Abstract

GONCALVES-DE-FREITAS, Eliane  and  FERREIRA, Aline Chimello. Female social dominance does not establish mating priority in Nile tilapia. Rev. etol. [online]. 2004, vol.6, n.1, pp. 33-37. ISSN 1517-2805.

Female dominance and size are important features for mating choices in fishes. As dominants are also the largest females in some species, we tested whether dominance per se favours mating priority in Nile tilapia females. Three matched-size adult females (n = 13) were grouped in a 140 l-aquarium during 3 days for hierarchical settlement. On the 4^th day a male larger than the females was introduced in the group and kept there for 12 consecutive days until reproduction. Spawning occurred in 8 out of 13 replicates, and the alpha female was the first to mate in only 50% of the cases. Males may thus choose females according to size and not according to rank, as occurs in other cichlid species. As confrontations and the establishment of hierarchical dominance involve high energetic expenditure in Nile tilapias, the reason why females invest in such behaviors is still a question to be elucidated.

Keywords : Reproductive behavior; Mate choice; Nile tilapias; Oreochromis niloticus.

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