Lec 15: Case Study - Hawaii Flashcards
what do subduction zones result in?
upwelling and volcano formation. over time, island formation
What do we often find at subduction zones in the ocean?
island chains
How was Hawaii formed?
by a volcanic hotspot
How does an atoll form?
volcano stops growing, erodes, but coral ring around it in shallow water continues to grow upwards.
For how long was Hawaii isolated from other land?
> 70 million years
What are the 3 dispersal options?
- ocean dispersal
- aerial dispersal
- avian dispersal
Where are most Hawaiian founder species from?
Asia
why are so many founders from asia?
seeds, insects, spores, and flying animals were carried by the jet stream
What biotic factors contributed to species diversity in hawaii?
- random genetic drift
- founder effect
- population size
What abiotic factors contributed to species diversity in hawaii?
- climatic heterogeneity
- open niches
What is random genetic drift?
the random change in a population over time, even when not under any selective pressure
explain the founder effect
founder population is smaller than mother population, and contains only a sub-set of the original population
what is a founder mutations
when one of the founding members has a rare mutation
why does the founder effect lead to FASTER evolution?
- genetic drift is faster in small populations
- a new mutation will have a higher chance being passed on in the smaller population
How does Hawaii’s environment affect species’ evolution?
- environmental heterogeneity means there is greater diversity of niches to be filled
- big range of temp, altitude, and rainfall
- rainshadow effect due to mountains
What are typical niches in most environments and who are they filled by?
- apex predator (often mammals)
- large grazing herbivore (often mammals)
who is the main grazer in hawaii?
ducks
in sum, which 3 factors have led to the species diversity in Hawaii?
- genetic characteristics of a founder pop
- heterogeneity of the environment
- open biotic niches
Why is Hawaii vulnerable to non-native species?
- loss of defenses due to lack of predators
How do disturbance cycles affect diversity?
- they contribute to diversity
- destruction and regrowth
- affects nutrient availability
how do ecosystems recover from devastation after lava flow?
- first colonizers –> soil formation
- biomass growth is greatest at intermediate substrate age (balance between new addition of nutrients and nutrient depletion)
explain the disturbance cycle on hawaii
1) volcano destructive in short run, beneficial in long run
2) soils erodes –> minerals brought to ocean
3) terrestrial biodiversity decreases –> marine biodiversity increases
