Publication Date

2020

First Advisor

Lisa A. Mangiamele

Document Type

Honors Project

Degree Name

Bachelor of Arts

Department

Biological Sciences

Keywords

Androgens, Androgen receptors, Interneuron, Motor neuron, Sexual selection, Spinal cord

Abstract

Sexual selection exerts pressure on males to evolve new communication signals in order to maximize reproductive success. The Bornean rock frog, Staurois parvus, is a small frog that lives by noisy streams and waterfalls in the rainforests of Borneo. While vocalizations are an ancestral trait present in all species of anurans, S. parvus has evolved a visual communication signal, known as a “foot-flag.” While prior work done by Mangiamele et al. (2016) has shown that S. parvus has increased androgen receptor (AR) expression in its leg muscle compared to two species who do not foot-flag (Rana pipiens and Xenopus laevis), it was also found that S. parvus has a higher expression of AR in its spinal cord compared to at least one non-foot flagging species. In order to better characterize differences in androgen sensitivity in the spinal cord, I used in situ hybridization to measure AR density in the lumbar spinal cord, as well as quantified the moto- and interneuron abundance and diameter to ascertain any physiological differences between these three frog species. The results show that there are differences in AR density and abundance of interneurons between S. parvus and at least one non-foot flagging frog, the most striking difference between species is in neuron morphology. S. parvus had the largest diameter motoneurons and interneurons of all the frog species examined when corrected for body size. These results indicate that the diameter of moto- and interneurons may be important for foot-flagging behavior, while perhaps the abundance of neurons and spinal AR density is less of a distinguishing feature of the spinal cord of foot flaggers, thus giving more insight to the physiology required to produce this novel signal.

Rights

2020 Kerry Marie LeCure. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.

Language

English

Comments

31 pages : color illustrations. Includes bibliographical references (pages 29-31)

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