Reproductive aspects of the Jenynsia multidentata.
consent of female. The males take position along the female posterior side and try to introduce their gonopod into the female urogenital opening as fast and furtively as they can (Bisazza et al. 2000). The males expend a great part of their daily time in this activity. This behavior probably make them less careful (compared with females) regarding avoiding predator’s attacks by piscivorous fishes and birds. This differential behavior between genders could result in a higher male predation rate, resulting in larger numbers of females in the population (Magurran & Nowak 1991, Magurran & Seghers 1991). An alternative hypothesis could be associated with differences in capture of males and females by the fish gear (beach seine hauls) employed during our sampling. In this case, the males could be simply under captured due their smaller size, resulting in a higher ratio of females in the samples. More studies should be conducted in controlled conditions at the laboratory and in natural environment in order to test these hypotheses.
We are grateful to the Fundação de Amparo a Pesquisa Rio Grande do Sul – FAPERGS for the scholarship provided to the first author, to CNPq- PELD for the financial support in permanent and consume materials, to the staff od the Laboratório de Ictiologia (FURG) for the logistical support, to Kátia L. B. Andrade and Jamile C. Oliveira for their collaboration in preliminary processing of samples.
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