Study%20Guide.D.%20Lec%2020.25

# Study%20Guide.D.%20Lec%2020.25 - BIS2B Lectures 20,21, 22...

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BIS2B Fall 2009 Study Guide Lectures 20,21, 22 The colors indicate small changes made each day. Don't print all the new versions, just check through to find the colored changes. Version C 5:15 Nov 24, 2009 VERSION B 9:50 November 20, 2009 Version D. 3PM, December 1, 2009 Reading, 54.3 pages 1173-1174 Topics: 1) Single-species population growth. a) Time, t b) Population Size, N c) Population size at time, N t d) Absolute Numbers of: i) Births, B ii) Deaths, D iii) Immigrants, I, disperse in from elsewhere. iv) Emigrants, E, leave, disperse away. e) Per Capita numbers of: i) Births, b= B/N ii) Deaths, d = D/N iii) Immigrants and emigrants with same logic, divide absolute number per unit time by number in the population, N. f) Area occupied by the population, A g) Density, N/A. h) Generations or time periods, the time t between censuses. i) Absolute change, or difference, in N between generations, N t+1 – N t . j) Exponential, density independent population growth . k) Doubling time. l) Density dependent, limited, regulated population growth. Introduction Malthus was the first to convince the intellectual world that all organisms have the potential for exponential population growth. He took this profound insight one step farther with the additional insight that while human population tends to grow exponentially in good times, food resources are limited by agricultural area so they can grow only arithmetically. He said, (his “geometrical” means our “exponential”). , , . “Population when unchecked increases in a geometrical ratio . Subsistence increases only in an arithmetical ratio A slight acquaintance with numbers will shew the immensity of the first power in comparison of . the second ” 1

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BIS2B Fall 2009 Study Guide Lectures 20,21, 22 :// . . / /4239/4239- /4239- . http www gutenberg org files h h htm . We know that science and technology have proven him wrong in the last 200 or so years, and exponentially increased food production and distribution (mainly based upon industrial N fixation and fossil fuel industrialization of agriculture) have fostered exponential increase in human population. In the last two lectures, we will discuss how these increases cannot continue. But, back to the quantitative basics of the basic science. 2
BIS2B Fall 2009 Study Guide Lectures 20,21, 22 We all have a rudimentary idea of the exponential arithmetic distinction, let’s review. The essence of exponential growth is given in such phrases and sentences as, “one becomes 2, then 2 become 4, four becomes eight” and so on. This kind of process or sequence means that numbers multiply, the rate process is multiplicative. Examples include number of atoms being smashed apart in a nuclear reaction, number of fixed carbon atoms oxidizing during a fire, or the amplification that occurs when a microphone is too close to an amplifier; unlimited multiplicative processes give positive feedback. Exponential change is contrasted with the sequences most familiar to us in which

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## This note was uploaded on 12/28/2010 for the course BIS 2B taught by Professor Strong during the Fall '08 term at UC Davis.

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Study%20Guide.D.%20Lec%2020.25 - BIS2B Lectures 20,21, 22...

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