Ecology – Lecture 3
- Biogeography: a branch of ecology that examines where species occur & what causes
patterns of species distribution & richness
- Historical biogeography: The study of how evolutionary lineages affect current &
historic distributions of species & biotas (collections of species), paying particular
attention to the roles played by speciation, extinction, & dispersal.
Why a Biosphere?
- Why is there life?
- Habital Zone: “sweet spot” for liquid water
Earth gets warm, but not too warm
- Planetary Crust: 1 degree, 2 degree, & 3 degree (very rare) surface is returned to mantle
Tertiary crust; always being regenerated & consumed
- Greenhouse Effect: dynamic equillibrium – CO atmo2phere versus erosion of
Normal effect; without it we wouldn’t have an atmostphere – keeps heat on Earth
from radiating back into space
- Water bodies: freeze from top down – coldest water on bottom.
- Non-linear relationship of water density/degree celcius
- Max. density at 4 degrees celcius (heaviest); gets lighter below that temperature
- EX. An ice cube floats because it is colder that 4 degrees.
- Cold water has the highest oxygen content
- Crust is the layer on the very top
- Continental granitic crust (silicates): very light
- Divergence: producing new crust as the crust moves away at the mid-ocean ridge.
Converges with continental crust, but since it is heavy & made of salt, it converges
below the continental crust (deep)
- Tertiary crust is returned to mantle = plate tectonics
1. Atmospheric CO di2solves in rainwater
2. Rainfall erodes rock on land; rivers carry broken-down minerals to the sea
3. Ca & H C2 in3o shells & exoskeleton
4. Broken-down minerals react with disolved CO to f2rm carbonate rocks.
5. Carbonate rocks subduct & melt, releasing CO 2
* * Marine organisms use & trap the CO for g2ological time scales = regulates
- Jigsaw puzzle - 1 : Pangea
- Ring of fire: pacific volcanoes in subduction zones
- Fossils: Dr. Seuss looked at fossil tree ferns that looked alike, & fossil reptiles that
looked the same but they were from different continents
- Found that when you went across the Atlantic Ocean there were patterns that matched
on either side of the ridge
- Youngest rocks are along the mid-atlantic ridge (where new rock is formed)
- 7 primary plates, 8 secondary plates & ~60 tertiary plates
- 15 (primary & secondary plates)
- Convergence: plates that collide
- Vicariance events Divergence: new plate growth
- Allows for species to be split & for evolution to occur
- Transform: plates ‘slip’ against each other & rip/tear (earthquakes)
- Ocean basins don’t grow as one wedge-shaped plate.
Spreading of ocean floor causes the plates to plow apart
- Frog A is widely distributed through ha