The impact of life-history trait evolution on the stability of population dynamics

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Population dynamics isby definitionthe aggregate response of life histories emerging from a group of interacting individuals. For a wide range of taxa, populations undergo single-generation cycles, which is a type of cycle that is strongly linked to individual life-history traits. Some spectacular examples from nature are the 4-5 outbreaks each season in tortrix moths and the four year cycles in sockeye salmon runs. Life-history traits are also where ecological and evolutionary processes connect, and much theoretical work reveals that life histories are the key to understanding the ecogenetic feedback between ecological and evolutionary dynamics. My long-term research goals are to understand how the ecological processes that determine life histories (e.g., resource competition, stage-structured interactions) scale-up to generate single-generation cycles and, it turn, how ecological dynamics impact the evolution of life-history traits. The end goal of my research is to answer the question Do intraspecific interactions result in the evolution of life-history traits that generate large amplitude single-generation cycles?The proposed research builds on my strong record of interdisciplinary research in mathematical and experimental biology. In this grant, myself along with 4PhD, 3MSc will study how the evolution of life-history traits impacts whether a population has steady-state dynamics (stable) or cycling dynamics (unstable). To study the full ecogenetic feedback loop, the proposal has 3 objectives. Within each, we will develop biological theory centred on organismal life histories and then experimentally test ecological and evolutionary predictions using two species of pest moths.Objective 1: Links life-history traits to population dynamics to identify traits most relevant for determining population stability (steady-state versus cycling). Objective 2: Evolves life-history traits in two model organisms to study evolvability of stability-related traits. Objective 3: Maps evolutionary trajectories of life histories to evaluate the direction of trait evolution under real population dynamics and their dynamical consequences.Our research will use two species of tortrix mothsone that has strong single-generation cycles (unstable) and one that has comparatively constant abundances (stable). These allow for an exciting scientific dichotomy whereby we experimentally evolve stability in one and instability in the other. Beyond their scientific value, these species typify the life-cycle of tortricids that are agricultural pests around the world. Biological and chemical interventions directly target pest life history, which has resulted in widespread resistance evolution. Our research studying life history evolution will provide the foundation to better understand how to direct trait evolution in a way that benefits pest control.