Phylogenomics and phylogeography of the leafcutter ants in the genus Atta Fabricius, 1804 (Formicidae: Attini) based on ultraconserved elements and transcriptomic data

Abstract

Leafcutter ants (genus Atta Fabricius, 1804) have a wide geographical distribution and are the dominant herbivores in the Neotropical region. Some species are important agricultural pests, with great economic impact in Brazil. The morphological delimitation between Atta species is very difficult, because the smaller workers do not have morphological characters useful for species differentiation. This is an important barrier to taxonomic studies of leafcutters, making it difficult to recognize species in the field, including the pest ones. Alternatively, molecular characters may provide phylogenetic delimitations among leafcutter ant species, supporting Taxonomy. In 2009, our research group clarified the main phylogenetic relationships within the Atta genus using multilocus data. However, it did not access all species or cover the entire geographic distribution of each species, so the phylogenetic delimitation between species was incomplete. In the present project, we propose to analyze all 15 Atta species currently recognized, covering the complete area of occurrence of these ants in the Americas and expanding the sample number. For this purpose, samples collected in the field will be studied, as well as those conserved in nine entomological collections in Brazil and abroad, using non-destructive procedures for DNA extraction. To increase the number of characters studied, molecular data will be obtained in large quantities by sequencing Ultraconserved Elements (UCE) and transcriptomes. With this groundbreaking strategy, it is intended to undertake a review of evolutionary relationships delimiting each species of Atta and characterize the biogeography and phylogeography of the genus. In addition, transcriptomic data will allow us to identify a set of phenotypic changes, ie in protein coding sequence, underlying the speciation of distinct ant groups. The project proposed here is strongly supported by Christian Rabeling, from the Arizona State University, who develops UCE markers and maintain a collection of Atta species. With this project, we expect to obtain tools for the taxonomic revision of the genus, which will support future studies to understand morphological boundaries between species. It is also expected to understand some of the phenotypic changes underlying the diversification of subgenera and ant species. (AU)