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Physiology Commons

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Portland State University

Theses/Dissertations

Red-sided garter snake -- Reproduction

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Full-Text Articles in Physiology

Temperature-Induced Activation Of The Reproductive Axis Through Melatonin-Mediated Changes In Thyrotropin, Treven J. Winters Jul 2021

Temperature-Induced Activation Of The Reproductive Axis Through Melatonin-Mediated Changes In Thyrotropin, Treven J. Winters

Dissertations and Theses

An animal's ability to synchronize life-history events or stages with optimal environmental conditions is paramount to successfully reproducing and maximizing fitness. Additional events including migration, foraging, rearing of young, and emergence from hibernation are all examples of processes under environmental control in one species or another. An exciting new mechanism involving neural thyroid hormone metabolism has been elucidated that links environmental control to the neuroendocrine reproductive axis. In birds and mammals with seasonal breeding cycles, this neuroendocrine pathway is activated by photoperiod-induced changes in thyroid stimulating hormone (TSH, also known as thyrotropin) production within the pars tuberalis region of the …


Energy Stores And Life-History Transitions In Red-Sided Garter Snakes (Thamnophis Sirtalis Parietalis), Rachel Catharine Wilson Jul 2020

Energy Stores And Life-History Transitions In Red-Sided Garter Snakes (Thamnophis Sirtalis Parietalis), Rachel Catharine Wilson

Dissertations and Theses

All organisms must prioritize investment in either reproductive or self-maintenance activities. Despite this established paradigm, our understanding of how organisms choose to prioritize certain behaviors and physiologies over others remains limited. It is likely that an organism's energy status not only influences variation in reproductive effort, but also transitions to and from reproductive activities. My dissertation aims to investigate how energy metrics (body condition index, adipocyte follicle size, and liver glycogen) relate to reproduction and associated life-history stages in red-sided garter snakes (Thamnophis sirtalis parietalis). Chapter two examines if energy metrics differ with migratory status and sex in …