October 8, 2008
1. Read and Discuss
2. Food chain & Food web
food chain
primary producers, herbivores, carnivores
general categories, trophic levels
loss at each level --> energy pyramid (link)
add in decomposers
food web (draw on board)
example
predator-prey (up and down)
competition (sideways)
compensation for variation in food sources
stability and resilience of the system
collapse of food web is possible
more likely a catastrophic simplification
invasive species
loss of natural capital such as soil
toxicity impacts where only a few organisms can tolerate the stress
biodiversity
more organisms lead to more ways they can interact
positive feedback (more leads to even more)
unfortunately - less leads to even greater losses
Concepts in Chapter 4:
evolution
requires three conditions: diversity, selection, barriers to overproduction
"survival of the fittest" is one of the most abused and mis-applied concepts from the natural sciences
adaptation (of the population): shifts in traits that were possible because of the diversity of the gene pool
(geologic history - not covering)
ecological niche - job of an organism
broad generalists
narrow specialists
niche narrowing and competition
competition doesn't always lead to exclusion, but can lead to a focusing of species efforts
genetic modifications
artificial selection through animal husbandry and plant genetics
genetic engineering
genetic modification