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Populations and Growth. Population Dispersion. Survivorship Curves. Type I Few offspring Low infant mortality Parental care of young Most survive until old age Large mammals, including humans. Survivorship Curves. Type II Equal chance of living or dying throughout the lifetime
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Survivorship Curves • Type I • Few offspring • Low infant mortality • Parental care of young • Most survive until old age • Large mammals, including humans
Survivorship Curves • Type II • Equal chance of living or dying throughout the lifetime • Birds, reptiles, small mammals
Survivorship Curves • Type III • High infant mortality rate • Many offspring • No parental care • Invertebrates, fish, amphibians, and plants
Changes in Population Size • Growth factors • Immigration: individuals moving into a population • Births • Shrinking factors • Emigration: individuals moving out of a population • Deaths
Exponential Growth • Early phase of growth • High availability of resources • Little competition • Little predation
Logistic Growth • Limits on growth appear • Competition for resources • Predation • Parasitism • Illness
Human Population Growth Are humans in exponential or logistic growth?
U.S. Population Density - 2000 People per square mile 0-1 (white) 10-24 (green) 100-249 (blue) 1-4 (yellow) 25-49 (teal) 250-66,995 (dark blue) 5-9 (yellow-green) 50-99 (dark teal)