1.3 Populations

Figure 1.15 page 18

Carrying Capacity It’s the largest population of a species that an environment can support. Seychelles Paradise Flycatcher requiring about one hectare of mixed woodland per breeding pair. Lives on small island north-east of Madagascar.

4 factors determine the carrying capacity 1) MATERIALS AND ENERGY Limited by amount of energy from the Sun Supply of water, carbon and other materials adventures.com/costarica_nature.asp

4 factors determine the carrying capacity 2) Food Chains Limited by amount food supply (so trophic level below) Limited by predators (so trophic level above)

4 factors determine the carrying capacity 3) Competition Competition for food, water, mate and space. Intraspecific competition: among members of the same species Interspecific competition: between species. ecran-photo-paon-p18507.html

4 factors determine the carrying capacity 4) Population density : how many individuals that can live in an area at one time.

Density-dependent factors When density increases beyond suitable level: Overcrowding may : –increase stress and spread of diseases or parasites –Increase aggression and neglect of offspring Therefore decreases population

Density-independent factors Limit a population regardless of its size. -Forest fire -Earthquake -Volcanic eruption -Tornado

Check your understanding Do bacteria population assignment Do p. 24 # 1 to 6