What You Need to Know

Key Concept Diagram

Natural selection favours heritable traits that increase reproductive success in a given environment

Genetic drift is random change in allele frequencies due to chance events, most significant in small populations

Gene flow is the transfer of alleles between populations through migration, reducing genetic differences

Mutations are changes in DNA sequence that introduce new alleles, providing the raw material for evolution

Key Vocabulary

Natural Selection

The process by which individuals with advantageous heritable traits survive and reproduce more successfully than others

Genetic Drift

Random fluctuation in allele frequencies within a population due to chance, particularly pronounced in small populations

Gene Flow

The movement of alleles between populations via the migration and interbreeding of individuals

Allele Frequency

The proportion of a particular allele among all alleles for that gene in a population

Knowledge Check

Select the correct answer for each question. Click "Check Answer" to see if you are right.

Question 1

Which mechanism of evolution is most significant in very small, isolated populations?

Genetic drift Gene flow Natural selection Mutation

Question 2

A new mountain range forms, separating one rabbit population into two. Over many generations, the two populations become reproductively isolated. This is called:

Gene flow Allopatric speciation Genetic drift Adaptive radiation

Question 3

Mutations are important for evolution primarily because they:

Always improve an organism's fitness Transfer alleles between populations Introduce new alleles that provide variation for natural selection to act upon Are always passed to the next generation

Mechanisms of Evolution