Relaxed selection on genomes
To uncover the selective forces shaping life-history trait evolution across species, we investigate the genomic basis underlying adaptations to seasonal habitat desiccation in African killifishes, identifying the genetic variants associated with positive and relaxed purifying selection in 45 killifish species and 231 wild individuals distributed throughout sub-Saharan Africa. In annual species, genetic drift led to the expansion of nuclear and mitochondrial genomes and caused the accumulation of deleterious genetic variants in key life-history modulating genes such as mtor, insr, ampk, foxo3, and polg.Relaxation of purifying selection is also significantly associated with mitochondrial function and aging in human populations. We find that relaxation of purifying selection prominently shapes genomes and is a prime candidate force molding the evolution of lifespan and the distribution of genetic variants associated with late-onset diseases in different species.
Genome evolution in hybrid zones
Using RNAseq data, I constructed a reticulate phylogeny of Xiphophorus, revealing a surprisingly high level of gene flow between clades. In collaboration with Molly Schumer, we looked at reproductive barriers reflected in the mosaic genomes of hybrid populations of two Xiphophorus spp. Following that initial study, we continued to characterize the Xiphophorus hybrid zones.
Olfactory imprinting in swordtails
Exposing female Xiphophorus malinche to conspecific and heterospecific males during development reveals an effect of sexual imprinting on mate choice. By performing RNA-seq comparisons of the olfactory system, I found a vomeronasal receptor differentially expressed between individuals exposed to con- vs. heterospecifics. Genes related to social behavior were also differentially regulated.