4.4 Genetic diversity and adaptation

What is genetic diversity?

The number of different alleles in a population

What is an allele?

Variations of a particular gene → different DNA base sequence

How do alleles arise?

By mutation

What is a population?

A group of interbreeding individuals of the same species

What is the importance of genetic diversity?

Enables natural selection to occur → mutation may create a beneficial allele, giving them an advantage (eg increased chances of survival and reproductive success)

What is evolution?

The change in allele frequency over many generations in a population, occurring through the process of natural selection

Describe the process of natural selection

Random gene mutations can result in new alleles

In certain environments, this new allele might be beneficial so organism has a selective advantage

Organism more likely to survive and have increased reproductive success

Advantageous allele is inherited by members of the next generation

Over many generations, allele frequency increases in population

Describe the three types of adaptations

Anatomical → Structural/physical features that increase chance of survival

Physiological → Processes/chemical reactions that increase chance of survival

Behavioural → Ways in which an organism acts that increases chances of survival

What are the two types of selection?

Directional

Stabilising

What is an example of directional selection?

Antibiotic resistance in bacteria

What is an example of stabilising selection?

Baby birth weight

Who has an advantage in directional stabilisation?

Organisms with an extreme variation of a trait (eg bacteria with a high level of resistance to a particular antibiotic)

Who has an advantage in stabilising selection?

Organisms with an average/modal variation of a trait (eg babies with an average weight)