title: The Size Advantage Model of Sex Allocation in the Protandrous Sex-Changer Crepidula fornicata: Role of the Mating System, Sperm Storage, and Male Mobility.
abstract: Sequential hermaphroditism is adaptive when the reproductive value of an individual varies with size or age, and this relationship differs between males and females. In this case, theory shows that the lifetime reproductive output of an individual is increased by changing sex (a hypothesis referred to as the size-advantage model). Sex-linked differences in size-fitness curves can stem from differential costs of reproduction, the mating system, and differences in growth and mortality between sexes. Detailed empirical data is required to disentangle the relative roles of each of these factors within the theory. Quantitative data are also needed to explore the role of sperm storage, which has not yet been considered with sequential hermaphrodites. Using experimental rearing and paternity assignment, we report relationships between size and reproductive success of Crepidula fornicata, a protandrous (male-first) gastropod. Male reproductive success increased with size due to the polygamous system and stacking behavior of the species, but females nonetheless had greater reproductive success than males of the same size, in agreement with the size-advantage theory. Sperm storage appeared to be a critical determinant of success for both sexes, and modeling the effect of sperm storage showed that it could potentially accelerate sex change in protandrous species.
authors.affiliation: Centre National de la Recherche Scientifique, Team Diversity and Connectivity of Coastal Marine Landscapes, Station Biologique de Roscoff, 29680 Roscoff, France; and Sorbonne Universités, Université Pierre et Marie Curie, Unité Mixte de Recherche 7144, Station Biologique de Roscoff, 29680 Roscoff, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Broquet
authors.forename: Audrey
authors.initials: A
authors.lastname: Barranger
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Billard
authors.forename: Anastasia
authors.initials: A
authors.lastname: Bestin
authors.forename: Rémy
authors.initials: R
authors.lastname: Berger
authors.forename: Gaelle
authors.initials: G
authors.lastname: Honnaert
authors.forename: Frédérique
authors.initials: F
authors.lastname: Viard
mesh_terms: D000818:Animals; D049628:Body Size; D005260:Female; D049851:Gastropoda / Q000254:growth & development / Q000502:physiology*; D057850:Hermaphroditic Organisms / Q000502:physiology*; D007814:Larva; D008124:Locomotion; D008297:Male; D018895:Microsatellite Repeats; D012098:Reproduction / Q000502:physiology; D012726:Sexual Behavior, Animal; D013094:Spermatozoa