Short Communication 1 Department of Biology, Central Connecticut State University, New Britain CT, USA; 2 Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee WI, USA; 3 Savannah River Ecology Laboratory, University of Georgia, P.O. Drawer E, Aiken, SC 29802, USA; 4 Department of Biology, University of Vermont, Burlington, VT, USA When recent and evolutionary histories meet: deciphering temporal events from contemporary patterns of mtDNA from fishers (Martes pennanti) in north-eastern North America PAUL HAPEMAN 1 ,EMILY K. LATCH 2 ,OLIN E. RHODES 3 and CHARLES W. KILPATRICK 4 Abstract The current spatial distribution of genetic lineages across a region should reflect the complex interplay of both historical and contemporary processes. Postglacial expansion and recolonization in the distant past, in combination with more recent events with anthropogenic effects such as habitat frag- mentation and overexploitation, can help shape the pattern of genetic structure observed in contemporary populations. In this study, we characterize the spatial distribution of mtDNA lineages for fisher (Martes pennanti) in north-eastern North America. The history of fishers in this region is well understood and thus provides an opportunity to interpret patterns of genetic structure in the light of known historical (e.g. recolonization from glacial refugia) and contemporary events (e.g. reintroductions, fragmentation and natural recolonization). Our results indicate that fishers likely recolonized north-eastern North America from a single Pleistocene refugium. Three genetically distinct remnant populations persisted through the population declines of the 1800s and served as sources for multiple reintroductions and natural recolonizations that have restored the fisher throughout north-east- ern North America. However, the spatial genetic structure of genetic lineages across the region still reflects the three remnant populations. Key words: Fragmentation – Martes pennanti – nucleotide diversity – spatial analysis of molecular variance Introduction Patterns of phylogeographic structure are influenced by both his- torical and contemporary processes. Evolutionary history, includ- ing divergence during geographic isolation in glacial refugia and gene flow during postglacial expansion, creates distinct and lasting patterns of genetic structure across the landscape (Avise 1992; Bermingham et al. 1992; Arbogast et al. 2001; Steele and Storfer 2006). In North America, extensive glacial coverage during the Pleistocene and a well-documented path of glacial recession have influenced phylogeographic patterns in predictable ways. For example, in eastern North America, glacial refugia are commonly found south of the Laurentide ice sheet in the southern Appala- chian Mountains, and patterns of postglacial recolonization often track glacial recession northward along the Atlantic coast (Wooding and Ward 1997; Sonsthagen et al. 2011). However, pat- terns of phylogeographic structure do not only reflect evolutionary history, but also have been altered by more recent events including population declines, fragmentation and long distance dispersal achieved through human-mediated translocations (Drew et al. 2003; Hickerson et al. 2010; Smith et al. 2011). Carnivores are an interesting group in which to study the interplay of historical and contemporary processes in shaping phylogeographic patterns, both because their history in North America is well documented and because they are often particu- larly sensitive to environmental perturbations (Stone et al. 2002; Wisely et al. 2008; Aubry et al. 2009). Fishers (Martes pennanti; Erxleben, 1777) are medium-sized carnivores native to North America with an extensive and well- documented evolutionary history. During the last glacial maxi- mum in north-eastern North America (~18 000 ybp), fishers were presumed to have persisted in a single refugium that extended from east of the Mississippi River, into the central and southern Appalachians, and along the mid-Atlantic coast (Anderson 1994; Graham and Graham 1994). Fishers expanded into north-eastern North America along the Atlantic coast, likely following the retreat of the Laurentide ice sheet and subsequently expanded westward from coastal regions (Graham and Graham 1994). Once fishers recolonized northern North America, they were widespread until the 1800s to early 1900s, when extensive trap- ping, habitat destruction by logging and an extended period of deep snow conditions resulted in severe declines (Hall 1981; Powell and Zielinski 1994; Krohn et al. 1995, 1997; Carr 2005). By the 1930s, only four remnant populations were presumed to exist in north-eastern North America, located in habitat fragments of the Adirondacks of New York, the White Mountains of New Hampshire, the Moosehead Plateau of Maine, and the Cumber- land Plateau of New Brunswick Canada (Brander and Books 1973; Hapeman et al. 2011). Following a period of closed trapping seasons, five major doc- umented reintroductions were initiated in north-eastern North America in an effort to repopulate areas where fishers once thrived (Fig. 1; Berg 1982; Powell 1993; Williams et al. 2000) and augment natural recolonizations into Massachusetts, Rhode Island and eastern Connecticut (originating primarily from New Hampshire; Hapeman et al. 2011). Through these concerted con- servation efforts, fishers have regained much of their historical distribution in north-eastern North America. Genetic signatures of these more recent restoration efforts are detectable in contemporary fisher populations (Hapeman et al. 2011). However, what remains unclear is the extent to which his- torical demographic events, such as range expansion and coloniza- tion following the Pleistocene, have contributed to present day structure of fisher populations in north-eastern North America. The main objective of this study was to characterize patterns of spatial genetic structure in fishers, focusing on the role of historical pro- cesses in shaping contemporary patterns of variation. We predict that contemporary patterns of variation will reflect documented Corresponding author: Paul Hapeman (hapeman@ccsu.edu) Contributing authors: Emily K. Latch (latch@uwm.edu), Olin E. Rhodes (rhodes@srel.uga.edu), Charles W. Kilpatrick (wkilpatr@uvm.edu) Accepted on 25 December 2013 © 2014 Blackwell Verlag GmbH J Zoolog Syst Evol Res doi: 10.1111/jzs.12060