Chromosomal polymorphism, morphometric traits and sexual selection in females of Leptysma argentina (Orthoptera).

COLOMBO, P.C., PENSEL, S.M. AND REMIS, M.I.

GENETICA

Año: 2004 p. 1 - 10

0016-6707

The neotropical genus Dichroplus and related genera are characterized by a relatively high uniform external morphology and a divergent male genitalia and hence its taxonomy is controversial. It also shows an extreme karyotypic diversification. In this study we used molecular and morphological characters to test the monophyly of the genus and to evaluate chromosome evolution. Twenty-seven species from Dichroplus and related genera were included in the analysis.  Morphological characters refer to the general morphology, male genitalia and female structures. Molecular studies were performed sequencing part of two mitochondrial genes, cytochrome oxidase I and II. Independent and combined phylogenetic analyses of the data were performed under maximum parsimony. The karyotypic characters (rearrangements) were mapped onto the combined topology. While the molecular analysis confirm some results attained with morphology, some other do not. All point towards the paraphyly of the genus. Our results show the relevance of morphological data in phylogenetic studies because morphology and molecules supply complementary evidence. The mapping of chromosome characters on the combined tree shows that the most extreme karyotype, in D. silveiraguidoi, is a derived condition, probably reached through several centric fusions. This repetition of the same rearrangement within a biological group has been attributed to both directional selection and skewed mutational input; we suggest Dichroplus as a case of the latter possibly mediated by transposable elements.