Post‐Pleistocene range expansion of the recently imperiled eastern little brown bat (Myotis lucifugus lucifugus) from a single southern refugium

Abstract

Myotis lucifugus, once among the most widespread and common bats in North America, has been forecast to be extirpated east of the Rockies in as few as 16 years by the spread of white-nose syndrome. Recent genetic research has demonstrated that this species is paraphyletic and part of a broader species complex; however, only one lineage (Myotis lucifugus lucifugus [M. l. lucifugus]) is present in eastern North America. I used molecular tools and niche modeling to validate this and investigate the role that historical biogeography has played in the phylogenetic and population genetic structure of this species to determine if the eastern subspecies represents an evolutionarily distinct population.To establish the genetic structure within M. l. lucifugus, I densely sampled maternity colonies in Minnesota and sequenced 182 individuals for a portion of cytochrome b. Phylogenetic reconstruction and a haplotype network were used to infer the relationships among mitochondrial haplotypes. Population growth statistics were calculated to determine if there was evidence of significant expansion, and an environmental niche model (ENM) was constructed based on conditions during the last glacial maximum (LGM) to illustrate potential glacial refugia. All individuals derived from a single mitochondrial lineage. Genetic evidence points to population growth starting approximately 18 kya. ENM results show that there was likely a single large southern refugium extending across the southeastern United States and possibly several isolated refugia in western North America. Myotis lucifugus lucifugus likely maintained both a large range and a large population during the peaks of the glacial cycles, and its population appears to have expanded following the retreat of the Laurentide ice sheet. This imperiled lineage likely diverged in isolation from other members of the M. lucifugus/western long-eared Myotis during the Pleistocene.

Range-wide genetic structure and demographic history in the bat ectoparasite Cimex adjunctus

“…Dixon [32] suggested that little brown myotis populations currently in Minnesota have dispersed from a single large southeastern US glacial refugium, and Neubaum et al [21] suggested that big brown bat populations have dispersed from several eastern and western US glacial refugia into what is now Colorado. Range and demographic expansion in little brown myotis has also been proposed on the east coast of Canada [22].…”

Rethinking refugia: Tree topology, divergence dates, and demographic history trace the distribution of the endangered Plymouth gentian (Sabatia kennedyana) from the Pleistocene glaciation to present day

“…Together, these results display a classic pattern of increasing genetic diversity nearing the glacial refugia ( Dixon, 2011 ). This result suggests that all three geographically distant sites were founded by individuals from the same refugium, likely off of the cost of current day Cape Cod.…”

Effect of oceanic straits on gene flow in the recently endangered little brown bat (Myotis lucifugus) in maritime Canada: implications for the spread of white-nose syndrome

“…Here we identified nDNA and mtDNA F ST values that were an order of magnitude higher (Burns et al 2014; nDNA F ST = 0.001, mtDNA ⌽ ST = 0.045) and identified patterns of IBD; neither Burns et al (2014) nor Miller-Butterworth et al (2014 found patterns of IBD. Although these studies and others (Lausen et al 2008;Dixon 2011aDixon , 2011b show evidence for high levels of gene flow across the range of M. lucifugus, landscape features and likely aspects of behaviour are impacting gene flow in ways that are genetically detectable and that negate full panmixia. For example, in western North America, Lausen et al (2008) found patterns of IBD in M. lucifugus within a prairie landscape along river routes and Miller-Butterworth et al (2014) attributed detectable genetic population structuring with mountain ranges.…”

“…1). Although extensively studied, only recently has DNA analysis been used to directly examine patterns of population structure throughout its range (Lausen et al 2008;Dixon 2011aDixon , 2011bMiller-Butterworth et al 2014;Burns et al 2014;Johnson et al 2015). Collectively, these studies suggest a general pattern of minimal structuring of nuclear genetic markers over distances in excess of 850 km and some mitochondrial DNA (mtDNA) structuring among summer maternity roosts, which is indicative of females exhibiting some degree of philopatry.…”