Describe how evolution occurs. In your description, include discussion of the reproductive poten

Describe how evolution occurs. In your description, include...

Key Concepts

Reproductive Potential

Reproductive potential refers to the ability of an organism to produce a large number of offspring. This creates a situation where more individuals are made than can possibly survive due to limited resources, setting the stage for competition.

Population Stability

Population stability involves the fact that, despite high reproductive outputs, the size of natural populations remains relatively constant. This occurs because environmental constraints such as limited resources, predation, and disease reduce the surplus of offspring to sustainable numbers.

Variation Among Individuals

Variation among individuals within a species is the presence of differences in traits such as morphology, physiology, and behavior. These differences provide the raw material for natural selection, as some traits may confer advantages that enhance survival and reproduction in a given environment.

Inheritance

Inheritance is the mechanism by which characteristics and genetic information are passed from parents to their offspring. This ensures that beneficial traits can be transmitted across generations and that the sources of variation can be retained and shaped by evolutionary processes.

Natural Selection

Natural selection is the process where individuals with advantageous traits are more likely to survive and reproduce in their environment, leading to an increased frequency of these traits in the population over time. It is a key mechanism of evolutionary change, acting on the variations present within a population.

Transcript

00:01 Hi, the purpose of this video is to describe natural selection with regards to evolution and then look at a specific example of how this could work.

00:09 The example we're going to look at today is in a predatory fish, a barracuda.

00:13 A barracuda is like to chase and eat other living things.

00:16 So they're a predatory fish.

00:18 So the very first thing we should probably talk about is what is natural selection.

00:22 So i like to use the word nature and selection kind of in the response.

00:26 So i like to think of it is nature selects, chooses.

00:30 Who's going to live more often and who's going to die more often? if you can survive, chances are you can reach an age at which you can reproduce and pass on those traits to your living things.

00:42 And those who die, if you're dead, obviously you can't reproduce.

00:46 You've maybe heard it's also referred to as like survival of the fittest.

00:49 We'll talk about fittest, fit or fitness here in just a second or sometimes referred to as a struggle for existence.

00:56 You know, out in nature, if you're an animal or some other living thing, it's a pretty wild.

01:00 Place.

01:01 You're constantly being put under what are called selective pressures, things that are urging you to maybe evolve or not evolve.

01:09 For example, maybe there's things that are competing with you.

01:12 Maybe there's environmental conditions that are stressing you.

01:15 Maybe there's things that are trying to kill and eat you, or maybe you're trying to find food or space or find a mate.

01:21 There's all these things you're struggling for, in other words, to stay alive.

01:25 So let's look at an example in a predatory fish a barracuda.

01:30 Okay? and we're going to kind of just like sketch this out as we go.

01:35 So we're going to kind of also label the steps.

01:37 So imagine, so we're going to look at the fitness of a fast swimming predatory fish.

01:42 And again, fitness doesn't necessarily mean physical fitness.

01:46 It's just can you survive and can you reproduce and become more common.

01:52 Fitness is often described as reproductive success.

01:55 So imagine if we have a.

01:57 A normal barracuda.

01:58 Okay, so we have just a normal fish here living in the ocean.

02:04 Whoops here.

02:04 Let me drop that a little bit better and show a fish.

02:11 All right.

02:12 So we have our fish.

02:13 There's our barracuda.

02:15 He's swimming.

02:15 He's looking for things to eat.

02:19 Okay, he's a hungry fish.

02:22 So in normal populations, there is going to be what's called variation.

02:27 There's going to be different sizes of fish.

02:29 Some fish are going to be faster than others.

02:32 Some are going to be smaller than others.

02:34 There's all these different variations that are due to random mutations.

02:40 So let's say we have two different fish, okay? and they're different again because of a mutation.

02:47 So i'm going to write number one, we have what are called random mutations.

02:53 Mutations are just a change in the dna.

02:57 Dna codes for all your traits...

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