Biology Unit 3

Limiting Factors

Anything that restricts the growth, abundance, or distribution of an organism or a population in an ecosystem.

Density-independent factors

are environmental factors that affect populations regardless of their density, such as weather events or natural disasters.

Density-dependent factors

are factors that influence population growth in relation to the population's density, such as food availability, predation, and disease.

What makes a population increase or decrease

is determined by various factors including birth rates, death rates, immigration, and emigration.

emigration

leaving (decreases population)

Immigration

arriving in a new area (increases population)

Exponential Growth (J-curve)

Resources abundant, limiting factors limited, population grows rapidly, lag phase (slow start), rapid decline

Logistics growth (s-curve)

growth slows as limiting factors increase and resources become scarce, population grows quickly at first, then growth slows due to density-dependent limiting factors.

Carrying capacity

the maximum number of organisms that an environment can hold.