Populations

ScienceBennett

Can any population of organisms keep growing forever?

• Changes in a population in one part of a food web affects populations in other parts of the web.

• The largest population of a species that an environment can support is called the carrying capacity.

• Species = a group of organisms that can interbreed and produce fertile offspring

What factors determine the carrying capacity?

• 1. Materials and Energy• 2. Food Chains- populations are limited by

their food supplies.• 3. Competition- among individuals for

resources– Intraspecific competition = competition among

members of the same species.– Interspecific competition = competition between

species.

• 4. Population Density = how many individuals can live in an area at one time

– Density-dependent factors = factors that increase in significance as a population grows , ex. overcrowding, aggression

– Density-independent factors = factors that can limit the population, regardless of size, ex. forest fire

• Ecological Niche = the way that an organism occupies a position in an ecosystem including all the necessary biotic and abiotic factors.

• Predator = an organism that kills and consumes other organisms

• Prey = an organism that is eaten as food by a predator

• Bottom-up population regulation = when the size of the prey population decreases causing a decrease in the predator population, due to the lack of food.

• Top-down population regulation = when the size of the predator population increases causing a decrease in the prey population. Eventually this results in a decrease in the number of predators.

• Mutualism = a symbiotic relationship between two species in which both species benefit from the relationship.

• Parasite = an organism whose niche is dependent on a close association with a larger host organism.

• Continue to “Monitoring Changes in Populations”