Females of all species belonging to the family Drosophilidae have two kinds of sperm-storage organs: paired spherical spermathecae and a single elongate tubular seminal receptacle. We examined 113 species belonging to the genus Drosophila and closely allied genera and describe variation in female sperm-storage organ use and morphology. The macroevolutionary pattern of organ dysfunction and morphological divergence suggests that ancestrally both kinds of organs stored sperm. Loss of use of the spermathecae has evolved at least 13 times; evolutionary regain of spermathecal function has rarely if ever occurred. Loss of use of the seminal receptacle has likely occurred only once; in this case, all descendant species possess unusually elaborate spermathecae. Data further indicate that the seminal receptacle is the primary sperm-storage organ in Drosophila. This organ exhibits a pattern of strong correlated evolution with the length of sperm. The evolution of multiple kinds of female sperm-storage organs and the rapidly divergent and correlated evolution of sperm and female reproductive tract morphology are discussed.

Evolution of multiple kinds of female sperm-storage organs in drosophila.

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The Biology of Plethodontid Salamanders

The chapter describes sperm competition as a major factor in the sexual behavior of many species. This is clearly a major factor that has led to the evolution in males of a variety of behavior patterns, morphological features and physiological processes that serve to reduce its impact, such as mate-guarding and sexual dimorphism. The potential for sperm competition may have shaped the evolution of anuran sexual behavior. In particular, amplexus, by which males sequester and guard females has evolved as an adaptation that prevents sperm competition. Among urodeles, the necessary conditions for sperm competition, internal fertilization, multiple mating by females and sperm storage are widespread, and several recent studies provide evidence that it has been very important in the evolution of urodele sexual behavior. A female strategy that incorporates multiple mating and sperm competition imposes a strong selection on how much males invest in sperm production and in the way that males allocate sperm to individual matings. This also leads to a diverse array of behavioral patterns and other adaptations.

12 - Sperm Competition in Amphibians

Summary. -Our experiment revealed the existence of significant variation in mating success in a salamander species in which males do not provide courtship feeding, nest sites, or parental care. Differences in mating success were based on natural variation among adult males and females, rather than on traits of an artificially selected set of potential mates. Courtship encounters deliberately involved only one male and one female, thus eliminating the potentially confounding effects of male-male competition and variations in mate encounter rate. Even after eliminating these effects and random error, some females were more likely than others to elicit spermatophore deposition by a male, and some males were more likely than others to inseminate a female. Such variation among individuals represents an opportunity for sexual selection to act on phenotypic characters that affect mating success. We advocate the use of a factorial experimental design to analyze sexual selection. This approach permits the statistical evaluation of separate male and female effects, interaction between these effects, and random effects. Designs which combine the evaluations of mating success and courtship behaviors could estimate the force of sexual selection on behavior.

A statistical study of mate choice: sexual selection in a plethodontid salamander (Desmognathus ochrophaeus)

Manner and roles of sperm acrosome reaction in a variety of animals were compared.Summary Sentence

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Claude Boisseau

Papers

Transport and Survival of Spermatozoa in Female Amphibia