cript:
Narrator: Now listen to part of a lecture in a biology class.
Professor: Let’s talk about two kinds of biological selection—two different ways that traits are selected in a species of animal as it breeds and reproduces. First, there’s natural selection. Here, living things develop features that help them survive in a certain kind of climate… escape from a certain kind of predator… that sort of thing. In contrast, we have artificial selection. Artificial selection happens outside of what we’d call nature. It happens when people deliberately breed living things for their own use. Now, it’s true that natural selection and artificial selection both give a living thing the traits it needs to reproduce and survive. But… these two types of biological selection also have very different effects, obviously.
Maybe one of the easiest places to see this difference is with wolves and dogs. Let’s start with wolves… So, uh—what’s a wolf’s job? It’s to survive in the wild and get enough to eat, right? So certain qualities are naturally selected: wolves need keen senses so that they can detect prey. They need to be fast, strong, and aggressive to catch their prey—and to survive even the harshest weather. Wolves that are born with these qualities live longer and pass the qualities on to their pups. That’s natural selection.
But a dog’s job—its role in its environment—is a little different. Dogs don’t need to survive in the wild—they need human protection… So to survive, a breed of dog needs to have traits that humans want. Take the—ah—golden retriever. People bred a dog big enough to be a good hunter, but not so big that it was hard to control. And it had to be obedient, unlike a wolf, right? A golden retriever has to be, well, friendly in order to be well liked enough that we humans decide to breed it, so we can get similarly friendly puppies—more pets.
Narrator: Using points and examples from the talk, explain the two types of biological selection.
| Post dates | Users | rates | Contents |
|---|---|---|---|
| 2016-08-03 | Enas Al lami | 80.00 | Check this speaking |
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Remove 'ehn' in the speaking.