Lecture 10 - Island biogeography

Question 1

MacArthur & Wilson

Answer 1

developed model predicting species richness on islands

Question 2

isolation and saturation

Answer 2

mainland = shallower slope
further from mainland = fewer species
degree of saturation decreases with distance

Question 3

island communities formation

Answer 3

immigration = must arrive
extinction = must persist
richness = balance of both

Question 4

(formation) immigration

Answer 4

declines as species increase

Question 5

(formation) extinction

Answer 5

increases with no. species

many = local extinction, resource competition suppress pop size

Question 6

(formation) equilibrium

Answer 6

no. species present constant after equilibrium reached

e. g. Krakatoa volcano exterminated flora and fauna = tests equilibrium theory

Question 7

(formation) dynamic species competition

Answer 7

new species (immigration) replace/drive extinction of residents

Question 8

colonisation curves

Answer 8

increase rapidly, then slow

Question 9

isolation effects

Answer 9

isolated = less chance reaching island, reduced immigration
- equilibrium species richness = declines with isolation

close to mainland = restock populations, reduced extinction
- equilibrium richness = increases, rescue effect

Question 10

area effects

Answer 10

immigration = increase with area, decline with isolation
extinction = decrease with area, increase with isolation

Question 11

testing equilibrium theory (observational)

Answer 11

assumes species reaches equilibrium, a-diversity declines with isolation, dynamic composition

e. g. birds California channel islands
- strong SAR, weak SIR
- evidence of turnover and equilibrium

Question 12

testing equilibrium theory (experimental)

Answer 12

defaunation Florida keys - Simberloff & Wilson

• fumigated mangroves
• collected terrestrial arthropods, surveyed recolonization
• colonisation curve = no. on near island soon reached pre levels 160 days
• far island = below original
• low turnover rate, similar set species return

Question 13

limitations equilibrium theory

Answer 13

• immigration extinction rate slopes unknown = vary island to island
• islands may not be in equilibrium = ex + imm vary among species
• ex + imm = not independent, high immigration saves from extinction (rescue effect)
• multiple islands and mainland immigration - multiple routes, assumes no speciation

Question 14

speciation Caribbean islands

Answer 14

adaptive radiation

Question 15

speciation fraction

Answer 15

species arise from insitu speciation

Question 16

evolutionary species area relationship

Answer 16

y axis = sp. fraction

x = area __/