1. Population Dynamics

2. Warm Up… According to research, a bacteria that reproduces every 20 minutes would form a layer of bacteria 1 foot deep across the entire earth’s surface in 36 hrs. Why hasn’t this happened? According to the lab, what effects do wolves have on the moose population on Isle Royale (Name at least 2) Why are dandelions randomly scattered around the lawn but elephants are not randomly scattered around the savanna? How many deer can the CVNP sustain?

3. Isle Royale Recap

4. What happens when a population overshoots? Overshoot = grow beyond carrying capacity Overshoots are always followed by a die- off or crash Results from a species continuing to reproduce at a high rate because the decline in resources hasn’t affected them yet Will White-tails in CVNP crash?

5. What happened on Isle Royale? Moose Pop. started out growing exponentially, no natural enemies, plenty of food When Moose outgrew food source, their Pop. Dropped dramatically then leveled

6. What happened on Isle Royale? When wolves arrived, they limited moose Pop. even further Eventually the Moose Pop. Controlled Wolf Pop. Wolf Pop. Limited Moose Pop. Overall health of Avg. Moose better w/ wolves present

7. 5,000 4,000 3,000 2,000 1,000 500 Number of moose 100 90 80 70 60 50 40 30 20 10 0 1900191019301950197019902000 1999 Year Number of wolves Moose population Wolf population

8. Population growth curves J-curve = exponential growth = Pop. Grows faster and faster as time goes on Conditions: no natural enemies, plenty of resources Prediction: Pop will overshoot carrying capacity and suffer a crash or die-off S-curve = logistic growth = Pop. Grows until it nears carrying capacity and then growth rate slows Conditions: = some natural enemies present Prediction: = Population will hover near carrying capacity

9. © 2004 Brooks/Cole – Thomson Learning Time (t) Population size (N) K Exponential GrowthLogistic Growth Make a sketch of each and label it

10. Other population curves Stable = slight variation near carrying capacity Cyclical = up and down pattern occurring at regular time intervals Irregular= unpredictable, no pattern Irruptive = sudden, un-predicted boom followed by a sudden return to normal stable levels

11. © 2004 Brooks/Cole – Thomson Learning Number of individuals Time Irruptive Stable Cyclic Irregular

12. How does Pop. Density affect Pop. Growth? Some factors affect population size regardless of density (density-independent) Ex. – widespread natural disasters, widespread pollution, habitat destruction, etc… Other factors are density-dependent Predation, disease, food shortage, competition, etc…

13. 2 reproductive strategies Focus on one of the two main aspects of biotic potential: IRI or Recruitment Both strategies work Not all organisms fit strictly into one category

14. r-selection Have tons of offspring but do not parent All energy is put into mass producing offspring Most young die, only one or two survive Smaller animals Useful for taking advantage of good conditions in a changing environment Short life cycles Insects, fish, etc…

15. K-selection Have few offspring but raise a high % to reach adulthood – parenting Put energy into raising young Most young survive, 1 or 2 out of a small brood Larger animals, high on food chain Longer life cycles / life spans Used by species that are highly adapted to cope with normal environmental changes Mammals, birds, people

16. Figure 9-9 Page 196 Number of individuals Time Carrying capacity K species; experience K selection r species; experience r selection K

17. Survivorship curves tell the story Type I – individuals die late in life (late loss), strict K-strategists Type II – individuals die out equally at all stages of life cycle (Constant loss) intermediate between K and r strategy Type III – individuals die early in life (Early loss) strict r-strategists

18. Percentage surviving (log scale) 100 10 1 0 Age

19. Importance of genetic diversity in populations Genetic diversity helps the population: survive disease outbreaks cope with changes in the environment develop advantages in competition

20. Factors that reduce genetic diversity Founder Effect = a population is genetically very similar to the members that first colonized the area Bottleneck = some catastrophe only allows certain individuals to survive, all sharing similar genetics Inbreeding = only certain genes keep getting passed on – increases frequency of defective genes

21. King Cheetah

22. Make a Prediction…. If I set up a camera at the turnpike looking back down the stream in the land lab ….and I take a photo once a day for 20 years….. What will I see as a look back through the photos?

23. Examples in Humans??? Fugate family of Kentucky

24. Principles of Sustainability 1) For ecosystems to be sustainable, waste must be decomposed and nutrients must be recycled 2) For ecosystems to be sustainable, the sun must be the primary source of energy 3) For ecosystems to be sustainable, populations levels must be maintained to prevent over-grazing / over-consumption 4) For ecosystems to be sustainable, biodiversity must be maintained

25. White-tailed Deer Populations Many communities have begun to allow hunting within city limits, why? http://www.youtube.com/watch?v=qO0qEklDZq c http://www.youtube.com/watch?v=JNhzdkFrf38 &feature=relmfu Go to kearnsm.edublogs.org

26. In your next lab project…. 1) Does anyone in your family hunt? 2) Why do you think the City Of Hudson recently decided to allow bow-hunting? 3) Do you agree with this decision? (explain) 4) What questions would you like to have answeredbefore a decision like this is made?