Charles Darwin’s Theory of Evolution Charles Darwin explored the world on the Beagle for 5 years collecting specimens for the Museum of Natural History in London. science/inventcdarwin.html SlideShow/SlideShow1a.html

Charles Darwin Galapagos Islands: a wide range of finch species descended from a single species. Different species adapted to different feeding niches (seeds, fruits, insects). Life Nature Library 1971

Charles Darwin Published his theory of evolution based on natural selection in Natural selection The increased reproduction of individuals that have traits (features / characters) better suited to survive and reproduce in an environment.

Traits Characters or features that are genetically inherited. They may be obvious, e.g. eye colour and height. They may be less obvious, e.g. aggression, speed, memory.

Evolution is the change in genetic make-up (traits) of populations through time (e.g. modern humans becoming taller). Population : members of a species that occupy a specific region and which come together to mate.

Biological species concept A group of interbreeding organisms that can produce fertile offspring. e.g. Homo sapiens – modern humans We can mate with anybody from anywhere in the world, and our children can have children. This makes us all ONE species.

Darwin observed: That all over the world, geological sequences contained simpler, more primitive forms lower down.

Genes are not the only factor that determine an organism’s appearance. Environmental influences: A person with a dominant gene for height could end up short due to poor diet and living conditions. Mutation: random change in an individual’s genes.

E.g. of a useful mutation: A lamb born with short, bent legs that prevented it from jumping fences. Used in breeding to establish short-legged sheep.

Traits that may ensure the survival of the fittest animal in a specific environment could include for example: An eagle that has inherited 1. very good eye sight for hunting 2. an ability to fly well 3. a means of attracting a lot of mates for reproducing with, e.g. a song.