May 4, 2012 Kyle Jager

Populations A population is all the members of one species that live in a defined area Populations fluctuate based on environmental factors Predators Food Supply Water Natural Disasters Shelter

Dispersion The distribution of species in an area can very greatly Clumped – sections of population group together Even – population spread evenly across area Random – population randomly exists in the area

Communities Predators and prey populations positively correlate to the population one another As prey populations increase, there is more food available to the predators so their populations rise. Community- all the members of all species that live in a defined area

Population Pyramids Population distributions can be displayed through graphs by both sex and age. Expanding – birth rate > mortality rate Stationary – birth rate = mortality rate Contracting – birth rate < mortality rate

Influences on populations Immigration and emigration Birth and death Why do populations stop growing? Exponential growth cannot be maintained with limited resources. Instead populations have a logistic curve and reach a limit called the carrying capacity.

Human Population Growth Human population growth appears to be growing very rapidly. Does this make our species except to the carrying capacity rule? To determine how human populations have changed over time, you will analyze the population of US age groups between 1980 and Please review some population pyramids of countries around the world to gain a better understanding of how societies differ over time. Links can be found in the “Interactive” blog post.