Populations

Demography

Demography is the study of processes that influence population size - it is the way we study changes brought about by births, deaths and dispersal For Northwest Montana, Greater Yellowstone, Central Idaho

The Fundamental Equation of Ecology – Harper 1977 Δ N = B – D + I – E Change in Number = Births – Deaths + Immigration - Emigration John L. Harper –

Rearrange Fundamental Equation Δ N = B – D + I – E N future = N now + B – D + I – E Often we assume that I = E, so no net dispersal

Common Field Grasshopper

Grasshopper – development and incomplete metamorphosis

Red Deer – Stag, Hind, Fawn

Isle of Rhum, Scotland

Red deer fawn being tagged for study

Arithmetic scaleLogarithmic scale

General types of survivorship curves

Human management of species may change survivorship curves A – fish mortality in typical population B – fish taken by fishing

Population Pyramid For France Jan. 1, 1967

Changes in population of Japan over time

Changes in population of Canada from