L21. Case study Hawaii

Question 1

Formation of Hawaiian islands

Answer 1

• exist over a hot spot (magma column)
• plate move over column sometimes permitting it to pass through and form island chain
• new islands still forming in Hawaii chain
• older islands eroding
• Atoll formation: when soil erosion is not being offset by new land added through volcanic activity, landmass erodes into surrounding marine environment, creates shallow sea shelves for coral growth

Question 2

Hawaii chain

Answer 2

• part of a chain of islands, atolls, and seamounts
• isolated from other groups for >70 million years

Question 3

Species there represent challenges reaching islands

Answer 3

• plants, insects, birds, fish, mammal are represented because they can fly or swim
• no amphibians or reptiles because they could not get there
• most founder species from asia due to jet stream patterns

Question 4

Dispersal methods

Answer 4

• ocean dispersal
• aerial dispersal
• avian dispersal

Question 5

Diversity in Hawaii

Answer 5

species diversity in Hawaii features:
- adaptive radiation in many colonizing lineages
- unique life strategies in some taxon relative to their mainland counterparts

Biotic factors:
- random genetic drift
- founder effect
- population size

Abiotic factors:
- climatic heterogeneity
- open niches

Question 6

environmental effects on evolution

Answer 6

• large difference between windward and leeward climates
• rain shadow effect
• diverse climate niches (island habitats often have fewer species available to fill typical species niches in an environment)

Question 7

Founder species in Hawaii

Answer 7

• fruit flies (800 species)
• snail (22 founder species to 796 species)
• honey creeprs

Question 8

Islands are especially vulnerable to invaders

Answer 8

• non-native species can cause a lot of destruction
• this is because animals living on islands evolve to have a lack of defense since there are no predators
• vulnerable to novel pests/pathogens

Question 9

How to control invasives

Answer 9

biocontrol

Question 10

Disturbance cycles contribute to diversity on Hawaii

Answer 10

• many islands still volcanically active
• cycle of destruction from lava flows and regrowth
• age of island influences organisms (nutrient availability)

Question 11

Disturbance cycles on Hawaii

Answer 11

• volcanic activity is destructive in short run but provides land area and minerals for plant growth
• soil eroded into the ocean brings mineral
• as terrestrial biodiversity decrease marine biodiversity increases
• circle of life