Mitochondrial gene divergence of Colombian Drosophila pseudoobscura

Isolated populations of drosophila pseudoobscura, separated from NorthAmerican populations by about 2,400 km, were found in Colombia in 1960. Wecompared for sequences of the small ribosomal RNA (srRNA) gene on themitochondria between North American and Colombian D. pseudoobscura in orderto clarify the age of the Colombian isolates. The North Americanpopulations were not genetically different from each other but weregenetically different from the Colombian populations. The Mexican strainsrepresent the area from which the Colombian founders might have come. Theestimated net nucleotide divergence between Mexican and Colombian D.pseudoobscura indicates that the Colombian population is not an ancientlineage. Phylogenies using both distance and parsimony methodologiesreinforced this conclusion. The Colombian samples group together with bothmethods but, according to the bootstrap analysis, not significantly. Itappears that the populations have not been separated long enough for theirDNA sequences to show much divergence.