A Fishy Tale of Diversity

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Science  02 Jun 2006:
Vol. 312, Issue 5778, pp. 1281
DOI: 10.1126/science.312.5778.1281b

The lifestyle of the mangrove killifish Kryptolebias marmoratus is a solitary one, in which the fish inhabits areas around red mangrove forests. Populations are generally made up of self-fertilizing hermaphrodites that are homozygous; however, high genetic diversity is observed among lineages. This diversity has been attributed to a high rate of mutation, migration, and genetic drift among populations. Mackiewicz et al. have surveyed 35 microsatellite loci in individual wild-caught fish from Florida. Based on the genotypes of these animals, the authors propose that genotypic diversity results, instead, from outcrossing. This represents a mixed-mating strategy—something that has been observed previously in hermaphroditic plants and invertebrates, but such extensive interspecimen genetic variation in vertebrates with negligible heterozygosity has not been observed. The outcrossing events provide inbred lines with a burst of genetic heterozygosity for subsequent generation of new recombinant inbred lines after self-fertilization resumes. The mixed-mating strategy is likely to provide an adaptive advantage for the harsh environment in which the killifish reside. — BAP

Proc. R. Soc. London Ser. B 10.1098/rspb.2006.3594 (2006).

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