ecosystems, populations, and biodiversity sci 7724
TRANSCRIPT
Ecosystems, Populations, and biodiversity
SCI 7724
Case Study: Costa Rica Cloud forest
What is evolution, really?
Natural selection
Natural selection works on POPULATIONS
Evolution can generate biodiversity
What is speciation and how does it happen?
Population separation
Allopatric speciation
• Sympatric speciation
Phylogenetic trees
Mass extinction events
• Most extinction occurs gradually– background extinction rate
• Mass extinctions can wipe out 50-95% of biodiversity
• 65 mya- K-T event• 250 mya- 75-95% of species extinct- volcano?
The sixth mass extinction
• http://www.well.com/~davidu/extinction.html
Levels of ecological organization
• Biosphere• Ecosystem• Community• Population• Individual
Niches
What’s so important about niches?
Population size
• How is it calculated/estimated?• Why is it important?
Population density
• How is it calculated/estimated?• Why is it important?
Population distribution
• How is it calculated/estimated?• Why is it important?
Sex ratios and age structure
• Why does it matter?
How populations change over time
Limiting factors and carrying capacity
R- and K-selected species
Conservation of Biodiversity
• Cloud forest
Interpreting graphs