A recent study soon to be published in The American Naturalist has brought to light an interesting aspect of the evolution of the lice that live in birds' feathers. Researchers examined 26 different pairs of bird species that are closely related but dramatically differ in coloration, such as the Brown Pelican and the White Pelican, and found that the lice living in the birds' feathers (an example of an ectoparasite) have evolved to match their host's feather color. Thus, the Brown Pelican is the host to dark-colored lice while the White Pelican hosts lighter-colored lice. The evolution of this cryptic coloration in bird lice makes it harder for the birds to remove lice during preening.
Very interesting. I will watch out for this. However, they should run a phylogeny of the lice to check that it is adaptive evolution (light and dark lice are distributed throughout the lice phylogeny) and not just switching between hosts and differential survival e.g. that light lice from one light bird switch to another light bird, irrespective of the birds' relatedness, and there survive better than dark lice.
Interesting discussion and thanks for posting Chantelle. Ben has a good point. it will be interesting to read the article. I've just spent a week trapping and handling Northern Gannets- an essentially white bird- and I can report that they carry dark brown chewing lice.
Thanks for the reply Ben, I hadn't thought of the point you made, but it makes a lot of sense. I'll take a closer look into the literature and see if I find anything pertaining to differential survival rates.
Evolution of Cryptic Coloration in Bird Lice
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