Concepts of Systematic Biology from Linnaeus to the Present (1707-2007): Three Hundred Years of Progressive Change
Jensen, Richard .
The Phenetic Revolution: A Natural Consequence?
Linnaeus had it right – essentially, a classification should allow ease of identification. However, his classification had a significant shortcoming: it could not be used to determine relationships in any meaningful way. As the desire for a natural system developed and, more especially, as the implications of Darwinian evolution were realized, biologists recognized that a system of classification should serve more than a single, artificial purpose. What that purpose is, or should be, continues to be a point of contention. Application of mathematical tools to taxonomic problems led to a logical conclusion: natural classifications, employing a large suite of characters, could be attained by newly developed tools of multivariate analysis. In particular, SAHN methods of cluster analysisnwere seen as approximations to traditional hierarchic taxonomies and could be viewed as analogous to synthetic methods of classification. The concept of overall similarity was, perhaps too blithely, likened to both naturalness and information content. Early pheneticists were not concerned with approximating phylogeny, but acknowledged that their classifications could form the basis for phylogenetic deductions under certain restricted conditions. Despite the promise of phenetics, the concurrent development of cladistic methodology (both under the rubric of numerical taxonomy, s.l.) shifted focus from classifications with high information-content, predictivity, and stability, to classifications reflecting hypothesized phylogenetic relationships. While a number of critics raised valid questions about the utility of phenetics and the underlying principles of proposed phenetic taxonomy, many criticisms consisted of over-simplified objections. Nevertheless, today phenetic analyses are de riguer for identifying fundamental units (populations, species) that form the bases for phylogenetic studies. After all, it is only natural that members of a species show greater overall similarity to each other than to members of different species, a view that can often be applied to higher ranks as well.
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1 - Saint Mary's College, Department of Biology, Notre Dame, Indiana, 46556, USA
Presentation Type: Symposium or Colloquium Presentation
Location: Stevens 1/Hilton
Date: Wednesday, July 11th, 2007
Time: 10:00 AM