The specific objective of this proposal is to examine the causal mechanisms and functional outcomes of the two major annual reproductive tactics -- associated and dissociated -- exhibited by higher vertebrates. In many seasonally breeding vertebrates, gamete maturation and maximum secretion of sex steroid hormones immediately precede or coincide with courtship and copulatory (mating) behavior. This annual pattern may be termed the associated reproductive tactic, or prenuptial gametogenesis (Figure 1). A markedly different annual pattern is exhibited in many vertebrates, including some mammals, in which the gametes are produced only after the breeding season has ended; the gametes are then stored until the next breeding period. In these species, mating occurs when the gonads are not producing gametes and blood concentrations of sex steroid hormones are basal. This pattern may be referred to as a dissociated reproductive tactic, or postnuptial gametogenesis (Figure 1). I will fucus on one representative species of each reproductive tactic. The green anole lizard is similar to many laboratory and domesticated mammals and birds showing the associated tactic. In contrast, the red-sided garter snake shows the dissociated patterns. In many instances a direct comparison of these two species will be made, whereas in other instances gaps in our knowledge must be filled before conceptually valid comparisons can be made. Thus, some of the proposed experiments deal with only one species or tactic. Ultimately, however, my goal is to compare the two tactics at as many levels of organization as are feasible and resonable. Such a broad approach is crucial if important generalities underlying vertebrate reproductive processes are to emerge. My proposed studies will also contribute directly to our understanding of related areas of reproductive biology, including gamete storage and animal husbandry.
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