1. Name:
AS Biology Topic 4 – Adaptation and Natural Selection
Adaptation
An adaptation is a feature common in a population because it provides some improved
function. Adaptations may take many forms:
• A behaviour that allows better evasion of predators
• A protein that functions better at body temperature
• An anatomical feature that allows the organism to access a valuable new resource
Natural Selection
• Mutations arise in the population
• Those that are unfavourable or deleterious result in reduced fitness
• Those that are advantageous result in improved fitness
Microevolution and Macroevolution
Small changes in the distribution and proportion of alleles within a species is known as
microevolution.
Many small changes can, in time, result in a population that is no longer capable of
reproducing and forming viable offspring with the parent population.

2. This means a new species has been formed. The formation of new species and other taxa
is known as macroevolution.