An extraordinary adaptation has been documented within mangrove forests and salt marshes of the western Atlantic. The Neotropical killifish Kryptolebias (formerly Rivulus) marmoratus is widely distributed, but locally rare, within coastal south and central Florida.
Habitat alteration has affected the species throughout the state, especially on the east coast (Indian River) where the destruction of mangroves and impounding of high marsh for mosquito control has altered and fragmented suitable habitat. Within tropical salt-marsh and
In south Florida and the west coast, Kryptolebias marmoratus is most often captured in stagnant pools in mangrove forests. Most populations of Kryptolebias marmoratus in Florida consist of arrays of homozygous clones since the fish self-fertilizes, the only vertebrate known to do so. Theoretically, isolated populations consisting of only a single clone could persist indefinitely. In contrast, in Belize, ~20% of the population are functional males, and in the presence of males, hermaphrodites start functioning as females and lay unfertilized eggs, which the males then fertilize externally. A 're-evolution of sex' in Belize! Why there? We don't know….many enigmas remain. While general questions remain about the adaptive significance of clonal diversity, the mere presence of this novel fish in salt marsh/mangrove habitats may indicate that other aspects of biodiversity are in good "order."
Brevard County Environmentally Endangered Lands Program
E-Mail - D. Scott Taylor
National Geographic News , November 6, 2007.