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Range Expansion Since in the 21st Century: Ecology and Population Genetics of the Virginia Opossum.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Range Expansion Since in the 21st Century: Ecology and Population Genetics of the Virginia Opossum./
作者:	Walsh, Lisa Lenoble.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
面頁冊數:	174 p.
附註:	Source: Dissertations Abstracts International, Volume: 82-07, Section: B.
Contained By:	Dissertations Abstracts International82-07B.
標題:	Ecology. -
電子資源:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28240322
ISBN:	9798684625404

Range Expansion Since in the 21st Century: Ecology and Population Genetics of the Virginia Opossum.
Walsh, Lisa Lenoble.

Range Expansion Since in the 21st Century: Ecology and Population Genetics of the Virginia Opossum. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 174 p.

Source: Dissertations Abstracts International, Volume: 82-07, Section: B.

Thesis (Ph.D.)--University of Michigan, 2020.

This item must not be sold to any third party vendors.

As climate change and anthropogenic disturbances threaten an array of communities, identifying factors that shape species' distributions is critical. Examining a species undergoing range expansion can reveal factors driving its distributional change. Determining traits that make a species resilient to ongoing changes will improve our ability to predict responses to fluctuating environmental pressures. With ancestors that evolved in the Neotropics, the Virginia opossum, Didelphis virginiana, baffled zoologists by its expansion into areas with harsh winters. In my dissertation, I evaluated morphological, ecological, and genetic factors that may explain how the opossum expanded beyond its hypothesized climate niche. For my first three chapters, I analyzed stable isotopes of carbon (δ13C) and nitrogen (δ15N) from guard hairs from opossums in a wildlife center and from museum institutions. In my first chapter, I evaluated isotope values of captive and wild opossums for evidence of biannual or incomplete biannual molting, a mammalian adaptation to harsh winters. My results suggest opossums do not exhibit either winter molting strategy, and that guard hairs capture the opossum's lifetime diet. In my second chapter, I used isotope values to test the hypothesis that a Type A generalist's niche is positively correlated with habitat heterogeneity and to evaluate which climate variables best explained isotope values. I found a positive correlation between isotopic niche size and habitat-diversity indexes. Climate variables that represent aridity and C4 plant abundance were positively associated with δ15N and δ13C values, respectively. The results reveal that opossums' isotopic compositions are shaped by the habitat in which they are found, as would be expected in a generalist species. In my third chapter, I used δ13C values from opossums in the Midwest and Northeast to test whether opossums rely on anthropogenic trash to survive extreme winters. There was no significant relationship between δ13C and winter variables, but there was a significant increase in variance of Midwest opossums' δ13C after the 1970 corn agricultural boom. The patterns observed for northern opossums suggest their foraging is influenced by agricultural land but not urban trash. In my final chapter, I used reduced-representation genome sequencing to evaluate how opossums spread into temperate North America. Bayesian clustering analysis identified four genetic clusters, with one cluster limited to the Yucatan Peninsula, one cluster found across Mesoamerica, and two clusters that largely co-occurred in temperate North America. I used approximate Bayesian computation to evaluate 19 phylogeographic scenarios. The best-performing scenario posited a single expansion into temperate North America, followed by divergence. Alternatively, the two temperate clusters may be a result of incomplete lineage sorting. Because opossums do not exhibit classic mammalian adaptations to winter, their expansion into areas considered to be too harsh for them has previously been explained using the conjecture that urban habitats facilitate their survival. My dissertation results suggest that the range expansion of a diet and habitat generalist can occur rapidly. Their ability to forage on a wide variety of food items in various habitats, including agricultural land, provides insight to the opossum's success in facing changing landscapes and indicates that their range expansion will continue. My results suggest that Type A generalists will be resilient to changing environments, even when they appear to lack adaptations specific to local habitats.

ISBN: 9798684625404Subjects--Topical Terms:

516476
Ecology.
Subjects--Index Terms:

ddRAD

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300 $a 174 p.
500 $a Source: Dissertations Abstracts International, Volume: 82-07, Section: B.
500 $a Advisor: Tucker, Priscilla K.
502 $a Thesis (Ph.D.)--University of Michigan, 2020.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a As climate change and anthropogenic disturbances threaten an array of communities, identifying factors that shape species' distributions is critical. Examining a species undergoing range expansion can reveal factors driving its distributional change. Determining traits that make a species resilient to ongoing changes will improve our ability to predict responses to fluctuating environmental pressures. With ancestors that evolved in the Neotropics, the Virginia opossum, Didelphis virginiana, baffled zoologists by its expansion into areas with harsh winters. In my dissertation, I evaluated morphological, ecological, and genetic factors that may explain how the opossum expanded beyond its hypothesized climate niche. For my first three chapters, I analyzed stable isotopes of carbon (δ13C) and nitrogen (δ15N) from guard hairs from opossums in a wildlife center and from museum institutions. In my first chapter, I evaluated isotope values of captive and wild opossums for evidence of biannual or incomplete biannual molting, a mammalian adaptation to harsh winters. My results suggest opossums do not exhibit either winter molting strategy, and that guard hairs capture the opossum's lifetime diet. In my second chapter, I used isotope values to test the hypothesis that a Type A generalist's niche is positively correlated with habitat heterogeneity and to evaluate which climate variables best explained isotope values. I found a positive correlation between isotopic niche size and habitat-diversity indexes. Climate variables that represent aridity and C4 plant abundance were positively associated with δ15N and δ13C values, respectively. The results reveal that opossums' isotopic compositions are shaped by the habitat in which they are found, as would be expected in a generalist species. In my third chapter, I used δ13C values from opossums in the Midwest and Northeast to test whether opossums rely on anthropogenic trash to survive extreme winters. There was no significant relationship between δ13C and winter variables, but there was a significant increase in variance of Midwest opossums' δ13C after the 1970 corn agricultural boom. The patterns observed for northern opossums suggest their foraging is influenced by agricultural land but not urban trash. In my final chapter, I used reduced-representation genome sequencing to evaluate how opossums spread into temperate North America. Bayesian clustering analysis identified four genetic clusters, with one cluster limited to the Yucatan Peninsula, one cluster found across Mesoamerica, and two clusters that largely co-occurred in temperate North America. I used approximate Bayesian computation to evaluate 19 phylogeographic scenarios. The best-performing scenario posited a single expansion into temperate North America, followed by divergence. Alternatively, the two temperate clusters may be a result of incomplete lineage sorting. Because opossums do not exhibit classic mammalian adaptations to winter, their expansion into areas considered to be too harsh for them has previously been explained using the conjecture that urban habitats facilitate their survival. My dissertation results suggest that the range expansion of a diet and habitat generalist can occur rapidly. Their ability to forage on a wide variety of food items in various habitats, including agricultural land, provides insight to the opossum's success in facing changing landscapes and indicates that their range expansion will continue. My results suggest that Type A generalists will be resilient to changing environments, even when they appear to lack adaptations specific to local habitats.
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