Population Growth: Exponential, Density-Dependent and Overlapping Generations - Prof. Sara, Study notes of Biology

Download Population Growth: Exponential, Density-Dependent and Overlapping Generations - Prof. Sara and more Study notes Biology in PDF only on Docsity! Population Growth Exponential Growth Non-overlapping Generations – Nt=(R)t N0 – where the parents die before the offspring reproduce • N = population • R = #offspring/female • t = generation or time interval • N0 = initial # of individuals Example: If ten fertile female lions each have three offspring then die, how many lions will exist after five generations? Nt=(R)t N0 ? = (3)510 The population of lions after t (5 generations) is 2,430 lions Overlapping Generations with Discrete Reproduction - Nt = (λ)t N0 – where parents are still alive when their offspring reproduce and reproduction does not occur continuously but during a mating season, for example. • λ = expected lifetime reproduction/generation time Overlapping Generations with Continuous Reproduction - Nt = (e)r t N0 – where parents are still alive when their offspring reproduce and reproduction occurs continuously • r = (birth-death) • e = math constant e Density Dependent Growth Logistic Growth Model - ΔN = rmax *[(K-N)/N] *N – where the population will only grow as large as the resources/environment will allow it • ΔN = population growth • N = population size (number of individuals) • K = carrying capacity (how many individuals the environment will support) • rmax = the maximum possible rate at which the population will increase • This is the value where there are no environmental restrictions—which is not a true explanation of a population over time! Think of this as more of a theoretical value. • Shows how many individuals are added to the population when it's growing at it's fastest (At a point where environmental restriction is not yet a factor.) • ractual = rmax *[(K-N)/N] = the rate at which the population is growing at a particular point • Shows how many individuals are being added to the population at a particular population number. ractual can be found at any point on the graph and is dependent on the size of the population (x axis)