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Sex ratios of juvenile green turtles (Chelonia mydas) in three developmental habitats along the east coast of Florida

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Date Issued:
2013
Abstract/Description:
The concept of temperature dependent sex determination (TSD) has been somewhat of anevolutionary enigma for many decades and has had increased attention with the growingpredictions 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.
Title: Sex ratios of juvenile green turtles (Chelonia mydas) in three developmental habitats along the east coast of Florida.
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Name(s): Sanchez, Cheryl, Author
Weishampel, John, Committee Chair
Ehrhart, Llewellyn, Committee CoChair
VonHolle, Mary, Committee Member
Wibbels, Thane, Committee Member
, Committee Member
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2013
Publisher: University of Central Florida
Language(s): English
Abstract/Description: The concept of temperature dependent sex determination (TSD) has been somewhat of anevolutionary enigma for many decades and has had increased attention with the growingpredictions 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.
Identifier: CFE0004747 (IID), ucf:49771 (fedora)
Note(s): 2013-05-01
M.S.
Sciences, Biology
Masters
This record was generated from author submitted information.
Subject(s): Chelonia mydas -- Climate change -- Marine turtles -- RIA -- Sex ratios
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFE0004747
Restrictions on Access: campus 2014-05-15
Host Institution: UCF

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