1. Defined as: Evolution is the cumulative change in the heritable characteristics of a population.

2. At twenty two years of age, Darwin embarked on a five year trip around the World on the HMS Beagle (1831). His ideas were presented in 1858 in conjunction with Alfred Russell Wallace.

5. This was drawn in 1871, published in a popular satirical magazine. What does it tell you about how his ideas were received?

6. Evidence? 1.Fossil record What conclusions can we draw from the fossil record? - Life is constantly changing! - We have evidence going back 500 million years

8. 2. Selective breeding Farmers have been artificially selecting ‘desirable’ characteristics for farm animals for generations. In no way the same as evolution in natural ecosystems, but does provide evidence of small evolutionary changes over time

9. 3. Homologous anatomical structures Similar forms found in different species. E.g. five fingered limbs found in Whales, Bats and Humans. This was viewed by Darwin as evidence of common ancestry.

10. How to explain the mechanisms for evolution? Living organisms typically produce more offspring than would be able to survive. Why does this happen? Creates a ‘struggle for survival’ ensures only the strongest offspring will survive and pass their genes on to the next generation. Darwin’s idea: Survival of the Fittest.

12. Variation & success Variation closely linked to survival rates. Mouth shapes can affect feeding ability Flowers attracting pollinators Colouring to hide from predators Etc…

14. What are the causes of variation? 1.Mutation 2.Sexual reproduction How do these two factors cause variation within a species?

15. Evolution by Natural selection Over production of offspring, population of new offspring contain useful and harmful variations Genetic traits that are not useful lead to the chance of the individual surviving to adulthood greatly reduced Well adapted genetic traits increase chance of survival Successful individuals are able to reproduce Over time, gene pool for a species changes because of this process. Evolution. Do ‘Only the Strongest Survive?’ or is evolution more complicated than that? Examples?

16. For the IB you need to be able to explain evolution in response to environmental change for two organisms. One must be antibiotic resistance in bacteria. Other examples include: The changes in size and shape of the beaks of Galapagos finches, Pesticide resistance in rats, Industrial melanism (moths), Heavy- metal tolerance in plants,