Lec 15: Case Study - Hawaii

Question 1

what do subduction zones result in?

Answer 1

upwelling and volcano formation. over time, island formation

Question 2

What do we often find at subduction zones in the ocean?

Answer 2

island chains

Question 3

How was Hawaii formed?

Answer 3

by a volcanic hotspot

Question 4

How does an atoll form?

Answer 4

volcano stops growing, erodes, but coral ring around it in shallow water continues to grow upwards.

Question 5

For how long was Hawaii isolated from other land?

Answer 5

> 70 million years

Question 6

What are the 3 dispersal options?

Answer 6

1. ocean dispersal
2. aerial dispersal
3. avian dispersal

Question 7

Where are most Hawaiian founder species from?

Answer 7

Asia

Question 8

why are so many founders from asia?

Answer 8

seeds, insects, spores, and flying animals were carried by the jet stream

Question 9

What biotic factors contributed to species diversity in hawaii?

Answer 9

• random genetic drift
• founder effect
• population size

Question 10

What abiotic factors contributed to species diversity in hawaii?

Answer 10

• climatic heterogeneity

- open niches

Question 11

What is random genetic drift?

Answer 11

the random change in a population over time, even when not under any selective pressure

Question 12

explain the founder effect

Answer 12

founder population is smaller than mother population, and contains only a sub-set of the original population

Question 13

what is a founder mutations

Answer 13

when one of the founding members has a rare mutation

Question 14

why does the founder effect lead to FASTER evolution?

Answer 14

• genetic drift is faster in small populations

- a new mutation will have a higher chance being passed on in the smaller population

Question 15

How does Hawaii’s environment affect species’ evolution?

Answer 15

• environmental heterogeneity means there is greater diversity of niches to be filled
• big range of temp, altitude, and rainfall
• rainshadow effect due to mountains

Question 16

What are typical niches in most environments and who are they filled by?

Answer 16

• apex predator (often mammals)

- large grazing herbivore (often mammals)

Question 17

who is the main grazer in hawaii?

Answer 17

ducks

Question 18

in sum, which 3 factors have led to the species diversity in Hawaii?

Answer 18

• genetic characteristics of a founder pop
• heterogeneity of the environment
• open biotic niches

Question 19

Why is Hawaii vulnerable to non-native species?

Answer 19

• loss of defenses due to lack of predators

Question 20

How do disturbance cycles affect diversity?

Answer 20

• they contribute to diversity
• destruction and regrowth
• affects nutrient availability

Question 21

how do ecosystems recover from devastation after lava flow?

Answer 21

• first colonizers –> soil formation
• biomass growth is greatest at intermediate substrate age (balance between new addition of nutrients and nutrient depletion)

Question 22

explain the disturbance cycle on hawaii

Answer 22

1) volcano destructive in short run, beneficial in long run
2) soils erodes –> minerals brought to ocean
3) terrestrial biodiversity decreases –> marine biodiversity increases