current and historical drivers of landscape genetic structure differ in core and peripheral salamander populations当前和历史的司机的景观核心和外围蝾螈人群的遗传结构不同.pdf

Current and Historical Drivers of Landscape Genetic Structure Differ in Core and Peripheral Salamander Populations 1 ¤ 2 1 2 Rachael Y. Dudaniec * , Stephen F. Spear , John S. Richardson , Andrew Storfer 1 Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada, 2 School of Biological Sciences, Washington State University, Pullman, Washington, United States of America Abstract With predicted decreases in genetic diversity and greater genetic differentiation at range peripheries relative to their cores, it can be difficult to distinguish between the roles of current disturbance versus historic processes in shaping contemporary genetic patterns. To address this problem, we test for differences in historic demography and landscape genetic structure of coastal giant salamanders (Dicamptodon tenebrosus) in two core regions (Washington State, United States) versus the species’ northern peripheral region (British Columbia, Canada) where the species is listed as threatened. Coalescent-based demographic simulations were consistent with a pattern of post-glacial range expansion, with both ancestral and current estimates of effective population size being much larger within the core region relative to the periphery. However, contrary to predictions of recent human-induced population decline in the less genetically diverse peripheral region, there was no genetic signature of population size change. Effects of current demographic processes on genetic structure were evident using a resistance-based landscape genetics approach. Among core populations, genetic structure was best explained by length of the growing season and isolation by resistance (i.e. a ‘flat’ landscape), but at the periphery, topography (s