Affiliation: | Department of Zoology. University of Guelph, Guelph, Ontario N1G 2W1, Canada,;Universität Tübingen. Zoologisches Institut Abteilung Zellbiohgie, Auf der Morgenstelle 28, 74 Tübingen, Federal Republic of Germany;Center for Molecular Evolution, Marine Biology Laboratory, Woods Hole, Massachusetts 02543 |