Role of temperature in sex determination in reptiles alive in Philadelphia

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Furthermore, females switching from haplodiploidy would lose the fitness benefit associated with producing uniparental sons. Zoological Journal of the Linnean Society — Berlin: Springer-Verlag, This pattern can be further divided in:. This stability could be due to an absence of genetic variation, particularly when multiple genetic steps are required for a transition to a new sex-determining system Figure 2.

The reverse transition, from ESD to GSD, is thought to be favored when the environment is unpredictable or not variable enough, in which case ESD could produce strongly skewed sex ratios or intersex individuals [3].

  • Sexual reproduction is an ancient feature of life on earth, and the familiar X and Y chromosomes in humans and other model species have led to the impression that sex determination mechanisms are old and conserved.
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  • In most animals the sex of an individual is determined at the moment of fertilization; when the egg and the sperm fuse together it is fixed if that animal will be male or female.
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Role of temperature in sex determination in reptiles alive in Philadelphia

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  • Jun 25,  · In temperature-dependent sex determination, however, it is the environmental temperature during a critical period of embryonic development that determines whether an egg develops as male or female. May 01,  · Temperature-dependent sex determination (TSD) in reptiles provides such a case. Several alternative explanations for the nature of the adaptive advantage conferred by TSD have been proposed4, 13, All of these hypotheses invoke a series of assumptions, most of which had little empirical support at the time the hypotheses were by:
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  • Two factors in reptile sex determination have been studied: (1) the presence or absence of heteromorphic sex chromosomes, and (2) the influence of temperature. Recognizable sex chromosomes are common in snakes and lizards, but are apparently rare in turtles and absent in crocodilians and the by: In many egg-laying reptiles, the incubation temperature of the egg determines the sex of the offspring, a process known as temperature-dependent sex determination (TSD). In TSD sex determination is an "all or none" process and intersexes are rarely formed. How is the external signal of temperature transduced into a genetic signal that determines gonadal sex and channels sexual development?
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