Science AHSGE Standard VI-1, part 2- Limiting Factors of Populations

Density-Dependent Limiting Factors of Populations Density-dependent factor- Variable affected by the number of individuals in a population Limited resources (in short supply)- food, water, air Higher population density:higher resource depletion Logistic model- Exponential growth limited by density- dependent factor Examples: Any required resources (biotic and abiotic) Disease/parasites Bacterial Disease- Caused by Pathogens Parasitic Disease- Caused by vectors Viral disease- Caused by virus Space

Logistic Growth Model S shaped curve Growth levels off at carrying capacity (K)- Population size that can environment can sustain

Density-Independent Limiting Factors of Populations Density-independent- Variable that affects a population regardless of the population density, such as climate Weather/climate; human activity (pollution); natural disasters Exponential model- Constant growth rate R-strategists- Live to reproduce; short life span K-strategists- Long-lived organisms that produce few young, develop slowly and reproduce late in life

Density-Independent Limiting Factors The Greenhouse Effect An increase in heat-trapping gases causing an increase in temperature Heat-trapping gases: Carbon dioxide and carbon monoxide pollution GLOBAL WARMING Affecting entire globe, all species

Exponential Growth Model J shaped curve Many temporary growth explosions

Primary Succession Succession- change in an ecosystem over time; reaches climax community (most stable) Pioneer species- 1 st species to inhabit an area

Secondary Succession

Non-Native Species An organism that has been introduced into an area Exotic, Invader, Alien, Introduced, Feral Do not belong and therefore have no natural predators Population numbers increase dramatically May out-compete native species May overgraze/over hunt native resources Examples: Melaleuca, fire ants, Africanized bees, Zebra mussells, Kudzu, rabbits in Australia, etc.