Evidence of how new species evolve has emerged from two decades of research into cuckoos. The theory of coevolution explains that when closely interacting species drive evolutionary changes in each other this can lead to ‘speciation’ – meaning the evolution of new species, but only now has real-world evidence of this been found by an international team of researchers. They have been studying the evolutionary arms race between cuckoos and the host birds they exploit. Bronze cuckoos lay their eggs in the nests of small songbirds and when the cuckoo chick hatches, it pushes the host’s eggs out of…
