Handout_5 human population and global disturbances

Handout_5 human population and global disturbances - Study...

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Study Guide # 5 J.W. Via General Biology 1006 Human Populations and Global Disturbances I. Human Population- Problem- Population Size Growth has been exponential last 200 years, Currently over 6.5 billion with 75-80 million added each year. Some areas such as developing countries have the highest rate of growth. Doubling time = the number of years it takes to double the size of the population. Projections currently are 38-39 years for doubling time, for the world population and some countries have a shorter period(underdeveloped countries) or longer period(developed). Replacement Reproduction = the number of children necessary to maintain population size, based in birth rate and death rate estimates. Why is the population size so much greater ? Demography (demographics) is the measurement of populations. 1) Increase in Birth rate 2) Decrease in death rate 3) decrease in infant mortality 4)Increased fertility 5) Age structure of the population. 6) Unlike populations of other animals, human populations often greatly exceed the carrying capacity for the environment. Human populations cannot permanently escape the Density Dependent Factors, which control populations. They can avoid them for a while because of their intelligence. Examination of the age structure of the US population figure 28.8 shows that the surge of “baby boomers” are the maximum reproductive ages now which will leave behind large numbers of offspring. This is projected to significantly increase the aging population over the next 100 years, and has implications for increasing the birth rate during economically good times. Why is the survival different for males and females? Males tend to die earlier, are more likely to be killed at an early age and are more
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This note was uploaded on 08/15/2011 for the course BIO 1005 taught by Professor Limcomb during the Spring '08 term at Virginia Tech.

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Handout_5 human population and global disturbances - Study...

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