Brent Cornell

Key Knowledge: Biological consequences of changing allele frequencies in terms of increased and decreased genetic diversity

Evolution at its most fundamental level simply describes a cumulative change over time

• In living organisms, this involves a change in the heritable characteristics of a population between one generation and the next
  

Heritable characteristics are encoded for by genes and may be transferred between generations as alleles 

• Hence biological evolution describes a change in the allele frequency of a population’s gene pool over successive generations

Gene Pools

A gene pool represents the sum total of alleles for all genes present in a sexually reproducing population

• A large gene pool indicates high amounts of genetic diversity, increasing the chances of biological fitness and survival
• A small gene pool indicates low amounts of genetic diversity, reducing biological fitness and increasing chances of extinction

Allele frequencies will change in a population over time (large populations with stable environments will experience less change)

• Genetic variation occurs naturally (via mutations) to increase the genetic diversity of a population by creating new alleles
• Evolutionary processes (e.g. natural selection) will decrease genetic diversity as species are adapted to suit the prevailing conditions