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Ecosystems and Organisms

Ecosystems and Organisms. What Are The Three Most Important Aspects of Organisms in an Ecosystem?. Populations Relationships Evolution. Populations. Definition: The simplest grouping of organisms in nature. Populations depend on: Resources Births Deaths Immigration Emigration.

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Ecosystems and Organisms

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  1. Ecosystems and Organisms

  2. What Are The Three Most Important Aspects of Organisms in an Ecosystem? • Populations • Relationships • Evolution

  3. Populations • Definition: The simplest grouping of organisms in nature. • Populations depend on: • Resources • Births • Deaths • Immigration • Emigration

  4. Resources • Limited resources such as food, water and living space will result in a population that levels off - carrying capacity. • This graph shows the growth of a yeast population in culture. After a period of exponential growth, the size of the population begins to level off and soon reaches a stable value. This type of growth curve is called an S-shaped graph

  5. If unlimited resources and growth this will result: Exponential graph or J curve Resources Cont…

  6. Factors Affecting Birth Rates • Age of reproduction • Number of females • Number of females at reproductive age • Amount of offspring produced if high infant mortality rate • Amount of time spent in raising and protecting young.

  7. Death • There are three types of organisms: • Type 1- high survival rate (low death rate) in the beginning of a life time then faster death rate at the end • Type 2 - fairly even mortality rate. • Type 3- High death rate in the beginning, then levels off at the end.

  8. Immigration and Emigration • The population will increase or decrease depending on the amount of organisms entering or leaving the area. • http://www.toppcensus.org/web/Archives/Multimedia.aspx?Category=MT&Filter=27

  9. Relationships • Predator prey - As the predators go up or down so does the prey

  10. Relationships cont.. • Symbiosis- organisms living in direct contact with each other. • Mutualism- both benefit • Commensalisms - one benefits and the other is not harmed • Parasitism - one benefits and the other is harmed

  11. Competition • Intraspecific competition- competition between organisms of the same species. • Interspecific competition- competition between organisms of different species. • http://www.globalchange.umich.edu/globalchange1/current/lectures/competition/competition.html • Invasive species and competition, may cause competition exclusion.

  12. Evolution • Adaptive behavior, physiology, and anatomy from genetic change can result in increased reproduction and ability to survive. • Coevolution - when two or more species influence each others evolution. • http://evolution.berkeley.edu/evosite/evo101/IIIF1Casestudyofcoevo.shtml • http://www.pbs.org/wgbh/evolution/educators/course/session4/elaborate_d.html

  13. Human Population • The human population continues to grow exponentially, why? • http://www.pbs.org/wgbh/nova/worldbalance/numbers.html • http://www.starch.dk/isi/energy/population.htm • http://www.learner.org/channel/courses/biology/units/humev/images.html

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