Ensatina:
SPECIATION IN PROGRESS
|
|
Research on enzymes, nuclear DNA and mitochondrial DNA, are now being conducted by David Wake at the Museum of Vertebrate Zoology in Berkeley. These studies by Wake, show evidence in support of the idea that Ensatina eschscholtzi is a species complex that is now breaking up into two or more species. While the hypotheses by Stebbins, 1949, for the Ensatina complex is supported by recent works, the original idea is too simple. Differentiation is greater than originally conceived, thus an argument could be made for dividing Ensatina into several species. However, incipient species formation is in its early stages and thus species borders and distinctions remain unclear. (Wake, D., 1997)
The biological complexity of Ensatina argues against a simple taxonomic resolution because the evolutionary realities of diversification in old and persistent complexes reqire compromises if Linnean taxonomies are to be used. A preferred taxonomy is one that calrifies the evolutionary relationships among the components and that highlights, rather than obscures, the complex interactions of the past and the present. A new taxonomy may be required when studies in progress are concluded, for the present the Ensatina complex will be recognised as a single taxonomic species.
The Ensatina complex appears to be a classical example of Darwinian evolution by gradualism; an accumulation of micromutations that is now leading to the formation of new species. (see the web site "Speciation in Progress")
