Estimation of sperm storage duration in captive loggerhead turtles (Caretta caretta)

Abstract

Multiple paternity within the same clutch has been detected in all sea turtle species. However, no study to date has addressed the likelihood of sperm storage across years in any sea turtle species in the wild because of the logistical difficulties associated with investigating the same individual females across breeding seasons. Here we provide paternity data from captive loggerhead turtles (Caretta caretta) during 2-4 successive breeding seasons and behavioral information to estimate sperm storage duration in this species. Data from interseasonal comparisons for individual females showed that paternity was identical between two successive breeding seasons. However, females were observed to copulate with males, which were sire of their hatchlings of the previous breeding season, just prior to the nesting period of the next breeding season. Therefore, it is appropriate to regard the consistency in paternity across two successive breeding seasons as a result of re-mating with a sire from the previous season. Conversely, paternity was entirely different from that in the previous season if copulatory behavior occurred just prior to the next season with a male that was not a sire of the female's hatchlings from the previous season. Furthermore, a female that had laid fertile eggs in the previous breeding season but was not observed to successfully copulate with any male during the next breeding season laid no fertile eggs during that next season. Taking these data into consideration, it appears that sperm storage across breeding seasons did not occur in this study of captive Caretta. © 2012 Elsevier B.V.