|
|
||||||||
The Biological Bulletin, Vol 183, Issue 3 448-455, Copyright © 1992 by Marine Biological Laboratory
ECOLOGY AND EVOLUTION |
H. Wada, K. W. Makabe, M. Nakauchi and N. Satoh
Department of Zoology, Faculty of Science, Kyoto University, Kyoto 606-01
Ascidians (tunicates) are primitive chordates. In spite of their elevated phylogenetic position in the animal kingdom, ascidians have evolved a varied reproductive repertoire; some of them live as individuals (solitary ascidians), while others form colonies (colonial ascidians). Colonial ascidians propagate asexually by budding and strobilation, and they have an extensive capacity for regeneration. However, the orthodox taxonomic classification of ascidians categorizes them into two major groups (the orders Enterogona and Pleurogona), irrespective of their solitary or colonial life style. To examine whether the orthodox classification of ascidians is substantiated by molecular phylogeny, the complete nucleotide sequence of a region of about 1000 base pairs in the central part of their respective 18S rDNAs was determined, and the sequences were compared among five solitary and three colonial ascidians. The phylogenetic tree deduced from these results suggests that the three species of Enterogona and the five species of Pleurogona examined form discrete and separate groups irrespective of their potential to form colonies. Therefore, a solitary or colonial life style is likely to have developed independently after the divergence of the two major groups of ascidians.
This article has been cited by other articles:
![]() |
L. Zeng, M. W. Jacobs, and B. J. Swalla Coloniality has evolved once in Stolidobranch Ascidians Integr. Comp. Biol., June 1, 2006; 46(3): 255 - 268. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. F. Hinman and B. M. Degnan Homeobox Genes, Retinoic Acid and the Development and Evolution of Dual Body Plans in the Ascidian Herdmania curvata Integr. Comp. Biol., June 1, 2001; 41(3): 664 - 675. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. B. Cameron, J. R. Garey, and B. J. Swalla Special Feature: Evolution of the chordate body plan: New insights from phylogenetic analyses of deuterostome phyla PNAS, April 25, 2000; 97(9): 4469 - 4474. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Ono, Y. Katsuyama, K. Nakajo, and Y. Okamura Subfamily-Specific Posttranscriptional Mechanism Underlies K+ Channel Expression in a Developing Neuronal Blastomere J. Neurosci., August 15, 1999; 19(16): 6874 - 6886. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |