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DYNAMICS OF POPULATIONS IN SEASONAL ENVIRONMENTS

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Title: DYNAMICS OF POPULATIONS IN SEASONAL ENVIRONMENTS
Author: Betini, Gustavo
Department: Department of Integrative Biology
Program: Integrative Biology
Advisor: Norris, RyanGriswold, Cortland
Abstract: One of the central problems in ecology and evolution is to understand temporal fluctuations in population abundance. In seasonal environments, where species have distinct breeding and non-breeding periods, the dynamics of populations can be influenced by variation in density at the beginning of each season, but also by variation in density during past seasons affecting the state of the individuals, which carry-over to influence individual’s performance in the following season. In my thesis, I developed a combination of mathematical and empirical tools to understand and make predictions about how seasonality affects changes in population size overtime. In Chapter 1, I investigate the role of life history variation for understanding population regulation and develop a framework to make inferences about where natural populations are most likely during the annual cycle. In Chapter 2, I use Drosophila melanogaster, the common fruit fly, to show how the interaction between seasonal density dependence and individual, non-lethal carry-over effects caused by variation in non-breeding density affects breeding output, which can stabilize long-term population dynamics. In Chapter 3, I provide empirical evidence that such density-mediated carry-over effects are caused by variation in the physiological condition of survivors that moved to the following season to breed, and show how carry-over effects help to explain breeding output in a long-term replicated population of Drosophila submitted to two distinct breeding and non-breeding seasons over 23 generations. In Chapter 4, I use controlled lab experiments and long-term seasonal populations to show how variation in parental breeding density negatively impact offspring size, and how this carries over to influence offspring survival during the non-breeding season. Overall, my thesis contributes to understand how events and processes that happen at multiple stages of the annual cycle influence vital rates and the dynamics of populations in seasonal environments.
URI: http://hdl.handle.net/10214/7828
Date: 2014-12


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