Date Approved

2024

Degree Type

Open Access Senior Honors Thesis

Department or School

Biology

First Advisor

Katherine Greenwald, Ph.D.

Second Advisor

Aaron Liepman, Ph.D.

Third Advisor

Natalie Dove, Ph.D.

Abstract

Within the genus Ambystoma exists a complex of unisexual (all female) polyploid salamanders, which can breed with males of five sexual species of salamander. Unisexuals face intense sexual selection from diploid males, who prefer to mate with females of their own species. At the Edwin S. George Reserve (ESGR), it has been observed that LLJ unisexuals with large body sizes migrate to breeding ponds earlier than small unisexuals. A possible explanation for this behavior is that large LLJ unisexuals are sexually selected against, when compared to small unisexuals. We hypothesized that A. laterale males would prefer smaller LLJ unisexuals, when compared to larger LLJ unisexuals. To test this hypothesis, male A. laterale salamanders were placed in a breeding box with unisexuals differing in size; offspring were then genotyped to see which unisexual reproduced. Little to no correlation was found between unisexual size and A. laterale males mate choice. Our results were unable to explain the phenomenon behind large unisexuals arriving to breeding ponds early. However, there were several instances of unisexuals reproducing without access to spermatophores in the breeding boxes, which could indicate that the unisexuals acquired spermatophores before being collected in the wild and were able to store sperm or fertilized eggs within their cloaca for an extended period. This behavior has only been observed in a single unisexual specimen prior to this study.

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