Current Research

Recombination, Selection and Supergene Adaptation

University of British Columbia - Mank Lab

Supergenes (suites of co-adapted genes inherited together as a linked group) present a puzzling contradiction. The loss of recombination accelerates adaptive evolution by fostering supergenes. Yet recombination suppression limits further adaptive evolution, as non-recombining regions are well known to experience reduced positive selection, and exhibit a rapid build-up of deleterious mutations. To determine how evolution resolves this contradiction I am focusing on Poecilia parae, a close relative to the common guppy. Males in this species occur as one of five morphs, which differ remarkably in size, colour and behaviour. Each of these morphs is encoded by one of five supergenes on the Y chromosome that are unique to this species. The recent formation and adaptation of the supergenes in P. parae offers a powerful model to study the interplay between recombination suppression, supergene formation and adaptive evolution.

Evolution of Opsin Gene Regulation

University of Maryland - Carleton Lab
National Institutes of Health - Swaroop Lab

All species of cichlid fishes possess seven opsin genes, yet express only a set of three, with sets differing across species. Traditional models of opsin gene regulation suggest the evolution of such shifts require two simultaneous regulatory changes (one for each opsin). However, we propose and test an alternative model for rapid changes across species: there is one regulatory change that simultaneously promotes expression of one opsin while repressing another. Using QTL analyses, genome sequencing, gene expression and protein-DNA interaction assays we have identified a candidate transcription factor (Tbx2a) that promotes LWS opsin gene expression while repressing RH2 opsin expression. The sudden shift in expression between species is due to a transposable element disrupting regulatory sequence of this transcription factor. 

Visual Tuning and Colour Preference

Simon Fraser University - Breden Lab
University of Toronto - Rodd Lab
University of Maryland - Carleton Lab

The interplay between natural and sexual selection in Trinidadian guppies has led to variation in colouration and colour preferences across populations. Using a combination of gene expression, allele frequency, behavioral assays and visual modeling of field and lab populations we are testing whether variation in the tuning of colour vision can explain differences in colour preference.

To discuss the projects I am working on, contact me!