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Phylogenetic Context and Basal Metazoan Model Systems 1
| Citations: | 13 - 6 self |
BibTeX
@MISC{Collins_phylogeneticcontext,
author = {Allen G. Collins and Paulyn Cartwright and Catherine S. Mcfadden and Bernd Schierwater},
title = {Phylogenetic Context and Basal Metazoan Model Systems 1},
year = {}
}
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Abstract
SYNOPSIS. In comparative studies using model organisms, extant taxa are often referred to as basal. The term suggests that such taxa are descendants of lineages that diverged early in the history of some larger taxon. By this usage, the basal metazoans comprise just four phyla (Placozoa, Porifera, Cnidaria, and Ctenophora) and the large clade Bilateria. We advise against this practice because basal refers to a region at the base or root of a phylogenetic tree. Thus, referring to an extant taxon or species as basal, or as more basal than another, can be misleading. While much progress has been made toward understanding some of the phylogenetic relationships within these groups, the relationships among them are still largely not known with certainty. Thus, sound inferences from comparative studies of model organisms demand continued illumination of phylogeny. Hypotheses about the mechanisms underlying metazoan evolution can be drawn from the study of model organisms in Cnidaria, Ctenophora, Placozoa, and Porifera, but it is clear that these model organisms are likely to be derived in many respects. Therefore, testing these hypotheses requires the study of yet additional model organisms. The most effective tests are those that investigate model organisms with phylogenetic positions among two sister groups comprising a larger clade of interest.
Keyphrases
model organism phylogenetic context basal metazoan model extant taxon comparative study phylogenetic tree many respect large clade bilateria additional model organism sound inference continued illumination much progress effective test phylogenetic position basal refers sister group metazoan evolution phylogenetic relationship
