Population Ecology

CHAPTER 9 NOTESAPES

Ms. Miller

Key Concepts

Factors affecting population size

Species reproductive patterns

Species survivorship patterns

Conservation biology and human impacts on ecosystems

Population Dynamics and Carrying Capacity Population dynamics—study of how populations change in

size, density, and age distribution Biotic potential--a populations capacity for growth

(intrinsic rate of increase [r])—rate of growth with unlimited resources

Environmental resistance—all factors that limit the growth of a population

Carrying capacity (K)—maximum number of individuals of a given species that can be sustained indefinitely in a given area

Exponential and Logistic Growth—two models of growth (J curve vs. S curve)

Population Density—number of individuals in a given area

J-Curve

S Curve

Exponential and Logistic Growth

Population Dispersion

Fig. 9-2 p. 164

Factors Affecting Population Size

Fig. 9-3 p. 166

Population Density Effects

Density-independent controls—affect a population’s size regardless of its density (climate, fire, natural disasters, meteor impacts, unseasonable weather, deforestation, etc)

Density-dependent controls—affect population size/growth as plate job population density increases (competition, predation, parasitism, disease transmission)

Natural Population Curves

Fig. 9-7 p. 168

The Role of Predation in Controlling Population Size Predator-prey cycles Top-down control vs. Bottom-up control

Fig. 9-8 p. 168

Reproductive Patterns and Survival Asexual reproduction Sexual reproduction

r-selected species K-selected species

Fig. 9-10 p. 170

Survivorship Curves

Fig. 9-11 p. 171

Human Impacts on Ecosystems

Habitat degradation and fragmentation Ecosystem simplification Genetic resistance Predator elimination Introduction of non-native species Overharvesting renewable resources Interference with ecological systems

Learning from Nature

Interdependence—all organisms on earth are dependent on one another

Unpredictability—things we do have unexpected or unintended side effects

Recycle wastes—we must find ways to use waste for energy

Dependence on Nature—we need the earth but the earth does not need us

Limited resources –we continue to deplete and degrade the Earth’s natural capital