Population Ecology Introduction (Chap. 9)   Introduction (Chap. 9) A. Examples: The scope of population ecology B. Definitions and properties Terms: population, distribution, abundance, density, age structure, growth rate, demographics II. Growth rates: intrinsic rates of increase (Ch. 11) A. Geometric growth B. Exponential growth C. Logistic growth

Definitions Population: a group of individuals of the same species occupying a particular space at the same time.

This is our world www.smalltownproject.org/ Given that human population is currently at over 6 billion people and isn’t expected to level out to between 9 and 12 billion people sometime later this century, how much of that NPP can we appropriate before we irrevocably http://www.nhm.ac.uk U.S. 306,560,607 World 6,783,691,069 14:44 GMT (EST+5) Jun 01, 2009

Global changes Loss of biodiversity Overharvest Pollution http://news.nationalgeographic.com/news/ http://www.oceansatlas.org/ http://library.thinkquest.org/ http://www.ourworldfoundation.org.uk/polar.jpg Overharvest Pollution Species invasions Climatic change Molles 2007 We already know that a population of 6.75 billion people is causing all these changes. What will the planet be like with 9 billion people? 12 billion? 15 billion? Land use change - type - intensity Loss of biodiversity

Questions Will exponential growth continue indefinitely? How will population distribution change with time? How many people can the Earth hold? - What’s the carrying capacity for Earth? - At what standard of living? http://www.fpsoftlab.com/images/screenshots/earth-640x480-2.jpg

Properties of a population: Distribution - over what area is the population found. This includes: Abundance – how many total individuals Density - how many individuals in the same area at the same time

Population Growth Growth rate: how many individuals are gained (birth and immigration) minus how many are lost (death and emigration). - what is happening to the net population size. Age structure: how many individuals in different age categories, usually related to reproduction http://www.nhm.ac.uk Taylor and Southard. 1997. http://www.ocs.orst.edu/reports/climate_fish.html

Other terms Demographics covers the basic statistical information about a population: age structure, density, births, deaths, growth, and reproduction.

ECOLOGY OF POPULATIONS Properties of populations Patterns of distribution and density Intraspecific competition Population dynamics Growth and regulation Altering population growth Human impact

Growth Curves

Human Population

Survival Curves Survivorship is the percentage of remaining survivors of a population over time; usually shown graphically.     Type I survivorship curve: most individuals live out their life span and die of old age (e.g., humans).     Type II survivorship curve: individuals die at a constant rate (e.g., birds, rodents, and perennial plants).      Type III survivorship curve: most individuals die early in life (e.g., fishes, invertebrates, and plants).