November13LecNotes

# November13LecNotes - November 13th 2008 Lecture Notes taken...

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November 13 th 2008 Lecture Notes taken by Dr Balko (ppt) Routine Class Matters ~ Reading assignments for Today Chp 36, thereafter Chp 37. (ppt) Clicker Question Answer = B [this has been on a final in the past] Review from last time ~ Survivorship Curves predict an individual’s statistical chance of dying or surviving during each interval of the individual’s lifetime. One of the best ways of studying patterns of mortality or survivorship in a population is through life tables . They consist of a series of columns each describing some statistic of the population; they are often used by life insurance companies to set premium rates (called an actuarial table). (ppt) Survivorship curves - depict the three basic patterns that are observed in nature. There are three basic types of curves: [Its very important you understand these figures). Type I curves are those where mortality is concentrated at the end of the life span, typical of many human populations. Type II curves are those where the probability of death remains constant with age. Hydra, small freshwater animals related to jellyfish, show this pattern. Type III curves are those where mortality is high early in life, but the survivors then enjoy high survivorship. Many organisms show elements of more than one of these curves in their lifetime, for example many songbirds have Type III survivorship for their first year, but then follow a pattern similar to Type II curves. ppt) A “J-shaped growth curve,” described by the equation G = rN , is typical of exponential growth, where: G = the population growth rate r = the intrinsic rate of increase, or an organism's maximum capacity to reproduce (births minus deaths—if b>d, population grows, whereas if b<d, population declines) N = the population size at starting point Exponential Growth - this is also called geometric growth, because the population keeps doubling with each time period (until resources such as food run out, at which time the population will crash); a graph of population size versus time shows the typical J-shaped curve. 1

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November 13 th 2008 Lecture Notes taken by Dr Balko The larger the population gets, the faster it grows. This situation is somewhat unrealistic; some organisms, such as bacteria, show this pattern; other organisms show this pattern when they newly colonize an area but revert to another growth pattern called logistic growth (see ppt after the next one) . (ppt) Example of an Exponential Growth Model illustrates an accelerating increase when growth is unlimited (much like “compound interest” in a savings account) The curve in Figure 36.4A is specific to G = the population growth rate, r = “intrinsic rate of increase” (b+d), and N = the population size (ppt) Carrying Capacity – what is it and what controls this? o
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## This note was uploaded on 10/21/2009 for the course BIO G 109 at Cornell University (Engineering School).

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November13LecNotes - November 13th 2008 Lecture Notes taken...

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