Variation - PowerPoint Presentation

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Variation - Description

Redbrowed finch House finch How do these two species of Finch vary Why do they vary DONT TOUCH ANYTHING ON THE TABLES All you need is a pen or pencil WALT understand how adaptation can lead to evolution ID: 540460 Download Presentation

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Red-browed finch

House finch

How do these two species of Finch vary?

Why do they vary?Slide2


All you need is a pen or pencilSlide3

WALT understand how adaptation can lead to evolution.Slide4


Red-browed finch

House finch

How are these species of Finch adapted?Slide5

Charles Darwin

Modern ideas of evolution started with Charles Darwin


In 1831 Darwin set out as a ship’s naturalist on HMS Beagle, it was a 5 year voyage to South America and the South Sea Islands.Slide6

Voyage of the Beagle

Darwin recorded observations of plants and animals that he saw on the voyage.In the Galapagos islands Darwin observed that each of the islands had similar types of finches, iguanas and tortoises, but that each was different to make the most of local conditions.Slide7

What are different types of beaks suited


Your task is to plan an investigation to find out which birds’ beak would be best at helping a bird to survive on a diet of a particular seed.You have 7 minutes of discussion with your group, then 5-10 mins to write up what you’re going to do.


10 minutes

Expectation:Everyone to complete first 3 finches.Slide8

Writing up an investigation

AimApparatusMethodFair test

PredictionResults DiagramConclusionSlide9

The birds have been separated by a storm onto two different islands. There has been a drought and most food types have died out, so the food that is available on each island is now different.


Finch DistributionSlide12

How does this model help us to understand why different species exist in different environments?Slide13

Darwin’s Theory

Darwin only observed one type of finch on the mainland- similar to the Galapagos Small Ground Finch.

He proposed that all finches evolved from the one species that lived on the mainland.Slide14

What factors would have to exist for a species to be able to change?

Genetic variation due to mutation.Competition; for food, mates, territory, to avoid predation.

‘Survival of the fittest’ the organism that is best adapted to its environment will survive.Reproduction- passing on the advantageous alleles to the offspring.Leading to change in the species over time- evolution.Slide15



In whichever way you’d like, explain the process of evolution.Slide17

What if . . .

The seeds on Espanola started to increase in size?

What would you expect to happen immediately to the population of Small Ground Finches?What would you expect to see happen to the population over the next 20 years?

What would happen if the size of the seeds decreased again in the future?Slide18

Exam question (5 marks)



Both species can be eaten by most


Amauris has a foul taste which birds do not like, so birds have learned not to prey on it.Hypolimnas

does not have a foul taste but most birds do not prey on it. Describe, in terms of natural selection, how


may have developed its wing markings

Two different species of butterf


Mark Scheme:

Mutation caused changes in marks in Hypolimnas

.Competition; less predation of butterflies with these markings.These butterflies survived to reproduce; other butterflies were eaten.Advantageous allele/

gene was passed on to offspring.Over time population of Hypolimnas start to look more like Amauris

; evolutionRemember: make your answer specific to example given.