Study Finds Evidence of Coevolution Driving Earth's Biodiversity

In a study, researchers led by the Australian National University (ANU) found rare evidence of coevolution by analyzing the evolutionary relationship of cuckoo birds and the birds in whose nests cuckoos lay their eggs, the Xinhua reported.

Coevolution is the process of different species that interact closely driving evolutionary changes in each other, leading to speciation - the process of a new species evolving.

It has long been considered a possible explanation for why there are so many species on Earth, but evidence of the theory has been scarce.

Naomi Langmore, lead author of the new study from the ANU Research School of Biology, said cuckoos were an ideal subject to research coevolution because they are costly to their hosts.

Cuckoos lay their eggs in the nests of other birds, called hosts. Once hatched, cuckoo chicks grow faster than the host species chicks and typically evict the eggs or chicks of the host species from the nest.

In response, Langmore said hosts have learned to recognize and eject cuckoo eggs from their nests.

"Only the cuckoos that most resemble the host's own chicks have any chance of escaping detection, so over many generations the cuckoo chicks have evolved to mimic the host chicks," she said in a media release.

The research found that when a cuckoo species exploits several different hosts it diverges genetically into several different species - each of which mimics the chicks of its host.

Cuckoos that are the most costly to their hosts were the most likely to drive speciation, leading to an evolutionary race between the host defenses and cuckoo's counteradaptations.

"This finding is significant in evolutionary biology, showing that coevolution between interacting species increases biodiversity by driving speciation," Clare Holleley, co-author from national science agency the Commonwealth Scientific and Industrial Research Organization (CSIRO), said.

Researchers from the University of Melbourne and University of Cambridge also contributed to the study.

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