Hypervariable DNA markers and population structure in three fish species

The utility of hypervariable DNA polymorphisms as a general population genetics method was studied in three fish species by the use of multilocus DNA fingerprinting. Laboratory lines and field caught specimens from Belize and Florida of the clonal species Rivulus marmoratus were examined to determine the relative contributions of mutation and migration to genetic variation in the species. Specimens of Poecilia latipinna, the sailfin molly, from Florida and Georgia were used to explore the properties of hypervariable markers in the context of an outbred and abundant species that exhibits typical levels of genetic variability at nuclear loci. The results were compared to those of a previous allozyme survey of the same populations. Samples of Morone saxatilis from the Chesapeake Bay system were used to investigate the utility of hypervariable markers in the description of genetic variation of an outbred species depauperate in other measures of genetic variation.

The results of this study indicate that variation observed among among R. marmoratus clones characterized by hypervariable loci may be the result of natural selection; based on the analyses of mutation rates and population structure. Results from the work with P.latipinna showed that hypervariable loci could have general utility as a method for studying population structure. This utility was demonstrated in the examination of Chesapeake Bay populations of M. saxatilis. Large degrees of interindividual variation at hypervariable loci permitted the characterization of population structure within Chesapeake Bay populations of this species.