Transcript ppt
Characteristics of Populations Chapter 5 Population Size The number of organisms of the same species living in the same area at the same time Factors that effect population size: ◦ ◦ ◦ ◦ Births Deaths Immigration (going into) Emigration (leaving) Population Density The number of organisms of the same species living in a certain area Population Dispersion Population Growth Rates #of Births-# of Deaths= Growth Rate If more individuals are being born than dying, an increase in population size will occur. ( + number) If more individuals are dying than being born, a decrease in population size will occur. (-number) Exponential Model J-Curve The larger the population gets, the faster it grows Exponential Growth Logistic Growth S-Curve Begins as exponential growth then levels off as growth rate slows down or evens Population has reached its carrying capacity Carrying capacity Carrying Capacity The maximum number of individuals of a particular species that can be supported by an environment Limiting Factors Factors that control the size of a population Density Dependent- factors that limit the size of the population based on the populations density Competition, Food Availability, Shelter, Mates, Water, Predation, Herbivory, Parasitism, Disease Density Independent-factors that limit the population size that are independent (NOT based) on the populations density Natural Disasters, hurricanes, draughts, floods, wildfire, How to tell the difference between density dependent and density independent factors: Will the factor’s effect increase if the population is higher? Will the factor’s effect lessen if the population is lower? If the answer to both questions is “No,” then it is a density independent factor. Density Dependent Density Independent Competition for nest sites Natural disasters Predators Fires Food Temperature Soil nutrients Pollution Diseases Hurricanes Limiting Factors Human Population Human Population Has dramatically increased over time Reasons: ◦ ◦ ◦ ◦ Improved nutrition Improved sanitation Improved medical care Reduced death rates, with high global birth rates * Birth Rates are higher in developing countries* Oh, Deer! Time (Generation) Number of Deer 1 2 2 4 3 8 4 14 5 10 6 17 7 6 8 9 10 11 12 Oh, Deer! Follow up questions and graphing Graph the results of the activity and include all the essential components of a graph. 2. What type of curve is your graph an example of? 3. What is the carrying capacity for the deer population in Braden Forest? 4. Label the carrying capacity on your graph using a single, straight, dashed line and add it to the key . 5. What happens if the population goes over the carrying capacity? 6. What happens if the population goes under the carrying capacity? 7. Can the carrying capacity of an ecosystem change? Explain. 8. What were the limiting factors in this activity? 9. In a real ecosystem, can a population keep growing and growing forever and ever and ever? Explain. 10. What are two examples of density dependent limiting factors that could have impacted the deer population in Braden Forest? 11. What are two examples of density independent limiting factors that could have impacted the deer population in Braden Forest? 12. What are two ways humans can impact the carrying capacity of an ecosystem? 1.