1. The Distribution of Species

2. How are organisms distributed in these biomes? Why are organisms found in some biomes but not others? The answer to these questions ecologists must look at biotic and abiotic factors

3. Dispersal is the movement of _________ ___________________________________

4. Figure 40.12-2 Why is species X absent from an area? Area inaccessible or insufficient time Predation, parasitism, competition, disease Yes No Yes No

5. Biotic Factors Do other species stop the ability for a species to reproduce and survive? ____________,__________,__________

6. Figure 40.12-3 Chemical factors Why is species X absent from an area? Does dispersal limit its distribution? Area inaccessible or insufficient time Predation, parasitism, competition, disease Water, oxygen, salinity, pH, soil nutrients, etc. Do biotic factors (other species) limit its distribution? Temperature, light, soil structure, fire, moisture, etc. Do abiotic factors limit its distribution? Physical factors Yes No Yes No

7. Abiotic Factors Do non-living factors stop the ability for species to reproduce and survive. Temperature Water & Oxygen __________ Sunlight ___________

8. Density and Dispersion Density: __________________________ __________________________________ ◦How practical is this?

9. Changes to population size Adding & removing individuals from a population ◦_________ 2005-2006

10. Population Dynamics How do populations change? What factors affect how changes occur in populations ?

11. Key Definitions Population -___________________ ______________________________ Population Density – ____________ ______________________________

12. Dispersion – ___________________ ______________________________ ◦Clumped, Even, or Random

13. How are individuals counted? Count all individuals within the boundaries – rare Large herds can be counted by plane. Most of the time, these strategies are impractical.

14. More accurate methods Sampling techniques:  ______________________________________ _________________________________________ Ex. ____________________________________ _________________________________________ ◦ The more _________, the more_______________.

15. Estimate density from indicators ◦_____________________________________. Mark Capture Method ◦Tag or “mark “ a random sample of individuals in a population and release. ◦A few weeks later scientists take another sample.  Number of marked in 2 nd sample (x)  Total number of animals captured in 2 nd sample (n)  Number marked and released in 1 st sample (s)  Estimated population size (N) ___ = ___ or (solving for population size) N = ___ x x sn n s N

16. So, what do the population numbers tell us?

17. How Populations Can Change Exponential Growth – ____________________ Logistical Growth – Population grows but levels off when it reaches ____________ ____________________ ◦Ecosystems have _______ _________which restrict the potential population

18. Population Regulation Factors Density-Independent Factors ◦Limiters that don’t depend on the size of the population ◦Ex. ____________________ ________________________ Density-Dependent Factors ◦Limiters that change with population size ◦Ex. ___________________ _______________________

19. Population Growth Exponential model of population: idealized population in an unlimited environment Change in population = Births during –Deaths during size during time interval time intervaltime interval ____________ We can simplify the equation and use r to represent the difference in per capita birth and death rates. N/t = rN OR dN/dt = rN Zero population growth (ZPG): B = D

20.  Under ideal conditions, exponential growth occurs. We may assume the maximum growth rate for the population (r max ) to give us the following exponential growth _________________

21. Unlimited resources are rare. ◦Population growth is therefore regulated by carrying capacity (K), which is the maximum stable population size a particular environment can support. Logistic population growth model incorporates the________________________ ______________________________________

22. dN/dt = r max N((K-N)/K) The graph of this equation shows an S- shaped curve. Fig. 52.11 Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

23. Table 52.3 A Hypothetical Example of Logistic Population Growth, Where K=1,000 and r max =0.05 per Individual per Year

24. Figure 52.12 How well do these populations fit the logistic population growth model?

25. The logistic Population Growth Model predicts different growth rates for different populations, relative to carrying capacity. ◦In K-selection, organisms live ___________________ ___________________ (Density Dependent) ◦In r-selection, organisms exhibit __________________ __________________ __________________ __________________ __________________ (Density Independent) 2005-2006

26. Different life strategies K-selection r-selection K-selection r-selection mortality constant

27. Reproductive strategies K-strategy ◦have few offspring & invest a lot of energy in raising them to reproductive age  ___________ r-strategy ◦have many offspring & invest little in their survival  ___________

28. Predator – prey interactions Population cycles 2005-2006

29. Age structure Relative number of individuals of each age 2005-2006 What do the data imply about population growth in these countries?

30. Human population What factors have contributed to this exponential growth pattern? 2005-2006 1650500 million 20056 billion