História evolutiva e filogeografia da formiga cortadeira Acromyrmex striatus (Roger, 1863) (Formicidae: Attini)

• Autor(a) principal: Cristiano, Maykon Passos
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1380
• topic: Filogenia; Filogeografia; Citogenética; Formiga cortadeira; Genética de populações; Attini; Phylogeny; Phylogeography; Cytogenetics; Leafcuter ant; Genetics of populations; Attini; CNPQ::CIENCIAS BIOLOGICAS::GENETICA

The species Acromyrmex striatus (Roger, 1863) is a polymorfic leafcuter ant that occurs in open and dry enviroments of southern South America, and it is easily distinguished within the Acromyrmex genus. Its distribution range includes the Pampas, the southern Brazilian coast of Santa Catarina and Rio Grande do Sul States, part of Chaco in Argentina and southern Paraguay. In order to understand the phylogenetic position of A. striatus in relationship to other leafcutter ants we carried out one study integrating different approaches that includes morphology, cytogenetics and molecular biology (Chapter 1). The phylogenetic relationship of A. striatus and remainder leafcutter ants analyzed was estimated by mean of four nuclear genes. A. striatus fell into a distinct clade that is sister group from the other leafcutter ants. The diploid chromosome number of A. striatus was 22 and is different from those known to other Acromyrmex species (2n = 36-38). These results suggest that A. striatus is a particular species within the leafcutter ants group, and likely was the first species to diverge from the most recent common ancestor. To infer the genealogical relationship among population of A. striatus, we used a phylogeography approach based on the mitochondrial gene cytochrome oxidase I (COI) (Chapter 2). A total of 128 colonies were sampled across 38 localities in Brazil and Argentina. The mitochondrial gene COI was sequenced and the genealogical relationship were estimated by mean median-joining algorithm. We also carried out the modeling of the potential distribution of A. striatus under current and past climatic data. Our results indicate that A. striatus may have experienced a demographic stability throughout the evolutionary time, and the phylogeographic pattern observed seems to be a result of isolation by distance among population groups. During our screening for a mitochondrial DNA marker for using in the phylogenetic and phylogeographic studies, we amplified a nuclear copy of mitochondrial gene cytochrome b (cytb), thus the aim of Chapter 3 was to report and characterize these pseudogenes in A. striatus. Using universal primers to amplify the gene cytb we obtained sequences of A. striatus and other leafcutter ants that was compared with cytb gene of other two ant species from GenBank. This is the first report of occurrence of pseudogenes in the Acromyrmex genus.