Biology Unit 1 Topic 7

Evolution

Darwin's theory of evolution

He has wrote a book called On the Origin of Species which explained his ideas.
It caused controversy and was only gradually accepted.
It conflicted with religious views
He did not have enough evidence but is not supported by evidence from fossils and by rapid changes that can be seen to occur in organisms.

His theory states that evolution happens by natural selection
Individuals in a species have a large range of variation as they have a difference in their gene.
Individuals with characteristics more suited for the environment are more likely to survive and reproduce.
Genes of these individuals pass down to offsprings.
Individuals poorly adapted are less likely to survive and reproduce.

Different organisms can be classified by their similarities and differences.
Evolutionary trees are used to represent relationships between organisms.

Lamarck developed an alternative theory of evolution.
Characteristics used by an organism becomes stronger, one that is not used eventually disappears. Features of an organism is improved as use is passed to its offsprings.

Mutation causes changes in genes.
A rapid change in a species may happen if the environment changes.

Peppered moths

Before the industrial revolution in Britain, peppered moths were mostly pale as they were camouflaged against pale birch trees they rest on.
Moths with a mutant black colouring were easily spotted and eaten by birds.
The white variety had an advantage and were more likely to survive and reproduce

Pollution then blackened the birch trees with soot.
Mutant black moths were now camouflaged and pale moths were more vulnerable to predators.
Black moths were more likely to survive and reproduce and is far more numerous in urban areas.