Abstract

Behavioural evolution can occur rapidly: even within a species different populations often exhibit distinct behaviours. We are using the free-living nematode C. elegans to investigate how behaviour evolve at the level of DNA and proteins, neurons and neural circuits, and the entire behaving organism. C. elegans offers special advantages to this endeavour, because hundreds of different wild isolates have been isolated from all over the world and can be frozen as viable stocks. The connectivity patterns of the 302 neurons that make up the C. elegans nervous system are also known from EM reconstructions. We are focussing our studies on variation in foraging behaviour. C. elegans feeds on micro-organisms, which it locates using olfactory, gustatory and mechanical cues, as well as ambient oxygen and carbon dioxide levels. These sensory inputs are integrated by the animal to coordinate its foraging behaviour. Different wild isolates of C. elegans show distinct patterns of foraging. I will discuss several ways in which C. elegans foraging behaviour has evolved: (1) By reconfiguring the contribution of different neural circuits to behavioral output; (2) By sculpting sensitivity to a sensory stimulus; (3) By altering sensory adaptation to a stimulus; (4) By altering hub molecules that coordinately regulate related sensory responses. These mechanisms are likely to be generally applicable to behavioural evolution in different animals.