Populations

Characteristics of Populations Three important characteristics of a population are its geographic distribution, density, and growth rate.

Population growth factors space (available range or territory), food, and predators The number of births, the number of deaths, and the number of individuals that leave the population

Population Growth Change in a population size is known as growth rate If a population is provided with ideal conditions, it will continue to increase.

Exponential Growth Occurs when individuals in a population reproduce at a constant rate. This pattern of growth is in a J curve

Logistic Growth As resources become less available, the growth of populations slows or stops! This pattern of growth is an S shaped curve

S-Shaped Curve-Logistic Growth Figure 5-4 Logistic Growth of Yeast Population S-Shaped Curve-Logistic Growth Section 5-1 Carrying capacity Number of Yeast Cells Time (hours) Go to Section:

Carrying Capacity The point at which a population becomes stable. It is the maximum, stable population size an environment can support over time. A number of factors help stabilize the population at this size. They are density-dependent and density-independent limiting factors.

Density-Dependent Limiting Factors Competition Predation Parasitism Crowding/Stress

Density-Independent Limiting Factors Weather Fires Drought/Floods Human Activities

Population density is the number of individuals that live in a defined area. Population density is a measurement of the number of individuals living in a defined space. Scientists can calculate population density.

Population dispersion refers to how a population is spread in an area. Geographic dispersion of a population shows how individuals in a population are spaced. Clumped dispersion Uniform Random Population dispersion refers to how a population is spread in an area.

There are three types of dispersion. clumped

There are three types of dispersion. uniform

There are three types of dispersion. random

Concept Map Population Growth Logistic Exponential growth Limits on Section 5-1 Population Growth can be Exponential growth Logistic characterized by represented by characterized by represented by Falling growth rate S-shaped curve Limits on growth No limits on J-shaped Constant Unlimited resources which cause a Go to Section: