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Ecological and evolutionary responses of tropical ectotherms to climate change / by Michael Latter Logan

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Author	Logan, Michael Latter
Title	Ecological and evolutionary responses of tropical ectotherms to climate change / by Michael Latter Logan
Date	2013
Abstract	Despite decades of research, the ability of scientists to predict the responses of ectothermic organisms to climate change remains remarkably low. Though an increasing number of models incorporate mechanistic relationships between environmental temperature and physiology, they often ignore other important pathways by which climate affects organismal fitness. Here, I explore some of these mechanisms, and the ways in which their inclusion can alter model outcomes for a group that is considered particularly vulnerable: tropical ectotherms. First, I show how models for the responses of populations to climate change must include biologically-relevant measurements of environmental temperature. In the Bay Islands of Honduras, I project warming onto fine-scaled temperature distributions generated from physical models and combine them with thermal performance curves from 5 populations of Anolis lizards. Contrary to the conclusions of previous studies, I show that the these populations may not be extremely vulnerability to warming. Second, I examine the relative effects of environmental temperature, wind speed, and humidity on the abundance of two lizard species from the island of Cayo Menor, Honduras. Though most models only include the effects of mean temperature, I show that temperature variation and wind speed may be more important drivers of lizard activity levels. Third, I conduct a field experiment to test the degree to which rapid climate change drives natural selection on thermal physiology. I transplant a population of Anolis sagrei from preferred habitat to a warmer, more thermally variable site and measure viability selection. Relative to a reference population studied in a less stressful thermal environment, the transplanted population experienced strong, directional selection on thermal performance traits. Finally, I examine the degree to which insular populations of A. sagrei in the Bahamas are locally adapted to their thermal environment in the face of gene flow from geographically disparate populations. Despite extremely high rates of gene flow across the archipelago, I find that the thermal optima of populations are positively correlated with both the mean and maximum environmental temperatures of each island. This suggests that metapopulation structure is unlikely to increase the vulnerability of A. sagrei to climate change
Format	application/pdf
Advisor	Ryan Calsbeek, Matthew P. Ayres, Douglas T. Bolger, Raymond B. Huey
Issuing Body	Dartmouth Dissertations are made available through the Dartmouth Digital Library.
Degree	Thesis (Ph.D.)--Dartmouth College.
Copyright	All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means without permission in writing from the author.
DOI	http://dx.doi.org/10.1349/ddlp.985

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