Diversidade genética, relações filogenéticas e morfologia das sensilas antenais da formiga ameaçada Atta robusta Borgmeier, 1939 (Hymenoptera, Formicidae)

• Autor(a) principal: Pinto, Denise Eliane Euzébio
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1359
• topic: DNA mitocondrial; Biologia molecular; Endemismo; Restingas; Mitochondrial DNA, molecular biology; Endemism; Restingas; CNPQ::CIENCIAS BIOLOGICAS::GENETICA::GENETICA ANIMAL

Atta robusta (Hymenoptera: Formicidae) is an ant species with distribution restricted to the restingas in the Brazilian states of Rio de Janeiro and Espírito Santo, and is threatened with extinction. Objectives of this study were: 1. to characterize and compare sequences of mitochondrial DNA (mtDNA) of Atta species, including A. robusta, as well as assess the genetic structure of the A. robusta population sampled; 2. estimate the time to the most recent common ancestor for A. robusta and the phylogenetic relationships among A. robust and other Atta species; and 3. describe and compare the morphology and morphometry of the antennal sensilla of two A. robusta populations. Collections of A. robusta were conducted at 16 locations in the states of Espírito Santo and Rio de Janeiro; and A. sexdens and A. bisphaerica were obtained in the municipality of Viçosa, Minas Gerais, Brazil. Total DNA from each sample was obtained and used as a template in amplification reactions for specific regions of the mitochondrial DNA (COI-COII) and nuclear DNA (EF1α). Antennal sensilla of two populations located geographically distant from each other were analyzed morphologically. The COI-COII sequence of the Atta species analyzed is rich in A+T nucleotides, where the highest percentage was encountered in the intergenic region (IGS). The A. robusta population showed low nucleotide diversity and high haplotype diversity, which are characteristic of recently formed populations. Eight mitochondrial haplotypes were identified that form three geographically structured haplogroups, indicating no or limited gene flow between haplogroups. The phylogenetic analysis showed that A. robusta is a monophyletic and derived group in relation to the other species of Atta analyzed. The species A. sexdens and A. robusta form clearly distinct sister groups with high Bayesian probability. Common ancestor time of A. robusta was estimated at 7.8 million years. The data obtained from genetic diversity, as well as the phylogeographic pattern suggested for A. robusta, reinforces the need to preserve the restinga environments for preservation of A. robusta populations, the object of study in this work. Independent of the populations evaluated, different types of antennal sensilla (straight and curved trichodea, basiconica, ampullacea and celoconic) were identified, most numerous in the distal flagellomeres. Differences in the number and length of straight and curved sensilla trichodea in the flagellomeres F8 and F9 were observed. Differences between the antennal sensilla of the two populations are resultant of a possible phenotypic plasticity of the species A. robusta, an important feature considering adaptation of this ant to environmental variations.