Variation in female reproductive quality and reproductive success of male Midland Painted Turtles (Chrysemys pietà marginata)

摘要

Although mate number is perceived to be the primary factor affecting male reproductive success in polygynous systems, differences in female reproductive qualities may also influence variation in male reproductive success. We combined 32 years of dataon variation in reproductive qualities (clutch size and clutch frequency) of female Midland Painted Turtles (Chrysemys pietà marginata Agassiz, 1857) with genetic data on patterns of repeated paternity (i.e., stored sperm use) and multiple paternity toexamine the potential influence on male reproductive success. Over 24 years (1983-2006), the number of reproductive females each year averaged 84 (minimum-maximum = 62-106) and, on average, 23% (minimum—maximum = 6%-40%) produced two clutches (intraseasonally). Among females with reproductive histories spanning 5-24 years (N = 167), 26% of individuals produced only one clutch annually, whereas 74% produced two clutches within a season. Among just intraseasonally iteroparous females, second-clutch production varied from 1% to 50%. Repeated paternity was observed in 97.5% of 40 paired clutches and 44% of 9 among-year comparisons of clutches from consecutive years. The frequent use of stored sperm to fertilize sequential clutches within and potentially among years can substantially increase a male's reproductive success, particularly if males can base mating decisions on phenotypic characteristics correlated with female quality.