Population genetic structure in Argentinean Drosophila buzzatii based on Cytochrome Oxidase I

LIPKO P, PICCINALI RV, HASSON E

Punta del Este, Maldonado, Uruguay

Congreso; 150 years of Darwin's Evolutionary theory. A South American celebration.; 2009

Sociedad uruguaya para el progreso de la Ciencia y la Tecnologia

Drosophila buzzatii (Diptera: Drosophilidae) is a cactophilic fly that breeds and feeds on the decaying tissues of species cactus of Cactaceae.and has a broad distribution in the arid zones of South. Previous studies of population structure based on allozymes and nucleotide sequences of nuclear markers yielded contradictory results. Allozymic surveys revealed a strong regional differentiation for certain loci, while DNA sequences failed to detect any population structure. With the aim to solve this controversy, we report a preliminary analysis of population structure in Argentinean Drosophila buzzatii using the mitochondrial gene COI. We analyzed flies from Eastern and Western natural populations and estimated levels of polymorphism and population differentiation. We also applied neutrality tests to determine whether levels of variation were in agreement with a model of mutation-drift balance. Levels of nucleotide variation were similar in Eastern and Western populations according to Watterson estimator (ThetaW) though the number of pairwise differences between sequences (Pi) was greater in Western populations. No departures from neutrality were detected with Tajima’s, Fu’s and Ramos-Onsins and Rozas’ tests. From the three haplotypes recorded in each population only one was shared between them.  However, differentiation between regions was low and non-significant. When compared to similar studies performed in other areas of the widely distributed D. buzzatii we found: a) higher levels of nucleotide variation than previously reported for another set of Western populations, and b) negligible population structure, as suggested by other DNA markers.