Genetic Variation & Survival

Goal: Explain how sexual reproduction creates variation and why variation helps species survive

Why does sexual reproduction produce genetic variation?

It combines genetic material from two parents and creates new genetic combinations

What is crossing over?

Homologous chromosomes exchange sections of DNA, creating new combinations of alleles

What is independent assortment?

Chromosomes are randomly distributed into gametes, creating different combinations

How does random fertilisation create variation?

Any one of millions of sperm can fertilise an egg, creating a unique combination of genetic material

What is genetic variation?

Differences in the genetic characteristics of individuals in a population

Why is genetic variation important for survival?

It means some individuals may have traits that help them survive diseases or environmental changes

What could happen to a genetically identical population when a new disease appears?

They are all likely to be similarly vulnerable, so a large part or all of the population could die

Why was the Irish potato crop vulnerable to disease?

The potatoes were genetically very similar, so they had little variation to resist the disease

Which is generally better for long-term survival: high or low genetic variation?

High genetic variation, because it increases the chance that some individuals can survive environmental changes or diseases

What is the connection between genetic variation and natural selection?

Variation means some individuals have traits that help them survive and reproduce, so those traits can become more common over generations