Keywords

Chelonia mydas, climate change, marine turtles, ria, sex ratios

Abstract

The concept of temperature dependent sex determination (TSD) has been somewhat of an evolutionary enigma for many decades and has had increased attention with the growing predictions of a changing climate, particularly in species that are already threatened or endangered. TSD taxa of concern include marine turtles, which go through various life stages covering a range of regions. This, in turn, creates difficulties in addressing basic demographic questions. Secondary sex ratios (from life stages post-hatchling) were investigated by capturing juvenile green turtles (Chelonia mydas), 22.6-60.9 cm in straight carapace length (SCL), from three developmental areas along the east coast of Florida (a region known to have important juvenile aggregations) by analyzing circulating testosterone levels. All three aggregations exhibited significant female biases with an overall ratio of 3.2:1 (female: male). The probability of a turtle being female increased as the size of the individual decreased. Ratios obtained in this study were slightly less female-biased, but not significantly different, than those observed in the late 1990s. However, they were significantly more biased than those found in a late 1980s pilot study. The shift to significantly female-biased ratios may be beneficial to a recovering population, an evolutionary adaptation, and is common among juvenile aggregations. A more skewed female bias in smaller size classes may be indicative of recent, warmer periods during incubation on the nesting beaches. This female bias could become more exaggerated if temperatures meet future climate warming predictions.

Notes

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Graduation Date

2013

Semester

Spring

Advisor

Weishampel, John

Degree

Master of Science (M.S.)

College

College of Sciences

Department

Biology

Degree Program

Biology

Format

application/pdf

Identifier

CFE0004747

URL

http://purl.fcla.edu/fcla/etd/CFE0004747

Language

English

Release Date

May 2014

Length of Campus-only Access

1 year

Access Status

Masters Thesis (Open Access)

Subjects

Dissertations, Academic -- Sciences, Sciences -- Dissertations, Academic

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