Colonizing Hawaii

Question 1

Hot spot

Answer 1

an anomalously hot area of the earth’s mantle, slowly convecting- melts and magma rises- formed with plume from core- usually forms strings of islands- Hawaii from subduction along American and mid-ocean ridge

Question 2

Loihi

Answer 2

youngest of Hawaii islands and underwater- active subaerial volcanism (will eventually form an island)

Question 3

Island formation

Answer 3

built from sea floor by volcanic eruptions- very fluid and low gas content (non-explosive), many flows

Question 4

Hawaii founder species

Answer 4

all organisms seem to have evolved from a few founder species- expanded through speciation (fruitfly hotspot)

Question 5

Mechanisms of dispersal

Answer 5

ocean dispersal, aerial dispersal (wind- ferns, mammals, birds), avian dispersal (flowering plants) (no amphibians or reptiles by these means)

Question 6

where they came from

Answer 6

investigated by traditional comparisons of morphology and more recently by genetic comparisons- most founders from asia

Question 7

Why did founders come?

Answer 7

Trade winds, high altitude jet stream from asia- transport spores, small seeds, insects (if they can stand the cold), migration from flying animals

Question 8

Climate

Answer 8

elevation difference- leads to difference of climates on either side of the islands

Question 9

colonizers of lava

Answer 9

ferns, colonize after cooling, lichen grow directly on lava- organic matter grows and decays- weathers rocks- enrich organic material and creates soil, most succession supported by “blocky” flow

Question 10

Volcanic ash

Answer 10

nutrient rich- creates lush rainforests- need less moisture- makes deep soil for luxurious growth- absorbs moisture so streams rare (only fall over lava beds

Question 11

Colonization factors

Answer 11

age of substrate, type of substrate, amount of rainfall

Question 12

genetic study

Answer 12

compare frequency of alleles among populations, rare allele shared by population- suggest all individuals from single ancestor

Question 13

unusual niche filling

Answer 13

common herbivores and predators absent from hawaii, leads to niche filling and potential loss of adapted defenses

Question 14

atoll formation

Answer 14

leads to coral reefs, underwater islands, coral low diversity and wont grow very large- only reachable by good dispersers i.e. pocillopora- hybridizes readily; deep water rely less on photosynthesis and more on food capture- deep water corals more sensitive to temperature fluctuation and grow more slowly/ reproduce less often