Exactly what is a species?

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From: David Doyle (kingfshr at northcoast.com)
Subject:  Exactly what is a species?

   Something that has been bothering me ever since I
began as a student of wildlife ecology was reinforced
the other day while reading a book on wolves by David
L. Mech, wherein he describes inbreeding and hybridization
of the gray wolf (Canis lupus), the domestic dog (C. familiarus),
and the coyote (C. latrans).  As Mech puts it:  "All offspring
that were tested from all generations (of cross-breeding) were
fertile."
   And then comes the red wolf (Canis rufus); a hybrid of a
wolf and a coyote, and now considered a rare "species" in and
of itself...
   Thus I point to a famous quote in which I am sure many of
you have heard:  Keeton (1972) states that a species is "the
largest unit of population within which effective gene flow
occurs or could occur."  Kirk (1975) adds that a species is
defined as "a group of related individuals that are actually
or potentially capable of interbreeding; a group of organisms
constituting a single gene pool."
   Under this restricted wording, which any good lawyer would
love to get his or her hands on, fertile crossbreeds are lost in
the shuffle...
   I wonder, just what are the implications and ramifications
of this discrepancy in the world of conservation biology, with
regards to threatened and endangered species?