>What if the Hybridization occurs
>between two sister species, and
>the offspring are better adapted,
>have higher variability, and are
>fertile. These creatures would not
>be evolutionary dead ends, instead,
>they would be evolutionary BEGINNINGS!
>FIG 3 shows just that. For a
>hybrid to take root in the parent species
>niche, we would expect this
>pairing happens often.
Well, *is* there a new species here? If members of the two sisters species
can and did mate, producing well-adapted and perfectly fertile offspring,
were the two really separate species in the first place? Speciation really
isn't an all-or-nothing kind of thing, and this is treading in a grey area.
Scientists, ecologists, and bureaucrats spend a lot of time arguing over
such things as whether the California Gnatcatcher is a separate species from
the Mexican one, or just a separate sub-species.
There was an isolation of sorts, that which produced the two sister species,
or sub-species, or whatever. If the isolation that made the sister species
was not adequate to avert fully fertile interbreeding then generally they are
considered merely sub-species and expected to merge, and the resulting merger
is just an evolution from the original species, not a new species. But this
is just definition (and frequently ignored if one of the subspecies has
environmental interest lobbying for it).
There's one case, I read, where an apparently new species of grass in North
America is thought to be a hybrid between a North American and an imported
species that appear to be not fertile, at least normally. This case would
indeed meet your definition. In general plants are more tolerant of distant
outbreedings than animals.