E.O. – To understand evolution

and inheritance

Focus: To identify how animals and plants are adapted to suit their

environment in different ways and that adaptation may lead to evolution.

SpeciesSpecies are organisms of the same type.

For example, even though there are different

breeds of dogs, they are all the same species. They

show variation.

Darwin recorded observations of plants and animals

that he saw on his sea voyage.

In the Galapagos islands Darwin observed that each

of the islands had similar types of finches. Although

they were the same species, each was different to

make the most of local conditions.

FinchesFinches are types of birds, many of them

eat different types of seeds and insects.

They have adapted the size of their beaks

to match the seeds and insects they eat.

Variation

Goldfinch Bullfinch

How do these two species of Finch vary?Why do they vary?

Darwin’s finches

https://www.youtube.com/watch?v=9uZGSuOxF

VM

As you watch this video, notice all how different all

of the finches look, and how they have different

beaks to eat different foods.

Here are 3 types of finches, each have a different

beak. Each finch has a beak that was the right size

and shape for the type of food on its island.

Finch 1. Finch 2. Finch 3.

The thinnest beak (finch 1) belongs to the green warbler finch which uses it

to probe for insects.

The massive, stout beak (finch 3) of the large ground finch enables it to

crush big hard seeds.

The longer pointed beak (finch 2) of the common cactus finch helps it extract seeds from cactus fruit.

Theory of EvolutionThe Galapagos Finches

I observed that there were lots of different types of finches. People believed

that these were different species of birds that happened to have some

similarities.

However, I realised that these birds were varieties of the same species and

were related.

Theory of EvolutionThe Galapagos Finches

I thought that all the Galapagos finches had originated from one type of finch.

The parents reproduced and created offspring. These offspring would have

variations but look similar to their parents. Some of the variations would be

useful (e.g. a longer beak to reach insects) and some of these variations would

be harmful (e.g. poor eyesight).

Theory of EvolutionThe Galapagos Finches

In one part of the Galapagos Islands, bad weather affected the plants and so

only those with larger seeds were left. Those finches who had slightly larger

beaks were able to eat these seeds while those with smaller beaks could not.

Theory of EvolutionThe Galapagos Finches

Only the offspring with large beaks could break open and eat the larger seeds.

Therefore, these offspring survived and the other, smaller beaked offspring

died. ‘Survival of the fittest’ means those that are most suited to their environment as a result of their inherited or adaptive traits survive while

others do not.

Theory of EvolutionThe Galapagos Finches

The Galapagos finches with large

beaks reproduced and had

offspring. More of these offspring

inherited large beaks and survived.

In other parts of the Galapagos

with different food types, smaller

beaks ensured better survival than

larger ones, larger eyes than

smaller ones, etc. The adaptations

caused by variation meant that

over a long period of time the

Galapagos finches evolved

adaptive traits that caused

differences between them.

Theory of EvolutionThe Galapagos Finches

These offspring would also have differed

due to inherited and environmental

factors and so eventually over time

stopped resembling their common finch

ancestors.

Evolution is the process of adaptation over

a long period of time.

This process, whereby certain inherited

and adaptive traits allowed them to live

and reproduce while others became

extinct, is called natural selection.

Finch Ancestors

Different varieties of finches

who evolved from a common

ancestor that exist today.

Independent Challenge

• Use your dinosaur packs from the previous lessons in this topic.

• Look at the worksheet with the 4 different habitats on (next slide).

• Imagine that your dinosaur has had 4 offspring and all have been born with slightly different features (e.g. the woolly mammoth offspring may have been born without fur, or with a hump, or slimmer).

• Draw a representation of what each offspring looks like and annotate, with sentences, the features that have changed and that are helpful to each new environment.