Meeting Abstract
49.4 Jan. 6 Siblicide in Crepidula coquimbensis (Gastropoda): the role of multipaternity BRANTE, Antonio*; FREDERIQUE , Viard; FERNANDEZ, Miriam; Pont. Univ. Catolica de Chile; Station Biologique de Roscoff; Pont. Univ. Catolica de Chile abrante@bio.puc.cl
Sibling cannibalism during intracapsular development is a common strategy observed across different marine invertebrate taxa. It is still an open question what factors are determining intracapsular cannibalism intensity and driving the evolution of this behavior in marine invertebrate species. Hamilton predicted that the average cost of consuming a mate on inclusive fitness decreases as the average relatedness among mates declines. Thus, intracapsular cannibalism may be favored by polyandry and sibling cannibalism should be commonly observed among distantly related victims. We tested this hypothesis using as a biological model Crepidula coquimbensis (Gastropoda), a marine gastropod exhibiting intracapsular cannibalism. Adults are sedentary and inhabit empty shells of marine snails. Females encapsulate their embryos and brood them in their shelters. These characteristics allowed us to collect the brooding females as well as all potential fathers from a single shelter, and therefore to study the paternity of the embryos. In order to test the proposed hypothesis we first conducted paternity analysis for this species, to assess if polyandry occurs in nature. We developed five polymorphic microsatellite markers to then quantify intracapsular paternity. We analyzed approximately 20 embryos per capsule, in five capsules of a clump, for a total of 10 females. The genetic variance of these clumps was estimated throughout embryonic development. We then tested the effect of embryos relatedness on cannibalism rate, constructing artificial groups of approximately 100 embryos with different level of relatedness. Our results show that cannibalism rate is directly related with level of relatedness between embryos and polyandry may play a critical role on the evolution of siblicide in marine gastropod.
