Do seasonal changes in developmental temperature have season-specific consequences in a lizard?
Type of DegreeMaster's Thesis
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Rapidly changing environmental conditions can reduce the fitness of a phenotype. Phenotypic plasticity can solve this problem by enabling individuals to develop phenotypes that are suited to their immediate environment. Seasonal shifts in environmental conditions are particularly important because they provide predictable cues to which organisms can respond in adaptive ways. For example, seasonal changes in temperature can induce phenotypes at different times of the year that have season-specific fitness benefits. A previous study has shown that temperature during different times of the season can affect phenotypes and performance. Here, I assessed whether the timing of oviposition is adaptively matched to the thermal environment that embryos experience at a given time of the reproductive season. I used the brown anole lizard (Anolis sagrei), which has an extended reproductive season (April-October), to address this question. Eggs were collected from two temporally-separated breeding colonies and exposed to two incubation treatments that mimicked the natural fluctuations in nest site temperatures during early and late periods of the reproductive season. Hatchlings were measured, and their locomotor performance was assessed in the lab, and then released on an island to quantify growth and survival. Hatchlings from the late season were larger and faster overall than those from the early season. Late-season incubation temperatures also produced larger, faster hatchlings. Early season hatchlings had higher survival than late season hatchlings regardless of incubation temperature. These results show that the timing of oviposition and incubation temperature can differentially affect phenotype and fitness.
- Pearson MS Thesis Final.pdf