Transcript To refer back to the Powerpoint from our lesson about evolution

Variation
Red-browed finch
House finch
How do these
two
of Finch vary?
Why
dospecies
they vary?
DON’T TOUCH ANYTHING
ON THE TABLES
All you need is a pen or pencil
WALT understand how
adaptation can lead to
evolution.
Variation
Red-browed finch
House finch
How are these species of Finch adapted?
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.
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.
What are different types of
beaks suited to?
 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.
Time:
10 minutes
Expectation:
Everyone to complete first 3
finches.
Writing up an investigation
 Aim
 Apparatus
 Method
 Fair test
 Prediction
 Results
 Diagram
 Conclusion
Imagine
 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 Distribution
 How does this model help us to
understand why different species
exist in different environments?
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.
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.
 https://youtu.be/BcpB_986wyk
 In whichever way you’d like, explain the process of
evolution.
What if . . .
The seeds on Espanola started to increase in size?
1. What would you expect to happen immediately to the
population of Small Ground Finches?
2. What would you expect to see happen to the
population over the next 20 years?
3. What would happen if the size of the seeds decreased
again in the future?
Exam question (5 marks)
Two different species of butterfly:
Amauris
Hypolimnas
Both species can be eaten by most birds.
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 Hypolimnas may
have developed its wing markings
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; evolution
Remember: make your answer specific to example given.