Olfactory evolution: genes, circuits and behaviours
For several hundred million years, animal brains have undergone remarkable diversification in their structure and function. Brain evolution occurs because the properties of these biological information processors are constantly being challenged and optimised (through natural selection of their organismal hosts) by the demands placed upon them in the ecological niche in which they operate. My lab is interested in defining the genetic mechanisms and environmental driving forces underlying neural evolution.
To address this problem, we focus on the olfactory system of the fruit fly, Drosophila melanogaster, for four principal reasons. First, Drosophila possesses a sophisticated but numerically relatively simple olfactory system, whose development and function is already well-studied, and which has many common properties with those of mammals. Second, powerful genetic tools for visualising and manipulating the anatomy and function of specific neurons – and the activity of individual genes within these neurons – are widely-available in Drosophila. Third, genomic and, more recently, genetic access to closely-related but ecologically diverse drosophilids and more distant insect species provide an unparalleled foundation for comparative genetic and functional analysis of their olfactory circuits. Finally, within the brain, olfactory systems display perhaps the most rapid evolution, as organisms acquire and discard odorant receptors, neurons and behavioural responses with the ever-changing landscape of volatile chemical stimuli in their environment that may signal the presence of food, danger, kin or mates.
Our overall goal is to understand how and why particular olfactory circuits and behaviours have evolved in Drosophila, with a view to obtain more general insights into the mechanisms of, and constraints on, brain evolution. Moreover, we anticipate that understanding how brains have been finely sculpted through random mutation and natural selection in the past may enable future directed manipulation of the connectivity and activity of neural circuits, with relevance for our basic understanding of brain function as well as potential clinical applications.