Population DynamicsAnd

Evidence for Evolution

Outline how population size is affected by natality, immigration, mortality and

emigration• Population – a group of organisms of the

same species living in the same area at the same time

• Ways population size can change:

• Natality

• Mortality

• Immigration

• Emigration

• Pop Change = (N+I) – (M + E)

Draw and label a graph showing a sigmoid (S-shaped) population growth curve

• Do it. Now!

Draw and label a graph showing a sigmoid (S-shaped) population growth

curve• Exponential vs. Logistic (Exponential) Growth

Explain reasons for the exponential growth phase, the plateau phase, and the transitional phase

between these two phases

• During the Exponential phase the population increases exponentially because the natality rate is higher than the mortality rate. The resources needed by the population such as food and space are abundant, and diseases and predators are low.

• During the Transitional Phase, the birth rate begins to decrease. Natality is still larger than mortality, but the difference between them is slowly decreasing.

• During the Plateau phase, available resources become so low that no further growth can take place. Mortality starts to become larger than natality. A species may have reached its Carrying Capacity (K).

List 3 factors that set limits to population increase

• 1.

• 2.

• 3.