Stability and Change

Ecosystems

communities and abiotic factors in an area

Community

populations of different species living in the same area

Populations

organisms of the same species living in the same area at the same time

Species

organisms that can interbreed to form fertile offspring

In terms of biological hierarchy… (smallest to largest)

species, population, community, ecosystems

What are the three requirements for stability in ecosystems

-steady supply of energy

-nutrients need to be cycled and stay in ecosystem

-high genetic variability of all species

Where does the large supply of energy usually come from? (/energy distribution)

Sunlight for producers, food chain, food web)

What type of organisms allow nutrients to be recycled?

Saprotrophs (i.e. fungi, bacteria)

What does a greater variability allow?

It allows the species to better withstand natural selection pressures

Keystone species

species that have a disproportionately large impact on their ecosystem relative to their abundance

What do keystone species maintain?

the structure and health of the environment

What can keystone species be used for?

can be used to indicate the health of an environment

What happens if keystone species are not present?

overpopulation of other species might occur