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Chapter # 10 – Population Growth (pg. 204 – 221). Statistical Results – Biased Coin-flipping. Tuesday’s Lab Thursday’s Lab. 2 0.05, 1,4 = 18.06 Reject Null Hypothesis (Statistically Significant) (P < 0.05). 2 0.05, 1,4 = 0.86 Accept Null Hypothesis (No Difference) (P > 0.05).
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Chapter #10 – Population Growth (pg. 204 – 221)
Statistical Results – Biased Coin-flipping Tuesday’s Lab Thursday’s Lab 20.05, 1,4= 18.06 Reject Null Hypothesis (Statistically Significant) (P < 0.05) 20.05, 1,4= 0.86 Accept Null Hypothesis (No Difference) (P > 0.05) 20.05, 2,8=7.28 Reject Null Hypothesis (Statistically Significant) (P < 0.05)
Chapter #10 – Population Growth (pg. 204 – 221) 10.1 Population Growth Reflects the Difference Between Birth and Death. 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. 10.3 Different Life Tables Reflect Different Approaches to Defining Cohorts and Age Structure. 10.4 Life Tables Provide Data for Mortality and Survivorship Curves.
Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. Life Tables provide an age-specific account of mortality. The construction of a life table begins with a cohort - a group of individuals born in the same period of time.
Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. x nx. • 0 530 • 159 • 80 • 48 • 21 • 5
Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. x nx. 0-1 530 1-2 159 2-3 80 3-4 48 4-5 21 5-6 5 Gray Squirrels (Sciurus carolinensis)
159/530 Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. lx = the probability at birth of surviving to any given age. x nxlx. 0-1 530 1.00 1-2 1590.30 2-3 80 0.15 3-4 48 0.09 4-5 21 0.04 5-6 5 0.01
159 - 80 530 - 159 Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. dx = an estimate of age-specific mortality. This is the number of individuals that died during any given time interval. x nxdx. 0-1 530371 1-2 15979 2-3 80 32 3-4 48 27 4-5 21 16 5-6 5 5
371/530 79/159 Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival. qx = an estimate of age-specific mortality. x nx dxqx. 0-1 5303710.70 1-2 159790.50 2-3 80 32 0.40 3-4 48 27 0.55 4-5 21 16 0.75 5-6 5 5 1.00
Chapter #10 – Population Growth (pg. 204 – 221) 10.2 Life Tables Provide a Schedule of Age-Specific Mortality and Survival.
Chapter #10 – Population Growth (pg. 204 – 221) Females Born Before 1900 Born After 1900 Males Born Before 1900 Born After 1900 Locations Falls City Cemetery Fircrest (Monmouth Cemetery Crystal Lake Cemetery (Corvallis)
Chapter #10 – Population Growth (pg. 204 – 221) 10.3 Different Life Tables Reflect Different Approaches to Defining Cohorts and Age Structure. Dynamic Life Table – Following the fate (cohort) of a group of individuals born at a given time (year). Time-specific Life Table – One sample period assumes: constant birth and death rates each cohort sample according to actual population proportions.
Chapter #10 – Population Growth (pg. 204 – 221) 10.4 Life Tables Provide Data for Mortality and Survivorship Curves.
Years and Months Gray Squirrel (Sciurus carolinensis) Stonecrop (Sedum smallii)
Chapter #10 – Population Growth (pg. 204 – 221) 10.4 Life Tables Provide Data for Mortality and Survivorship Curves.
Chapter #10 – Population Growth (pg. 204 – 221) 10.4 Life Tables Provide Data for Mortality and Survivorship Curves. Type I – when individuals live out their physiological life span followed by heavy mortality at the end (convex). ex. - large mammals and humans
Chapter #10 – Population Growth (pg. 204 – 221) 10.4 Life Tables Provide Data for Mortality and Survivorship Curves. Type II – when survivorship rates do not vary with age (straight line). ex. – adult birds (some waterfowl and migratory songbirds, small mammals and reptiles.
Chapter #10 – Population Growth (pg. 204 – 221) 10.4 Life Tables Provide Data for Mortality and Survivorship Curves. Type I – when mortality rates are extremely high early in life (concave). ex. – fish, invertebrates, plants (annual and perennial).
Chapter #10 – Population Growth (pg. 204 – 221) 10.6 Birthrate and Survivorship Determine Net Reproductive Rate (R0). Fecundity – the potential reproductive capacity of an organism or population. Net Reproductive Rate (R0) – the average number of females that will be left (progeny) during a lifetime by a newborn female. If (R0) is < 1.0, the population is decreasing. If (R0) is = 1.0, the replacement. If (R0) is > 1.0, the population is increasing.
Chapter #10 – Population Growth (pg. 204 – 221) 10.7 Age-Specific Mortality and Birthrates Can Be Used to Project Population Change.
Chapter #10 – Population Growth (pg. 204 – 221) 10.7 Age-Specific Mortality and Birthrates Can Be Used to Project Population Change. From such a projection table (life table) you can calculate the age distribution (stable or stationary) for each age class or cohort in the population and to project population growth (λ - lambda).
Chapter #10 – Population Growth (pg. 204 – 221) 10.8 Stochastic Processes Can Influence Population Dynamics. Stochasticity –variation in a population from random effects within a season or time period (t). Demographic Stochasticity – variation in population growth/declining rates from random effects among individuals in survival and reproduction within a season or time period (t). Environmental Stochasticity – variation in population growth/declining rates from random effects arising from environmental factors or the occurrence of natural disasters such as fire, flood, and drought within a season or time period (t).
Chapter #10 – Population Growth (pg. 204 – 221) • 10.9 A Variety of Fators Can Lead to Population Extinction. • Resource Shortage • Restoration/Reintroduction • Potential new competitors, • predators, etc. (Human-assisted)
Chapter #10 – Population Growth (pg. 204 – 221) • 10.10 Small Populations are Susceptible to Extinction. • Stochastic Effects. • Wide Dispersal/Small Populations may have trouble locating mates. • Allee Effect – a decline in reproduction or survival at low densities. • Genetic Drift – random change in gene frequency. • Inbreeding.