Estimating the heritability of thermal tolerance in Acropora cervicornis and the physiological basis of adaptation that correlates to survival at elevated temperatures

Author

Kelsey L. Yetsko, University of North FloridaFollow

Year

2018

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. Matthew Gilg

Second Advisor

Dr. Cliff Ross

Third Advisor

Dr. Mauricio Rodriguez-Lanetty

Department Chair

Dr. Cliff Ross

College Dean

Dr. George Rainbolt

Abstract

Human activities have substantially increased the atmospheric concentrations of greenhouse gases, resulting in warmer ocean temperatures that are having a negative impact on reef corals, which are highly susceptible to changes in temperature. Understanding the degree to which species vary in their tolerance to elevated temperatures and whether this variation is heritable is important in determining their ability to adapt to climate change. In order to address this, Acropora cervicornis fragments from 20 genetically distinct colonies were kept at either ambient or elevated temperatures, and mortality was monitored for 26 days. Heritability of thermal tolerance was estimated using a clonal method comparing the difference in lifespan within and among clones in a one-way ANOVA, as well as a marker based method using the program MARK (Ritland 1996) to estimate relatedness between colonies. To understand the physiological basis of thermal tolerance, tissue samples from both treatments were taken after 12 hours to investigate gene expression associated with sub-lethal temperature stress at both the mRNA and the protein level. The results revealed that this population of A. cervicornis has a relatively high amount of total genetic variation in thermal tolerance (H2 = 0.528), but low additive genetic variation for this trait (h2 = 0.032). In addition, both gene expression and protein expression among colonies were highly variable and did not show consistent patterns related to differences in thermal tolerance among colonies. These results reveal that this population of A. cervicornis may have a limited capacity to respond to projected increases in ocean temperatures. In addition, the results suggest that the molecular basis of thermal tolerance in this species is complex and that there are potentially many genotypic combinations that can result in a heat-tolerant phenotype.

Suggested Citation

Yetsko, Kelsey L., "Estimating the heritability of thermal tolerance in Acropora cervicornis and the physiological basis of adaptation that correlates to survival at elevated temperatures" (2018). UNF Graduate Theses and Dissertations. 801.
https://digitalcommons.unf.edu/etd/801