Profile
Project Title: Evolution of Olfactory Perception
Summary: Olfaction allows individuals to gather information about the chemical world around them and is involved in several behaviours which significantly impact reproductive fitness, including predator avoidance, foraging, and the identification of potential mates.
The “canonical” view of odour processing involves a one-neurone-one-receptor rule, whereby each olfactory sensory neuron (OSN) expresses one odorant receptor (OR). OSNs expressing the same type of OR then project to the same part of the antennal lobe resulting in a discontinuous chemotopic map. ORs have unique but overlapping tuning profiles which then allow a broad range of odours to be identified from the combined activity of comparatively few receptor classes.
This canonical view holds relatively well in mammals, but increasingly evidence suggests this model doesn’t reflect the nuances of the insect olfactory system, which despite organisational similarities is not homologous to the mammalian system. It is not uncommon for OR classes in insects to exhibit copy number variation due to gene duplications, which can result in coexpression in a single OSN i.e., breaking the one-neurone-one-receptor ‘rule’.
My project focuses on a particular OR family – Or67a – which exhibits copy number variation and co-expression in some Drosopholids, particularly those closely related to D. melanogaster making it an appealing model system to investigate. My research questions can be broadly summarised as:
- Have recent Or67a duplicates gained expression in new or different OSN populations? I will address this question by analysing single nucleus RNA-seq datasets from the antenna of five species.
- Where are these neuron populations located? To accomplish this, I will investigate spatial expression of these in the antenna using HCR-FISH.
- How has selection has acted on the gene family? I will test for adaptive changes on Or67a orthologues and paralogues using molecular evolutionary and population genetics approaches.
- What is driving differential expression of paralogues? To identify the genetic changes that have led differential expression patterns I will carry out sequence analyses of their regulatory regions, and then design manipulative experiments in D. melanogaster to test candidate transcription factor binding site changes.
Supervisor: