Date of Award

January 2022

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Cy L. Mott

Department Affiliation

Biological Sciences

Second Advisor

Stephen C. Richter

Department Affiliation

Biological Sciences

Third Advisor

Kelly Watson

Department Affiliation

Biological Sciences

Abstract

Climate change will elicit various species responses as it causes habitats to change. Species with limited dispersal must respond to these changes “in place”, yet some biogeographical hypotheses indicate isolated and less abundant populations experience reduced gene flow and genetic diversity that may limit phenotypic plasticity, contrasting with evidence suggesting more variable habitats select for increased plasticity in peripheral populations. To gain insight into associations between range position and intensity of plasticity, mesocosm experiments were done to assess plasticity in larval growth, size at, and time to, metamorphosis, and survivorship in larval Ambystoma jeffersonianum salamanders from geographically core and peripheral populations. These populations were exposed to longer and shorter hydroperiods reflecting current and predicted future air temperatures, respectively, consistent with the A2 Climate Scenario for 2050. Growth rates and times to metamorphosis of edge populations were faster, yet larvae metamorphosed at smaller sizes. Populations experiencing future climate treatments were smaller and exhibited faster times to metamorphosis, and had higher survivorship than populations exposed to current climate treatments. In 2020, metamorphs were smaller on average than in 2021. Though these differences indicate plasticity in some larval traits, no differences in the magnitude of plasticity were observed between populations or years, tentatively suggesting populations may exhibit similar levels of genetic diversity, or that habitats may not be far enough away or differ enough in stochasticity between collection sites to detect variation in plasticity. These results improve our understanding of population-level differences in responses to environmental change, and the potential needs to incorporate population-level variation in future conservation and management efforts in the face of global climate change.

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