balancing act between selection and migration. With the unprecedented resolution of contemporary sequencing technologies, selection and migration can now be effectively quantified such that researchers can identify genetic elements involved in introgression. Furthermore, genomic patterns can now be associated with ecologically relevant phenotypes, given availability of annotated reference genomes. We do so in North American box turtles (Terrapene) by deciphering how selection affects hybrid zones at the interface of species boundaries and identifying genetic regions potentially under selection that may relate to thermal adaptations. Such genes may impact physiological pathways involved in temperature-dependent sex determination, immune system functioning and hypoxia tolerance. We contrasted these patterns across inter-and intraspecific hybrid zones that differ temporally and biogeographically. We demonstrate hybridization is broadly apparent in Terrapene, but with observed genomic cline patterns corresponding to species boundaries at loci potentially associated with thermal adaptation. These loci display signatures of directional introgression within intraspecific boundaries, despite a genome-wide selective trend against intergrades. In contrast, outlier loci for interspecific comparisons exhibited evidence of being under selection against hybrids. Importantly, adaptations coinciding with species boundaries in Terrapene overlap with climatic boundaries and highlight the vulnerability of these terrestrial ectotherms to anthropogenic pressures.

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“…interspecific hybrids (Torres and Gutiérrez, 2018). This phenomenon can lead to genetic erosion, outbreeding depression, and genetic swamping in the guayabillo (López-Caamal et al, 2014;Ellstrand and Rieseberg, 2016;Chafin et al, 2019) while enriching the currently low genetic diversity of the guava populations of the Galapagos, further enhancing its invasive potential (Urquía et al, 2019). Such a case has already been reported in an insular Psidium endemic, P. socorrense, where hybridization with an introduced close relative took place in a particular zone of Socorro Island (López-Caamal et al, 2014).…”

Section: Genetic Diversity In Guayabillo and Its Contributing Factorsmentioning

confidence: 97%

Understanding the genetic diversity of the guayabillo (Psidium galapageium), an endemic plant of the Galapagos Islands

Urquía

Pozo

Gutierrez

et al. 2020

Preprint

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Oceanic archipelagos are known to host a variety of endemic plant species. The genetic diversity and structure of these species is an important indicator of their evolutionary history and can inform appropriate conservation strategies that mitigate the risks to which they’re exposed, including invasive species and environmental disturbances. A comprehensive consideration of the role of their natural history, as well as the landscape features and the geological history of the islands themselves is required to adequately understand any emerging patterns. Such is the case for the guayabillo (Psidium galapageium), an understudied endemic plant from the Galapagos Islands with important ecological and economic roles. In this study we designed and evaluated 13 informative SSR markers and used them to investigate the genetic diversity, population structure and connectivity of the guayabillo populations from San Cristobal, Isabela and Santa Cruz islands. A total of 208 guayabillo individuals were analyzed, revealing a strong population structure between islands and two distinct genetic lineages for the Santa Cruz population. Overall, the guayabillo genetic diversity is relatively high, an unusual pattern for an insular endemic species which is possibly explained by its polyploidy and the geographical features of the islands. These include their broad altitudinal ranges and habitat heterogeneity. For populations displaying a lower genetic diversity such as San Cristobal, the history of human disturbance could be an important factor explaining these observations. Some similarities between individuals in Santa Cruz and the San Cristobal population could be explained by population differentiation or distinct natural histories of separate lineages. Our findings highlight the complex population dynamics that shape the genetic diversity of species like the guayabillo and emphasize the need to explore the currently unresolved questions about this Galapagos endemic plant.

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Hybridization drives genetic erosion in sympatric desert fishes of western North America

Cited by 37 publications

References 78 publications

Defining Relictual Biodiversity: Conservation Units in Speckled Dace (Cyprinidae:Rhinichthys osculus) of the Greater Death Valley Ecosystem

Defining Relictual Biodiversity: Conservation Units in Speckled Dace (Cyprinidae:Rhinichthys osculus) of the Greater Death Valley Ecosystem

Contrasting signatures of introgression in North American box turtle (Terrapene spp.) contact zones

Understanding the genetic diversity of the guayabillo (Psidium galapageium), an endemic plant of the Galapagos Islands

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