Galapagos Hawk

© Cassiano “Zapa” Zaparoli

“The fact that we were able to work with these birds, which are the top predators in their habitat, and reveal some answers to fundamental questions in biology shows why such places should continue to be preserved.”   Dr. Noah Whiteman

The Galapagos Islands are once again providing scientists with tantalizing insights about how new life forms come into existence. A recent University of Arizona-led study on the relationship between Galapagos hawks and their lice appears to provide evidence that populations of hosts and their parasites diverge into new species together and that this process, called co-divergence, is an important driver of biodiversity.

Here is how it works: mother hawks “pass on” their feather lice to their offspring in the nest, almost like genes. For this reason, lice living on a particular bird and its offspring are more closely related than the lice living on other unrelated birds. As the birds diversify into distinct populations on different islands, so do their lice. In a sense, each bird and each distinct population of birds, is its own evolutionary island where new species of lice are born. Scientists had long suspected that this relationship between host and parasite existed, but had been unable to verify it until now.

Why is this important? For starters, it helps explain how huge numbers of parasite species, which make up about half the total species on Earth, came into existence. The researchers also say that their findings will have implications for biomedical sciences.