Causes and consequences of fitness component variation in wild non-model animal systems

Abstract

Patterns of adaptive variation in organismal traits are mechanistic drivers of population-level patterns of demography and viability. It is therefore crucial to investigate the evolutionary processes underlying this trait variation to identify the causative factors influencing population persistence. Such investigations benefit from a multi-pronged approach incorporating representative empirical studies in natural contexts as well as synthesis- or simulation-based approaches that can assess theory generalizability and validity without the logistical constraints of field work limiting a single study’s scope of work. In this dissertation, I use meta-analytical, empirical, and simulation-based approaches to assess the conservation implications of among individual-trait variation within wild animal populations. In addition to a comparative taxonomic approach in my first chapter synthesis, my final two chapters focus on characterizing the nesting ecology and mating system dynamics of the Mississippi diamond-backed terrapin (Malaclemys terrapin pileata) as a case study. In chapter one, I conduct a meta-analysis to assess the disparity in fitness-related performance measures of translocated organisms relative to their wild-resident conspecifics. My dataset, consisting of 171 studies representing 101 species of invertebrate and vertebrate animals identifies significant under-performance by translocated cohorts and provides evidence-based recommendations to minimize these performance disparities and maximize future translocation impact. In chapter two, I used UAV-based photogrammetry to assess microhabitat-scale nest habitat selection of an entire M. terrapin nesting beach in Mississippi, USA. I find that terrapins exhibit scale-dependent selection for a number of variables related to topography and vegetation, and that variation in these microhabitat variables can influence nest hatching success. In chapter three, I use simulation models to validate whole genome-based parentage assignment software across a variety of demographic and mating system structures common in non-model organisms, using the Mississippi M. terrapin system as a case study. I find that existing software can exhibit biased inference in response to certain demographic and breeding system scenarios, especially in combination with increased inbreeding. My dissertation demonstrates a comprehensive workflow for quantifying trait variation in wild contexts. I show that harnessing analytical and technological advances can allow researchers to acquire accurate estimates of individual variation and population parameters in challenging field contexts. This dissertation demonstrates how understanding adaptive variation can inform evidence-based conservation interventions for threatened populations.