Barron, M. G. | bioRxiv Science

bioRxiv2018

A new species in the Anopheles gambiae complex reveals new evolutionary relationships between vector and non-vector species

Complexes of closely related species provide key insights about the rapid and independent evolution of adaptive traits. Here, we described and studied a presumably new species in the Anopheles gambiae complex, Anopheles fontenillei, recently discovered in the forested areas of Gabon, Central Africa. Our analysis placed the new taxon in the phylogenetic tree of the An. gambiae complex, revealing important introgression events with other members of the complex. In particular, we detected recent introgression with An. gambiae and An. coluzzii of genes directly involved in vectorial capacity. Moreover, genome analysis of the new species also allowed us to resolve the evolutionary history of inversion 3La. Overall, Anopheles fontenillei has implemented our understanding about the relationship of species within the gambiaecomplex and provides insight into the evolution of vectorial capacity traits, relevant for the successful control of malaria in Africa.

evolutionary biology↗

bioRxiv2018

Stress response, behavior, and development are shaped by transposable element-induced mutations in Drosophila

Mapping genotype to phenotype is challenging because of the difficulties in identifying both the traits under selection and the specific genetic variants underlying these traits. Most of the current knowledge of the genetic basis of adaptive evolution is based on the analysis of single nucleotide polymorphisms (SNPs). Despite increasing evidence for their causal role, the contribution of structural variants to adaptive evolution remains largely unexplored. In this work, we analyzed the population frequencies of 1,615 Transposable Element (TE) insertions in 91 samples from 60 worldwide natural populations of Drosophila melanogaster. We identified a set of 300 TEs that are present at high population frequencies, and located in genomic regions with high recombination rate, where the efficiency of natural selection is high. The age and the length of these 300 TEs are consistent with relatively young and long insertions reaching high frequencies due to the action of positive selection. Indeed, we, and others, found evidence of selective sweeps and/or population differentiation for 65 of them. The analysis of the genes located nearby these 65 candidate adaptive insertions suggested that the functional response to selection is related with the GO categories of response to stimulus, behavior, and development. We further showed that a subset of the candidate adaptive TEs affect expression of nearby genes, and five of them have already been linked to an ecologically relevant phenotypic effect. Our results provide a more complete understanding of the genetic variation and the fitness-related traits relevant for adaptive evolution. Similar studies should help uncover the importance of TE-induced adaptive mutations in other species as well.

evolutionary biology↗