Population Ecology

Population Ecology MRS. bENJAMIN

What two countries contain the largest human populations? a. United States & China b. India & United States c. China & India d. Australia & China

2. The current world population is approximately a. 6,900,000,000 b. 9,000,000,000 c. 5,000,000,000

3. According to this graph of Finland’s population, which is true? a. The largest portion of the population are males and females between the ages 40-44. b. The largest portion of the population are males and females between the ages of 60-64. c. The largest portion of the population are males and females between the ages of 15-19.

4. According to this graph at what age are there the least males? a. 75-79 b. 40-44 c. 20-24

5. According to this graph of the Afghanistan population which age group has the most number of males and females? a. 45-49 b. 20-24 c. 5-9

6. According to this graph the birth rates in Sudan are a. increasing b. decreasing c. staying the same

Population Ecology The study of how plant and animal populations within a community affect each other. Can be affected by the attributes of density, age, population growth, competition, and predation. Image: http://www.bitbetter.com/?xc=MC900078708

Population Density • The measure of how crowded organisms are in their environment. • Because organisms compete for resources, keeping a balance is important. • If the population is too high, some organisms will die.

Limiting Factors • Density-dependent • Dependent on the population size. • Density-independent • Affect the same percentage of a population regardless of population size.

Density-dependent limiting factors • Related to competition and other interactions between organisms. • Density-Dependent limiting factors include: • Food supply • Predation • Disease • As population grows each factor acts more strongly to limit growth (helps control growth)

Density-independent limiting factors • These limit growth of population density by changing or destroying the habitat. • Examples include: • Natural disasters such as • Hurricanes • Fires • Floods • These can cause dramatic fluctuations in population size but they do not regulate size.

Population Age • Three groups of ages: • Pre-reproductive • Reproductive • Post-reproductive. • Pre-reproductive organisms are young and have not reproduced. Image: Microsoft clip art

Population Age • Reproductive organisms are in the process of reproducing • Post-reproductive organisms are past the stage of reproducing. • To be productive, a community should contain each of these three age groups. Images: Microsoft clip art

Population Growth • Determined by immigration, emigration, natality, and mortality. Image: http://www.istockphoto.com/microsoftclipartimages.php?xc=MP910221037

Population Growth • Emigration is the act of an organism moving out of a habitat. • Immigration is the act of an organism moving into a habitat. • Image: Microsoft clip art

Population Growth • Natality is the production of new individuals in a habitat. • Mortality is the death rate in a population.

Exponential Growth A population grows at a rate in which each generation is a multiple of previous generation. All populations if given the perfect environment has the potential to increase exponentially. However, reality is that resources are limited thus and exponential growth can only happen for short periods.

Exponential Growth In reality what usually happens is known as a “boom and burst curve.” The organism grows exponentially while conditions are good but then collapses when the conditions change. Usually populations follow this pattern are density-independent populations. This happens a lot with insects due to climate or rainfall.

Logistic Growth Growth that occurs slowly and stops following a period of exponential growth Usually populations controlled by density-dependent factors. Generally an S-shaped curve on a graph Plateaus and usually stabilizes at carrying capacity

Carrying capacity The number of individuals which a species can support within an ecosystem. Generally as a organism reaches its carrying capacity it levels off and stops growing creating an S-shaped curve.

Exponential & Logistic Growthhttp://www.bio.georgiasouthern.edu/Bio-home/George-Sophie/Ecologyquestions.html

Competition • The use of the same resources by different organisms to live. • Population ecology can also be affected by competition. • All resources are limited in supply. • Because of this, some organisms will die or will be forced to move to other communities to survive. Image: Microsoft clip art

Predation • One living organism serving as food for another organism. • The organism that consumes another is called a predator, the organism being consumed is called the prey. Image: http://www.nvtofficeclips.com/microsoft/?xc=MC900444848

Predation • Cannibalism, or the eating of your own kind, is also considered predation. • An example of cannibalism is the female praying mantis eating the male during mating. Image: Microsoft clip art

External Environment • All organisms are encountered with changes in their external environment. • Failure to change may cause elimination of the species. • The ability for an organism to change with their environment is called adaptation. Image: http://marketplace.veer.com/officeonline/?xc=MP900448006

Adaptation The ability to change with environment is called adaptation. An example of adaptation is homeostasis.

Human Population Density http://www.pbs.org/wgbh/nova/worldbalance/numb-flash.html

Resources Carter, J. (2004). Protista. Retrieved January 31, 2011 from http://biology.clc.uc.edu/courses/bio106/protista.htm, DuBay, D., Tweed, A., Schoch, R., & Lapinski, A. (1999). Ecological Interactions. Environmental Science. Addison Wesley Longman Inc. United States of America. 50-88. Illinois State Core Curriculum Postlethwait, J., & Hopson, J. (2006). Ecology. Modern Biology. Holt, Rinehart and Winsten. Austin, Texas. 358-379. Prentiss, D. What is a biomass pyramid? University of California. Retrieved on January 31, 2011 from http://earth.rice.edu/mtpe/bio/biosphere/topics/energy/40_biomass.html Ricklefs. R. (2008). The Economy of Nature. W.H. Freeman and Company. New York. 4-15.

Population Ecology