The Definition of Protista

Charles J. O'Kelly okellyc at megasun.BCH.UMontreal.CA
Mon Aug 1 19:56:09 EST 1994

In article <31c1ou$o1d at>, kangj at (Joe Kang) writes:
|> Why was a separate kingdom, the Protista Kingdom created?

in recognition that not all creatures, especially not all unicellular creatures,
could be slotted into the Linnaean plant and animal kingdoms, nor into the bacteria.
this separation of protists into a kingdom (Protista, Protoctista, other names) was 
first done in the 1860s(!) in Europe, and resurrected in the middle years of this
century, especially after 1970.

Whittaker RH.  1969.  New concepts of kingdoms of organisms.  Science 163: 150.

|> What are some of the unique characteristics of a Protista and how do they fit in the 
|> world today?

As Paddy Patterson has already indicated, there are no unique characteristics.
Any eukaryote that does not have the multicellularity and embryonic development of
a green land plant (metaphyte) or a "true" animal (metazoon), nor the mycelial development
of a "true" fungus (zygomycete, ascomycete, basidiomycete, deuteromycete) may be considered
"a protist".

buried among the protists are true phylogenetic lineages.  when these lineages can be
reliably traced, "Kingdom Protista" will vanish, replaced by kingdoms that include the
ancestors and all the descendants of major eukaryotic lineages.  (Plantae, Animalia and
Fungi may disappear too, or at least be subordinated into subkingdoms within a single
clade that represents only a portion of the total phylogenetic diversity of eukaryotes.)

Margulis L, Corliss JO, Melkonian M, Chapman DJ.  1990.  Handbook of Protoctista.  Jones
and Bartlett, Boston.  Take all phylogenetic proposals in this book with tons of sodium
chloride, they are the subject of fierce debate.

|> --John

Charley O'Kelly			Complex problems have simple, easy-to-understand
Mad Protistologist			wrong answers
okellyc at

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