Topic 5: Ecology and Evolution

What do you know about evolution?

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

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)

5.4.2 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

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

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

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

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

5.4.3 State that populations tend to produce more offspring than the environment can support. 5.4.4 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

Sexual reproduction results in genetic variation 5.4.5 State that the members of a species show variation. 5.4.6 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.

Two sources of genetic variation: 5.4.5 State that the members of a species show variation. 5.4.6 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)

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.

Natural selection: Head lice

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’

Mimicry

Camouflage

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 140-142); one must be antibiotic resistance ‘Survival of the fittest’