1. 1.Review When do populations grow exponentially Apply Concepts Why does exponential growth show a characteristic J-shaped curve 2.Review What is the characteristic shape of a logistic growth curve Explain Describe when logistic growth occurs Form a Hypothesis What factors might cause the carrying capacity of a population to change.

2. CH 5 POPULATIONS 5.1 How Populations Grow

3.  In the 1950s, a fish farmer in Florida tossed a few plants called hydrilla into a canal  Today, their tangled stems snag boats in rivers and overtake habitats; native water plants and animals are disappearing  Why did they get out of control and what can be done.

4. Populations  A group of interbreeding individuals of the same type that live in a particular area  Needed to define  Type of individual  Time  Place.

5. Geographic Range  Area inhabited by a population  Range can vary greatly.

6. Density and Distribution  Population Density  The number of individuals per unit area  Distribution  How individuals are spaced out across the range: randomly, uniformly, or clumps.

7. Random Distribution  Wild flowers grow randomly in a field.

8. Uniform Distribution  King penguins or a tree farm.

9. Clumped Distribution  School of fish or pack of wolves.

10.  Population density  Number of individuals of a species / (divided by) area  Dispersal  Organisms spreading out to other area  Open population  Individuals can come and go as they wish  Closed population  Individuals must stay within the population.

11. How do you find the population size

12. Counting Individuals  Works well for  Limitations  Large areas  Similar looking organisms  Large or small numbers  Organisms often don’t stand still while you count.

13. Sampling Nonmoving Populations  3 Steps  Find number of individuals in many smaller areas  Find the population density  Multiply by the area.

14. Nonmoving Population Example  Number of Ponderosa pines in 100,000 acre section of Yellowstone National Park  Plot 1: 20 trees in 1 acre; Plot 2: 10 trees in 1 acre; Plot 3: 30 trees in 1 acre  Number of trees in sampled area 60 trees in 3 acres = 20 trees per acre  Total number of trees = average density X area 20 trees per acre X 100,000 acres = 2,000,000 trees.

15. Nonmoving Population Example 2  Number of Ponderosa pines in 100,000 acre section of Yellowstone National Park  Plot 1: 150 trees in 3 acres, Plot 2: 90 trees in 1.5 acres, Plot 3: 60 trees in.5 acre  Number of trees in sampled area 150+90+60 = 300 trees 3+1.5 +.5= 5 acres 300 trees per 5 acres = 300/5 = 60 trees per acre  Total number of trees 60 trees per acre X 100,000 acres = 6,000,000 trees.

16. Sampling Moving Populations  Capture Recapture method, catch recatch, tagging  Catch a number of individuals from the population, tag them, record the number of tagged individuals, then release them  Later (time depends on specie) go back to same area and catch individuals, record the total number caught AND the number that you tagged earlier.

17. Moving Populations Example  How many Walleyes are in Howard Lake  Catch, tag, and release 50 walleyes then a week later catch 60 walleyes, 20 of which are tagged  How many walleyes in the lake  Use Ratios and cross multiple.

18. Number caught and tagged ---------------------- Total number Number caught second time that are marked ----------------------- Total number caught the second time =

19. 50 walleyes caught 1st time ---------------------- Total number of walleyes in the lake 20 tagged walleyes that were recaught ----------------------- 60 walleyes caught the second time = 50 x 60 / 20 = 3000/20 = 150 Walleyes in the lake.

20. Moving Populations Example 2  How many Rainbow Trout are in a 2 mile section of the Madison River  First time with an electrofisher you catch, clip the adipose fin, and release 100 fish  Second time you get 20 fish 5 of which were marked.

21. 100 trout caught 1st time ---------------------- Total number of trout in the river 5 tagged trout that were recaught ----------------------- 20 trout caught the second time = 100 x 20 / 5 = 2000/5 = 400 trout in that section of river.

22. Capture Recapture  Downfalls  Electrofisher  Catch them all  Technique  Injuries  Length of time between catches  Length of time trying to catch.

23. Population Growth  Tells you if population is growing or not  Four rates affect the population size  Mortality  Natality  Emigration  Immigration.

24. Birthrate and Death Rate  Mortality  Death rate, population decreases  Natality  Birth rate, population increases.

25. Immigration and Emigration  Immigration  Individuals move In, population increases  Emigration  Individuals leave, Exit, population decreases.

27. Age Structure  The number of males and females of each age a population contains  Helps to determine population growth.

28. Exponential Growth  The larger a population gets, the faster it grows  Requires unlimited resources  Cannot continue  Creates a J Curve.

29.  Organisms in a new environment can grow exponentially for a time.

30. Logistic Growth  Population’s growth slows and then stops after a period of exponential growth  Happens in natural populations  S Curve.

31. Phase 1  Exponential growth  Resources are unlimited, rapid reproduction  Low mortality.

32. Phase 2  Growth slows down  Due to high population size and less resources.

33. Phase 3  Growth stops  Population will remain at or near this size indefinitely.

34. Analyzing Data  Suppose that a pair of rabbits produces six offspring: 3 male and 3 female and that now offspring die Calculate If each pair of rabbits breeds only once how many offspring would be produced each year for five years Interpret Graphs Construct a graph of your data. What type of growth is occurring?

35. Growth Rate  May go up (+) or down (-)  Growth rate = (Natality + Immigration) – (Mortality + Emigration)  What is a good growth rate.

36. Growth Rate Example  Start off with 50 elk  You have 20 elk calves born  You have 4 die of old age  You have 3 that jump the fence and escape  What was your growth rate for the year.

37. Carrying Capacity  The largest population an area can support forever without harming the environment.