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Population Ecology Population Dynamics • Population: • All the individuals of a species that live together in an area • Three Key Features of Populations • Geographic distribution • Density • Growth Rate Three Key Features of a Population • Geographic Distribution: is the area inhabited by a population of species. • Example: Three Key Features of Populations Density: measurement of population per unit area or unit volume Three Key Features of Populations • Growth Rate: • Growth Rate depends on: 1. Immigration: movement of individuals into a population 2. Emigration: movement of individuals out of a population 3. Birth Rate: 4. Death Rate: How do Populations Grow? • Exponential Growth: • Logistic Growth: Factors Limiting Growth Rate • Declining birth rate or increasing death rate are caused by several limiting factors including: • Competition: • Parasitism and Disease: • Predation: • Drought and other climate extremes: • Human Disturbances: Density Dependent Vs. Density Independent Factors • Competition, predation, parasitism and disease are density dependent factors. - Density dependent factors become limiting only when there are large and dense populations. - Example: • Human Disturbances, drought and climate extremes are density independent factors. - Density independent factors become limiting any time they strike. They are independent of population size. - Example: Classwork • Can limiting factors such as shortage of food cause mass extinctions of a species? • Discuss how limiting factor(s) can contribute to mass extinction? Use examples from the article to support your answer. History of the Human Population