The sex of young sea turtles is difficult to determine because they lack externally dimorphic characteristics and heteromorphic sex chromosomes, yet internal dimorphic morphology is defined at hatching. We tested the reliability of nine internal gonad and accessory duct characteristics to identify the sex of 558 posthatchling loggerhead sea turtles accurately. We modified existing laparoscopic procedures, previously used to classify the sex of larger sea turtles and other turtle species, for use in posthatchlings. Here we describe our approach and quantify the reliability of our morphological criteria. Sex was verified by histological examination of gonadal biopsies from a subset of the turtles. We noted seasonal shifts in early gonadal structure so that some characters which were reliable in the summer and fall were not reliable other times of the year. Thus, we confined the analysis to the six characters that were reliable year round: gonad shape, paramesonephric duct size, gonad size, paramesonephric duct lumen presence, paramesonephric duct mobility, and gonad attachment. Using discriminant analyses of the biopsy and morphological data, we found high correlations between sex from tissue biopsies and these six morphological characters; this analysis misclassified just 2% of the animals with histological verification. Applying the classification functions to animals without histology and comparing those results to our visual classification resulted in 2% reclassification. The analysis reclassified animals that we or the histology correctly identified that had both female-like and male-like characters. Our method provided accurate identification of sex in very young sea turtles. This methodology enables sex ratio assessments in early life stages, which are critical to species recovery efforts. Additionally, sex assignment data are basic to our understanding of patterns and processes directing dimorphic changes of the gonads and their ducts.
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March 2007
Research Articles|
March 01 2007
DETERMINING SEX IN POSTHATCHLING LOGGERHEAD SEA TURTLES USING MULTIPLE GONADAL AND ACCESSORY DUCT CHARACTERISTICS
Jeanette Wyneken;
Jeanette Wyneken
5
1 Department of Biological Sciences, Bldg. 01, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991, USA
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Sheryan P. Epperly;
Sheryan P. Epperly
2 NOAA Fisheries, Southeast Fisheries Sciences Center, 75 Virginia Beach Drive, Miami, FL 33149, USA
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Larry B. Crowder;
Larry B. Crowder
3 Duke Center for Marine Conservation, Nicholas School of the Environment and Earth Sciences, 135 Duke Marine Lab Road, Beaufort, NC 28516, USA
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Jason Vaughan;
Jason Vaughan
4
1 Department of Biological Sciences, Bldg. 01, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991, USA
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Kimberly Blair Esper
Kimberly Blair Esper
1 Department of Biological Sciences, Bldg. 01, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991, USA
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Herpetologica (2007) 63 (1): 19–30.
Article history
Accepted:
August 09 2006
Citation
Jeanette Wyneken, Sheryan P. Epperly, Larry B. Crowder, Jason Vaughan, Kimberly Blair Esper; DETERMINING SEX IN POSTHATCHLING LOGGERHEAD SEA TURTLES USING MULTIPLE GONADAL AND ACCESSORY DUCT CHARACTERISTICS. Herpetologica 1 March 2007; 63 (1): 19–30. doi: https://doi.org/10.1655/0018-0831(2007)63[19:DSIPLS]2.0.CO;2
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