Adaptive radiations can be a direct consequence of three of the following four factors. Select the exception. a. vacant ecological niches b. genetic drift c. colonization of an isolated region that contains suitable habitat and few competitor species d. evolutionary innovation

Video transcript

Hi everyone. Next we'll look at the question. Darwin's finches on the Galapagos islands with different beak forms are an example of which of the following. So we're gonna look over at our answer choices and it's always a good idea to glance over them as a whole really quickly. Because here I see that choice D. Is both B and C. And that gives me a heads up that there may be more than one correct answer here. So let's start to look through our choices. Choice A. Is convergent evolution. Well, as we recall from our concept videos, that's when we have different ancestor species and they evolve to become more similar due to similar environments, similar food sources, similar selection pressures. Well in this case we had the common ancestor of the finches that involved different forms. So that's the opposite of convergent evolution. So we can eliminate choice A. Now let's look at choice B, adaptive radiation. Well, this occurs when we start with a common ancestor and the number of species with that common ancestor increases quite rapidly. So we see more and developing significant differences more biologically. So we start with a common ancestor evolving rapidly into many different species with differences. So that is what is happening here. A whole bunch of different finches with different beak shapes. So that is correct. But we know we can have more than one correct answer. So I'm not going to select it as my answer yet, but I'm going to note that it is correct. Now let's move on to choice C. That is divergent evolution. Well as the name might suggest this is the opposite of convergence. We start with a common ancestor that evolves into different forms due to different selection pressures or to take advantage of different environments. So again, we have here, the common ancestor of the finches that evolved different beak shapes so that it can take advantage of different sources of food on that island. So divergent evolution is happening here, so we'll just select that. So we see that both B and C are correct. So therefore our answer to the problem is Choice D. Both B and C are correct. See you in the next video.