Bio 100 chapter 13 - human population Lecture

S residents comprise 5 of earths us population but

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Unformatted text preview: calories every day – 200 billion more than are necessary (this could feed 80 million more people) people) 1 person U.S. uses as many resources as: 2 Japanese 31 Indians 31 2 Spaniards 128 Bangladeshians 3 Italians 301 Tanzanians 301 6 Mexicans 370 Ethiopians 370 13 Chinese Unlike other species, the human population is Unlike not completely at the mercy of the environment not Through ingenuity humans have the ability to Through transform environmental conditions – at least the hypothetical ability the A population crash is a steep decline in population number as death rates soar and birth rates drop after a too large population competes for too few resources too Even if birth and growth rates continue to Even grow for awhile grow Fish die off – population crash Some populations crash over and over again as a Some result of a tendency to grow beyond carrying capacity result “Booms” and “busts” continual indefinitely This is called a population cycle This population Stored resources (such Stored as energy in the form of fossil fuel) are a factor that allow populations to (temporarily) overshoot carrying capacity carrying In the 1700s a human In population overshoot and crash occurred on the Pacific Island of Rapa Nui (Easter Island) Rapa Ecologists notice is a lag between the time Ecologists humans reduce birth rates and when the population size responds and call this lag demographic momentum demographic The demographic momentum can be estimated The by looking...
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