Is Sperm Stored over Winter in Juveniles? A Study of Crotaphytus collaris Reproduction

Abstract

Females of many reptiles, including several species of lizards, are known to be able to store sperm over long periods of time for later use in fertilization of their eggs. This is especially true for species found in areas of low population density where encounters with members of the opposite sex may be few and far between. While Collared lizards (Crotaphytus collaris) are not found in areas of low population density, both adults and juveniles participate in pair bonding where Juvenile females bond with a juvenile male in the fall and are then part of that male’s harem in the spring mating season. In addition to this, some larger juvenile males have been found to produce sperm near the end of their first fall. This raises the question of whether or not it is possible that juvenile males and females mate during the fall and if so whether or not females are able to store this sperm over winter to fertilize their eggs in the spring. To test this question, we captured juvenile females in the fall and induced them into a simulated brumation in the laboratory over the winter. In the spring, when outside temperatures began to warm up, we began bringing them out of brumation. Now, we will place males with half of the captured females as a control for laboratory conditions and leave the other half of the captured females separated from any males. The production of viable or non-viable eggs from the females without access to males in the spring will determine the results of our study.