Admixture between released and wild game birds: a changing genetic landscape in European mallards (Anas platyrhynchos)

Söderquist, Pär; Elmberg, Johan; Gunnarsson, Gunnar; Thulin, Carl‐Gustaf; Guillemain, Matthieu; Guillemain, Matthieu; Kreisinger, Jakub; Prins, Herbert H. T.; Crooijmans, R.P.M.A.; Kraus, Robert H. S.

doi:10.1007/s10344-017-1156-8

Cited by 42 publications

(43 citation statements)

References 64 publications

(91 reference statements)

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“…Until recently, molecular methods did not distinguish among mallards across their Holarctic distribution (Kraus et al, ). However, Söderquist et al () used genomic sequencing and reported feral European mallards not only have a distinct genetic signature, but also showed them to have a significant impact on wild European mallard stocks. Although the authors did not find the same trend in North America, they did not adequately sample east of the Mississippi River and thus likely missed the non‐western genetic signature captured here.…”

Section: Discussionmentioning

confidence: 99%

Identifying hybrids & the genomics of hybridization: Mallards & American black ducks of Eastern North America

Lavretsky

Janzen

McCracken

2019

Ecology and Evolution

101

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Resolving evolutionary relationships and establishing population structure depends on molecular diagnosability that is often limited for closely related taxa. Here, we use 3,200 ddRAD‐seq loci across 290 mallards, American black ducks, and putative hybrids to establish population structure and estimate hybridization rates. We test between traditional assignment probability and accumulated recombination events based analyses to assign hybrids to generational classes. For hybrid identification, we report the distribution of recombination events complements ADMIXTURE simulation by extending resolution past F4 hybrid status; however, caution against hybrid assignment based on accumulated recombination events due to an inability to resolve F1 hybrids. Nevertheless, both analyses suggest that there are relatively few backcrossed stages before a lineage's hybrid ancestry is lost and the offspring are effectively parental again. We conclude that despite high rates of observed interspecific hybridization between mallards and black ducks in the middle part of the 20th century, our results do not support the predicted hybrid swarm. Conversely, we report that mallard samples genetically assigned to western and non‐western clusters. We indicate that these non‐western mallards likely originated from game‐farm stock, suggesting landscape level gene flow between domestic and wild conspecifics.

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Section: Discussionmentioning

confidence: 99%

Identifying hybrids & the genomics of hybridization: Mallards & American black ducks of Eastern North America

Lavretsky

Janzen

McCracken

2019

Ecology and Evolution

101

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“…Moreover, the translocation of individuals of non-local origin may lead to introgression that disrupts spatial genetic structure, alters local genetic diversity, and ultimately threatens local adaptations (e.g., Söderquist et al 2017 and references therein). Hybridisation between translocated farmed and wild individuals might also be a driver of biodiversity loss (Randi 2008;Sutherland et al 2006;Söderquist et al 2017).…”

Section: Potential Impacts Of Commercial Trade On Ball Python Populatmentioning

confidence: 99%

The first genetic assessment of wild and farmed ball pythons (Reptilia, Serpentes, Pythonidae) in southern Togo

Auliya¹,

Hofmann²,

Segniagbeto³

et al. 2020

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The ball python (Python regius) is the world’s most commonly traded python species for the “exotic” pet industry. The majority of these live snakes are produced via a number of python farms in West Africa that have been in operation since the 1960s and involved with “ranching” operations since the 1990s. However, to date no thorough taxonomic review or genetic studies have been conducted within its range, despite the fact that the evaluation of a species’ genetic variability is generally considered mandatory for effective management. We used mtDNA sequence data and eight polymorphic microsatellite markers to assess the underlying population genetic structure and to test the potential of the nuclear markers to assign farm individuals to wild reference populations in southern Togo. Despite the relatively large distances between sample locations, no significant genetic population structure was found, either in mtDNA sequence data or in the microsatellite data. Instead, our data indicate considerable gene flow among the locations. The absence of a distinct population subdivision may have resulted from an anthropogenic driven admixture of populations associated with commercial wildlife trade activity in recent decades. Given the ongoing largely unregulated nature of the commercial ranching of ball pythons in West Africa, should a wild release component continue, as a first measure we recommend that the Management Authorities should develop an action plan with specific release protocols for python farms to minimise any potential negative conservation impacts resulting from admixture (genetic pollution) between farmed and wild individuals.

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“…We explicitly test whether the two genetic mallard clusters in North America are due to natural (i.e., divergence within wild mallards) or artificial (i.e., anthropogenic release of domesticated game‐farm mallards) processes. The former seems unlikely as wild mallards show no discernible structure across their Holarctic distributions (Champagnon et al, ; Kraus et al, ; Söderquist et al, ), with the only genetic structure within Eurasian mallards due to hybridization with captive‐bred mallards (Söderquist et al, ). Furthermore, tracking data show that when mallards migrate between Eurasia and North America, the path used is eastward through Alaska and not westward across the Atlantic Ocean (Hupp et al, ; Lam et al, ; Shin et al, ; Yamaguchi et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…The former seems unlikely as wild mallards show no discernible structure across their Holarctic distributions (Champagnon et al, 2013;Kraus et al, 2011;Söderquist et al, 2017), with the only genetic structure within Eurasian mallards due to hybridization with captive-bred mallards (Söderquist et al, 2017). Furthermore, tracking data show that when mallards migrate between Eurasia K E Y W O R D S ancient DNA, biological collections, hybridization, introgression, population genetics, speciation and North America, the path used is eastward through Alaska and not westward across the Atlantic Ocean Lam et al, 2012;Shin et al, 2015;Yamaguchi et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Assessing changes in genomic divergence following a century of human‐mediated secondary contact among wild and captive‐bred ducks

et al. 2020

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Along with manipulating habitat, the direct release of domesticated individuals into the wild is a practice used worldwide to augment wildlife populations. We test between possible outcomes of human‐mediated secondary contact using genomic techniques at both historical and contemporary timescales for two iconic duck species. First, we sequence several thousand ddRAD‐seq loci for contemporary mallards (Anas platyrhynchos) throughout North America and two domestic mallard types (i.e., known game‐farm mallards and feral Khaki Campbell's). We show that North American mallards may well be becoming a hybrid swarm due to interbreeding with domesticated game‐farm mallards released for hunting. Next, to attain a historical perspective, we applied a bait‐capture array targeting thousands of loci in century‐old (1842–1915) and contemporary (2009–2010) mallard and American black duck (Anas rubripes) specimens. We conclude that American black ducks and mallards have always been closely related, with a divergence time of ~600,000 years before present, and likely evolved through prolonged isolation followed by limited bouts of gene flow (i.e., secondary contact). They continue to maintain genetic separation, a finding that overturns decades of prior research and speculation suggesting the genetic extinction of the American black duck due to contemporary interbreeding with mallards. Thus, despite having high rates of hybridization, actual gene flow is limited between mallards and American black ducks. Conversely, our historical and contemporary data confirm that the intensive stocking of game‐farm mallards during the last ~100 years has fundamentally changed the genetic integrity of North America's wild mallard population, especially in the east. It thus becomes of great interest to ask whether the iconic North American mallard is declining in the wild due to introgression of maladaptive traits from domesticated forms. Moreover, we hypothesize that differential gene flow from domestic game‐farm mallards into the wild mallard population may explain the overall temporal increase in differentiation between wild black ducks and mallards, as well as the uncoupling of genetic diversity and effective population size estimates across time in our results. Finally, our findings highlight how genomic methods can recover complex population histories by capturing DNA preserved in traditional museum specimens.

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Admixture between released and wild game birds: a changing genetic landscape in European mallards (Anas platyrhynchos)

Cited by 42 publications

References 64 publications

Identifying hybrids & the genomics of hybridization: Mallards & American black ducks of Eastern North America

Identifying hybrids & the genomics of hybridization: Mallards & American black ducks of Eastern North America

The first genetic assessment of wild and farmed ball pythons (Reptilia, Serpentes, Pythonidae) in southern Togo

Assessing changes in genomic divergence following a century of human‐mediated secondary contact among wild and captive‐bred ducks

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