Evolutionary relationships among Eimeria spp. (Apicomplexa) infecting cricetid rodents

Abstract

Evolutionary relationships among seven species of Eimeria from five species of cricetid rodents (Neotoma albigula, Peromyscus eremicus, Peromyscus leucopus, Peromyscus maniculatus, Peromyscus truei) were examined by phenetic and cladistic analysis of oocyst structure, life-history data, and isozyme banding patterns. Phenetic and cladistic analyses revealed two distinct lineages of Eimeria spp.: type A Eimeria spp. (Eimeria albigulae, Eimeria arizonensis, Eimeria peromysci), characterized by subspheroid oocysts with rough outer walls, lemon-shaped sporocysts, oocyst residua, prominent Stieda bodies, and two obvious wall layers; and type B Eimeria spp. (Eimeria delicata, Eimeria lachrymalis, Eimeria ladronensis, Eimeria lange-barteli), characterized by ellipsoid oocysts with one obvious, smooth wall, no residuum, and ellipsoid or teardrop-shaped sporocysts with thin walls and tiny Stieda bodies. Cladistic analysis of the type A and type B data sets, using Eimeria nieschulzi and Eimeria papillata (hosts: Rattus norvegicus and Mus musculus, respectively) for outgroup comparison, showed the more derived nature of Eimeria spp. infecting Peromyscus spp. relative to those species infecting N. albigula. Comparison of parasite phylogenies to a hypothesized phylogeny for the hosts based on enzyme electrophoretic data revealed patterns of host–parasite phylogenetic congruence that were most evident at the generic level of the hosts.