Lecture #23Date _______ Chapter 52 ~ Population Ecology

A wealthy business man owns a acre island and wants to have his own private pheasant hunting ranch so he releases 100 pheasant onto the island (50 male and 50 female). The island is covered in wild grasses and each bird needs a minimum of a 50 yard X 50 yard area to support them with the resources to survive each year. Look up the clutch size and age of fertility in the ring necked pheasant and then project what the population growth of the pheasant will look like. Assume that the pheasants have no natural predators on this island and that the weathy business man starts hunting in 5 years and then only kills 20 pheasants per year.A wealthy business man owns a acre island and wants to have his own private pheasant hunting ranch so he releases 100 pheasant onto the island (50 male and 50 female). The island is covered in wild grasses and each bird needs a minimum of a 50 yard X 50 yard area to support them with the resources to survive each year. Look up the clutch size and age of fertility in the ring necked pheasant and then project what the population growth of the pheasant will look like. Assume that the pheasants have no natural predators on this island and that the weathy business man starts hunting in 5 years and then only kills 20 pheasants per year.

The business man wants to plant a second island with Pheasant, but the second island has 3 native species of birds that already occupy the island and depend upon the grassland for survival and reproduction.The business man wants to plant a second island with Pheasant, but the second island has 3 native species of birds that already occupy the island and depend upon the grassland for survival and reproduction.

Propose a two pronged study plan.Propose a two pronged study plan. –PART 1: a study to predict what the impact would be of introducing pheasant to the island. –PART 2: a study plan to monitor bird populations after pheasant are introduced to determine if pheasant cause impacts to the native bird populations.

Population characteristics Density ~ # of individuals per unit of area counts sample size estimate indirect indicators mark-recaptureDensity ~ # of individuals per unit of area counts sample size estimate indirect indicators mark-recapture Dispersion ~ pattern of spacing random ~ unpredictable, patternless spacing (a) clumped ~ patchy aggregation (b) uniform ~ even spacing (c)Dispersion ~ pattern of spacing random ~ unpredictable, patternless spacing (a) clumped ~ patchy aggregation (b) uniform ~ even spacing (c)

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

Population Growth Models Exponential model (red) idealized population in an unlimited environment (J- curve); r-selected species (r=per capita growth rate)Exponential model (red) idealized population in an unlimited environment (J- curve); r-selected species (r=per capita growth rate) Logistic model (blue) carrying capacity (K): maximum population size that a particular environment can support (S-curve); K-selected speciesLogistic model (blue) carrying capacity (K): maximum population size that a particular environment can support (S-curve); K-selected species

Population life history “strategies” r-selected (opportunistic)r-selected (opportunistic) Short maturation & lifespanShort maturation & lifespan Many (small) offspring; usually 1 (early) reproduction; no parental careMany (small) offspring; usually 1 (early) reproduction; no parental care High death rateHigh death rate K-selected (equilibrial) Long maturation & lifespan Few (large) offspring; usually several (late) reproductions; extensive parental care Low death rate

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