Evolutionary origins and age of vestimentiferan tube-worms
In: Cahiers de Biologie Marine. Station Biologique de Roscoff: Paris. ISSN 0007-9723; e-ISSN 2262-3094, more
Also appears in:(1998). Proceedings of the First International Symposium on Deep-Sea Hydrothermal Vent Biology: Funchal, Madeira, Portugal 20-24 October 1997. Cahiers de Biologie Marine, 39(3-4). Station Biologique de Roscoff: Roscoff. 219-392 pp., more
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| Authors | | Top |
- Halanych, K.M.
- Lutz, R.A.
- Vrijenhoek, R.C.
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| Abstract |
Vestimentiferan tube-worms are one of the dominate groups of organisms present at deep-sea hydrothermal vent habitats in the eastern Pacific Ocean. Understanding how they have evolved to thrive in such harsh environments is a subject of great interest to marine biologists. In order to assess the degree and polarity of this evolutionary change, we have used a molecular phylogenetic approach to examine the age and history of the vestimentiferans.Considerable debate persists concerning the taxonomic status and evolutionary origins of vestimentiferans. Jones (1985) argued that the vestimentiferan body plan was sufficiently distinct to warrant placement in a unique phylum, the Vestimentifera. On the other hand, Southward (1988), among others, challenged the erection of a separate phylum for these worms. During the course of recent taxonomic debates, various authors have also referred to these worms as the Order Vestimentifera (Class Afrenulata: Phylum Pogonophora) and the Subclass Obturata (Class Pogonophora: Phylum Annelida). Although the rationale behind such changes in taxonomic rank may be legitimate, higher taxonomic categories are manmade constructs that are not meaningful for describing the diversity or the age of a monophyletic clade of organisms. To avoid assigning rank to taxonomic names throughout this manuscript, we use the terms "vestimentiferan" and "perviate pogonophoran" (i.e., the traditional non-vestimentiferan pogonophorans). To date, our work has focused on partial sequences from the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene (Black et al., 1997), sequences from the nuclear small ribosomal subunit (18S rRNA), and a 3' region of the large ribosomal subunit (28S rRNA). The present molecular data provide support for the inclusion of perviate pogonophorans and vestimentiferans as a clade within a paraphyletic grade of traditional annelid taxa. Furthermore, extant vestimentiferans appear to be a relatively young group that radiated during the Cenozoic. |
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