And that definition is in turn complicated by the need to define an equivalence relation for "species" (i.e. a definition with the property that, there does not exist any set of three animals X, Y, and Z such that X is of the same species as Y and Z, but Y and Z are not the same species as each other.).
Actually, even if one accepts a fairly tight definition of species, it's not inconceivable that a population which is geographically split into disjoint populations which are geographically incapable of interbreding (e.g. because an ice flow transported them too far apart) might, over enough succeeding generations, diverge enough to be called different species.
On the other hand, accepting that a rare combination of events could occur on occasion to produce a new species still leaves open the 'problem' for evolutionists that there is way too much diversity of life on this planet for such events to account for all of it (or even most of it).
you won't find me defending creationists trying to use natural science to prove God/the Bible/etc. but I'm not blind to the holes in evolution either.
"On the other hand, accepting that a rare combination of events could occur on occasion to produce a new species still leaves open the 'problem' for evolutionists that there is way too much diversity of life on this planet for such events to account for all of it (or even most of it)."
ironic that the age of the earth has gotten older the more we know about it yet there is still a conflict between what is statistically possible and the current accepted age of the earth (both in the underwhelming number of fossils and the overwhelming variety in the non-extinct species). it is almost as if there is a hidden dispute within evolution between the geological/astronomical determined age and the biological determined age. (ok maybe not so hidden)