O Programa de Pós Graduação em Genética do ICB-UFMG Convida para o Seminário intitulado: "Fast chromosomal evolution in the cactophilic Drosophila mojavensis lineage: a molecular appraisal"
Palestrante: Prof. Alfredo Ruiz
Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Spain
Resumo:The rate of chromosomal evolution varies significantly between lineages. Several factors may contribute to this variation. However, the actual reason for the high evolution rate in some particular lineages is unclear and different studies invoke different explanations. We investigated the fast chromosomal evolution of Drosophila mojavensis using genome sequence information from D. mojavensis, D. buzzatii and D. virilis. D. mojavensis is a cactophilic species of the repleta group living under extreme ecological conditions in the deserts of the Southwestern USA and Northwestern Mexico. The genomes of D. mojavensis and D. virilis were sequenced in 2007 by the Drosophila 12 genomes consortium. We have recently sequenced the genome of D. buzzatii, another member of the repleta group and thus a closer relative to D. mojavensis than D. virilis. The D. buzzatii scaffolds have been anchored to the chromosomes using diverse procedures (conserved linkage, BAC-end sequencing and in situ hybridization) and the chromosome organization compared between D. mojavensis and D. buzzatii using MUMmer and GRIMM software. The results confirmed that chromosome 2 differs between these two species by ten inversions, chromosomes X and 5 differ by one inversion each, and chromosome 4 is homosequential as previously described. In contrast, we find that chromosome 3 differs by five inversions instead of the expected two that were previously identified by cytological analyses. Thirteen of these inversions took place in the D. mojavensis lineage: twelve are fixed and one of them has been identified as a polymorphic inversion previously described in populations from Sonora and Baja California. We have investigated the breakpoint regions of all D. mojavensis inversions in chromosomes 2 and 3 identifying the flanking genes and (when possible) inferring the molecular mechanism that generated the inversion. Overall, our results reveal a number of gene alterations at the inversion breakpoints with putative adaptive consequences that directly point to natural selection as the cause for D. mojavensis fast chromosomal evolution.
Data: 02/07/2015/14:30h/Sala I3236/ICB/UFMG