Can microsatellites be used to infer phylogenies? Evidence from populationaffinities of the Western Canary Island lizard (Gallotia galloti)

Population phylogeographic studies are generally based solely on mtDNA with out corroboration, from an independent segregating unit (i.e., nuclear gene s), that the mtDNA gene tree represents the organismal phylogeny. This pape r attempts to evaluate the utility of microsatellites for this process by u se of the Western Canary Island lacertid (Gallotia galloti) as a model. The geological times of island eruptions are known, and well-supported mtDNA p hylogenies exist (corroborated as the organismal phylogeny rather than just a gene tree by nuclear random amplified polymorphic DNAs (RAPDs)). The all elic variation in 12 populations from four islands (representing five haplo type lineages) was investigated in five unlinked microsatellite loci. Analy sis of molecular variance showed this data to be highly structured. A serie s of genetic distances among populations was computed based on both the var iance in allele frequency (i.e., F-st related) and the variance in repeat n umbers (i.e., R-st related). The genetic distances based on the former were more highly correlated with the mtDNA genetic distances than those based o n the latter. All trees based on both models supported the primary division shown by mtDNA and RAPDs, which is dated at ca. 2.8 to 5.6 mybp (depending on calibration of the mtDNA clock) and which could, under the evolutionary species concept, be regarded separate species. This was achieved despite t heoretical problems posed by the use of few loci, suspected bottlenecks, an d large population sizes. The finer details were less consistently represen ted. Nevertheless, this study demonstrates that even a small number of micr osatellites can be useful in corroborating the deeper divisions of a popula tion phylogeny. (C) 2001 Academic Press.