1. Topic 5: Ecology and Evolution

2. What do you know about evolution?

3. 5.4.1 Define evolution
The process of cumulative change in the heritable characteristics of a population.

4. 5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
Fossil record
Fossils were not identical but had similarities to existing organisms
It shows that life on earth is constantly changing (over millions of years)

5. 5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
Selective breeding/artificial selection
Accumulation of small changes over several generation to produce animals with desired characteristics
Manipulated by humans/not natural

6. Example : all mammals have 7 neck bones
5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
Homologous structures
Anatomical structures found in different species but are similar in form/structure
This suggests that there was a common ancestor
Example : all mammals have 7 neck bones

7. Horse/bat/cat/human/whale/bird
5.4.2 Outline the evidence for evolution provided by the fossil record, selective breeding of domesticated animals and homologous structures.
Horse/bat/cat/human/whale/bird
Five fingered limbs in animals 1 2 3 4 5 6

8. Can you guess which is human?
vertebrates including humans, chickens, and fish all have a bony tail.
Fish, salamander, turtule, chicken, pig, cow, rabbit, human

9. Mechanism for Evolution
Suggested by Darwin and Wallace
Tries to describe how evolution occurs
It consists of two main aspects:
Over production of offspring
Natural variation in a population due to sexual reproduction and mutations

10. 5.4.3 State that populations tend to produce more offspring than the environment can support Explain that the consequence of the potential overproduction of offspring is a struggle for survival.
Observation: More offspring are produced than can survive
Result: Struggle for survival/resources can lead to adaptive behaviours

11. Sexual reproduction results in genetic variation
5.4.5 State that the members of a species show variation Explain how sexual reproduction promotes variation in a species.
Sexual reproduction results in genetic variation
Remind that variation comes for meiosis (prophase 1)
Is it better to have genetic variation in a population? Explain your answer.

12. Two sources of genetic variation:
5.4.5 State that the members of a species show variation Explain how sexual reproduction promotes variation in a species.
Two sources of genetic variation:
Random mutations may lead to diseases, may be neutral, or may be advantageous. However, this is minor source of variation as there are few mutations each generation
Sexual reproduction (lotteries)
Meiosis: random distribution of chromosomes from mum/dad; crossing over
Fertilisation: which sperm will fertilise the egg?
Remind that variation comes for meiosis (prophase 1)

13. 5.4.7 Explain how natural selection leads to evolution.
1) Each species shows variation. Giraffes have different neck lengths.
There is competition within each species for food, living space, water, mates etc
Get off my land
Noooo 
The “better adapted” members, the long necked giraffes, are more likely to survive and breed since they are more likely to feed.
Remind that variation comes for meiosis (prophase 1)
Yum
Survivors will pass on their beneficial genes to their offspring as long as the environment stays the same, more giraffes will have long necks over time.

14. Natural selection: Head lice

15. 5.4.7 Explain how natural selection leads to evolution.
Evolution is not random. The survival of organisms is dependent on the compatibility of their traits with the environment they live in. The steps are:
Overproduction of offspring with genetic variation
Members with genetic characteristics that are poorly adapted the environment are less likely to survive and pass on their genes
Members with genetic characteristics that are better adapted are more likely to survive and pass on their genes
Over many generations, accumulation of the heritable characteristics results in evolution (gene pool has changed)
‘Survival of the fittest’

16. Mimicry

17. Camouflage

18. 5.4.8 Explain two examples of evolution in response to environmental change; one must be antibiotic resistance in bacteria.
Task: In your notes, describe two examples of evolution (pages ); one must be antibiotic resistance
‘Survival of the fittest’