Rita Highland

Publication Date


Document Type


First Advisor

Nadler, Steve

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Biology


Pocket gophers--Middle West; Ectoparasitic infestations--Middle West; Mallophaga--Middle West


Chewing lice of the genus Geomydoecus and Thomomydoecus are obligate ectoparasites on pocket gophers of the genus Geomys and Thomomys and other genera. Each louse taxon is normally host-specific. This host-parasite assemblage presents an ideal system to test for evidence of cospeciation. Allozyme characters were obtained from Midwestern pocket gophers (Rodentia: Geomyidae) and their ectoparasitic chewing lice (Mallophaga: Trichodectidae). Morphological characters were obtained from SEM (scanning electron microscopy) and light microscopy for the chewing lice. Seven comparisons to test for cospeciation were performed using TREEMAP. The six equally parsimonious PAUP generated trees from the gopher allozyme data were each compared with the single tree inferred from the combined data set, morphology and allozyme characters, of the lice. The FREQPARS inferred allozyme trees for both gophers and lice were also compared. Of the comparisons done to test for evidence of cospeciation, the allozyme data set inferred from FREQPARS, provided the best support for cospeciation. Six cospeciation events occurred for allozyme comparisons only, whereas four events occurred with the rest of the comparisons. For all pairwise comparisons, the observed degree of fit between gopher and louse trees was better (P<0.05) than the fit between louse trees and 1000 randomized host trees. This indicates that the observed degree of fit was better than that occurring by chance alone. The inclusion of morphological characters from the chewing lice and coding of allozyme data for both groups decreased this support.


Includes bibliographical references (pages [87]-90)


viii, 108 pages




Northern Illinois University

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