ECOLOGY

ecology

the study of the interactions between organisms and their environments

environment

encompasses all that is external to the organism and is necessary for its existence

two components - abiotic and biotic

abiotic environment

physical or nonliving components, includes climate, temperature, availability of light and water

biotic environment

living components, includes all living things that directly or indirectly influence the life of an organism (relationships that exists between organisms)

organism

the individual unit of an ecological system

levels of biological organization

organism → organ → tissue → cells → molecules → atoms → subatomic particles

species

any group of similar organisms that are capable of producing fertile offspring

population

a group of organisms of the same species living in the same habitat, eg. lions in a grassland

affected by environmental factors, nutrients, water, sunlight to maintain levels

niche

defines the functional role of an organism or population

describes where an organism eats, where and how it obtains food, what climate it can tolerate or function optimally at, its parasites and predators, where and how it reproduces, etc.

embodies every aspect of an organism’s existence

habitat

the physical place where an organism lives

community

consists of populations of different plants and animal species interacting with each other in a given environment

generally contains populations from all six kingdoms, eg. a lawn containing dandelions, grasses, mushrooms, earthworms, nematodes, bacteria

biotic community

includes only the population and not their physical environment

ecosystem

includes the community and the environment, encompasses the interaction between living/biotic communities and the nonliving/abiotic environment

ecological succession

the orderly process by which the structure of an ecological community evolves over time

primary succession

occurs in areas uninfluenced by a pre-existing community

secondary succession

occurs in areas where a pre-existing community has been disrupted

sere

a community stage that is identified by a dominant species (exerts control over others) in an ecological succession

climax community

the living part of an ecosystem in which populations exist in balance with each other and with the environment, the most stable stage of ecological succession

type depends on abiotic factors

persists until a major climactic or geological change disrupts the abiotic factors or a major biotic change (disease, mutation, etc) occurs

once the equilibrium is upset, new conditions are produced and a new series of successions is initiated to establish new communities in the ecosystem

self-sustaining ecosystem

stability occurs if three conditions are met:

• the abiotic factors and biotic community are relatively stable

• there is a constant energy source and a biotic community incorporating this energy into organic compounds

• materials are cycled between the abiotic factors and biotic community

nonnative species

invasive, if introduced, the balance of the ecosystem can be disrupted and result in harm to the environment, the health of native species, or the local economy

biomes

formed from ecosystems within a specific geographic region, conditions select for plants and animals possessing suitable adaptations

origin of plants and animals

can be traced to the seas, had to adapt to colonize land due to the lack of water, lack of food and supporting medium, varying temperature, and varying soil composition compared to the ocean

terrestrial biomes

includes desert, grassland, rainforest, temperate deciduous, temperate coniferous, taiga, tundra, polar

climax vegetation

the vegetation that becomes dominant and stable after years of evolutionary development

used to characterize land biomes, plants determine the nature of the inhabiting animal population

climax animal population

determined by the climax vegetation