Hennig's Parasitological Method: A Proposed Solution

Brooks, D. R. (Department of Zoology, University of British Columbia, 2075 Wesbrook Mall, Vancouver, B.C., Canada V6T 2A9) 1981. Hennig's parasitological method: a proposed solution. Syst. Zool., 30:229-249.-A quantitative solution for Hennig's parasitological method is presented. Cladograms summarizing natural relationships among parasite taxa are converted into host-group characters by means of additive binary coding. Unrooted Wagner analysis followed by most parsimonious rooting produces a maximum information-content representation of natural host-parasite relationships. Because host-parasite relationships result either from random colonization or from co-speciation, host relationships well corroborated by a multi-parasite analysis correspond to host phylogeny. Poorly corroborated host relationships indicate an ambiguous parasite message alerting a worker to possible host transfers. Thus, such analyses point out co-speciation and random colonization components of host-parasite systems. Single or multiple parasite taxa may be used. A host phylogeny based on non-parasite characters is neither necessary nor sufficient for studying phylogenetic aspects of coevolution, although such may be helpful in testing ambiguous aspects. Once a host-group cladogram based on parasites has been established, phylogenetic interpretations for each observed host-parasite relationship may be made according to a listed set of necessary and sufficient criteria. Finally, evaluation of two models of coevolution, a "vicariance" model and the "resource-tracking" model, indicates that the latter cannot be extrapolated successfully to explain congruent phylogenetic differentiation of hosts and parasites and that the former model represents the general pattern of natural relationships among hosts and parasites. [Cladistics; coevolution; phylogeny; quantitative systematics.]