Evolutionary dynamics of gene families in blowflies (Diptera: Calliphoridae)

Abstract

The birth and death of genes are an important source of new and complex biological phenotypes. With the increasing availability of genomic data, the contribution of expansions and contractions of gene families for genome evolution and biological diversification have been widely explored in comparative analysis. Parasitism is a complex phenotype whose origin across different eukaryotic groups is associated with diverse evolutionary dynamics of these families. Chemosensory genes have been specially focused in the study of free-living to parasitic habit transitions given their importance in detecting and selecting substrate, and thus in delimiting trophic niches. Blowflies (Diptera: Calliphoridae) are excellent models to investigate these transitions, as they occurred independently on at least six occasions throughout the evolutionary history of the family. Its members show contrasting trophic habits in the larval stage. Larvae of saprophagous species feed on decaying matter and the obligate parasites develop on living tissues of vertebrate hosts. Facultative parasites, however, can feed and develop on both types of substrates. In this proposal for an internship abroad, we aim to investigate the basis of parasitism in Calliphoridae under the light of the birth-and-death model, accounting for the impacts of the expansion and contraction of gene families, particularly the chemosensation-related ones, in free-living to parasitic habit transition. To do so, I intend to visit Dr. Julio Rozas' laboratory in the University of Barcelona (Barcelona, Spain) for six months where I will be trained in methods of gene curation and in statistical analyses that characterize the evolution of gene families. Specifically, I aim to refine my set of putative chemosensory-genes, previously identified using a pipeline I developed, by identifying and eliminating false-positive sequences. Additionally, I intend to estimate the rates of their expansions and contractions and evaluate whether in-tandem copies originated from a recent or an ancestral duplication. Moreover, I plan to apply similar estimations to biological functions using orthogroups and their associate Gene Ontology (GO) terms.