Genetic Diversity in Populations of <I>Dalbulus maidis</I> (DeLong and Wolcott) (Hemiptera: Cicadellidae) from Distant Localities in Brazil Assessed by RAPD-PCR Markers

Abstract

Populations of Dalbulus maidis (DeLong and Wolcott) from the northeastern and central-southern regions of Brazil differ morphologically, suggesting that they could be genetically isolated. Here we used the random amplified polymorphic DNA (RAPD)-polymerase chain reaction (PCR) technique to estimate genetic structuring of this leafhopper species among five geographically distant localities across those regions and to estimate gene flow between populations. Ten specimens were sampled per population and genotyped with RAPD markers generated from amplification with nine oligonucleotides. The percentage of polymorphic loci was 78% in relation to the total number of amplified loci, and genetic similarity either between or within populations was higher than 0.72. Cluster analysis grouped specimens from the northeastern population (Mossoró/RN) into a single group, whereas central-southern specimens were not grouped in relation to their places of origin. Overall, the genetic subdivision index (Fst) was low (<or=0.113), whereas the gene flow estimate (Nm) was high (up to 8.53) between populations, except between the Mossoró/RN population and those of the central-southern region (Fst >or= 0.192 and Nm <or= 1.05). The relatively high rates of gene flow between central-southern populations suggest the occurrence of migration within that region, whereas the Mossoró/RN population seems to be genetically isolated.