Exactly what is a species?

[Thomas G. Lammers]

Two thoughts come to mind.  First, that taxonomists may not have correctly
circumscribed the species.  If gray wolves, red wolves, coyotes, and dogs
freely interchange genes and bear fertile offspring, perhaps it would be
better to consider them subspecies within a single biological species.

Second, that the extent to which hybridization occurs must be borne in
mind.  Yes, hybrids are possible.  But do they occur in nature frequently
enough to threaten the integrity of one of the species genetic makeup?
In other words, do dogs and coyotes hybridize so often that a significant
number of individuals encountered are bastards rather than "purebreds"?
Many many plants are capable of producing fertile hybrids if they are
purposely cross-pollinated; but the actual number of such naturally
occurring events are so low as not to threaten the gene pools.

In a nutshell, it must be borne in mind that mechanisms of reproductive
isolation that are external (e.g., behavior, ecology, geography, phenology,
etc.) may be just as powerful as genetic differences.

Thomas G. Lammers
Department of Botany            lammers at fmnh.org
Field Museum of Natural History
Chicago IL 60605 USA