The project started in 2006 with a grant from the National Science Foundation. The first step was to obtain specimens of many free-living and parasitic mitesno simple task given that some mite species are associated with rare mammal or bird species around the world.
The research team relied on a network of 64 biologists in 19 countries to obtain specimens. In addition, Klimov and OConnor conducted field trips to North and South America, Europe, Asia and Africa. On one occasion, it took two years to obtain samples of an important species parasitizing African birds.
A total of around 700 mite species were collected for the study. For the genetic analysis, the same five nuclear genes were sequenced in each species.
How might the ecological shift from parasite to free-living state have occurred?
There is little doubt that early free-living dust mites were nest inhabitantsthe nests of birds and mammals are the principal habitat of all modern free-living species in the family Pyroglyphidae. Klimov and OConnor propose that a combination of several characteristics of their parasitic ancestors played an important role in allowing them to abandon permanent parasitism: tolerance of low humidity, development of powerful digestive enzymes that allowed them to feed on skin and keratinous (containing the protein keratin, which is found in human hair and fingernails) materials, and low host specificity with frequent shifts to unrelated hosts.
These features, which occur in almost all parasitic mites, were likely important precursors that enabled mite populations to thrive in host nests despite low humidity and scarce, low-quality food resources, according to Klimov and OConno
|Contact: Jim Erickson|
University of Michigan