Apes Unit 3 - Populations

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Population

group of individuals of same species living in same area

Population dynamics

how populations change in size and composition over time

Limiting factors

factors that restrict population growth (food, water, space, disease)

Carrying capacity (K)

max population an environment can sustainably support

Generalist species

broad niche; can use many resources and habitats

Specialist species

narrow niche; specific diet/habitat; vulnerable to change

r-selected species

many offspring, little parental care, early reproduction, short lifespan

K-selected species

few offspring, high care, slow reproduction, long lifespan

Type I survivorship

high survival until old age; humans, elephants

Type II survivorship

constant death rate; birds

Type III survivorship

many offspring, most die early; fish, insects

Overshoot

population temporarily exceeds carrying capacity

Die-off

sharp decline in population after overshoot

Exponential growth (J-curve)

fast growth with no limits

Logistic growth (S-curve)

growth slows as it reaches carrying capacity

Density-dependent factors

disease, competition, predation (affect large populations more)

Density-independent factors

natural disasters, weather (affect all equally)

Biotic potential

maximum reproductive capacity of a species

Age structure diagram (rapid)

wide base; fast-growing population

Age structure diagram (stable)

straight sides; stable growth

Age structure diagram (declining)

narrow base; aging population

Total Fertility Rate (TFR)

average number of babies per woman

Replacement-level fertility

about 2.1 in developed countries

Factors that lower TFR

education for women, birth control, higher income, later childbirth

Factors that raise TFR

poverty, child labor, lack of contraception

Crude birth rate (CBR)

births per 1,000 people

Crude death rate (CDR)

deaths per 1,000 people

Population growth rate

(births – deaths + immigration – emigration) ÷ population × 100

Doubling time

70 ÷ growth rate

Population momentum

continued growth after fertility declines

Stage 1 DTM

high birth and high death rates; little growth

Stage 2 DTM

high birth, falling death; population boom

Stage 3 DTM

falling birth, low death; slower growth

Stage 4 DTM

low birth and low death; stable population

Stage 5 DTM

very low birth; declining population