POPULATION REVIEW

Population All the individuals of a species that live together in one place. Population

The area inhabited by a population geographic range

Population density Number of individuals per unit area. Two ducks Hundreds of fish

Distribution

The number of individuals in a population. Population size

The increase in the size of a population over time. Population growth

When does a population grow? A population grows when births exceed deaths.

What does a population need to grow? water food space few predators less disease

What type of growth is this? Exponential growth

What is exponential growth? Exponential growth is how a population grows in the beginning when resources are plentiful. As the population gets larger, it grows faster.

Populations do not grow exponentially forever. Population growth is limited by food water predators disease space These are limiting factors

Limiting factors Any biotic or abiotic factor that regulates the growth of a population. Limiting factors

Some limiting factors may be water food predators disease competition temperature natural disasters

Some density-dependent limiting factors are: water food predators disease competition

Some density-independent limiting factors are: flood earthquake wild fires drought hurricanes natural disasters temperature

Limiting factors prevent a population from growing exponentially forever. Therefore, most organisms’ populations follow a logistic growth curve, an S-shaped curve. Number of Organisms Time

Logistic growth occurs when a population’s growth slows and then stops, following a period of exponential growth.

Phases of Growth: The population grows rapidly. The population remains constant. The population growth slows. The population grows slowly.

Logistic Growth (S-shape) Growth slows. Carrying capacity Growth stops. Population grows rapidly.

The maximum number of individuals of a species that an environment can support. Carrying capacity 1000

What is the carrying capacity? 1000 bison. 1000

Populations fluctuate around the carrying capacity.

Desertification – turning farm land into desert as a result of over farming, overgrazing, and seasonal drought.

Deforestation – Loss of forest as a result of clear-cutting.

Biological magnification – when a pollutant accumulates in organisms. Top predators have the highest concentration of pollutant.

Primary succession is the colonization of new sites by communities of organisms. It often occurs after a devastating event has wiped out the organisms that lived in the area, or with the creation of a new habitat. 

Secondary succession is the ecological succession that occurs on a preexisting soil after the primary succession has been disrupted or destroyed due to a disturbance that reduced the population of the initial inhabitants. soil

Invasive species – a plant or animal that is not native to a specific location; and has a tendency to spread, and cause damage to the environment.

Invasive species in Florida: python, iguana, lionfish