Reproductive Biology ofSceloporus consobrinus(Phrynosomatidae): Male Germ Cell Development and Reproductive Cycle Comparisons within Spiny Lizards

Abstract

Reproductive cycles of lizards have long been studied in both field and laboratory scenarios. However, comparisons of spermatogenic cycles and germ cell development strategies in different populations across a large geographic range have yet to be explored. The purpose of this study is to A) describe the spermatogenic cycle and germ cell development strategy of a population of Sceloporus consobrinus in southeast Louisiana, B) compare this cycle to a more northern population of this species, and C) compare the reproductive cycles of species within Sceloporus (N = 21). In S. consobrinus from Louisiana, recrudescence begins in the fall (October and November), and the peak of spermatogenesis is reached the following spring/summer (May, June, July). This spermatogenic cycle is similar to that of a more northern population of S. consobrinus from Missouri. Within the genus Sceloporus, there are two seasonal patterns of spermatogenesis: initiation of spermatogenesis in the summer/fall and initiation of spermatogenesis in the spring. In both summer/fall and spring spermatogenic patterns, spermiogenesis occurs in the spring and may continue into the summer. The seasonal timing of recrudescence is an extremely plastic trait that has evolved multiple times throughout the Sceloporus clade. However, there appears to be an association of summer/fall and spring recrudescence with latitude. Tropical populations have a higher frequency of spring recrudescence and temperate populations have a higher frequency of summer/fall recrudescence.