The North American pronghorn looks and acts like the antelopes of Africa. But the pronghorn is the only survivor of a family of mammals restricted to North America. Propose a hypothesis to explain how these widely separated animals came to be so much alike.

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Welcome back. Here's our next question. Dolphins are mammals whereas penguins are obvious despite their different families. The flippers of penguins and dolphins have similar functions. What is this phenomenon called? So let's recall when we have similar structures but different ancestors. So the similarities in the form and function of those structures are not due to descent from a common ancestor. We call that convergent evolution and we remember that because the species were different and they converged became closer. Um So we look at our answer choices and we see that choice D. Is convergent evolution. Well let's just look through our other answer choices here. Choice A. Is divergent evolution. We can recall that's the opposite of convergent. That's when you have a common ancestor and structures descended that were in that common ancestor have now become different in form and function. So different structures. So we think of the flipper of a dolphin, the hand of a human being descended from a common ancestor. They were, you know the same structure and a common ancestor. They've become very different in form and function. So that is not our answer choice. And that choice B. Is adaptive radiation. And that's rapid diversification from a single ancestor. So you have a single organism and it very rapidly evolves into a multitude of different forms usually in response to the opening of a new environment. New niches. So it very quickly evolves many different forms to go ahead and take advantage of all these different niches. Um We think of Darwin's finches as an example and adaptive radiation as an example of divergent evolution. because you had a single ancestor and it evolved into different forms so that's why that's not an answer. Choice. And then choice C. Is natural selection. Um A natural selection is of course the that principle that's an organism that is better adapted to a given environment is more likely to survive and reproduce. So that's not our answer in terms of describing what's going on here. Although of course natural selection is what causes convergent evolution. The penguins and the dolphins from different ancestors face similar natural selection pressure, evolving their flippers to let them move through the similar environment they were in. But again despite the different families, the flippers of penguin and dolphins have similar functions. What's this phenomenon called? Choice D convergent evolution? See you in the next video.

The North American pronghorn looks and acts like the antelopes of Africa. But the pronghorn is the only survivor of a family of mammals restricted to North America. Propose a hypothesis to explain how these widely separated animals came to be so much alike.

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Key Concepts

Convergent Evolution

Adaptive Radiation

Ecological Niches