Colonizing Hawaii Flashcards Preview

ENVR 202 pt. 2 > Colonizing Hawaii > Flashcards

Flashcards in Colonizing Hawaii Deck (14):

Hot spot

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



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


Island formation

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


Hawaii founder species

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


Mechanisms of dispersal

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


where they came from

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


Why did founders come?

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



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


colonizers of lava

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


Volcanic ash

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


Colonization factors

age of substrate, type of substrate, amount of rainfall


genetic study

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


unusual niche filling

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


atoll formation

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