Hooded parrot (Psephotellus dissimilis) from Australia.
A major question in evolutionary biology is whether species' traits can affect how often they form new species. A study published today in the scientific journal Evolution shows that brain size could play such a role in birds.
A team of scientists from the University of Gothenburg, Sweden and CREAF-CSIC in Barcelona, Spain, compared the brain size of hundreds of species around the world. They found that groups of birds with larger brains divide into new species more often than those with smaller brains.
It isn't only up to chance
Physical characteristics and how species use them are important in understanding how new species come to be. New species can arise by processes that are unrelated to chance or their environment, according to this study.
"Evolution and speciation is not only a matter of being at the right place at the right time, but also about having some characteristics that allow species to diversify" says University of Gothenburg and Gothenburg Global Biodiversity Centre researcher Ferran Sayol, who led the study.
Changing behaviour drives evolution
Charles Darwin was convinced that behavioural changes could be the first step leading to the development of new species. But the idea was difficult to prove. Now, Sayol and his colleagues have tested these ideas using analytical methods.
They show that—as was predicted by the theory—species with enhanced abilities to modify their behaviour (i.e. with larger brains) have undergone faster diversification rates, resulting in more new species.
But what if the high number of birds descended from big-brained ancestors that we see is simply because species that descend from smaller-brained birds were more likely to die out? The study also tested this, and found that extinction rates did not explain the difference we see today. The larger brained birds did give rise to more new species.
Studying thousands of bird brains
The team compiled information on brain size from more than 1900 bird species. By looking at how species are related to each other, they were able to estimate how often new species arose.
"The study sheds light onto our understanding of evolutionary processes" explained Ferran Sayol.
The findings are also relevant in light of the UN's recent report from IPBES, which explored biodiversity loss associated with human activities.
Sayol added that "Although big-brained lineages were successful in the past, this might no longer be true during the current biodiversity crisis driven by human-induced environmental changes."
IPBES stands for the Intergovernmental Science-Policy Panel on Biodiversity and Ecosystem Services
The study, which was published in the scientific journal Evolution, was led by Ferran Sayol of the University of Gothenburg and the Gothenburg Global Biodiversity Centre (GGBC).
