Ecological and evolutionary effects of dispersal on freshwater zooplankton

diapause;dormancy;dispersal;Daphnia;Metacommunity;founder effect;priority;monopolization;community;ecology;evolution

Allen, Michael R.

关键词: diapause;    dormancy;    dispersal;    Daphnia;    Metacommunity;    founder effect;    priority;    monopolization;    community;    ecology;    evolution;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/11711/MR%20Allen%20Dissertation%202009.pdf?sequence=4&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

A recent focus on contemporary evolution and the connections betweencommunities has sought to more closely integrate the fields of ecology and evolutionarybiology. Studies of coevolutionary dynamics, life history evolution, and rapid localadaptation demonstrate that ecological circumstances can dictate evolutionarytrajectories. Thus, variation in species identity, trait distributions, and geneticcomposition may be maintained among ecologically divergent habitats. New theoriesand hypotheses (e.g., metacommunity theory and the Monopolization hypothesis) havebeen developed to understand better the processes occurring in spatially structuredenvironments and how the movement of individuals among habitats contributes toecology 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 that connect habitats to oneanother. Both processes allow organisms to leave conditions that are suboptimal orunfavorable, and enable colonization and invasion, species range expansion, and geneflow among populations. Freshwater zooplankton are aquatic crustaceans that typicallydevelop resting stages as part of their life cycle. Their dormant propagules alloworganisms to disperse both temporally and among habitats. Additionally, because anumber of species are cyclically parthenogenetic, they make excellent model organismsfor studying evolutionary questions in a controlled environment.Here, I use freshwater zooplankton communities as model systems to explore themechanisms and consequences of dispersal and to test these nascent theories on theinfluence of spatial structure in natural systems. In Chapter one, I use field experimentsand mathematical models to determine the range of adult zooplankton dispersal over landand what vectors are moving zooplankton. Chapter two focuses on prolonged dormancyof one aquatic zooplankter, Daphnia pulex. Using statistical models with field andmesocosm experiments, I show that variation in Daphnia dormant egg hatching issubstantial among populations in nature, and some of that variation can be attributed togenetic differences among the populations. Chapters three and four explore theconsequences of dispersal at multiple levels of biological organization. Chapter threeseeks to understand the population level consequences of dispersal over evolutionary time on current patterns of population genetic differentiation. Nearby populations of D.pulex often exhibit high population genetic differentiation characteristic of very lowdispersal. I explore two alternative hypotheses that seek to explain this pattern. Finally,chapter four is a case study of how dispersal has influenced patterns of variation at thecommunity, trait and genetic levels of biodiversity in a lake metacommunity.