I have a genuine question regarding evolution of new species from an ancestral species.
Suppose species A lives in environment X.
Some specimen of species A (population Ay) reach environment Y, where they are isolated from other members of their species (population Ax).
Y is fundamentally different from X in many ways and exerts selective pressure on Ay.
In the long run, the differences between Ay and Ax accumulate and result in speciation. Population Ay slowly becomes species B.
However, environment X remains mostly constant over all this time, so there is little change in population Ax, which remains the unaltered original species A.
Suppose further that a process similar to the one that converted population Ay into species B will convert a population Az in environment Z into species C. C is different from both A and B.
To summarize, species A is the common ancestor to species A, B, and C. A, B, and C will exist simultaneously at some point in time.
My question is this:
Is there any example of such a case in the real world? We all know that, according to the theory of evolution, humans (B) and chimpanzees (C) evolved from a common ancestor (A), however this ancestral species went extinct. This happened because humans and chimpanzees were better adapted to the environments they lived in than the ancestral species.
From an evolutionary point of view, I believe the scenario I described to be plausible and possible. Is there any known case in which an ancestral species (A)
and one or many "daughter" species (B, C, D...) existed at the same time? Preferably a case involving creatures that reproduce sexually (because for them the term 'species' is more clearly define IMHO).
Thank you very much!
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