POPULATIONS

The study of the interactions that take place among organisms and their environment

Biosphere The part of Earth that supports life Top portion of Earth's crust All the waters that cover Earth's surface Atmosphere that surrounds Earth.

Ecosystem All the organisms living in an area and the nonliving features of their environment

Population All the organisms in an ecosystem that belong to the same species

Community All the populations in an ecosystem

KEY FEATURES OF POPULATIONS 1. Population size is the number of individuals in a population. has an important effect on the ability of the population to survive. A small population is more likely to become extinct: in the case of a natural disaster due to inbreeding where the population is more genetically alike. Recessive traits, including diseases, are more likely to appear. Variation is reduced, so it is harder to adapt to changes.

The place in which an organism lives Habitat The place in which an organism lives provides the kinds of food and shelter, the temperature, and the amount of moisture the organism needs to survive

KEY FEATURES OF POPULATIONS, con’t 2. Population density – the number of individuals in a given area. – if they are too far apart they may only rarely encounter one another resulting in little reproduction.

Competition Demand for resources that supply a community Food Water Space

Competition Competition caused by population growth affects many organisms, including humans Limits population size

Limiting Factor Anything that restricts the number of individuals in a population. Includes living and nonliving features of the ecosystem Examples: food, sunlight, temperature

Population size is limited by: Depend on how many are in an area: Disease Competition Predators Parasites Food Crowding The greater the population, the greater effect these factors have. Ex. Black plague in the Middle Ages – more deaths in cities Does NOT depend on how many are in an area: Volcanic eruptions Temperature Storms Floods Drought Chemical pesticides Major habitat disruption (as in the New Orleans flooding) Most are abiotic factors

Biotic Potential The potential growth of a population if it could grow in perfect conditions with no limiting factors.

Carrying Capacity Biotic potential is nice to think about…but doesn’t happen because of limiting factors. The carrying capacity is the largest number of individuals of one species that an environment can support

Kaibab Deer Population