Student_Outline_Unit_6_starr1

Student_Outline_Unit_6_starr1 - Population Ecology I....

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Population Ecology I. Population demographics – need to know to make predictions A. Population size- number of individuals of a species B. Population density – number of individuals of a species per unit area 1. Quadrat sample plots – estimation, measure several plots and multiply by total number of plots occupied by that space. 2. Capture-recapture- estimation! Good for mobile animals. #marked (catch 1) = #marked (catch 2) solve for N Total # in pop (N) total # caught in catch 2 C. Population ___ distribution __ patterns must be taken into account when estimating population density. There are three types: 1. clumped 2. uniform 3. random II. Population size and growth A. Gains and losses to a population 1. Gains: birth, immigration 2. Losses: death, emigration B. Zero population growth- gains = losses Book: ignore immigration and emigration Births = death 1
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C. So, what is growth? Births are greater than deaths Example population: 2,000 mice in a corn field. 1,000 mice are born in one month to these 2,000 mice. Birth rate = 1000/ 2000 = .5 per mouse per month In this month, 200 of the 2,000 mice die. Death rate = 200/2000 = 0.1 per mouse per month Net growth rate (per mouse/month) = .5-.1= .4 = r So, population growth (G) = r x N = .4 x 2000 So the population will be at _ 800 (2800) __at the end of the first month. What will it be at the end of the second month (assuming r is constant)? .4 x 2800 = 1120; 1120 + 2800 =3920 D. Exponential growth model 1. Definition – unregulated growth of a population under ideal conditions 2. Curve- “j”-shaped Growth =r x N 3. Human population – has been exponential for centuries E. Logistic growth model 1. Definition – population growth is slowed by limiting factors as population size increases 2. Curve – “s”- shaped; as population size increases, N approaches K. 3. Carrying capacity – “k” maximum population size an environment can support G = r x N (K-N/K) K is not constant, If environment changes, K can change 2
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Ecological footprint = ESTIMATES HOW MUCH PRODUCTIVE LAND AND WATER YOU NEED TO SUPPORT WHAT YOU USE AND WHAT YOU DISCARD Check out: www.ecofoot.org ARE YOU AN OVERCONSUMER??? III. Comparing populations: populations have different strategies for surviving long enough to pass along their genes…we can see these differences when we look at survivorship curves and life histories. A. Survivorship curves- plot of the _ % of individuals _ alive at each age category over the population’s lifespan 1. Type I – high death rates for the old; few offspring are both but good parental care. (large mammals) 2. Type III – high death rates for the young; lots of offspring but little or no parental care. (plants, invertebrates) 3. Type II – intermediated death through life. Ex: lizards, small mammals, large birds B. Life Histories- the adaptations that influence _ reproduction ____ and account for the differences seen in the survival curves. 1. Life History traits :
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This note was uploaded on 02/16/2009 for the course BIOL 101 taught by Professor Hogan during the Spring '08 term at UNC.

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Student_Outline_Unit_6_starr1 - Population Ecology I....

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