Hardy-Weinberg Equilibrium: Migration

Question 1

what is migration

Answer 1

• gene flow
• Genes moving from one place to another, forever
• Individuals reproduce in that environment and contributing genes

Question 2

what does migration do to allele frequencies when acting alone

Answer 2

if alleles are selectively neutral (no selection) migration homogenizes allele frequencies among populations

Question 3

what is the migration-selection balance

Answer 3

analogous to the mutation-selection balance

Question 4

migration-selection balance - What if selection and migration are in the same direction?

Answer 4

If selection and migration tend to increase the frequencies of the same alleles, selection can amplify effect of migration.

Question 5

migration-selection balance - What if selection and migration are opposed?

Answer 5

• selection > migration: differences among populations will be maintained at some equilibrium frequency, even in the face of migration.
• migration > selection: differences among populations will be reduced (homogenization).

Question 6

migration-selection balance example

Answer 6

• Water snakes (Nerodia sipedon)
• dominant allele: banded color pattern
• recessive allele: unbanded colar pattern
• Natural selection favors banded on mainland and unbanded on islands

Question 7

migration-selection balance example - What direction does migration occur in?

Answer 7

From banded mainland (bc it’s a big population) to unbanded island (tiny island population)

Question 8

migration-selection balance example - What happens to island populations?

Answer 8

• homogenization among populations
• 2 phenotypes are in equilibrium

Question 9

migration-selection balance example - how is selection working here

Answer 9

• Selection is favoring unbanded but its not going to fixation (or evolving) bc enough banded ones keep showing up via migration
• Creates equilibrium or balance