1. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 36 Population Dynamics

2. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The Spread of Shakespeare’s Starlings The European Starling –Has become an abundant and destructive pest in North America European starling

3. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Starling populations have become very successful –And spread throughout North America since their introduction in 1890 Current 1955 1945 1935 1925 1915 1905 1925 1935 1945 1955 Current The spread of starlings across North America

4. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Population ecology –Is concerned with changes in population size and the factors that regulate populations over time

5. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.1 Population ecology is the study of how and why populations change A population –Is a group of individuals of a single species that occupy the same general area

6. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings POPULATION STRUCTURE AND DYNAMICS 36. 2 Density and dispersion patterns are important population variables Population density –Is the number of individuals of a species per unit of area or volume

7. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Environmental and social factors –Influence the spacing of individuals in various dispersion patterns: clumped, uniform, or random Figure 36.2A Figure 36.2B

8. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.3 Life tables track mortality and survivorship in populations Life tables and survivorship curves –Predict an individual’s statistical chance of dying or surviving during each interval of the individual’s lifetime Table 36.3

9. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The three types of survivorship curves –Reflect species’ differences in reproduction and mortality Percentage of survivors (log scale) 100 10 1 0.1 0 50100 III II I Percentage of maximum life span Figure 36.3

10. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.4 Idealized models help us understand population growth

11. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The Exponential Growth Model Exponential growth –Is the accelerating increase that occurs when growth is unlimited

12. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The equation G  rN describes this J-shaped curve –G  the population growth rate –r  an organism’s inherent capacity to reproduce –N  the population size Figure 36.4A TimeNumber of Cells 0 minutes 20 40 60 80 100 120 (= 2 hours) 3 hours 4 hours 8 hours 12 hours 1 2 4 8 16 32 64 512 4,096 16,777,216 68,719,476,736 = 2 0 = 2 1 = 2 2 = 2 3 = 2 4 = 2 5 = 2 6 = 2 9 = 2 12 = 2 24 = 2 36 Number of bacterial cells (N) 70 60 50 30 40 20 10 0 020406080100 120140 G = r N Time (min)

13. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Limiting Factors and the Logistic Growth Model Limiting factors –Are environmental factors that restrict population growth Breeding male fur seals (thousands) 10 8 6 4 2 0 1915192519351945 Year Figure 36.4B

14. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Logistic growth –Is the model that represents the slowing of population growth as a result of limiting factors –Levels off at the carrying capacity, which is the number of individuals the environment can support Number of individuals (N) K 0 Time G = r N (K – N) K Figure 36.4C

15. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The equation G  rN(K – N)/K describes a logistic growth curve –Where K  carrying capacity and (K – N)/K accounts for the leveling off of the curve

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.5 Multiple factors may limit population growth As a population’s density increases –Factors such as limited food supply and increased disease or predation may increase the death rate, decrease the birth rate, or both 4.0 3.6 3.8 3.4 3.2 3.0 2.8 0 1020304050607080 Density of females Clutch size Figure 36.5A

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Abiotic factors such as weather –May limit many natural populations Exponential growth Sudden decline Number of aphids AprMayJunJulAugSepOctNovDec Figure 36.5B

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Most populations –Are probably regulated by a mixture of factors, and fluctuations in numbers are common Time (years) 197519801985199019952000 0 20 40 80 60 Number of females Figure 36.5C

19. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.6 Some populations have “boom-and-bust” cycles Some populations –Undergo regular boom-and-bust cycles of growth and decline 160 120 80 40 0 1850187519001925 9 6 3 0 Snowshoe hare Lynx Hare population size (thousands) Lynx population size (thousands) Year Figure 36.6

20. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.7 Evolution shapes life histories An organism’s life history –Is the series of events from birth through reproduction to death LIFE HISTORIES AND THEIR EVOLUTION

21. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Populations with so-called r-selection life history traits –Produce many offspring and grow rapidly in unpredictable environments Figure 36.7A

22. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Populations with K-selected traits –Raise few offspring and maintain relatively stable populations

23. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Life history traits –Are shaped by natural selection Experimental transplant of guppies Predator: Killifish; preys mainly on small, immature guppies Guppies: Larger at sexual maturity than those in pike-cichlid pools Predator: Pike-cichlid; preys mainly on large, mature guppies Guppies: Smaller at sexual maturity than those in killifish pools Figure 36.7B

24. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.8 Principles of population ecology have practical applications Principles of population ecology –Are useful in managing natural resources CONNECTION 900 800 700 600 500 400 300 200 100 0 19601970198019902000 Yield (thousands of metric tons) Figure 36.8

25. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings THE HUMAN POPULATION CONNECTION The Plague 6 5 4 3 2 1 0 8000 B.C. 4000 B.C. 3000 B.C. 2000 B.C. 1000 B.C. 01000 A.D. 2000 A.D. Human population size (billions) Figure 36.9A 36.9 Human population growth has started to slow after centuries of exponential increase The human population – Has been growing almost exponentially for centuries, standing now at about 6.4 billion

26. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The ecological footprint –Represents the amount of land per person needed to support a nation’s resource needs 16 14 12 10 8 6 4 2 0 02 4 68 121416 Available ecological capacity (ha per person) Ecological footprint (ha per person) Japan UK Spain Germany Netherlands Norway USA World China India Sweden Canada Australia New Zealand Figure 36.9B

27. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The ecological capacity of the world –May already be smaller than the population’s ecological footprint Traffic in downtown Cairo, Egypt Manhattan, New York City Refugee camp in Zaire Figure 36.9C

28. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 36.10 Birth and death rates and age structure affect population growth The demographic transition –Is the shift from high birth rates and death rates to low birth rates and death rates 50 40 30 20 10 0 1900192519501975200020252050 Year Birth rate Death rate Birth or death rate per 1,000 population Figure 36.10A

29. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The age structure of a population –Is the proportion of individuals in different age-groups –Affects its future growth Age 85+ 80–84 75–79 70–74 65–69 60–64 55–59 50–54 45–49 40–44 35–39 30–34 25–29 20–24 15–19 10–14 5–9 0–4 84620246864202466420246 Percent of population Primary reproductive ages Rapid growthSlow growthDecrease AfghanistanUnited StatesItaly MaleFemaleMaleFemaleMaleFemale Figure 36.10B

30. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Increasing the status of women –May help to reduce family size