BIOTIC FACTORS AFFECTING POPULATIONS

I. THE CONCEPT OF DENSITY DEPENDENCE I. THE CONCEPT OF DENSITY DEPENDENCE u Vital rates change as density changes

I. THE CONCEPT OF DENSITY DEPENDENCE I. THE CONCEPT OF DENSITY DEPENDENCE u Vital rates change as density changes u Evidence for density dependence

II. LIMITATION AND REGULATION OF POPULATIONS u Limiting factors u any environmental factor quantifiably affecting population growth u biotic and abiotic

II. LIMITATION AND REGULATION OF POPULATIONS u Limiting factors u Regulating factors u density-dependent factors (depress growth as N increases) u biotic (competition, predation, disease)

III. LOGISTIC MODEL OF POPULATION GROWTH III. LOGISTIC MODEL OF POPULATION GROWTH

IV. INTRASPECIFIC COMPETITION IV. INTRASPECIFIC COMPETITION A. Food As a Proximate Cause

IV. INTRASPECIFIC COMPETITION u Food supplementation experiments u home-range size declined u home-range overlap increased u the breeding season was lengthened u litter sizes increased in poor habitat u population density increased 2-3 fold

IV. INTRASPECIFIC COMPETITION A. Food As a Proximate Cause Limitation? Yes Regulation? No

IV. INTRASPECIFIC COMPETITION A. Food As a Proximate Cause

IV. INTRASPECIFIC COMPETITION A. Food As a Proximate Cause

IV. INTRASPECIFIC COMPETITION A. Food As a Proximate Cause B. Space As a Proximate Cause

IV. INTRASPECIFIC COMPETITION A. Food As a Proximate Cause B. Space As a Proximate Cause C. Effects of Competition on Vital Rates u Dispersal rate…

IV. INTRASPECIFIC COMPETITION u Dispersal rate u lower survival rate of dispersers u nondispersers survive better

IV. INTRASPECIFIC COMPETITION C. Effects of Competition on Vital Rates u Survival rate: Juvenile mammals u snowshoe hares

IV. INTRASPECIFIC COMPETITION C. Effects of Competition on Vital Rates u Survival rate: Juvenile mammals

IV. INTRASPECIFIC COMPETITION u Survival rate: A dult mammals

IV. INTRASPECIFIC COMPETITION IV. INTRASPECIFIC COMPETITION u Fertility rate (Inversity)