The Joint Effect Of Phenotypic Variation And Temperature On Predator Prey Interactions

Author : Caolan Kovach-Orr
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (922 download)

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Download or read book Mechanistic Concepts of Predator-prey Interactions and Their Effect on Community Dynamics written by Caolan Kovach-Orr and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Trophic interactions, in some form, exist in all natural communities; thus, understanding the factors that allow for the long-term coexistence of predators and their prey is an important first step towards the management of sustainable ecological systems. It is well known that the presence of within-individual and within-species variation for traits that affect trophic interactions can have substantial impacts on community dynamics. However, the generality of such effects has been obscured by disparate sources and trophic locations of traits as well as by the existence of many disparate traits that can exhibit variation. In this thesis, I use mathematical models to compare the effects of distinct phenomena related to within-individual and/or within-species variation. I pay particular attention to their dynamical consequences and abilities to promote the coexistence of trophically linked populations.First, I assess whether the presence of within-species variation for defense traits can 'rescue' entire communities that are being threatened by environmental change. I compare the potential for evolutionary rescue (through genetic diversity) and plastic rescue (through phenotypic plasticity) by analyzing their differential ability to produce persistence and stable coexistence in model food webs. Furthermore, my analyses consider whether these effects are dependent on the trophic location of variation. I find that plasticity promotes persistence and stable coexistence more than genetic diversity; variation at the second highest trophic level promotes stability and persistence more than variation at the autotroph level; and more than variation at two trophic levels.I then use models of bitrophic systems to investigate how different categories of plastic defenses affect model predictions. In natural systems, there are three major categories of plastic defenses: pre-encounter defenses, post-encounter defenses, and post-consumption defenses. Furthermore, the few previous comparative studies that exist have produced conflicting results. I show that plastic defenses can decrease the risk of extinctions due to population oscillations and that clear hierarchies exist. Pre-encounter inducible defenses are most likely to promote stable coexistence at low carrying capacities, whereas post-encounter and post-consumption inducible defenses are most likely to promote stable coexistence at high carrying capacities.Finally, I investigate the dynamical consequences and prevalence of plasticity in predators. The widely used Holling type 2 functional response assumes that the components of predation (i.e. attack rate and handling time) are unaffected by changes in prey density. However, a growing body of empirical and theoretical research suggests that plasticity in predators can allow these components to depend on prey density. In this study, I explore a variety of functional response equations that incorporate prey density-dependent attack rates and/or handling times. In terms of the community dynamics and stability properties of systems facing nutrient enrichment, I find that some, but not all, models that incorporate prey density-dependent attack rates and/or handling times are capable of making categorically and fundamentally different predictions than models that incorporate the type 2 functional response. I interpret these findings to mean that predictions of frequent or inevitable destabilization may be overstated. This investigation also highlights the importance of rechecking accepted principles in ecology.These studies indicate that within-individual and within-species variation for traits that affect trophic interactions may, in general, promote the persistence and stable coexistence of trophically linked populations. However, taken as a whole, this thesis shows that proper evaluation of the dynamical consequences of variation critically depends on its origin, trophic location as well as the specific traits that exhibit variation." --