Title: HISTORICAL BIOGEOGRAPHY AND MODES OF SPECIATION ACROSS HIGH LATITUDE SEAS OF THE HOLARCTIC: CONCEPTS FOR HOST-PARASITE COEVOLUTION AMONG THE PHOCINI (PHOCIDAE) AND TETRABOTHRIIDAE (EUCESTODA)
Submitted to: Canadian Journal of Zoology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 2, 1994
Publication Date: N/A
Interpretive Summary: The parasite assemblage that occurs in pinnipeds in the Holarctic provides a robust model system for examining modes of speciation and host-parasite evolution. Concepts developed from analysis of the tapeworm faunas of phocid seals can be directly applied to developing a broader understanding of the history of other parasite-host associations that have originated and diversified in the Northern Hemisphere since the Pliocene. Recent discovery of new species of Anophryocephalus in phocids from the eastern Canadian Arctic provides the basis for extension of hypotheses for coevolution and historical biogeography in the Arctic. New concepts of host-parasite coevolution and distributional history for species of Anophryocephalus recognize the Arctic basin as a paraphyletic area and ringed seals of the Atlantic-Arctic as ancestral hosts. Cospeciation of Anophryocephalus and phocine hosts was driven by intense isolation of definitive host populations during glacial maxima of the late Pliocene and Pleistocene. Biogeography of this assemblage during the Pliocene and Quaternary in part contrasts with the history elucidated for some free-living invertebrate taxa in the Arctic basin.
Phylogenetic analysis of 7 species of Anophryocephalus (single tree; CI = 74.4%; HSR = 36.45%) postulates A. anophrys as the basal taxon and A. inuitorum as basal to A. skrjabini; A. arcticensis is basal to the remaining 3 species. New concepts of host-parasite evolution and historical biogeography for species of Anophryocephalus recognize the Arctic basin as a paraphyletic area (with respect to the North Pacific) and ringed seals of the Atlantic-Arctic as ancestral hosts. Cospeciation within this assemblage was dependent on intense isolation of small effective populations of definitive hosts during late Tertiary and Pleistocene glacial stages. Rapid speciation, compatible with microallopatry and peripheral isolation, appears to have been associated with isolation in refugial habitats. Biogeography of host-parasite assemblages among pinnipeds and Alcidae (Charadriiformes) during the Pliocene and Quaternary, in part contrasts with the history elucidated for some free-living invertebrate taxa in the Arctic basin.