State Dependent Life History Evolution And Predator Prey Population Dynamics

Author : Troy Alexander Perkins
Publisher :
ISBN 13 : 9781267240682
Total Pages : pages
Book Rating : 4.2/5 (46 download)

DOWNLOAD NOW!

Download or read book Coupled Evolutionary and Population Dynamics of Managed Populations written by Troy Alexander Perkins and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a growing awareness in ecology that rapid evolutionary change can precipitate rapid ecological change, and vice versa, too. Due to the unprecedented intensity of human activites in nature and the (un)natural selection often imposed by those activites, the interplay between evolutionary and ecological dynamics is only growing in importance. This growing recognition and the need to sustainably manage dwindling natural resources demand better understanding of the dynamics of these forces in managed populations. To this end, my dissertation investigates coupled evolutionary and population dynamics in two applied contexts: life-history variation in a threatened species and life-history and dispersal evolution in invasive species.In Chapter One, I propose and fit to data a model to account for spatial and temporal patterns of life-history variation in Snake River fall Chinook salmon, which are considered threatened under the U.S. Endangered Species Act. A dichotomy in life-history exists whereby some juveniles migrate to the ocean as age-0 subyearlings, as fall Chinook salmon typically do, whereas others overwinter in freshwater and migrate to the ocean as age-1 yearlings. The latter strategy was thought to be atypical of fall Chinook salmon and has arisen only in the past few decades in Idaho's Snake River population. The recent appearance of the yearling strategy has conservation implications for this threatened population because of survival and reproductive differences between the two life histories. I advance a hypothesis for the mechanism by which juveniles adopt a life history, formalize it with a model, and present the results of fitting this model to life-history data. The model captures patterns of variation in yearling proportions among reaches and years, and offers those interested in the management and conservation of Snake River fall Chinook salmon a useful tool to account for life-history variation in population viability analyses and decision making.Chapter Two considers the implications of rapid evolution in invasive species, or in native species that invaders interact with, for the spatial spread dynamics of invasive species. Motivated by observations that both invasive and native species sometimes evolve in response to invasions, I use a mathematical model of an interacting invasive predator and its native prey to determine when and how evolutionary lability in one or both species might impact the dynamics of the invader's spatial advance. The model shows that evolutionarily labile invaders continually evolve better adapted phenotypes along the moving invasion front, offering a new explanation for accelerating spread and spatial phenotype clines following invasion. I then analytically derive a formula to estimate the relative change in spread rate due to evolution and use available parameter estimates to show that moderate heritabilities and selection strengths are sufficient to account for changes in spread rates observed in historical and ongoing invasions. Evolutionarily labile native species can slow invader spread when genes flow from native populations with exposure to the invader into native populations ahead of the invasion front. This outcome is more likely in systems with highly diffuse native dispersal, advection, or human inoculation of uninvaded native populations.Chapter Three continues the theme of invader evolution and spatial spread, but it considers the potential simultaneous evolution of life-history and dispersal traits and assesses the roles that each of those factors played in the cane toad invasion of Australia. To do this, I describe a stage-structured integrodifference model of population dynamics coupled with a quantitative genetics model of life-history and dispersal evolution. Although a precise attribution of spread dynamics to evolution is not warranted given parameter uncertainty and model simplicity, analysis of the model suggests that observed changes in those traits during the toads' invasion are capable of accounting for most of the increase in spread rate between the cane toad's introduction in 1935 and its more recent status as of 2006. Furthermore, I show that life-history evolution, dispersal evolution, and an interaction between the two all contribute to increased spread, with no single evolving trait or evolutionary process dominating spread dynamics. These results are the first to address the relative importance of spatial evolutionary processes like spatial assortment and spatial selection, as compared to the conventional process of natural selection within a well-mixed population.