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United States Department of Agriculture

Agricultural Research Service

Title: Systematics of the Eucestoda: Advances Toward a New Phylogenetic Paradigm, and Observations on the Early Diversification of Tapeworms and Vertebrates

Authors
item Hoberg, Eric
item Gardner, Scott - UNIV. NEBRASKA, LINCOLN
item Campbell, Ronald - UNIV MASS., DARTMOUTH

Submitted to: Systematic Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 5, 1998
Publication Date: N/A

Interpretive Summary: Phylogenetic relationships of the tapeworms have remained unresolved despite a century or more of intense study. In 1996 the landscape changed, coinciding with the development of comprehensive hypotheses for inter- and intraordinal relationships for tapeworms that emanated from the 2nd International Workshop for Tapeworm Systematics at the University of Nebraska- Lincoln. Current knowledge of the phylogeny of the tapeworms includes robust hypotheses for phylogeny among the orders based on morphological and molecular characters; phylogenies for 8 of 12 recognized orders have also been developed for the first time. These studies provide the basis for the first estimate of the temporal history for diversification of tapeworms extending into the Paleozoic, near 400 million years ago. New phylogenetic information for the tapeworms is critical to the development of classifications, refinement of diagnostic capabilities, and for applications to theoretical issues in coevolution and biogeography. The current studies constitute an umbrella for development of a detailed understanding of the evolution and distribution of economically significant tapeworms in humans and domestic animals.

Technical Abstract: Evolutionary relationships of the Eucestoda have received intense but sporadic attention over the past century. Since 1996, the landscape has dramatically changed with respect to our knowledge of the phylogenetic relationships among the tapeworms. The 2nd International Workshop for Tapeworm Systematics, Lincoln, Nebraska, October, 1996 provided the catalyst for development of novel hypotheses for inter- and intraordinal phylogeny. The working-group structure of the 2nd IWTS and results of phylogenetic studies are briefly introduced in the present manuscript. Higher-level phylo- genies derived from parsimony analysis of independent data bases representing comparative morphology or molecular se- quences were largely congruent and supported monophyly for the Eucestoda. These studies provide a foundation for reso- lution of inter- and intraordinal relationships for the tapeworms. Additionally, the first comprehensive phylogenetic hypotheses for the Pseudophyllidea, Diphyllidea, Trypano- rhyncha, the paraphyletic Tetraphyllidea, Proteocephalidea and Cyclophyllidea were developed. These studies have also served to emphasize the rich genealogical diversity of tapeworms and the temporally deep history for their origin. A coevolutionary history and radiation of eucestodes may involve deep cospeciation with vertebrate host taxa, accom- panied by some level of colonization and extinction, extend- ing into the Paleozoic, minimally 350-400 million years ago.

Last Modified: 8/22/2014