Reproductive behavior analysis in the annual killifish Austrolebias nigripinnis (Regan, 1912) (Cyprinodontiformes: Rivulidae)

Annual killifish have an annual life cycle unique among vertebrates. Adults lay desiccation-resistant eggs in the soil of the temporary pools they inhabit. Courtship behavior of some Neotropical killifish consists of a series of displays performed by males and females that ends in the total or partial burial of the couple. However, little information exists on their reproductive isolation mechanisms, including a detailed analysis of courtship signals. In this study, we analyzed the courtship behavior of a Neotropical annual killifish (Austrolebias nigripinnis) within a comparative frame. The most frequent units in males were lateral (44%) and sigmoid displays (26%), where males exhibit morphological and color patterns to females. Females showed a high frequency (44%) of quiescence, suggesting that this unit may have an evaluative role during courtship. Behavioral units recognized in this species show some differences with other related species (i.e., Austrolebias affinis), mainly in frequency and duration, but also in sequence. Although the results of this work cannot determine if these differences constitute reproductive isolation mechanisms, it provides fundamental elements to try to establish kinship relationships and solve the complexity implicit in the definition of species.