title: The evolutionary expansion and host-parasite relationships of the Digenea.
abstract: Relevant data on the Digenea extracted from a host-parasite data-base are analysed in relation to host-groups, host-specificity, speciation, radiation and geographical distribution. The classification, evolution, co-evolution, and co-speciation of the group are discussed. Principal components analyses indicated that 119 families formed 11 groups in relation to their vertebrate hosts and the 55 families with molluscan records formed 6 groups in relation to their molluscan hosts. The most prominent host-groups are the Fish and Mammals. Individual digenean families did not exhibit the host combinations Fish+Birds, Fish+Mammals, Herpetiles+Birds and Herpetiles+Mammals. Families with Fish hosts tended to use Prosobranch and, to a lesser extent Bivalve, molluscs, whereas families in Herpetiles, Birds and Mammals tended to use Pulmonates. Families using 3 or 4 mixed vertebrate groups tended to use mixed molluscan groups. Families using Herpetiles as the vertebrate host tend to be the most host-specific and the least speciose, whereas those using 3 to 4 mixed vertebrate groups are the most speciose. In a detailed examination of three zoogonid genera, few indications of co-evolution with their vertebrate hosts were detected, and geographical information from the data-base appeared to shed no light upon the geographical origins of the Digenea. Some of these findings are commented upon in relation to the evolution of the Digenea.
authors.affiliation: Department of Zoology, Natural History Museum, London.
authors.forename: D I
authors.initials: DI
authors.lastname: Gibson
authors.forename: R A
authors.initials: RA
authors.lastname: Bray
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000469:parasitology; D016208:Databases, Factual; D005399:Fishes / Q000469:parasitology; D005843:Geography; D006790:Host-Parasite Interactions; D008322:Mammals / Q000469:parasitology; D008974:Mollusca / Q000469:parasitology*; D015999:Multivariate Analysis; D012104:Reptiles / Q000469:parasitology; D013045:Species Specificity; D014200:Trematoda / Q000145:classification / Q000502:physiology*; D014714:Vertebrates / Q000469:parasitology*