Meeting Abstract

S2-1.3  Wednesday, Jan. 4  Population genetics and phylogeography of a selfing killifish, Kryptolebias marmoratus TATARENKOV, A.; Univ of California, Irvine

The mangrove rivulus, Kryptolebias marmoratus, is one of only two related vertebrate animals known to self-fertilize. Mitochondrial DNA (mtDNA) divergence from the related species, K. ocellatus, shows that selfing in K. marmoratus persisted for hundreds of thousands years. Populations of this fish in the Caribbean consist primarily or exclusively of hermaphroditic individuals, although gonochoristic males occur at about 20% in some populations in Belize. Here, microsatellite loci and mtDNA are used to describe mating system, geographical population structure, and phylogeography of K. marmoratus. The mangove rivulus reproduces by a combination of selfing and outcrossing, known as mixed-mating system. Selfing is predominant in most populations in Florida and Bahamas where it can reach 90%-100%, but in some localities in Belize the degree of selfing is much lower, about 45%. Distribution of individual heterozygosity indicates that within each locale fish have equal chances to outcross, in accordance with average outcrossing rate of that locale. Populations with high rates of self-fertilization consist of highly homozygous individuals, which are effectively clonal. The “clonemate” lineages are transient and restricted to narrow area. Significant population structure is detected at spatial scales ranging from a few hundred meters to hundreds of kilometers in Florida, Belize, and Bahamas. Pattern of variation at mtDNA shows decrease of population size in the last several thousand years. Such decline is probably a result of inability of mangrove forests to keep up with rapid sea level rise following last glacial event.