DNA sequences for the gene encoding mitochondrial cytochrome oxidase I in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times.

We examined the intersection of students' understanding and acceptance of evolution and their epistemological beliefs and cognitive dispositions. Based on previous research, we hypothesized there would be a relation between understanding and acceptance. We also hypothesized that students who viewed knowledge as changing and who have a disposition toward open-minded thinking would be more likely to accept the scientific explanation of human evolution, and that beliefs and dispositions would not be related to acceptance of a topic that is generally perceived as noncontroversial. Ninety-three undergraduate students enrolled in a nonmajors biology class completed measures of their (a) content knowledge of evolution and photosynthesis and respiration; (b) acceptance of theories of animal evolution, human evolution, and photosynthesis; and (c) epistemological beliefs and cognitive dispositions. Although our findings did reveal a significant relation between knowledge and reported acceptance for photosynthesis, there was no relation between knowledge and acceptance of animal or human evolution. Epistemological beliefs were related to acceptance, but only to the acceptance of human evolution. There was no relation between students' epistemological beliefs and their general acceptance of animal evolution or photosynthesis. Three subscales, Ambiguous Information, Actively Open-Minded Thinking, and Belief Identification, were significantly correlated with understanding evolutionary theory. We argue these findings underscore the importance of intentional level constructs, such as epistemological beliefs and cognitive dispositions, in the learning of potentially controversial topics. ß

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Historical flood records for the Rio Grande Valley of New Mexico suggest that a pocket gopher (Thomomys bottae) hybrid zone previously thought to be 10,000 years old may actually be closer to 50 years old. Measured zone width (defined genetically) is consistent with the hypothesis of recent contact, if we assume a reasonable dispersal distance of approximately 400 m/year for pocket gophers. A five-year study of movement of the contact zone between the two species of chewing lice that parasitize these pocket gophers also is consistent with the hypothesis of recent origin of the zone.