Lesson video

Hello there.

My name is Mr. Wilshire, and in this lesson we're going to be looking at the survival of the fittest.

The outcome for this lesson is I can explain the meaning of survival of the fittest and give examples in animals or plants.

There are some key words to consider as we work our way through this lesson.

The first is Charles Darwin.

Next is adaptation, then offspring.

After that, survive and finally reproduce.

Don't worry if you're not too sure what some of these words mean, the meanings will flash up on the screen for you now.

So you can pause the video here and remind yourself if you need to.

First part of this lesson is called Darwin's Theory.

Now, Charles Darwin was an English naturalist who was born in 1809.

Here you can see a picture of Charles Darwin.

Now he's most famous for his theory about how living things change over time.

So what do you already know about Darwin and his work? Pause video here and discuss.

Restart when you've done that.

What do you already know about Charles Darwin? Was there anything in particular that stood out for you? Let's find out some more.

Now, in 1835, when he was 26 years old, Darwin travelled to South America to investigate what sort of plants and animals lived there compared to those in Europe.

Here you can see a picture of the world map, and South America is indicated for you.

You can see that it was a very, very long way away from England.

On a small set of islands off the coast of Ecuador called the Galapagos Islands he observed some finches that looked a little bit different to the ones living on mainland South America.

Here you can see an image of four different types of birds, and he observed that the birds on each island had beaks that were slightly different shapes.

You can see that one is very large.

There is another which is very pointy and sharp.

Charles Darwin wanted to know exactly why the birds had different beak, even though they were all the same type of bird.

So let's stop and think.

What did Darwin notice about the finches on different Galapagos Islands? Was it that they were all identical to each other, that they were similar to each other, but had some clear differences, or they were all completely different to each other? The answer here is B.

They were similar to each other, but had some clear differences.

So this made Darwin think about why the birds were different.

You can see an image there of the Americas with North America, Central America, and South America.

He thought that perhaps all of the finches had shared common ancestors long ago.

They'd all flown from the mainland and settled down on different islands.

Here you can see the Galapagos Islands pinpointed for you on the map.

Down here is the mainland of South America, which is where Charles Darwin thought that the finches could have come from.

Darwin suggested that these finches had all looked the same to begin with, but they'd all adapted over time to the best food sources on the islands that they lived on.

This resulted in them looking very different to one another.

Here you can see an image of different Galapagos finches.

Take a little look now at that image and have a think.

What is so different about the two different types of finches? Each finch is quite unique.

One of them is a very large bill, and the other one has more of a needle shaped bill.

Both of them have different ways of gathering food.

Darwin went on to suggest that perhaps all the kinds of living things that exist today and developed from earlier types in the same way that these different finches have developed from a single original species.

Over time, scientists have been able to build up lots of evidence using living species as well as fossils to support this theory.

So let's stop and think.

Darwin suggested that all the kinds of living things that exist today had moved from one country to another, had developed from extinct animals or had developed from earlier types.

The correct answer here is C, had developed from earlier types, which brings us now onto task A.

Sam has been writing about Darwin's theory, so find and correct the mistakes in her work, says here that Charles Darwin was an English engineer who developed some important theories.

So have a scan through and decide which parts are the mistakes and which parts has she got correct.

Good luck with your task.

See you in a moment.

So how did you get on? Well, here we've got some of Sam's mistakes highlighted for you.

Charles Darwin was an English, not an engineer, but a naturalist or a type of scientist who developed some important theories about how living things change over time while travelling around South America, not Africa.

He noticed that finches on different small islands were different to each other, not identical.

This made him wonder how different species were developed.

He suggested that perhaps all kinds of living things that exist today had developed from earlier species, not been the same throughout all of history.

Well done for that first task.

The second part of this lesson is called survival of the fittest.

To help explain how different species of living things develop from other types, Darwin formed a revolutionary theory.

He observed that some animals and plants within a species are more likely to survive than others based on their physical characteristics.

Here you can see an image of a giraffe reaching high up into a tree to nibble at some leaves.

This is a good example.

Giraffes with longer necks that can reach the tallest trees are more likely to survive than those with shorter necks that can only reach the shorter trees.

This is because the taller giraffes have got access to more food, so stop and think.

True or false, some organisms in a species are more likely to survive than others.

The answer here unfortunately is true.

Can you remember the giraffe that we just saw? Let's justify our answer.

Which of these statements match? The answer here is A.

It's true because living things with certain characteristics are more likely to survive than others in their species.

So the living things that do survive can reproduce and then pass on their characteristics to their offspring.

For example, taller giraffes are more likely to reproduce and can pass on their heights to their offspring, which may also be very tall.

This means that generally the most useful and strongest adaptation are passed on to enable the next generation of plants or animals to survive.

Here you can see an image of two giraffes.

Looking like the adult and the youngling.

So stop and think.

Living things that survive longer are more likely to reproduce and pass on their characteristics.

Show others in their species how to adapt or help weaker members of the species to survive? The correct answer here is A, to reproduce and pass their characteristics on to their offspring.

Stop and think again.

Which adaptations are generally passed through several generations of offspring? Is it the weakest and the least useful adaptations? The strongest and most useful adaptations, or the most unusual adaptations? The correct answer here is B.

The strongest and most useful adaptations are generally passed through several generations of offspring.

So over many generations, as species reproduced, most of the living things within a species will have these helpful adaptations.

Here you can see an image of changes to giraffes over time.

Darwin called this theory the survival of the fittest.

That means that those who are more able to survive, whether they have longer necks for reaching taller trees or are stronger so can last for longer in fights or arguments over food or territory, they're the ones who are more likely to survive.

They're the fittest ones.

They're the ones who will survive the longest.

Stop and think.

What does survival of the fittest mean in relation to Darwin's theory? Read the statements here and decide which best matches? The correct answer here is A, living things that are better adapted to their environment are most likely to survive and reproduce.

Some of the children are talking about Darwin's ideas.

Jun says, does survival of the fittest apply to plant adaptations as well as animals? Alex says, I think it does because plants are all adapted to survive in their habitats.

Lucas says, I don't think it does, because plants can't be fit or healthy in the same way that animals can.

So what do you think here? Who do you agree with? Pause the video and restart when you've done that.

So what do you think? Well, in this context, fittest doesn't necessarily mean the most physically fit or healthy.

It means the best suited to the environment an organism is living in, survival of the fittest applies to all living things, including plants.

Here you can see an image of three different types of plants.

There's a spiky leafed holly plant.

There's a rubbery, textured leaf there, and also some pink sticky looking leaves as well.

This is how plants have become well adapted to survive in their habitats.

For example, if there are some flowers in a plant species that have very brightly coloured petals and some that aren't, the colourful flowers are more likely to attract insects be pollinated and then reproduce.

You can see here a pollinator on a flower.

Meanwhile, the plants that don't det attract pollinators and can't be pollinated by wind will find it harder to reproduce and pass on characteristics.

So the plants that we're able to adapt pass on their seeds and their pollen in different ways are able to survive a lot longer rather than waiting around for a pollinator to come along and help them.

This means that the plants with brightly coloured petals are more likely to reproduce and produce more offspring.

As the offspring are more likely to have brightly coloured flowers, they too are more likely to reproduce.

The more colourful the plant, usually the higher the chance of a pollinator being attracted to it.

Eventually, over many generations, most of or the whole species of that plant will have their brightly coloured flowers characteristic.

Here you can see an example of some brightly coloured flowers.

So true or false, survival of the fittest only applies to animals and not plants because plants can't be fit in the same way that animals can.

The answer here is false.

Can we justify our answer? The correct statement is B.

Plants can also have adaptations that make them as fittest to survive in their habitats.

This is task B part one.

Carry out a modelling activity to explore how survival of the fittest may apply to caterpillars.

Follow the instructions given by your teacher and record your findings on the table.

Here you can see an image of a caterpillar.

Here's the table.

Good luck with your task.

See you in a moment.

How did you get on? Using what you found in that table, see if you can answer some of these questions.

Which colour caterpillars increased in number? Which colour caterpillars decreased in number? Did any of your caterpillar colours become extinct? And which caterpillars were the best adapted or the fittest to survive in this habitat? So look through some of your answers and decide, best of luck! Here's an example of some findings.

Here's Laura's results.

They could be similar to yours.

You can see there that the different caterpillar colours down the side in the red section there, the number in the first generation was 10, the second was two, and then nothing.

Hmm, wonder which of these survived the longest.

Let's have a look.

So the caterpillars that increase in numbers were green and black.

The caterpillars which decreased in number was red and yellow.

The caterpillar colours that became extinct was red, and the one that we think is the fittest here is the green.

Were your answers similar to ours? Well done for completing that task.

The final part of this lesson is called peppered moths.

The peppered moth is a species of moth that lives in forests in the UK.

Here you can see an image of some peppered moths.

I wonder if you can spot all of the peppered moths in this picture.

Pause the video and restart when you've done that.

Did you find all of the peppered moths? Well, there's one.

There's another.

Here's another.

There's one more.

Did you find all of them there? They're very well-camouflaged, aren't they? So peppered moths come in two variations, white with black speckles and black.

Here you can see an image of the peppered moths.

One white with black speckles and the other one just black.

Peppered moths are nocturnal.

So in the day they perch on tree trunks, it's very important that they're camouflaged or otherwise hungry predators are gonna come along and find them and eat them.

Which variation of peppered moths do you think will be best adapted to survive in a habitat with trees a little bit like this? Have a look at this image here of the tree and decide which species will survive.

Did you decide which species? Well, the white speckled moths are gonna be much better hidden in bark like this, aren't they? They're the best adapted to survive in this environment.

Here you can see an example of how the white and speckly moth is going to blend in a lot more.

The black moth, however, really stands out here for any predator to come along and eat it.

So stop and think.

Why are white speckled moths more likely to survive in this habitat than black ones? Is it because they'll be able to fly faster? They can find food more easily, Or they blend in with the tree bark? The correct answer here is C.

They'll blend in with a tree bark better than the black moths.

Up until the 1800s, the white speckled moths were much more common because more of them survived and reproduced than the black moths.

Around this time, factories started using more machinery to produce goods.

Here you can see an illustration from 1839.

Around the time of the Industrial Revolution, the machines needed to burn lots of coal to work.

This sent lots of soot and ash into the air.

The soot then caused the tree bark to turn black.

So which variation of peppered moths do you think will be the fittest to survive in this example? Which one did you guess? It'd be much harder for birds to spot the black mo on trees like this.

So they are much better suited to their environment.

The white one there really stands out.

As more factories created more soot and trees became darker.

Far more of the black peppered moths survived and reproduced.

The lighter moths almost disappeared entirely.

A couple of centuries later, the white speckled variety of moth is now much more common than the dark one.

Why do you think this is? Pause the video and discuss.

So why did you think? Let's find out more.

Now, people are conscious of the impact their actions have on the environment.

So there are lots of efforts to reduce pollution and burn fewer fossil fuels.

So this has resulted in a cleaner environment.

So tree trunks are no longer black with soot.

So stop and think.

If a plant disease caused all of the trees in a forest to turn black, which type of peppered moth would be the fittest to survive in this habitat? Read the statements there and decide.

The correct answer here is B.

The ones with darker colouring.

Here is task C.

Izzy's little sister has heard her talking about the story of peppered moths to her parents.

She hasn't completely understood though, so Izzy sister says, so the moths decided to have lots of babies with black wings so they could survive in city forests? Explain why the moths became darker in the 1800s.

Remember to keep your explanation simple and clear, because Izzy sister is a lot younger than you are.

Best of luck with your task.

See you in a moment.

So how did you get on? Here's an example of something that you could have written, in the 1800s, pollution from factories made trees in the moths' habitat look black.

This meant black moths could hide from predators better, and more of the lighter moths got eaten before they could reproduce, the dark moths had more offspring that were dark like them.

So more and more of the moths were dark-colored over time.

I wonder if you wrote something similar.

Well done for completing that task.

Let's summarise our lesson.

Charles Darwin suggested that all the kinds of living things that exist today developed from earlier types.

He knew that some animals and plants are more likely to survive than others, and the ones that do survive can reproduce to pass on characteristics to their offspring.

The most useful and strongest adaptations are passed on to the next generation of plants or animals.

Darwin called his theory about adaptation, the survival of the fittest, which means that living things that are better adapted to their environment are most likely to survive and reproduce.

I hope you enjoyed learning about the different aspects of Charles Darwin's theories there.

It's certainly fascinating to find out that there are different of animals that are able to change over time.

So I wonder how we might change over time in the future.

I've been Mr. Wilshire.

Thank you very much for listening.