RESUMO
RFLP analysis of mtDNA in natural populations is a valuable tool for phylogeographic and population genetic studies. The amplification of long DNA fragments using universal primers may contribute to the development of novel homologous probes in species for which no previous genomic information is available. Here we report how we obtained the complete mtDNA genome of Sinipta dalmani (Orthoptera) in 2 fragments (7 and 9 kb) using primers of conserved regions. The specificity of the PCR reactions was ultimately confirmed by several lines of evidence. These fragments were used as a probe for a mtDNA RFLP study in S. dalmani that analyzed the pattern of haplotype distribution and nucleotide diversity within and among chromosomally differentiated natural populations. Our results suggest that the restriction in gene flow detected at the molecular level may explain the chromosome differentiation detected previously and the maintenance of chromosome polymorphism in some areas of S. dalmani geographic distribution.
Assuntos
Sondas de DNA , DNA Mitocondrial/genética , Variação Genética , Gafanhotos/genética , Mitocôndrias/genética , Animais , Sequência Conservada , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
Leptysma argentina (Acrididae: Orthoptera) is polymorphic for a centric fusion between pairs 3 and 6 of its basic chromosomal complement. With the aim of carrying out an analysis of selection components in this species, male mating success, in relation to karyotype and three morphometric traits, was assessed by using experimental contests with four males and one female per mating cage. Karyotype was assessed in terms of fused chromosome 3/6 dosage and coded as "0", "1" and "2" for unfused homozygotes, heterozygotes and fusion homozygotes, respectively. The individual ANOVA showed significant differences between "successful" and "unsuccessful" males in all four measured characters. Fusion carriers showed a higher relative fitness. Since the phenotypic correlations among traits were significant, the selective effects were assessed by means of a multivariate analysis, which demonstrated that selection acted significantly on femur length only, selection on karyotype being indirect. Given that the fusion frequency has been constant since 1985, the presence of selective trade-offs cannot be ruled out.