IB Biology Sub-topic D4.1 Notes

Previously, the concept of evolution and evidence supporting the theory was covered. This topic focuses on the process of evolution via natural selection.

Natural selection is the process by which an organism that is more adapted to its environment can survive, and so pass on the genes for its adaptation to its offspring. In order for this to occur, two criteria must be met:

1. There must be genetic variation within the population that causes different characteristics. These are caused by:
   1. Mutation - to form new alleles.
   2. Meiosis - to form new combinations of alleles via crossing over in prophase I or random orientation in prophase II.
   3. Sexual reproduction - combining alleles from two individuals to form groups of alleles.
2. This variation must result in an adaptation. This is defined as a characteristic that make an organism suited to a particular way of life.