Mitochondrial DNA polymorphism and heteroplasmy in populations of the three species of Tropidurus of the nanuzae group (Squamata, Tropiduridae)

Abstract

The nanuzae group of lizards includes three species, Tropidurus nanuzae, T. divaricatus and T. amathites. The first species is found along Serra do Espinhaço, in eastern Brazil, and the other two in the northern region of the Brazilian State of Bahia, in continental dunes on both margins of the São Francisco River. Restriction fragment length polymorphisms (RFLP) of the mtDNA in these species were detected in 53 restriction sites. Site and fragment length polymorphisms were characterized, and cases of heteroplasmy involving length variation were observed. In T. divaricatus, these variations involved changes of 50-200 bp, probably in the control region of the molecule. In T. amathites, variation was apparently due to duplication/deletion of a 400-bp segment. Fragment length mutation rate varied among the species, being smaller in T. amathites than in T. divaricatus. Relatively low nucleotide diversity values were detected in these populations, the smallest being found in T. nanuzae. The most polymorphic population was T. divaricatus from Alagoado, followed by that of the same species from Ibiraba, suggesting both probable recovery of mtDNA genetic diversity after putative reductions in population size, and recent population expansion.