BIOLOGY AND ECOLOGY OF RIVULUS MARMORATUS: NEW INSIGHTS AND A REVIEW
Rivulus marmoratus (Pisces: Aplocheilidae) is a small cyprinodontid indigenous to mangroves of the western tropical Atlantic. This species is well known as the only selffertilizing, hermaphroditic vertebrate, and populations normally consist of genetically diverse groups of homozygous clones. However, male fish are known from a few populations, and outcrossing and heterozygosity have been documented from two areas in Central America. Rivulus marmoratus also exhibits a number of behaviors and environmental tolerances unusual in fishes, and since the species is secretive, rare in some habitats and difficult to collect, knowledge of its natural history has been limited until recently. Within the last decade field and laboratory work and ongoing investigations into R. marmoratus genetics have added greatly to our knowledge of this unusual fish. This study provides a general review of the biology and ecology of R. marmoratus.