Environmental change is occurring at an unprecedented rate. Consequently, alterations in environmental cues such as temperature, discharge, and depth influence the reproductive behavior of adult fishes. Maternal environmental effects including selection of mates, spawning site, and maternal yolk-sac provisioning determine the environmental influences offspring experience during critical early development and growth periods. Using genetic parentage analysis and experimentally-manipulated environmental regimes, I examined the effects of adult reproductive behavior and altered environmental conditions on larval lake sturgeon (Acipenser fulvescens) development and behavior. Lake sturgeon are long-lived, iteroparous fishes that reside in freshwater, and migrate to riverine areas in early spring and summer to spawn. Analyses in my studies were conducted using a well-known adult population of approximately 1200 lake sturgeon from Black Lake, Michigan. First, I individually marked all spawning adults, examined the demographic and environmental factors affecting the timing of the reproduction, collected blood samples to determine female ovary/egg quality, and used genetically-based parentage analysis to assign female reproductive success (RS). The time females spent on the spawning grounds was dependent on temperature, discharge, number of males, size of males, an interaction between temperature and size as well as discharge and number of males. Female RS was dependent on the above factors as well as the OSR; however, the time females spent in the river had no effect on female RS or her ovary/egg quality indicating there does not appear to be a reproductive cost in being plastic in the timing and location of spawning. Next, I empirically tested whether adult-selected and anthropogenically modified egg incubation conditions affect larval traits at hatch and until the timing of emergence by experimentally manipulating velocity and thermal regimes. A genotype-by-environment interaction was detected for all traits at hatch, and the greatest range in phenotypic variation was observed in the “High” velocity (0.8m/s) and “Warm” (18C) thermal treatments. Additionally, egg incubation conditions and genetic (family) effects affected growth and behavior at the timing of emergence indicating that conditions experienced during early development persist until later stages (i.e. “ontogenetic contingency”). Lastly, I quantified microhabitat variation at female egg deposition sites, collected wild-produced eggs from the stream, quantified offspring trait variation at hatch and four weeks post-emergence, and used genetically-based parentage analysis to determine the influence of genetic (parentage) effects on offspring traits. Traits at hatch were influenced by environmental conditions at egg deposition sites, but traits post-emergence were influenced by additive genetic effects and potential differences in feeding efficiency. Overall, findings indicate how environmental variation affects adult reproductive success, timing of spawning, and larval trait variation during critical growth and development stages providing a greater understanding of how the phenotypic and genotypic variation within wild populations will be affected by environmental change.
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