| 文件类型： |
文章 |
| 所有的著者/提供者： |
Frederic J Janzen |
| ISSN: | 0014-3820 |
|---|
| OCLC号码： |
478767057 |
| 语言注释： |
English |
| 奖励： |
|
摘要：
The evolutionary significance of sex-determining mechanisms, particularly temperature-dependent sex determination (TSD) in reptiles, has remained unresolved despite extensive theoretical work. To investigate the evolutionary significance of this unusual sex-determining mechanism, I incubated eggs of the common snapping turtle (Chelydra serpentina) at a male-producing temperature (26<sup>⚬</sup>C), a female-producing temperature (30<sup>⚬</sup>C), and an intermediate temperature that produced both sexes about equally (28<sup>⚬</sup>C). Laboratory experiments indicated that two performance variables, but no morphological measurements, were significantly influenced by incubation temperature (P ≤ 0.05): hatchlings from cooler incubation treatments swam faster than turtles from warmer incubation treatments, and hatchlings from 28<sup>⚬</sup>C exhibited a greater propensity to run than did individuals from 26<sup>⚬</sup>C and 30<sup>⚬</sup>C. In the field, hatchlings from the all-male and all-female producing temperatures had significantly higher first-year survivorship than did consexuals from the incubation temperature that produced both sexes (G = 6.622, P = 0.03). Significant directional selection was detected on propensity of hatchlings to run (β′ = -0.758, P = 0.05): turtles that tended to remain immobile had a higher probability of first-year survivorship than did individuals that moved readily. Thus, the effects of the gender × incubation temperature interaction on survivorship of hatchling turtles observed in the field experiment may have been mediated by temperature-dependent antipredator behavior. These results provide a possible functional explanation for the evolutionary significance of TSD in turtles that is consistent with predictions of theoretical models.
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文章 : 英语