Similarity in skin color among different human populations appear...

Question

Similarity in skin color among different human populations appears to be primarily the result of                   .
a. natural selection;
b. convergent evolution;
c. which biological race they belong to;
d. A and B are correct;
e. A, B, and C are correct

Accepted Answer

Welcome back. Here's our next question. Which of the following structures show convergent evolution. So let's recall from our content videos what the definition is of convergent evolution and I'm just going to open up real quickly there convergent evolution is the independent evolution of similar features in different species not due to common ancestry. So two different species have evolved a structure that a similar uh function, similar appearance, similar shape. Um but that's due to similar pressures driving the selection of that structure, not due to shared genes from a common ancestor. So great example, the wing of a bat versus the wing of a bird. They look similar, they sort of similar function of allowing flight but are not the result of inheritance from a shared ancestor. So with that in mind let's look at our answer choices. Choice A says homologous organs. Well homologous organs are when you have um organs that are inherited from a common ancestor. So they descend from the same structure and a common ancestor but they have a different appearance or different function. So they have different function but common ancestry. So this is obviously the reverse of convergent evolution. This is divergent evolution where two species descended from a common ancestor um due to different selection pressures evolved. A shared structure will then evolve in two different directions and become very different in appearance or function. So example there is the flipper of the whale and the arm of a human. So evolved both evolved from the fore limb of a common ancestor but have evolved to take very different shapes and functions. So that's obviously not our answer as it's sort of an opposite example. And then therefore we can also eliminate Choice D. Which is all of the above because obviously not all of our answers are correct. So let's look down at Choice B. That says a vestigial organs. Well a vestigial organ is an organ that no longer has an adaptive function. So it doesn't have any um adaptive purpose in helping the species in its environment. Um But it descended from something that did in an ancestor. So in general it becomes a smaller, they think of the tail bone of a human. Originally was a full length tail no longer um serves an adaptive purpose, but you still have this little small bit of bone there. So that's not what we're talking about here. So that is not our answer. So we can eliminate choice B. And finally we've got choice C. Which is analogous organs and analogous organs are structures that have similar function or appearance but not due to common ancestry. And those things like the wing of a bat and wing of a bird are indeed examples of convergent evolution. So which of the following structures show convergent evolution that would be choice. See analogous organs. Thanks for watching see you in the next video

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