Key Concepts in Ecology
I. Organisms are adapted to their environments.
1. The crucial determinates of an organism’s habitat are water, soil, temperature, O2 and CO2, inorganic nutrients, osmotic potential, light, and the size of the organism.
2. Salt balance, water balance, nitrogen excretion, gas exchange, and temperature regulation are interlinked for all organisms.
3. Individual organisms try to maintain internal homeostasis in a variety of parameters.
II. Ecological systems function according to the laws of physics, particularly thermodynamics.
4. All ecosystems rely on the sun for energy.
5. Because energy use is not 100% efficient, energy is lost from ecosystems in the form of heat.
6. Unlike energy, nutrients can be cycled through an ecosystem.
7. Biomes are controlled by climatic factors, habitats by local irregularities of topography. Therefore, distribution of organisms is also determined by these factors.
III. The physical environment controls and otherwise influences the development of the biological community and its population dynamics.
8. Organisms can respond to environmental change or patchiness with varied behavior or life cycles.
9. Reproduction in organisms is also influenced by the environment.
10. Groups of organisms of a single species (populations) are not usually distributed in an even manner no matter what the scale.
11. Community structure is determined by both biotic and abiotic factors.
12. Under ideal conditions, most organisms undergo exponential growth.
13. Two types of factors may limit population growth - density independent and density dependent factors.
14. Population levels may fluctuate due to internal or external factors.
17. Individual differences between members of a population affect their survival and birth rates and are ultimately reflected by a change in the genetic makeup of the population.
IV. The functioning of a community is dependent on a number of inter-species...