Evolutionary and functional significance of lengthy copulations in a promiscuous apple snail, Pomacea canaliculata (Ampullariidae, Caenogastropoda). ,

BURELA, SILVANA; MARTÍN, PABLO RAFAEL

JOURNAL OF MOLLUSCAN STUDIES

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2011 vol. 71 p. 54 - 64

0260-1230

The peculiar adaptations of the dioecious freshwater snails belonging to the family Ampullariidae have been recently recognized as important, albeit neglected, models for evolutionary ecology studies. A review of the literature, mostly reports from unsystematic observations under laboratory conditions, exposed considerable variation (38 minutes to 20 h) in the duration of copulation in this family, both at inter and intraspecific levels. The aims of our study were to investigate if the lengthy copulations of Pomacea canaliculata occur naturally in the wild and if a significant part of the copulation duration is not devoted to sperm transference but to accomplish genital connection or to impede the access of other males. The effect of single versus repeated copulations in terms of female reproductive output, and the effect of some proximate factors (male size, mating status, time of the day and prowler males) in the duration of the copulation were also evaluated. Our field results indicate that lengthy copulations previously reported for P. canaliculata were not entirely an artefact. The laboratory evidence obtained indicates that the completion of the genital connection or a pre-insemination mate guarding comprises only 20% of the copulatory period and that there is no post-insemination guarding. Most of the copulation time is apparently necessary to transfer an amount of sperm that will ensure the fertilization of the thousands of ova produced during the entire lifetime of females. There was no effect of male size, the time at which copulation began, the mating status of snails nor of the presence of prowler males on the duration of copulations.