Density Independent vs. Density Dependent Factors

What impacts the number of members in a herd or a school? 7-3

Population will be affected by: 7-3

Biotic Factor = any living influence on an organism within the ecosystem. Examples include: predators, plants, bacteria. Abiotic Factor = any NON living influence on an organism within the ecosystem. Examples include: Rain, fire, weather, temperature. 7-3

Types of Growth 1. EXPONENTIAL Growth  Under ideal/perfect conditions with unlimited resources a population will grow exponentially  Growth increases slow and steady at first  Growth then increases larger and larger 2. LOGISTIC Growth  As resources become less available, growth rate of population slows or stops  Can happen when birth rate is lower then death rate  Can happen when immigration is less then emigration 7-4

Carrying Capacity: Climax Community: – Final stage of succession where the number of organisms remains stable The carrying capacity is the maximum population size of the species that the environment can sustain – given the food, habitat, waterhabitatwater and other necessities available in the environment.

Limiting Factor: A limiting factor limits the growth or development of an organism, population, or process – What lack of resources will limit your growth? – Write down what the limiting factor was in our dust bowl scenario.

Density Dependent Factors: CompetitionParasitismDiseasePredation Why are these factors typically BIOTIC? Name an organism that would not be affected by this factor. Factors that effects on the size or growth of population vary with the population density. 7-5

Density Independent Factors Why are these factors typically ABIOTIC? How does a weather event affect population. A factor that affects the size of a population independent or regardless of the population density. Fire Weather Temperature Precipitation 7-5