Crown Eukaryotes - Another myth
kinman2 at YAHOO.COM
Sun Mar 5 00:23:19 CST 2006
I agree!!! As a matter of fact, my 1994 classification had chromalveolates at the crown of Protista (where they still remain in the updated classification I currently use). It is quite a derived group based on BOTH the hosts AND their highly derived plastids. Of course, there has been a great deal learned in the past 12 years, and now I place my Opisthokont clade at the base of Protista (replacing the excavates and other taxa, which have been shown to be phylogenetically more derived). Anyway, I will post that classification tomorrow, after I have had time to check a few more recent papers (and perhaps "tweak" the coding a bit). With the Kinman System, it's largely just a matter of shuffling the taxa around somewhat, and recoding the order in which they split off phylogenetically.
But, as you will see, Kingdom Protista is still relatively compact, even with the inclusion of chromists and eumycotans, so I still prefer the four-kingdom classification (although a five-kingdom system isn't too shabby either). However, I have never accepted a 6th Kingdom Chromista (a mere subset of the chromalveolate clade).
Although I do disagree with Cavalier-Smith in some ways, we certainly do agree that claims of large numbers of new major clades (based mainly on RNA sequences alone) are completely overblown. This is true for both prokaryotes and protists. I may criticize Cavalier-Smith's classifications for being somewhat inflated, but he is very restrained compared to some workers who have gone crazy proposing new candidate kingdoms and phyla (although thankfully most have not been formally named yet and hopefully never will be). Even sixty major clades is probably way overblown (200 is a splitter's imagination running wild). Anyway, I will post my updated classification of Kingdom Protista tomorrow.
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