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Population Ecology

Population Ecology. Science 10. Definitions. Population - a group of individuals of the same species living within a particular area or volume. Population dynamics- changes in a population characteristics determined by a number of possible outcomes. Ex: mortaility, immigration.

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Population Ecology

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  1. Population Ecology Science 10

  2. Definitions Population- a group of individuals of the same species living within a particular area or volume. Population dynamics- changes in a population characteristics determined by a number of possible outcomes. Ex: mortaility, immigration

  3. Characteristics of Population • Habitat- the place where an organism or species normally lives. • Species- organisms that resemeble one another in appearance, behaviour, genetic make-up. • Niche – the way an organism occupies a position in an ecosystem including all the necessary biotic and abiotic factors.

  4. Population Size and Density • Population Size is the number of individuals of a certain species occupying a certain area/volume at a given time. • Population Density is the number of individuals of the same species that occur per unit of area or volume

  5. Calculations Formula: D= N/S D- Population Density N- Total Number “Count” of that species S- Space occupied by the population

  6. Examples: 1. 480 moose living in a 600 hectare(ha) region. D= N / S D=480 moose / 600 ha D= 0.8 moose/ha 2. What is the density of a population of bacteria if there are 1000 bacteria in a testtube of 10mL?

  7. Changes in population There are two types of factors which can effect a population: 1. Density independent factors – any factor which does not depend on density eg. extreme storms, fires and floods. 2. Density dependent factors – any factor which does depend on the density eg. Disease, lack of food, predation, and competition. *** Read pages 288-289 Questions 1-4 page 290

  8. Measuring and Modeling Population Change • Carrying capacity is the maximum number of organisms that can be sustained by available resources over a given period of time. • the largest population of a species that an environment can support. • Eg. – 100,000 white tailed deer in Nova Scotia • These are often shown in graphs • Complete graph on page 291

  9. Four main factors that determine carrying capacity 1. Materials and Energy – energy from Sun, water, carbon 2. Food Chains – populations are limited by food supply 3. Competition – demand for resources among individuals 4. Density – amount of available space. Two types of competition Intraspecific Competition – competition among members of the same species – wolves competing with wolves Interspecific Competition – competition between species – lions and tigers competing for food - seals and dolphins competing for food

  10. Different types of populations Open population- a population in which change in number and density is determined by births, deaths, immigration, and emigration. Closed population- a population in which change in size and density is determined by birth and death rates!

  11. Population Growths A closed population will exhibit exponential growth- a pattern of population growth where organisms reproduce continuously at a constant rate.

  12. Open Population Growth • An open population will show the following type of growth which is referred to as an S-curve – a pattern of exponential growth at first then a leveling off once carrying capacity is reached.

  13. Human Population and Carrying Capacity • What is happening to the human population of earth? • http://www.npr.org/2011/10/31/141816460/visualizing-how-a-population-grows-to-7-billion • http://www.youtube.com/watch?v=sc4HxPxNrZ0 • Read pages 293-294 Questions 5-7 page 295

  14. Ecological footprints • Ecological footprints: is a measure of the impact of a human individual or population on the environment. • Unsustainable: large ecological footprints and dependence on fossil fuels. • Sustainability: modern societies must seek to establish ecological footprints which use water and land at levels which can continue forever.

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