Comparative body size relationships in pocket gophers and their chewing lice |
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Authors: | SERGE MORAND MARK S HAFNER RODERIC DM PAGE DAVID L REED |
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Institution: | Centre de Biologie et d'Ecologie tropicale et Mediterraneenne (UMR CMRS 5555) Universite de Perpignan, 66 860 Perpignan Cedex, France;Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, U.S.A.;Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ |
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Abstract: | In this paper, we use the method of independent contrasts to study body size relationships between pocket gophers and their chewing lice, a host-parasite system in which both host and parasite phylogcnies are well studied. The evolution of body size of chewing lice appears to be dependent only on the body size of their hosts, which confirms the 1991 findings of Harvey and Keymer. We show that there is a positive relationship between body size and hair-shaft diameter in pocket gophers, and that there is also a positive relationship between body size and head-groove width in chewing lice. Finally, we show a positive relationship between gopher hair-shaft diameter and louse head-groove width. We postulate that changes in body size of chewing lice are driven by a mechanical relationship between the parasite's head-groove dimension and the diameter of the hairs of its host. Louse species living"on larger host species may be larger simply because their hosts have thicker hairs, which requires that the lice have a wider head groove. Our study of gopher hair-shaft diameter and louse head-groove dimensions suggest that there is a 'lock-and-key' relationship between these two anatomical features. |
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Keywords: | comparative analysis body size independent contrasts |
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