What is natural selection
Animals who adapted the quickest and most suited, and follow the rule of ‘survival of the fittest’ will overrule any other animal it is competing with. It was first thought up by Charles Darwin in 1859
What were the 5 main points of Darwin’s theory
- within any species there is always natural variation
- organisms produce much more young that will survive
- there will be competition for limited resources such as food
- only the best adapted will survive; survival of the fittest
- those that survive pass on their successful adaptations onto their offspring in their genes
How are survival adaptations passed on to the next generation
They are passed on through genes that are found inside cells, specifically in DNA, however Darwin didn’t know this at the time of his theory
Why did people object to Darwin’s theory
- many didn’t think he had enough evidence to back up his theory
- many disagreed because they thought God created all species
- some objected to the idea that humans evolved from apes
How do genes control the colour of the peppered moth
In parts of the country that have high pollution, lichen growing on the bark of the trees is killed by the pollution and the bark becomes darkened. Dark moths are camouflaged on dark tree bark, so there are more dark moths in polluted areas. The opposite happened in cleaner areas (more pale coloured moths)
How does bacteria evolve against antibiotics
When doctors give us antibiotics, they try and fight harmful bacteria. However more and more bacteria are developing resistance towards antibiotics, so if the antibiotic doesn’t kill the bacteria, the bacteria will reproduce (asexually) and pass on the resistance gene to the next generation
What is Lamarck’s theory of evolution
The law of acquired characteristics - giraffes would acquire long necks to feed by stretching, and pass on this characteristic. It has now been discredited
How can penguins adapt in different ways to survive
- some penguins will be able to live and breed closer to the South Pole
- some can survive really bad weather
- others are better swimmers and can catch more fish, and also have a better chance of escaping predators such as killer whales and leopard seals
Why do animals go extinct
Because the environment around it changed but it failed to evolve, and so a more evolved and adapted species will take its place
