| resources for science teachers who like to think TopicEvidence for evolutionLevelA Level Outcomes1.To describe the key points of Darwin’s theory of evolution by natural selection 2.To state and explain the main pieces of evidence for evolution

How did such tremendous diversity of life come to exist on this planet?

Evolution Each organism is unrelated and is created independently Life evolved many times All life shares common ancestry - all life is related Life evolved once only

What Did Darwin Do? Two key things: 1. He provided evidence for evolution 2. He proposed a theory to explain the mechanism by which evolution occurs

Evolution Darwin's definition: descent with modification.,

1.Organisms have changed overtime 2.All organisms share common ancestors 3.Change is gradual Darwin’s Evolution

1. Fossil Record – Change over time

2. Shared Structures – Common Ancestry

3. Similarities Between Embryos – Change is gradual

The Mechanism for Evolution Natural Selection

1. There is a "struggle" (metaphorically) to survive and reproduce (organisms produce potentially more offspring that can possibly survive) 2. Organisms show variation in characters that influence their success in this struggle for existence. 3. Parents possessing certain traits that enable them to survive and reproduce will contribute disproportionately to the offspring that make up the next generation. 4. The population in the next generation will consist of a higher proportion of individuals that possess whatever adaptation enabled their parents to survive and reproduce. 5. Overtime the population will become adapted to the environment

Requirements for Natural Selection 1. Heritable variation for some trait 2.Differential survival and reproduction associated with the possession of that trait.

Antibiotic resistance – an example of modern day evolution by natural selection

Variation in population  over production of offspring  competition between offspring  best adapted survive and reproduce  favourable characteristics passed onto next generation

Why haven’t polar bears got white noses?

4. Genetic Changes

Darwin's Theory of Evolution by Natural Selection Individual characteristics of an organism are vitally important for its ability to survive and to breed Individuals of a given species vary in many characteristics Individuals produce more offspring than can survive i.e. there is competition Only a small proportion of offspring will therefore survive. If those characteristics which help the oranThese individals that survive

Did humans evolve from chimpanzees?

Evidence for Evolution 1.Fossil evidence shows the course of evolution through time 2. Similar structures are shared by many organisms 3. Comparative embryology (looking at similarities between developing embryos of different species)