Impacts of Polyploidization on Endocrine Regulation and Vocalization in the Gray Treefrog Complex

Author

Avery Thigpen, University of MississippiFollow

Date of Award

Spring 5-10-2025

Document Type

Undergraduate Thesis

Department

Biology

First Advisor

Christopher Leary

Second Advisor

Michel Ohmer

Third Advisor

Lainy Day

Relational Format

Dissertation/Thesis

Abstract

Comparative genomics data suggest that vertebrates are descendants of ancestral polyploids and that historical polyploidization events fueled evolutionary innovations. For example, polyploidization can modify gene expression patterns and/or increase gene mutation rates to alter the phenotype. While considerable emphasis has been placed on the evolutionary impact of ancient polyploidization events, less is known regarding phenotypic modifications in extant polyploids. I examined circulating levels of adrenal glucocorticoids and gonadal steroids in the diploid-tetraploid gray treefrog complex to understand how polyploidization has impacted hormonal regulation. Furthermore, I examined the relationships between levels of these hormones and acoustic signals to examine if and how hormone levels potentially regulate vocal features that are known to be important in mate choice by females. Results revealed that baseline adrenal glucocorticoid levels were higher in males of the diploid species than males of the tetraploid species in one of the two years of data collection. In contrast, there was no evidence that baseline levels of gonadal steroids (e.g., androgens, estrogen, and progesterone) differed between diploid and tetraploid males. Results also revealed evidence that crosstalk between the hypothalamic-pituitary-adrenal and -gonadal axes are modified in tetraploids. For example, diploids subjected to a standardized stress test showed an inverse relationship between glucocorticoids and androgens while tetraploids did not. Finally, results provided little support that androgens levels mediate changes in vocal effort in calling males, and little evidence that males with higher vocal effort have higher corticosterone levels, contrary to predictions of models describing hormone-vocal relationships in anuran amphibians. Further work is needed to better understand how polyploidization has impacted endocrine regulation in these species and how modifications potentially contribute to variation in sexually selected acoustic signals.

Recommended Citation

Thigpen, Avery, "Impacts of Polyploidization on Endocrine Regulation and Vocalization in the Gray Treefrog Complex" (2025). Honors Theses. 3198.
https://egrove.olemiss.edu/hon_thesis/3198

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