Evolution - Lecture Two

Question 1

What are olfactory genes and why were they lost?

Answer 1

• Olfactory receptor genes were lost in some animals through evolution because they weren’t used
• Eg as cetaceans evolved to live underwater they lost their olfactory genes because they can’t smell underwater

Question 2

What are lactase persistence genes?

Answer 2

• They allow humans to digest lactose
• Levels are different over the world due to different traditions, eg in Europe we drink more milk so have evolved to have the lactase persistence gene

Question 3

What is neutral theory?

Answer 3

• The idea that most changes at a molecular level have little consequences, are neutral
• If the mutation has no fitness consequence, its future in a population is determined by chance
• This means we can’t predict whether a neutral mutation will be fixed in a population, only the rate neutral substitutions occur