Adaptations in the brain may play a key role in the evolution of new species – a Bristol-led study of Heliconius butterflies in Central and South America shows how.
Researchers have discovered that changes in the way butterflies perceive and process information from their environment can support the emergence of new species.
The study, led by the University of Bristol, shows the underappreciated role of changes in the brain and helps us understand how new species might evolve.
Scientists studied two distinct but closely related types of tropical forest-dwelling butterfly in Panama, Costa Rica, Peru and French Guiana.
The first type, including the species Heliconius cydno, lives in deeper forests where light levels are low.
The second type, including a species called Heliconius melpomene, lives around the edges of the forest where there is more light.
After comparing the brains of these two butterflies, the researchers discovered substantial differences. For instance, the deep forest species invested more in parts of the brain that process visual information – perhaps helping it to survive in the darker environment.
These butterflies are closely related and live close together – in fact, they can still interbreed - so it’s not distance or geography that make them distinct.
The way certain genes are expressed in the brain also evolved quickly between the two species, and the differences are heritable (passed on to the butterflies’ offspring). The researchers therefore think that the butterflies’ brain structures, and the way they function, are finely tuned to their different habitats.
Supporting this theory, the study also showed that hybrid offspring bred from both the butterfly types showed intermediate traits, with features of both parental species - which may suggest their behaviour would be ill-suited to the habitats of either species. If so, hybrids would survive less well, helping to maintain the two distinct species.
Conserving complex habitats
This work also shows how important it is to protect habitat complexity in tropical forests. In order to protect the diversity of species like these butterflies, preserving the forest’s own natural micro-habitats is of great importance.
The international team of researchers was led by Dr Stephen Montgomery from the School of Biological Sciences at the University of Bristol. Stephen leads the Evolution of Brains and Behaviour Lab and also currently teaches on our undergraduate biology course.
Many of our four-year undergraduate degrees include a research project, and several students have completed projects in the Evolution of Brains and Behaviour Lab.
You can read more about this research project in our news item.
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