Interpreting the graphs Population graphs Interpreting the graphs

What is Carrying Capacity? Carrying capacity is the number of individuals of a species that an ecosystem can support.

Pleasant Island Pheasants Carrying Capacity Growth rate = 0 Growth rate slows down Pleasant Island Pheasants 1937 – 8 pheasants introduced 1945 – 1325 pheasants on island 1947 – 1600 pheasants on island

Why Did the Pheasant Population Stabilize? Females were laying the same number of eggs Death rate increased, number of surviving chicks decreased Births > deaths pop. Up Births < deaths pop. Down Births = deaths zero population growth

Carrying Capacity Maximum population size indefinitely supported by available resources Determined by sustained availability of renewable resources such as nutrients, water and light space Influenced by environmental resistance

A = lag phase (very few organisms to begin with – reproduction is slow B = acceleration phase C = exponential phase F = population crash due to limited resources

Grand Canyon Kaibab Deer 1907 – 4000 deer on Kaibab Plateau beginning in 1907– removal of predators 1924 – 100,000 deer very severe winter in 1925-26 1927 – 10,000 deer 1907 - 1939 removed 816 cougars 1907 - 1926 removed 30 wolves 1907 - 1939 removed 7,338 coyotes

What Were the Effects of the Deer Population at Its Peak? Forest was over browsed leading to Loss of ground cover Soil compaction – less water and increased erosion Carrying capacity reduced for years

Carrying capacity 1. What is the carrying capacity of the cockroach population? 2. At what day did the cockroach population meet the carrying capacity?

Carrying Capacity Sometimes a best fit line is used to represent the carrying capacity. 3. What is the carrying capacity of this population? 4. At what year did it reach the carrying capacity? 5. Why did the population decrease in 1950?

Population Crash 6. What is happening between 1944-1960? 7. What do you think happened in 1963?

8. Which letter points to the x axis? 9. Which letter points to the y axis?

The number of predators increased this year. 10. Which of the following best describes why the population of foxses declined at point A? The number of predators increased this year. Competition increased and foxes were limited by the number of rabbits available? A natural disaster wiped out a large portion of the foxes The rabbits were hibernating and there was less food available. A