July: Brain structure in Amazonian butterflies | News and Features

Habitat differences help determine changes in the nervous system of tropical butterflies, scientists at the University of Bristol have found.

By analyzing a tribe of neotropical butterflies called Ithomiini, found in the Amazon rainforests of eastern Ecuador, researchers were able to show that habitat changes – indicated by a mimicry model – accurately predict changes in brain structure, especially in areas of the butterfly’s brain that process visual information.

The findings, published today in Evolution, provides strong evidence that these investment changes are adaptive and that local adaptation to distinct light environments can occur at very small ecological scales.

Lead author Benito Wainwright from Bristol’s School of Biological Sciences explained: “It was known that the distribution of niches in complex habitats, such as tropical rainforests, could pose perceptual problems for the animals that lived there.

“Work on fish in freshwater ecosystems had previously shown that dramatic changes in light availability with depth can drive impressive visual adaptations, but it was unclear whether evolution could select for such adaptations. in an earthly environment like a rainforest.”

Approximately 160 samples from 16 species were used, making this one of the largest neuroanatomical comparisons performed in an insect.

Now, scientists aim to study sensory evolution across the entire butterfly community to rigorously test whether convergence in habitat predicts convergence in brain structure.

Mr Wainwright explained: “In other words, we want to know, when faced with the same perceptual challenges, whether species develop sensory adaptations via similar mechanisms.

“We also want to quantify the light environment in these forests to determine how small changes in forest structure affect the sensory environment.”

Their study crosses the disciplines of evolutionary biology, ecology, and neurobiology and provides broad scale evidence of the importance of visual ecology in the adaptive formation of entire communities of closely related species in complex terrestrial environments. .

He added: “Ithomiine butterflies play a crucial role in many tropical ecosystems and so understanding these evolutionary responses will allow us to make more accurate predictions of how sudden changes in the sensory environment might affect the composition of entire rainforests.

“Our work shows that how species have evolved to deal with the world around them plays an important role in how entire animal communities are structured. Natural selection can lead to adaptive change in brain structure over relatively short periods of evolution.

This work was funded by a NERC, the Royal Society and a Royal Commission for the Exhibition Research Fellowship. We are also grateful to the people at Estación Científica Yasuní (ECY) and Pontificia Universidad Católica del Ecuador (PUCE) in Ecaudor for allowing us to conduct the fieldwork.

Paper:

Neuroanatomical Changes Reflect Patterns of Ecological Divergence in Three Diverse Clades of Mimetic Butterflies by Beneto Wainwright and Dr. Stephen Montgomery in Evolution.

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