How do new species evolve ?
Understanding the mechanisms that generated the world’s biodiversity has been a major focus of evolutionary biology since its beginning in the 19th century. Speciation may happen in various ways, but this project focused on ecological speciation: a process through which divergent selection pressures drive population divergence until the formation of distinct species.
A mounting body of evidence has demonstrated the potential of the sensory environment to underlie divergent selection: incipient species are likely to be exposed to contrasting sensory conditions, representing significant adaptive challenges. In turn, divergence in sensory systems may promote reproductive isolation between locally adapted populations.
Two sister species in the Nymphalid butterfly genus Heliconius, H. cydno and H. melpomene, exhibit significant adaptive differences in visual acuity, which are hypothesized to correlate with divergent microhabitat preferences. However, the exact nature of the selection acting on their visual systems remains unclear. This project set out to fill in the gaps.
Research questions:
Do the natural microhabitats of both species exhibit quantitative differences in spatial complexity ? Do the two taxa show distinct behavioural responses to local variation in spatial complexity ?
In the field
Behavioural experiments
Heliconius melpomene, Colombia
Post-processed photograph of a H. cydno capture site (understorey).