There does seem to be some lack of uniformity regarding the definition of microevolution. However, it hardly matters, as I see it. We apparently all agree that new species do arise from earlier species, regardless of how we label that reality. In other words, a species accumulates changes over time until finally it is different enough from the original that it only makes sense to give it a new name. If such a process continues long enough, surely that series of species will become different enough from the original that it would have to be classified in a new genus. It is difficult for me to appreciate that in the overall scheme of nature, a different process is involved in the production of new phyla or classes than is involved in the production of new genera and families. I thought taxonomy viewed this as a continuum? It is also well to keep in mind that phylum is not a concept which nature recognizes. Nature recognizes only diversity. Taxonomy is our own creation, an artificial attempt to organize nature's diversity into something our limited minds can deal with. We might think in terms of a species needing a new genus, or having to be moved to a new family. Nature only produces ongoing change in all things, living and non-living, and leaves the classification of such things to us. Paul M.