Population Dynamics Dynamic=“changing” Photo Credit: http://www.flickr.com/photos/solidether/1084349065/

Geographic distribution or Range – the area a pop. lives

Population Density – the number of individuals in an area

Population Growth depends on: Number of births Immigration (in) Number of deaths Emigration (out)

In a heard of elk in North Santiam valley, 25 calves are born in the year 2008. 15 adults died that same year. 5 elk joined from the South Santiam river. What is the growth rate for the herd? Births - Deaths +/- Migration = Growth Positive Growth rate = population increase Negative Growth rate = decrease

Exponential Growth –reproduce at a constant rate Exponential Growth –reproduce at a constant rate. Occurs under ideal conditions (no limits) J-shape curve ?! # of individuals Time

Logistic Growth – resources become less available, growth slows or stops near carrying capacity S-shape curve Carrying Capacity – the population size an environment can support

5-2 Limits to Growth Limiting Factor – causes population growth to decrease Density-Dependent Limiting Factors –depends on population density Competition (for food and space) predation parasitism and disease

Density-Independent Limiting Factors – does not depend on population size Unusual weather Natural disasters Human activities = (pollution, habitat destruction, introduction of invasive species)