HCNSO Student Theses and Dissertations

Defense Date

4-24-2017

Document Type

Thesis

Degree Name

M.S. Marine Biology

First Advisor

Joana Figueiredo

Second Advisor

Tamara Frank

Third Advisor

Steve Kessel

Abstract

A primary goal of climate change research is to determine if species will be able to persist in a warmer environment. Most studies predict climate change will cause many species to become extinct. However, these predictions are based on experiments where only a single life stage or generation of a species was exposed to predicted future conditions (i.e. shock treatments), and thus overlook the possibility of species adapting or acclimatizing to new environmental conditions over multiple generations. As a result, current projections of species persistence through climate change are likely to overestimate species extinction. In this study, the rate and extent to which adaptation and transgenerational acclimation may allow species to persist through climate change was measured. Marine rotifers, Brachionus plicatilis, were reared for ~75 generations at: i) Optimal temperature (25°C), ii) Optimal temperature (25°C) with weekly sub-lethal shocks (35°C), iii) Maximum temperature (33°C), and iv) Maximum temperature (33°C) with weekly sub-lethal shocks (35°C). Changes in population growth rates and fitness were assessed weekly through rotifer density, adult size and aerobic performance (respiration rate). There was no adaptation observed, but there was evidence of transgenerational acclimation. However, populations were unable to acclimate when exposed to high temperature shocks. This study shows that acclimation through the selection of thermally tolerant individuals can occur over multiple generations in a thermally stable environment, as seen by a reversible increase in aerobic performance, and thus species with short life cycles may be better able to keep up with the pace of climate change. This multi-generational study can enhance our understanding of the rate and extent in which transgenerational acclimation may allow species to persist through climate change. These estimates can then be incorporated into models to improve projections of survival through climate change of species with longer lifespans.

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