lecture 37 - island biogeography

Question 1

What is the effect of increased island area on species richness?

Answer 1

increased species richness

Question 2

What is Darlington’s rule of thumb?

Answer 2

constant relationship

if you move from one area to one 1/10th the size, the number of species in a particular group will be more than halved

Question 3

Describe equilibrium

Answer 3

rate of arrival of new species on an island drops over time as species accumulate over time
extinction rate increases over time as individuals from different colonising species compete for resources
eventually these rates balance each other at equilibrium

smaller islands have fewer species at equilibrium than larger islands
larger islands have more colonists and lower rates of extinction compared to smaller islands
assumes no difference in isolation of islands

Question 4

What is extinction debt?

Answer 4

the occurrence of more species than an area can support, because not all species have yet died off once an area has reduced in size

Question 5

What is relaxation time?

Answer 5

time taken to lose species after fragmentation

Question 6

Which species will be lost?

Answer 6

species living at low population densities
those with large range requirements
those high up the trophic ladder
those that depend on rare habitats or scarce resources