1. 1 Shaping Communities 5.3

2. 2 Shaping Communities 5.3 Niche  a species way of life, or role/function the species plays in its environment… “occupation” How does “it” use the physical environment? How does “it” interact with other species? Others… Fundamental niche: range of conditions and resources a species can tolerate and potentially use (no influence of competition, predation, etc.)… very broad Realized niche: range of resources it actually uses (influenced by competition)… narrow, more specific generalists (organisms with broad niches) vs specialists (organisms with narrow niches) Ex. koala and opossum (which is which?)

3. 3 Competition for resources  Winner/Loser: competitive exclusion (one species eliminating another through competition). Ex. invasive species vs. native species Coexisting: division of resources (aka “resource partitioning”); fundamental niche vs. realized niche. Ex. fig. 9 pg. 114

4. 4 Ecosystem Resiliency (stability) predation, keystone species, & biodiversity Predation can reduce the effects of competition among species Ex. mussels (good competitors for space in ocean) --sea stars eat mussels --when sea stars are present, a variety of species are able to live in the same area that the mussels live (intertidal zone) Ex. sea otters (eat sea urchins) --sea urchins eat kelp --kelp forests provide habitat for many aquatic animals --predict what would happen if the sea otters were removed from the ecosystem

5. 5 Keystone species: one that is critical to an ecosystem b/c it affects the survival and number of many other species in its community (ex. sea otters and sea stars from previous slide). Biodiversity…# of species w/i a community. higher biodiversity  increased resiliency (“healthy” ecosystem). predation helps increase biodiversity …explain how this is possible.