BIO 103 Lecture Notes - Lecture 10: Primary Production, Carrying Capacity
11 Apr 2017
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Document Summary
Carrying capacity and logistic growth: populations have the potential to grow exponentially. Limited food supply, increased risk of disease, increase in waste levels. Can cause decrease in birth rates, increase in death rates, or both: density-independent factors not influenced by population numbers. Droughts, temperature extremes, natural disasters: fruit flies. When grown in the laboratory, as the population grows: When grown in an aquarium, as the population grows: Females do not have enough energy for egg production. Leads to decreased birth rate: white-tailed deer. Females do not have enough energy to carry pregnancy to term. Earth"s carrying capacity for humans: there is uncertainty about future human population growth rates. Human population growth rates at highest in 1960s, ~2. 1% Unclear what future trends are, un has released 3 projections: signs that earth"s is not near carrying capacity. One reason for declining growth rates is choice. Earth"s resources can be measured by net primary productivity (npp) = the total amount of plant growth.
