Drift

Question 1

What is drift?

Answer 1

Random fluctuations in population size

Question 2

Whats the lottery model?

Answer 2

• Space is limited in coral reefs and forests

- Each time an individual dies, replace with another species at random

Question 3

Whats the neutral theory of biodiversity?

Answer 3

• Species may (unstably) co-exist if they go extinct slowly
• New species gradually added by dispersal or speciation
• Leads to an equilibrium species distribution

Question 4

What can the neutral theory of biodiversity give good predictions for?

Answer 4

Species abundances

Question 5

Whats the difference between neutral drift and niche based selection?

Answer 5

-Neutral- No fitness differences,
No stabilizing effects

-Niche- Large fitness differences,
Large stabilizing effects

Question 6

What happens if fitness differences are small?

Answer 6

• Time to extinction is long
• Unstable coexistence
• Weak stabilization enables coexistence

Question 7

What happens if fitness differences are large?

Answer 7

• Time to extinction is short
• Potential for competitive exclusion
• Strong stabilization required for co-existence