Sperm storage and low incidence of multiple paternity in the European pond turtle, Emys orbicularis: A secure but costly strategy?

Abstract

Sperm storageMultiple paternity Microsatellite Conservation A B S T R A C TThe freshwater pond turtle, Emys orbicularis, has recently suffered from population declines throughout its range, mainly due to habitat destruction. The mating strategies of this species were studied using genetic data from successive clutches within and between years. To test for the occurrence and frequency of multiple paternity and sperm storage, genetic paternity at six microsatellite markers was assessed in 114 embryos and hatchlings from single and subsequent clutches of 11 females (including clutches from the same or consecutive years). Multiple paternity was rare and only found in two out of 20 clutches from 11 females. All annual successive clutches and 58% of the clutches in the next year, were fertilized with sperm from the same male. The use of stored sperm is thus a frequent strategy in E. orbicularis. However, hatching rate, hatchling mass, and hatchling length decreased in clutches fertilized by stored sperm, suggesting sperm depletion or deterioration through time. The occurrence of stored sperm despite an associated reduced reproductive output indicated that mating and/or the fertilization process is costly to females. The low incidence of multiple paternity may simply be the residual consequence of the capacity to store viable sperm. These results provide important and innovative insights for the conservation of E. orbicularis. In threatened populations, management strategies may aim to enhance effective copulations in order to increase the reproductive output of females.

The reproductive ecology of exotic Trachemys scripta elegans in an invaded area of southern Europe

“…The low proportion of males could be compensated for by sperm storage, which has been reported to occur in this species (Gist and Congdon, 1998). Fertility rates were even higher in clutches of T. s. elegans than in native aquatic turtle species, which may also use stored sperm; however, fertility in native clutches fertilized by stored sperm has been reported to decrease (Roques et al, 2006).…”

“…This long period is favoured by the climatic character of the study area, in which other reptiles such as the terrestrial chelonian Testudo graeca (Dı´az-Paniagua et al, 1996) have a similar nesting season. In contrast, the two native aquatic turtles of the same study area concentrate their nesting in only two months, mainly June and July (Keller and Busack, 2001;Roques et al, 2006). In North America, females mainly nest on warm days after rains.…”

“…Thus, the Keller (1997). b Roques et al (2006). c Authors' unpublished data based on incubation of 76 eggs (from 14 clutches) at constant 288C.…”

Ultrastructure of Anterior Uterus of the Oviduct and the Stored Sperm in Female Soft‐Shelled Turtle,Trionyx sinensis

“…It is suggested that females probably re-mate for reasons other than the acquisition of gametes for fertilization, such as to increase genetic diversity of offspring (Pearse et al, 2001). The effect of stored sperm on fertility and/or hatching success of across-year clutches is contradictory, with no significant change in some species (Pearse et al, 2001(Pearse et al, , 2002, but a decrease in others, suggesting sperm depletion or deterioration through time (Roques et al, 2006). However, there is very little about the anatomy of sperm storage in turtles (Gist and Congdon, 1998;Sarkar et al, 2003).…”

Assignment tests applied to relocate individuals of unknown origin in a threatened species, the European pond turtle (Emys orbicularis)

“…were recently used for this species for paternity analysis in Doñana population (Roques et al, 2006).…”