Chapter 52 ~ Population Ecology

Demography: study of factors that affect growth & decline of populations Birthrate (natality, fecundity)~ # of offspring produced Death rate (mortality) Immigration Emigration Age structure~ relative number of individuals of each age Survivorship curve~ plot of numbers still alive at each age

Age structure diagrams

Population Growth Models Exponential growth • idealized population in an unlimited environment (J-curve); Logistic growth Sigmoid (S-shaped pop. Growth curve) carrying capacity (K): maximum population size that a particular environment can support (S-curve)

Sigmoid (S shaped) growth Explain: Exponential growth phase Transitional phase Plateau phase What are limiting factors? Any factor that sets limits to population increase. List 3…

The following slides are either not in IB or are found in option G

Population life history “strategies” r-selected (opportunistic) Short maturation & lifespan Many (small) offspring; usually 1 (early) reproduction; no parental care High death rate K-selected (equilibrial) Long maturation & lifespan Few (large) offspring; usually several (late) reproductions; extensive parental care Low death rate r-selected species– high repro rates, quick to mature, shorter lives K-selected species– long life, slower to mature, parental care

Population limiting factors Density-dependent factors •competition •predation •stress/crowding •waste accumulation Density-independent factors •weather/climate •periodic disturbances

p.104 regular bio book for simulation Describe one technique used to estimate the population size of an animal species based on a capture-mark-release-method. One method of estimating the population size of an animal species is the capture-mark-release method. 1. As many individuals of a population are caught. These individuals are marked. 2. The individuals are released back into their environment. 3. After a while, as many individuals of a population are caught in the same area again. 4. The total number is taken note of and the number of those caught which are marked This is known as the "Lincoln Index" The formula (n1 × n2) / n3 is then used where: n1 = the number of individuals caught in the first trial. n2 = the number of individuals caught in the second trial. n3 = The number of individuals in the second trial which were marked.

Population characteristics Density~ # of individuals per unit of area -- measured by counting, sample size estimates, indirect indicators (tracks, nests etc.), mark-recapture Dispersion~ pattern of spacing •random~ unpredictable, patternless spacing (a) •clumped~ patchy aggregation (b) •uniform~ even spacing (c)