Demographic and phenotypic reactions to climate by western North American woodrats (Neotoma spp.)
AuthorHornsby, Angela D.
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Species can react or adapt to climate in many ways, which can be studied through both space and time and using a number of perspectives and tools. North American woodrats (Neotoma spp.) are widespread across a variety of climates and also represented extensively in late Quaternary deposits, making them an excellent system for studying the effects of climate in a variety of ways. My dissertation includes three chapters that employ several methods and perspectives to explore how Neotoma spp. have reacted and adapted to climate. In my first chapter, I use a statistical phylogeographic approach to determine the accuracy of quantitative demographic signals derived from common proxies of Pleistocene-Holocene population history, finding that these proxies accurately reflect the most recent population expansion but may fail to capture other demographic events for a variety of reasons. In my second chapter, I use ancient DNA to determine the pattern and pace of Neotoma spp. turnover along a 33,000-year elevational transect, finding that the turnover was abrupt, final, and reflects the role of species interactions in reaction to climate. In my third chapter, I use geometric morphometrics to assess the developmental causes and morphometric consequences of adherence to ecogeographic rules, finding that N. cinerea are smaller in warmer and less productive climates, that the size differences among climates are established prior to weaning, and that smaller-bodied groups avoid pedomorphism through a break in the size-shape (allometric) relationship. Though these chapters do not build explicitly as a single narrative, they address complementary pieces of the very large question of species reactions to climate, and provide a step towards a more complete and integrated view of the myriad effects of climate through space and time.