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Bell & Howell Information and Learning 300 North Zeeb Road, Ann Acbor, MI 48106-1346 USA 8001521-0600 A PHYLOGENETIC ANALYSIS OF THE METAZOA WITH SPECIAL CONSIDERATION OF THE ACANTHOCEPHALA Scott Monks A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Zoology University of Toronto O Copyright by Scott Monks (1998) National Library Bibliothhue nationale 1*1 of Canada du Canada Acquisitions and Acquisitions et Bibliographic Services services bibliographiques 395 Wellington Street 395. nre Wellington Ottawa ON K 1A ON4 OttawaON KlAON4 Canada Canada The author has granted a non- L'auteur a accorde une licence non exclusive licence allowing the exclusive pennettant a la National Library of Canada to Bibliotheque nationale du Canada de reproduce, loan, distribute or sell reproduire, prgter, distribuer ou copies of this thesis in microform, vendre des copies de cette these sous paper or electronic formats. la fotme de microfiche/film, de reproduction sur papier ou sur format electronique. The author retains ownership of the L'auteur conserve la propriete du copyright in this thesis. Neither the droit d'auteur qui protege cette these. thesis nor substantial extracts from it Ni la these ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent 6tre imprimes reproduced without the author's ou autrement reproduits sans son permission. autorisation. Abstract A phylogenetic analysis of the Metazoa with special consideration of the Acanthocephala. Doctor of Philosophy, 1998. Scott Monks, Department of Zoology, University of Toronto. The purpose of this study was to examine phylogenetic relationships among the Metazoa, identify appropriate outgroups to the Acanthocephala, and make a phylogenetic analysis of the Acanthocephala. A database of 144 characters for the metazoan phyla was obtained by examination of primary and secondary literature. The Choanoflagellata was used as outgroup for 33 multicellular phyla. Phylogenetic analysis yielded 17 equally parsimonious trees. Using successive weighting, these were reduced to two trees (Length=361; CI=0.46; HI=0.58) differing only in placement of the Platyhelminthes. Monophyly of the Mesozoa was not supported but mesozoans were placed basal to the Porifera +(Cnidaria + (Ctenophora + remaining Metazoans)). The remaining Metazoans formed two major clades. The Acanthocephala was the basal member of a clade, the Ecdysozoa, containing Rotifera + (Gastrohicha + ((Nematoda + Nematomorpha) + (Pentastomida + (Kinorhynchida + (Tardigrada + (Onychophora + (Chelicerata + (Uniramia + Crustacea)))))))). The second clade consisted of two sub-clades; Chaetognatha basal to Chordata + (Echinodermata + (Phornida + Brachiopoda)) and Priapulida basal to Gnathostomulida + (Platyhelminthes + Nemertea + Mollusca + (Sipuncula + (Echiura + (Pogonophora + (Clitellata + Polychaeta))))). A novel approach to identification of early cleavage patterns involved coding of individual cleavage events as independent characters. Reinterpretation of the dassic assignment of 'spiral' cleavage to arthropods supported placement within the Ecdysozoa. Deuterostomes were only monophyletic by including protostomes, thus 'spiral' cleavage is derived from 'radial' cleavage. The position of the Ecdysozoa as sister-group to the deuterostomes + protostomes supports the conclusion that 'modified-spiral' cleavage is not derived from 'spiral' deavage. Priapulida and Rotifera were supported as outgroups for the analysis of relationships among the Acanthocephala. Direct examination of specimens identified 138 characters for 21 well-defined genera. Phylogenetic analysis yielded a single tree (Length=404; CI=0.545;HI=0.455) which provided support for the monophyly of the Palaeacanthocephala and Eoacanthocephala but not the Archiacanthocephala, which were placed basal to the two other classes. To rectify taxonomic problems encountered while characters were being evaluated, Koronacantha, was described with a single species, k mexicana. Teeorhynchus brevis was redescribed and Z pectinarius transferred to Koronacantha. Results supported placement of 1.pectinarius in Koronacantha and retention of both Tegorh nchus and Illiosentis as distinct genera. Acknowledgments The person whose name is listed as author of a manuscript usually receives the credit, or blame, for the piece of work. However, it is obvious to all except the most egotistical that little that is worthwhile is accomplished alone. This dissertation is no different. One could argue that this project could not have been accomplished in exactly the fashion it was without m~!having done it, but I would have to argue even more strongly that it might not even have been accomplished at all without the assistance, guidance, and friendship of those around me. For the inevitable errors, I take full blame, but recognition of any value in this work I gratefully share with aLl who contributed. Acknowledgments in publications often go at the end of manuscripts, and I suspect that they are not often noticed by the majority of readers who look only for 'hard data'. I believe that it is more appropriate to acknowledge others here at the beginning, because in this manner their contributions may receive a little more attention. 1 would like to thank the following people, in temporal order rather than by rank or importance, for their contributions, both personal and professional. First, I would like to thank Brent Nick01 for providing my first instruction in the systematics of the Acanthocephala. I regret that I was no able to 'convince' him of my interest in this area, but the fault is mine for being too bashful to approach the subject rather than his. I do not expect him, or anyone else, to agree with all of my work, but it is one of my strongest hopes that he will never feel ashamed to claim me as a former student-I will always be proud of my association with him! I am indebted to Dan Brooks for his interest and encouragement of my desire to work with the Acanthocephala. Since our first meeting in 1986, long before I came to the University of Toronto, he has continued to convince me that I was capable of accomplishing this project. The 'stories' of Dan's accomplishments during his time at the University of Nebraska that I had heard from his former fellow-students, as well as his vast publication record, had not given me any hope of ever being able to work with him. His encouragement of my coming to the University of Toronto to work in his lab was a big surprise to me, and it made me feel that what I wanted to accomplish there was also worthwhile to others. Dan also gave me the opportunity to work in Central America, where I met Griselda, and the many other friends I now have there. I have long way to go before I am able to 'absorb' and put into practice all that Dan has hied to teach me about Phylogenetics. I hope I have not forgotten more than 1 remember! I cannot even begin to thank Fernando Marques for his support during the past four years- there is nothing more than my continued friendship that deserves be offered in return for this. He has been beside me during my darkest hours as well as my brightest. Sometimes nothing else could keep me going except his 'kicking' me in the butt when I needed it, and he was, and still is, a source of encouragement. The figures of Koronacantha and Tegorhynchus included herein were originally drawn by Femando, and are an example of artistic, yet scientifically accurate, drawings that all should aspire to make. Femando also was my introduction to jazz, although some other Zoology Department 'inhabitants' might not have appreciated that as much as I did! Now that my graduate 'career' is over, the one thing I will miss is the hours he and I spent working together in the lab together. tn many ways, those were the happiest and most fulfilling times of my life. I will miss the inspiration of our discussion while we processed specimens, 'arguments' over methodology, and his constant borrowing of my dissection tools-Fernando is the brother that I never had. I consider it a great honor, and a privilege, to be able to continue collaborating with him. I especially thank him for arranging my first 'date' with the woman that is now my wife. You can always be sure, Fernando, that "nuestra casa es tu casa". I am particularly fortunate to have been able to spent time with Malcolm Telford. In contrast to some others in the Department, Malcolm is very quiet and unassuming, so many students may not even be aware of the loss the University has suffered because of his retirement. The focus of science has turned away from organismal biology to more reductionist pursuits, and I do not believe that a student today can receive the broad appreciation of the diversity of life that someone with Malcolm's background can offer.