Species definitions!

[Kenelm Philip]

> Are there, and do we know - that plants and animals are different?

What about the single-celled organisms that may, or may not, contain
chlorophyll? Back when there were only two kingdoms, it was totally unclear
as to whether these were plants or animals. The hypothetical  3 year old
might have a bit of trouble dealing with five kingdoms, let alone the
Woese system of domains with _lots_ of kingdoms.

> How about moths and butterflies?  Does a 7 year old know they are
> different? If so, then the rank of Suborder is evident to him/her even
> though they likely do not know the terms Heterocera/Rhopalocera.

The Heterocera/Rhopalocera split is outmoded taxonomy, since Heterocera
do not form a monophyletic group. And note that the family Hedylidae now
is included in the Rhopalocera, although they do not have clubbed antennae,
and are not primarily diurnal--thus causing a problem for the hypothetical
7 year old.

	As far as the concept of species goes, we have a number of differ-
ent and incompatible species concepts wandering around. Most of us were pre-
sumably brought up on the BSC (biological species concept), according to
which reproductive isolation is the key factor involved. Before that there
was what one might call a morpholgical species concept. However, we cur-
rently have the phylogenetic species concept (PSC), a close relation of the
ESC (evolutionary species concept). See Zink & McKitrick: 'The Debate over
Species Concepts and its Implications for Ornithology'. The Auk 112(3):701-
719, 1995. These concepts will yield different breakdowns of organisms
into species--a problem which may appear in the courts as more laws and
regulations are keyed to species, with respected taxonomists arguing for
both sides of various issues.

	The trouble is that taxonomy is not simple, nor free from contro-
versy. And the controversies will not be solved by appealing to the abil-
ities of young children who are unaquainted with the full diversity to
be found within any group of organisms.  :-)

							Ken Philip
fnkwp at uaf.edu




 
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