The Neotropical Genus Austrolebias: An Emerging Model of Annual Killifishes

Annual fishes are found in both Africa and South America occupying ephemeral ponds that dried seasonally. Neotropical annual fishes are members of the family Rivulidae that consist of both annual and non-annual fishes. Annual species are characterized by a prolonged embryonic development and a relatively short adult life. Males and females show striking sexual dimorphisms, complex courtship, and mating behaviors. The prolonged embryonic stage has several traits including embryos that are resistant to desiccation and undergo up to three reversible developmental arrests until hatching. These unique developmental adaptations are closely related to the annual fish life cycle and are the key to the survival of the species. Most of the available data on Neotropical annual fishes derive from studies on the genus Austrolebias. Herein, we review and summarize the available data on the evolution, reproduction strategy, developmental biology and conservation status of these Neotropical fishes.