Meeting Abstract
The major function of the testes is sperm production, or spermatogenesis. Across species, there are dramatic differences in sperm morphology, and this variation results (at least in part) from differences in the duration and patterns of cell division during spermatogenesis. Further, testis architecture may evolve in correlation with sperm morphology, as for example, sperm tail length is correlated with the evolution of thicker epithelia of the seminiferous tubules in birds. In this study, we examined relationships between testis architecture and sperm morphology in a group of 28 species of Anolis lizards from the Dominican Republic, Puerto Rico, Bahamas, and the United States. Using cryosectioned testis tissues, we measured the cross-sectional area of each testis, the seminiferous tubules within the testis, and the lumina of the tubules. We also measured sperm head, midpiece, and tail lengths for each species. Preliminary analyses in a subset of 16 species suggest that, after controlling for body size, species with larger testes produce sperm with longer heads, and seminiferous tubules with larger lumina and thicker epithelia produce sperm with longer tails. Our current work examines the cell-type distribution and density in the testes of each species, to determine patterns of tissue efficiency in sperm production. This study will allow us to better understand the relationship between the evolution of testis morphology and sperm production strategies across a species group.
