1. Why are there so many species?
Interactions between species
1. Competition(-/-)
2. Symbiosis(+/+)
3. predation – Parasitism(+/-)
1 – 3 affects evolution, persistence of species, and overall diversity of life

2. Competitive Exclusion Principle
The American gray Squirrel vs the British red squirrel
Red squirrel – hazelnuts
Gray squirrel - acorns

3. Niches: How Species Coexist
Flour beetle(Tribolium) experiments – Fig p.130
Ecological niche and habitat – knowledge is helpful in assessing impact of development or of changes in land use
Measuring niches – Hutchinsonian niche – described as the set of all environmental conditions under which a species can persist and carry out its life functions
See fig – flatworm’s fundamental temperature niche vs realized temperature niche

4. Symbiosis Beneficial to both organisms
Ex) bacteria in our large intestine, bacteria in rumen of reindeer
Obligate symbionts

5. Predation and Parasitism
Predation – one organism feeds on another
Parasitism – one organism lives off of another
a moderately grazed pasture has more species of plants than an ungrazed one

6. Environmental Factors That Influence Diversity
See Table 7.2 p. 133 – Factors that tend to increase vs factors that tend to decrease diversity
Biogeography – the large-scale geographic pattern in the distribution of species

7. Why Preserve Biodiversity?
See list of values on p. 135
How are we protecting our resources?