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Veit and Lewis 1996. Am. Nat. 148(2):255-274
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Allee Effect & Demographic Stochasticity? At each time step, 50% chance of birth, 50% chance of death 1 100 Time 1 0
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Allee Effect & Demographic Stochasticity What is mean lambda for an infinitely large population? 1 because MM mates with FF. What is mean lambda for population size = 2? 0.5 because MM and FF do not mate. At each time step, 50% chance of male, 50% chance of female Each breeding pair produces two offspring, then die. M,M M,F F,M F,F M,F
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Sea Turtle Management Eggs, Hatchlings Novice Breeders Juveniles Mature Breeders Sub-Adults
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Sea Turtle Management Eggs, Hatchlings Novice Breeders Juveniles Mature Breeders Sub-Adults
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Snow Goose Management Eggs, Hatchlings Juveniles Breeders (Age > 2)
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Deaths l x = f x / f 0 d x = l x - l x+1 q x = d x / l x
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Survivorship Graphs http://www.sciencemag.org/cgi/content/full/291/5508/1491
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Births Mean number of female (or reproductive) offspring produced per female (or reproductive) individual. Represents mean offspring produced for females that have survived to year “x”. Agebxbx 0 (to 1)0 1 (to 2)1.1 2 (to 3)3.5 3 (to 4).7
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Births What would the birth schedule look like for Pacific salmon? Agebxbx 0 (to 1) 1 (to 2) 2 (to 3) 3 (to 4)
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Births What would a possible birth schedule look like for Pacific salmon? Agebxbx 0 (to 1)0 1 (to 2)0 2 (to 3)0 3 (to 4)1000
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R0R0 “Net reproductive rate” Mean number of female offspring produced per female over her lifetime Mean number of reproductive offspring produced per reproductive individual over its lifetime
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Can We Calculate R 0 From b x Mean number of female offspring produced per female golden lion tamarin. Agebxbx 0 (to 1)0 1 (to 2)1.1 2 (to 3)3.5 3 (to 4).7
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Can We Calculate R 0 From b x Mean number of female offspring produced per female golden lion tamarin. NO! Represents mean offspring produced for females that have survived to year “x”. Agebxbx 0 (to 1)0 1 (to 2)1.1 2 (to 3)3.5 3 (to 4).7
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R0R0
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Calculate R 0 for a population of tamarins in which 50% of the females survive to the breeding season each year, starting one year after birth, and then produces 6 offspring (3 females) per year. This continues until the end of their 3 rd breeding season, at which time all survivors die of old age. xlxlx bxbx lxbxlxbx 0 1 2 3 4 R0R0
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Calculate R 0 for a population of tamarins in which 50% of the females survive to the breeding season each year, starting one year after birth, and then produces 6 offspring (3 females). This continues until the end of their 3 rd breeding season, at which time all survivors die of old age. xlxlx bxbx lxbxlxbx 01 1.5 2.25 3.125 40 R0R0
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Calculate R 0 for a population of tamarins in which 50% of the females survive to the breeding season each year, starting one year after birth, and then produces 6 offspring (3 females). This continues until the end of their 3 rd breeding season, at which time all survivors die of old age. xlxlx bxbx lxbxlxbx 010 1.53 2.253 3.1253 400 R0R0
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Calculate R 0 for a population of tamarins in which 50% of the females survive to the breeding season each year, starting one year after birth, and then produces 6 offspring (3 females). This continues until the end of their 3 rd breeding season, at which time all survivors die of old age. xlxlx bxbx lxbxlxbx 0100 1.531.5 2.253.75 3.1253.375 4000 R0R0
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Calculate R 0 for a population of tamarins in which 50% of the females survive to the breeding season each year, starting one year after birth, and then produces 6 offspring (3 females). This continues until the end of their 3 rd breeding season, at which time all survivors die of old age. xlxlx bxbx lxbxlxbx 0100 10.531.5 20.2530.75 30.12530.375 4000 R 0 =2.625
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Growth Rates Population increases if r > 0, lambda >1, R 0 > ? Population is constant if r = 0, lambda =1, R 0 = ? Population declines if r < 0, lambda < 1, or R 0 < ?
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R 0 vs. λ R 0 defines population growth per generation. λ defines population growth for a given time step. R 0 = λ where 1 time step = 1 generation.
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Mean Generation Time (G) and r Mean age of all reproducing females Mean age of mothers of all newborn females Mean time between birth of a mother and all her offspring
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