Literaturdatenbank
Literaturdatenbank |
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Horne, B. D. , Why do some turtles take so long to hatch? Paper presented at Turtle Survival Alliance 2006 Annual Meeting.
Added by: Admin (13 Dec 2008 16:50:12 UTC) |
| Resource type: Proceedings Article BibTeX citation key: Horne2006 View all bibliographic details  |
Categories: General Keywords: Chelidae, Chelodina, Chelodina longicollis, Malacochersus, Malacochersus tornieri, Pelodiscus, Pelodiscus sinensis, Schildkröten = turtles + tortoises, Testudinidae, Trionychidae, Zeitigung = incubation Creators: Horne Collection: Turtle Survival Alliance 2006 Annual Meeting |
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| Abstract |
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Testudinidae The length of incubation (defined here as the time from oviposition to hatching) is quite variable amongst turtles. The shortest reported incubation periods reported to date have come from the Chinese softshell (Pelodiscus sinensis) with a mere 23 days of total incubation; where as incubation periods of greater than 2.5 years has been reported for the common Australian sideneck (Chelodina longicollis). But it is perhaps our bias towards North American Emydids with a majority of their incubation periods ranging 50-75 days that we have come to think of any incubation period longer than this as being abnormal. A geographical analysis of turtle diversity was performed to quantify the number of turtle species that have distributions that overlap the distribution of turtles that are known to posses the life history traits of embryonic diapause (ED); a mechanism for prolonging incubation periods. Using this geographical analysis and additional life history data I was able to make predictions concerning which species previously undocumented as having ED and/or EA would posses these traits. Of the approximately 264 species of freshwater turtle and tortoises only 33 species are known to express ED, 3 species have a high probability of expressing ED, and an additional 23 species are considered as possible expressers of ED based on incubation duration, timing of oviposition, egg type, nesting habitat, adult habitat, and phylogeny. Accounting for the geographic distribution of turtles known to express ED, excluding Malacochersus tornieri, an equatorial tortoise that expresses ED; 191 species were categorized as having some part of their distribution within environments that would promote the expression of ED. Of those 191 species 61 (31%) are known not to express ED, 7 (4%) probably do not express ED, 32 (17%) express ED, 1 (1%) has a high probability of expressing ED, 49 (25%) are possible expressers of ED, and 42 (22%) were categorized as unknown due to insufficient data. Understanding the role of ED has in prolonged incubation periods is a critical factor in differentiating maternal from environmental effects; and only with a clearer understanding of this mechanisms will we be able to shed more light onto why some turtles take so long to hatch.
Added by: Admin |