Mammalian hair diameter as a possible mechanism for host specialization inchewing lice

We examined the relationship between mammalian hair diameter and body mass at several taxonomic levels (interordinal, intrafamilial, intrageneric, and intraspecific) and showed a significant, positive allometric relationship between hair diameter and body size at all taxonomic levels examined. The a llometric coefficient (alpha) ranged from 0.13 to 0.33. Within pocket gophe rs (Geomyidae), a significant positive relationship exists between hair dia meter and rostral groove dimensions of their chewing lice, Geomydoecus, whi ch use the rostral groove to grasp hairs of their host. Coupled with previo us evidence of a strong allometric relationship between rostral groove widt h and louse body size, our findings suggest that hair diameter of the host is an important determinant of body size in chewing lice that parasitize po cket gophers.