Sexual selection influences the reproductive success of each individual and it is not limited to competition for access to the opposite sex. In species in which females copulate with several males during the reproductive period, the paternity dispute can occur even after copulation, through sperm competition and female cryptic choice. Loliginidae squids exhibit complex sexual behaviors and multiple paternity is common in the group. In addition, males of the same species adopt alternative reproductive tactics. Consort males mate in male-parallel position and deposit spermatophores inside the female's mantle cavity, whereas sneaker males mate in head-to-head position and deposit spermatophores in the seminal receptacle. Using the loliginid Doryteuthis plei (Blainville, 1823) as a model species, this project aims to: (i) estimate the number of sneaker males that can potentially contribute to fertilisation of the egg mass, by genotyping spermatozoa naturally stored in the seminal receptacle; (ii) compare the reproductive success of sneaker and consort males through experimental manipulations and paternity analyses; (iii) associate experimental manipulations and paternity analyses with histological analyses of the seminal receptacle of experimental females, aiming at testing previous hypotheses about the existence of seminal plugs in the species; (iv) evaluate the possibility of female cryptic choice through behavioural observations; and (v) investigate the morphology of the copulatory appendage and spermatozoa in order to deepen the characterization of male intrasexual dimorphism in the species. The results of this project will serve as a basis for the understanding of the mechanisms of postcolulatory sexual selection in an animal group that presents two fertilization sites.
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