Lanterna Rally

Author: Michael R. Allen

Publisher:

Published: 2009

Total Pages: 135

ISBN-13: 9781109570984

A recent focus on contemporary evolution and the connections between communities has sought to more closely integrate ecology with evolutionary biology. Studies of coevolutionary dynamics, life history evolution, and rapid local adaptation demonstrate that ecological circumstances can dictate evolutionary trajectories. Thus, variation in species identity, trait distributions, and genetic composition may be maintained among ecologically divergent habitats. New theories and hypotheses (E.G., metacommunity theory and the Monopolization hypothesis) seek to understand better the processes occurring in spatially structured environments and how dispersal contributes to ecology and evolution at broader scales. As few empirical studies of these theories exist, this work seeks to further test these concepts. Spatial and temporal dispersal are the mechanisms connecting habitats to one another. Both processes allow organisms to leave suboptimal or unfavorable conditions, and enable colonization and invasion, species range expansion, and gene flow among populations. Freshwater zooplankton typically develop resting stages as part of their life that allow organisms to disperse both temporally and spatially. Additionally, because many species are cyclically parthenogenetic, they make excellent model organisms to study in a controlled environment. Here, I use freshwater zooplankton communities to examine the mechanisms and consequences of dispersal and to test these nascent theories on the influence of spatial structure in natural systems. In Chapter one, I use field experiments and mathematical models to determine the movement vectors and range of adult zooplankton dispersal over land. Chapter two uses statistical models with field and mesocosm experiments to examine prolonged dormancy in "Daphnia pulex." I show that variation in dormant egg hatching is substantial among populations in nature and can be attributed to genetic differences among the populations. Chapters three and four explore the consequences of dispersal at multiple levels of biological diversity. Chapter three looks at population level consequences of dispersal over evolutionary time on current patterns of population genetic differentiation. I test two alternative hypotheses addressing why nearby populations of "Daphnia" exhibit high population genetic differentiation. Finally, chapter four is a case study of how dispersal has influenced patterns of variation at the community, trait and genetic levels of biodiversity in a lake metacommunity. [The dissertation citations contained here are published with the permission of ProQuest llc. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.].