Brief overview
We are interested in the genetic and neural bases of how sensory systems change between species. This question ties into evolutionary genomic topics including the genetics of local adaptation and gene family evolution. We draw on approaches from neurogenetics, population/comparative genomics, and behavioral biology. The sensory modalities we are using as models to investigate these questions are chemosensation and thermotaxis. Both evolve quickly and are involved in local adaptation. To do this work we use Drosophila species and populations from around the globe.
Evolutionary diversification
of
sensory circuits
Sensory systems vary extensively between species. Some animals possess seemingly minimal and streamlined systems, while other animals have large and complex sensory systems. Why do these changes arise, and what are the molecular changes and evolutionary forces required to expand or contact these systems?
We are using evolutionarily recent gains and losses of olfactory receptors as a starting point for studying neural circuit evolution. As most fly olfactory neurons express only a single receptor type, these copy number changes provide an initial 'label' for which species and cell types are good targets for functional studies. We would like to know how these gains/losses relate to the underlying evolution of neural circuits, the evolution of odor tuning, and the evolution of behavior. Currently, we are using the Or67a subfamily as our model system because it is the most duplicated/deleted olfactory receptor among species closely related to D. melanogaster.
Evolution of temperature-related behavior
Given the small size of most insects, and the often large temperature differences that exist at their scale, the behaviors that enable efficient body temperature regulation are critical for their survival. The tolerable range for insects varies between species, and this has been a topic that biologists have long studied. While the molecular and neuronal basis for temperature-related behavior is quickly becoming better understood in model systems, which of these molecules and neurons are involved in between-species changes in temperature-related behaviors is largely unknown.
We are combining behavioral studies with genomic approaches to identify species that have evolved differences in temperature-related behavior, with the goal of identifying the genes and neurons underlying the changes.
Molecular and cellular evolution of sensory organs
We are interested in genes and gene expression patterns that underlie the diversification of sensory organs. We are using a combination of bulk tissue RNA-seq and single nucleus RNA-seq to identify instances of species differences in tissue specificity, developmental stage, or sex-biased expression patterns of sensory genes. We additionally aim to understand the functional and regulatory basis of these modifications.
Evolutionary history of the D. takahashii and D. suzukii groups
Several of our projects focus on species from these two groups. Aspects of their biology has drawn us to them (i.e. temperature-related differences, Or67a copy number differences, ecological diversity), however relatively little evolutionary/population genomics work has been carried out on these species. Open questions include speciation dates for several of our targeted lineages, as well as rates of ongoing gene flow. We have been contributing to the genome assemblies for these species, as well as generating population genomic datasets, to help address these questions.