Am 29.11.2017 um 04:08 schrieb omniverse:

> Or in other words, the way evolution seems to be mostly finished. You don't see
> a creature becoming future whales or dolphins anymore. What happened to their
> land-based counterparts? How could they only be 100% water-borne since they
> began taking to the ocean, why not half and half, like seals and walruses?

... or maybe like hippos?

https://en.wikipedia.org/wiki/Whippomorpha
(Spolier Alert!)


The most common phenomenon in evolution is that you have some animal
developing a trait that is of benefit in its natural environment, and
such traits tend to get passed on until they are prevalent throughout
the species' population. In such a manner, species may change as a whole
in response to their environment.

But now and again you have populations being separated, and one develops
in another direction than the other (because their natural environments
differ somewhat, or just because one beneficial mutation arises in one
population but not the other). As each population undergoes its own
changes from the original form, they become so different that if they
ever meet again later they can't (or won't) interbreed anymore, and have
thus become different species -- each differing from the original
species in its own way. The original species isn't gone -- it has been
absorbed into the two new species, each of which is better adapted to
its respective habitat than the original form.

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