Kim writes:

> One of my biggest additional problem is that IF a new species
> did appear via evolution, a similar one of the opposite sex
> would have to evolve AT THE SAME TIME to propagate the species.

This seems to be one of the major misunderstandings inherent to those who
learn their biology at the hands of bible-thumping preachers on Sunday
morning. Species don't come into being on any one given day, full-blown,
ready to be unwrapped, any more than the HP3000 appeared in that manner.

Moreover there's nothing magical in the term "species," something almost
every creationist I've ever met wants to emphasize. The biological concept of
a species is defined as no more than: "an interbreeding population of
individuals, genetically isolated from all other such populations." At some
point, divergent lineages, divergent because they are no longer in genetic
communication with one another, generally due to geographical separation,
become so divergent, either by random drift or by the processes of local
adaptation, that they can no longer produce viable offspring. The code now
borne in the two germlines simply doesn't match up well enough to work
sufficiently well to produce viable (or competitive) progeny. The technical
term is called "outbreeding depression", where the depression lies in the
competitiveness or viability of the hybridized progeny.

Quite often before such outbreeding depression occurs, species recognition
protocols (which are called "pre-zygotic isolating mechanisms") are often
erected, generally behaviorally, but sometimes mechanically. While lions and
tigers will breed when in captivity and generally produce healthy offspring,
called "ligers", they never do in the wild. Indeed, the more likely outcome
would be that one would kill the other, if given the chance. But they're
rarely given the chance nowadays because tigers are primarily confined to
Asia while lions are African. However, there was a time not long ago when
both roamed Europe.

Nevertheless, both species come from the same manufacturer, Cats R Us. The
separation in code between lions and tigers is not very large and thus they
produce perfectly viable offspring. But no biologist (nor for that matter,
any kid) I know has any reservation about calling them separate and distinct
species, simply because they meet the very basic criteria of two
non-genetically communicating, self-interbreeding populations.

A second attribute of this fire-and-brimstone version of biology is the
foolish distinction between "microevolution" and "macroevolution." There is
no process in biology called "macroevolution." (Actually, there is, but it
has nothing to do with this idea that species just pop into being.) There's
only one form of evolution, and it's all "microevolution," just one small
change at a time, accumulated over substantial periods of time, as a phyletic
lineage moves through time.

Evolution is generally painfully slow, but sometimes it can be amazingly
fast. In the early 70's, my wife and I toured various scientific institutions
in New Zealand and Australia for six weeks and it was there that I heard one
of my favorite stories (I've got about a hundred of these, but let this one
represent all of the rest):

The barn fly is a blood-sucking fly that is an incredible pest of sheep in
Western Australia. Like all flies, it "tastes" with its feet. The people at
CSIRO in Canberra had worked out an extremely efficacious and long-lasting
toxin that could be sprayed on the upper surfaces of barn walls, where the
flies preferred to gather. The flies would then walk through the toxin,
absorb it into their body and almost immediately die.

As you would expect, it was an almost miraculous solution. The barn fly
problem was almost completely eliminated in the first year. And the second
year was almost as good. But by the third year, the flies were back.

Completely puzzled, the CSIRO people gathered up the flies, took them back
into the laboratory and dropped a bit of poison on them to see what would
happen. The flies died just as readily.

After a bit of investigation, what they found was that due to the extremely
intense selection pressure presented by the toxin, they had inadvertantly
selected for that very small fraction of the population that had tarsal hairs
on their feet that were longer than normal, keeping these flies' feet pads
off of the barn surface. In essence, they were walking on their tiptoes
through the poison and thereby being completely unaffected by it. As a result
of these individuals' differential survival, what had once been an extremely
rare trait had become the most common in the population in just a couple of
years.

That's all evolution is. Just one small change after another. Ecology becomes
evolution by nothing more mysterious than the passage of time, as one body
form replaces another as that change is warranted by current circumstances.

Wirt Atmar

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