Contemporary genetic structure of the northern bobwhite west of the Mississippi River

Abstract

We used mitochondrial DNA to study the population structure and genetic diversity of the northern bobwhite (Colinus virginianus) west of the Mississippi River. We observed a lack of phylogeographic structure, high haplotype diversity, and low nucleotide diversity for northern bobwhites in this part of their geographic range. Despite the discordance between geographic patterns of mtDNA diversity and subspecies designations, we detected significant genetic differentiation among 4 subspecies, the plains (C. v. taylori), eastern (C. v. virginianus), Texas (C. v. texanus), and masked (C. v. ridgwayi) bobwhites. Evidence of significant isolation by distance and a latitudinal gradient with regard to the geographic distribution of haplotypes was also apparent. Neutrality tests, Bayesian skyline plots, and test of spatial expansion provided evidence of demographic and range expansion following the end of the last Pleistocene glaciation. Lack of phylogeographic structure indicates that morphological differences that are the basis of subspecies designations are of recent origin. Ecoregions may provide a better basis for management units than subspecies taxonomy for northern bobwhites in the western part of their geographic range. Our results indicate that much of the northern bobwhite's geographic range in the United States is the result of relatively recent colonization, which was a response to climate and habitat changes at the close of the Pleistocene. The northern bobwhite may be as vulnerable to fluctuations in climate as it has been to habitat and landscape changes during the past century. Ó 2014 The Wildlife Society.

Phylogeography of the bobwhite (Colinus) quails

“…Regional studies of mtDNA sequence variation in northern bobwhites from southern Texas and the southeastern United States also have found evidence of recent demographic expansion (Wehland 2006, Eo et al 2010, Williford et al 2014c. Previous studies of bobwhites were limited by sampling distribution or sample size, and thus were unable to detect post-Pleistocene expansion, place the results into context with climatic changes, or to estimate the timing and origin of expansion.…”

“…Studies of reintroduction efforts have found that the introduction of non-native stocks of wild turkey (Meleagris gallopavo) and white-tailed deer (Odocoielus virginianus) altered the genetic structure across the ranges of both species throughout the United States (Leberg et al 1994, Leberg and Ellsworth 1999, DeYoung et al 2003, Mock et al 2004, Latch et al 2006). However, mtDNA phylogeographic analysis of the wild turkey (Mock et al 2002), white-tailed deer (Ellsworth et al 1994a), and the northern bobwhite (Williford et al 2014c) were still able to recover contemporary biogeographic patterns. Aldrich (1946a, b) believed that lack of adaptation to local environments doomed most transplanted wild stocks, and that intermixing of different subspecies had little lasting effect on the plumage and morphology (but see Phillips 1928 andPitelka 1948).…”

“…Others proposed either recognition of a single species, with plumage-color variants considered subspecies (Dickerman 2007), or a superspecies (Mayr and Short 1970). To date, genetic studies have been restricted to either fine-scale or regional studies of the northern bobwhite (Ellsworth et al 1989, Nedbal et al 1997, Eo et al 2010, Berkman et al 2013, Williford et al 2014c; no genetic studies have been conducted on either the black-throated or crested bobwhites.…”

Two centuries of human‐mediated gene flow in northern bobwhites

“…To what degree habitat fragmentation and loss have influenced population connectivity, however, is equivocal. Multiple studies over the past decade have evaluated whether restricted gene flow existed among areas within the bobwhite geographic range, suggesting a recent range and population expansion with few dispersal barriers (Evans et al ; Berkman et al ; Williford et al , 2016). However, it is important to note that patterns of genetic differentiation have also been documented at the local scale, possibly due to recent anthropogenic land‐use changes (Berkman et al ).…”

“…This pattern is supported among multiple avian species, such as the house sparrow ( Passer domesticus ; Kekkonen et al ), black grouse ( Lyrurus tetrix ; Caizergues et al ), white‐tailed ptarmigan ( Lagopus leucura ; Fedy et al ), greater prairie‐chicken ( Tympanuchus cupido ; Johnson et al , 2004), golden‐cheeked warbler ( Setophaga chrysoparia ; Lindsay et al ), white‐breasted wood wren ( Henicorhina leucosticta ), and gray‐headed tanager ( Eucometis penicillata ; Brown et al ). However, despite recent population fragmentation of bobwhites and their presumed low propensity for dispersal (Brennan et al ), several recent studies have documented minimal or low levels of genetic differentiation among bobwhite populations, including among historically recognized subspecies (Eo et al ; Evans et al ; Berkman et al ; Williford et al , 2016). Those studies suggest sufficient gene flow exists across the bobwhite range, and ultimately imply that habitat fragmentation has had little to no effect on their population demographics.…”