Literaturdatenbank
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Valenzuela, N., Botero, R., & Martinez, E. (1997). Field study of sex determination in podocnemis expansa from colombian amazonia. Herpetologica, 53, 390–398.
Added by: Admin (17 Aug 2008 17:24:02 UTC) |
| Resource type: Journal Article BibTeX citation key: Valenzuela1997 View all bibliographic details  |
Categories: General Keywords: Fortpflanzung = reproduction, Habitat = habitat, Podocnemididae, Podocnemis, Podocnemis expansa, Schildkröten = turtles + tortoises, Südamerika = South America Creators: Botero, Martinez, Valenzuela Collection: Herpetologica |
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| Abstract |
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We studied the relationship between fluctuating temperatures in the field and sex ratios of the giant river turtle (Podocnemis expansa) obtained from nests incubated in seminatural conditions using a stepwise logistic regression model. The number of hours above 31 C and mean temperature above 31 C during day 29-30 were the two parameters that best explained sex ratios. We also monitored incubation temperatures of natural nests. Mean incubation temperature and the combination of mean and variance were not predictors of sex ratio. We found a beach effect on sex ratios and incubation time. Natural nests hatched earlier than seminatural nests. Length of the incubation period was negatively correlated with degree days and mean incubation temperature in seminatural nests but not in natural nests. We found no evidence of an influence of length of the incubation period on sex ratio. Our results support current conservation practices in the study region.
Added by: Admin |