Species

Reproductive Isolation Concepts 231

Recognition Concepts

There have been numerous conceptions of species following Mayr that are fully or

partially isolationist. The views of Hugh Paterson in particular^8 have influenced Niles

Eldredge and Elisabeth Vrba,^9 among others.^10 Paterson’s version of the biospecies con-

cept requires that organisms share a mating system, which he terms the “Specific-Mate

Recognition System” (SMRS). He intends this to apply to plants, animals, and other

organisms, so the term “recognition” should be taken in the same way the term “selec-

tion” is, without voluntaristic or cognitive implications. Paterson defines a species thus:

We can, therefore, regard a species as that most inclusive population of individual

biparental organisms which share a common fertilization system.^11

He refers to this as the Recognition Concept. Mayrian and Dobzhanskyan con-
cepts he calls Isolation Concepts. Since Paterson’s version applies, as did previous
isolation concepts, only to fully sexual and gendered (anisogamous) organisms, it
follows that like them, he does not regard non-sexual organisms as forming species.^12
Paterson’s criticisms of the Isolation Concept include its being teleological, since spe-
cies are seen as “adaptive devices,”^13 but this is hardly fair. Biospecies are not, on
Mayr’s account, adaptive any more than higher taxa, and on his account, they are
formed through isolation and subsequent local adaptation, not in virtue of their adap-
tations. The main difference between the isolation conception of Mayr and that of
Paterson is well noted by Scoble, the following contributor to that volume, who notes,
“... the BSC [biological species concept] can apply to only actually, not potentially,
interbreeding groups of organisms. However, if the recognition concept of species
... is accepted ... then we may be able to directly compare at least some of the very
characters involved in mate recognition in allopatric and allochronic populations.”^14
However, this does not follow, since we cannot say whether the mate recognition
sequences are compatible enough to form viable progeny, either occasionally or repeatedly
enough to make them count as the “same” species, until we have actually managed to test
it in the lab and the wild. Scoble also notes the problem of uniparental species, and sug-
gests that a homeostatic view might pertain. Since the SMRS is only one kind of homeo-
static mechanism, there is no reason to restrict species-hood to sexual organisms only.

Genetic Concepts

We have several genetic concepts of species, ranging from Dobzhansky’s comment

that species are “the most inclusive Mendelian population,” and Carson’s comment

(^8) Paterson 1985, 1993.
(^9) Eldredge 1989, 1993.
(^10) Lambert and Spencer 1995.
(^11) Paterson 1985, 25, italics original.
(^12) Op. cit., 24.
(^13) Op. cit., 28.
(^14) Scoble 1985, 33.