Understanding genetics, and particularly hybridizing, may be more important than is obvious.

An recent article in American Scientist magazine (May June 2002)¹, "Hybridization and Extinction," by Donald A. Levin from the University of Texas at Austin, points out that hybridization between species is actually relatively frequent, and can either aid or hinder the preservation of endangered species. Online articles are not available without a subscription, hence a longer than usual comment:

The European mallard (Anas platyrhynchus) was introduced into New Zealand in the mid 1800s and has mated freely with the native grey duck (A. superciliosa) to the extent that now more than half of the "nominally native" grey ducks are in fact hybrids. Extrapolation of this trend predicts the effective extinction of the New Zealand grey duck as a separate species in the not too distant future.

The european wildcat (Felis silvestris) may in fact no longer exist as a separate species due to cross-breeding with "imported" feral and domestic cats (Felis catus). Considered extinct due to loss of habitat in most of Europe, except in Scotland, where they are protected, it's unlikely that any pure examples of the previously distinct species still exist due to hybridization.

The Ethiopian wolf is considered "the most endangered Canid," and now consists of fewer than 500 animals. Loss of habitat has been the main cause of their dwindling population. Extreme measures have been invoked to protect them and their habitat; but recent studies indicated that up to 17% (and increasing) of the animals in the protected packs have been cross bred with wild dogs, which will likely, if present trends continue, result in the extinction of the species in the near future, with their descendants indistinguishable from other wild dogs.

The Florida panther (Felis concolor coryi) was pushed nearly to extinction by loss of habitat, with the result that inbreeding of the few remaining had led to unsuccessful reproduction due to inbreeding. Cited as "the worst sperm in any animal" males were producing in excess of 95% "deformed/defective" sperm. Cryptochordism had risen from negligible occurance to nearly 80% of males. The lack of genetic variation had also made all existing specimens vulnerable to parasite loads that produced debilitation and death from disease. In this case, the introduction of a few Texas cougars (Felis concolor stanleyana) has provided, through hybridization, sufficient genetic variability to offer some hope that "nearly pure" Florida panthers may recover a viable population. Not quite as good as saving the pure subspecies, but better perhaps than saving nothing at all of them.

The red wolf, endangered in the southeastern US, was found to be cross-breeding with coyotes, and the number of "pure" red wolves was declining rapidly. A few specimens were captured and bred in captivity to keep a pure line, but - - - - recent studies have revealed that the red wolf actually was/is a hybrid between coyotes and a now ²extinct grey wolf. … … … so some question whether it really did any good to save them as a separate hybrid subspecie(?).

Examples, and puzzles, are much more common in plants and marine life; but they're not as cute and cuddly as the ones cited. Introduction, deliberate or inadvertent, of "foreign species" is a the leading cause of species extinctions, in plants or in animals, but has received relatively little attention until quite recently. Invading species have been noted for being obnoxious, but the hazard to competing native species due to hybridization with the invading species has been given only marginal notice.

The bottom line is that Maw Nature is quite a trickster, and when you fool aroun' with her, she's liable to whop ya with an unexpected result or two.

¹ Okay, so I'm a little behind on my reading.

² The genetic line of the extinct grey wolf appears to be quite strong in current wolves, and the coyote genetic line is little changed since the time when the cross appears to have occurred, so no "genetic information" was preserved that wasn't present in the two parent/descendant subspecies.(?)

John