8.3/8.4 population ecology*

population interactions - one another (4)

competing for food, seeking mates, defending territory, cooperating in groups

population interactions - the environment

using available resources - food, water, shelter, climate conditions

interactions result

shape population growht and change over time

factors influencing population growth (4)

birth rate, death rate, population size, time

population size

number of individuals present - influences rate of population growth

time

population changes accumulate across generations

factors influencing population growth importance

helps ecologists predict population expansion and contraction

exponential growth

population reproduction without limits - accelerating rate of growth

exponential growth example

bacteria - nutrient rich culture > doubles population numbers in less time

exponential growth sustainability

rarely sustainable

population growth limits

competition - food, space, nesting sites - limits growth

population density limits

population density > resources available = increased starvation, diseases, mortality

population density limits on exponential growth

slow growth, prevent indefinite exponental increase

logistic growth model (the "realistic model")

growth starts rapidly, slows as limiting factors are added

logistic growth model (the "realistic model") - result

population eventually levels off at a carrying capacity

influences on logistic growth (2)

density dependent factors, density independent factors

density dependent factors

effects that intensify as population density increases

density dependent factors examples (3)

competition, predation, disease

density independent factors

effects that impact populations regardless of density

density independent factors examples

natural disasters, temperature shifts, droughts

influences on logistic growth result

create an s shaped curve characteristic of logistic growth