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Kuchling, G. , How to assess sex ratios and how to avoid gender bias mistakes in recovery projects of critically endangered turtles. Paper presented at Turtle Survival Alliance 2006 Annual Meeting. 
Added by: Admin (13 Dec 2008 16:50:14 UTC)
Resource type: Proceedings Article
BibTeX citation key: Kuchling2006b
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Categories: General
Keywords: Aldabrachelys, Aldabrachelys dussumieri, Astrochelys, Astrochelys yniphora, Batagur, Batagur baska, Batagur borneoensis, Chelidae, Chitra, Chitra chitra, Erymnochelys, Erymnochelys madagascariensis, Geochelone, Geoemydidae, Haltung = husbandry, Podocnemididae, Pseudemydura, Pseudemydura umbrina, Schildkröten = turtles + tortoises, Testudinidae, Trionychidae, Zeitigung = incubation
Creators: Kuchling
Collection: Turtle Survival Alliance 2006 Annual Meeting
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Abstract     
Testudinidae The sex determination mechanism of a species is of practical importance for conservation programs involving captive breeding and/or the relocation of natural nests and/or artificial incubation: under those scenarios temperature dependent sex determination (TSD) can lead to highly biased offspring sex ratios, whereas genotypic sex determination (GSD) should provide an equal sex ratio independently of the incubation environment. I assessed with non-lethal endoscopy sex ratios in breeding and head starting projects of Geochelone yniphora, Dipsochelys dussumieri, Erymnochelys madagascariensis, Batagur baska and Callagur borneoensis. All those species appear to have TSD and adjustments of incubation conditions allow the manipulation of sex ratios. Pseudemydura umbrina appears to have GSD. After the horrendous masculinizing biases in many early sea turtle conservation programs and after three decades of TSD research it is imperative to evaluate offspring sex ratios in all conservation and recovery programs of critically endangered turtles that involve manipulation of egg incubation. Sometimes this self evident necessity is still ignored, as in the Chitra chitra breeding program at Kanchanaburi, Thailand, which produced 983 eggs and 710 hatchlings from 2001 to 2004. This would have been an ideal opportunity to investigate sex determination and, since Chitra chitra no longer reproduced since 2004, very timely. Lack of appropriate expert consultation and technical advice in implementing critically endangered species recovery can jeopardize the species itself: in early 2006 I found heavy male bias (ten out of ten) in the captive bred Chitra chitra, 79 of which were already released to reinforce the dwindling wild population.The sex determination mechanism of a species is of practical importance for conservation programs involving captive breeding and/or the relocation of natural nests and/or artificial incubation: under those scenarios temperature dependent sex determination (TSD) can lead to highly biased offspring sex ratios, whereas genotypic sex determination (GSD) should provide an equal sex ratio independently of the incubation environment. I assessed with non-lethal endoscopy sex ratios in breeding and head starting projects of Geochelone yniphora, Dipsochelys dussumieri, Erymnochelys madagascariensis, Batagur baska and Callagur borneoensis. All those species appear to have TSD and adjustments of incubation conditions allow the manipulation of sex ratios. Pseudemydura umbrina appears to have GSD. After the horrendous masculinizing biases in many early sea turtle conservation programs and after three decades of TSD research it is imperative to evaluate offspring sex ratios in all conservation and recovery programs of critically endangered turtles that involve manipulation of egg incubation. Sometimes this self evident necessity is still ignored, as in the Chitra chitra breeding program at Kanchanaburi, Thailand, which produced 983 eggs and 710 hatchlings from 2001 to 2004. This would have been an ideal opportunity to investigate sex determination and, since Chitra chitra no longer reproduced since 2004, very timely. Lack of appropriate expert consultation and technical advice in implementing critically endangered species recovery can jeopardize the species itself: in early 2006 I found heavy male bias (ten out of ten) in the captive bred Chitra chitra, 79 of which were already released to reinforce the dwindling wild population.
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