Ecology Notes Chapters 13-16

I. Factors in the environment; A. Biotic; All organisms (living things) that inhabit an environment and their relationships to one another. All organisms depend directly or indirectly on other organisms for food , shelter, reproduction and / or protection. B. Abiotic; nonliving factors. Includes climate, temperature, light, soil, water, and air.

II. Levels of organization; A. Organism; individual made of cells that requires nutrients and uses energy in the environment B. Population; group of organisms that are all of one species, living at the same place, at the same time.

C. Biological Community; All populations of different species that live in the same place at the same time.

D. Ecosystem; Population of plants and D. Ecosystem; Population of plants and animals that interact with each other in a given area, and with the abiotic components of that area. E. Biome; Major regional or global in size. Includes interactions between biotic and abiotic factors in an area characterized by specific climatic factors.

A. Mutualism; Both species benefit. 1. ants and acacia trees. III. Symbiosis; The relationship in which there is close association between organisms of different species. A. Mutualism; Both species benefit. 1. ants and acacia trees. The acacia tree provides nectar and protein for the ants. The ants provide protection for the tree, from other insects and bacteria.

2. protists in the guts of termites: the. protists have an enzyme that 2. protists in the guts of termites: the protists have an enzyme that digests the cellulose in wood. 3. nitrogen fixing bacteria in the roots certain plants: they remove nitrogen from the air and change it into a form the plant can use.

B. Commensalism; One species. benefits, the other is neither B. Commensalism; One species benefits, the other is neither harmed, nor receives a benefit. 1. Cattle egrets and cattle: as the cattle walk through the grass, they cause insects to jump out of the grass. The egrets can easily find the insects. The cattle are not affected.

2. Demodicid mites and humans; microscopic 2. Demodicid mites and humans; microscopic mites found in about 70% of teen agers and about 99.9% of adults. They live in the follicles of eyelashes, consuming dead cells and oils.

C. Parasitism; One species benefits C. Parasitism; One species benefits (parasite) at the expense of another (host). This is not the same as predation, where a predator kills and eats its prey. With parasitism, the harm to a host may occur over a period of days, weeks or even years. 1. Tick feeding from the blood of a dog.

2. Mistletoe on a tree. Steals nutrients from the tree, and may eventually kill it.