1 / 48

Chapter 6

Chapter 6. Population Dynamics. Objective 1 & 2. Appreciate the potential of exponential growth Draw a diagram of the J and S curves and explain what they mean. What is Exponential Growth?. Exponential growth.

lorin
Download Presentation

Chapter 6

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 6 Population Dynamics

  2. Objective 1 & 2 • Appreciate the potential of exponential growth • Draw a diagram of the J and S curves and explain what they mean

  3. What is Exponential Growth?

  4. Exponential growth • Exponential growth is said to follow an exponential law; the simple-exponential growth model is known as the Malthusian growth model. • For any exponentially growing quantity, the larger the quantity gets, the faster it grows. An alternative saying is 'The rate of growth is directly proportional to the present size'

  5. Exponential Growth • We are familiar with geometric growth in the context of compound interest. You put $1000 in a savings account. Suppose that the account pays 4 percent interest annually. How much will you have in the bank after 10 years? • The basic equation for growth is Yt = Y0(1+r)t • where Y0 is the initial amount ($1000 in this example), r is the growth rate expressed as a decimal (.04 in this example), and t is the number of years of growth (10 in this example). The amount you will end up with after 10 years is $1000(1 + .04)10 = $1480.24.

  6. Which is Which?

  7. Which Type of Growth is which?

  8. Geometric growthon a graph Population growth rate is expressed as a fraction: the population is calculated by multiplying (J curve results) SLOW AT FIRST, THEN HUGE GAINS!!!!!!!!!!

  9. Arithmetic growth The population is growth at a constant amount per time. (linear curve results) STEADY RISE IN POPULATION

  10. Are both found here?

  11. What does this graph say?

  12. What is a J CURVE? • Short gains early • Big gains later • Population is meeting/exceeding biotic potential • Theoretical unchecked growth • This is real for some populations (bacteria in particular…..but not ALWAYS!)

  13. J curve

  14. What is an S CURVE? • The result of a population growth that has experienced environmental resistance. • NOTE: what happens to the influence of Env. Resistance as the population approaches the carrying capacity?

  15. S curve

  16. What factors can we glean fromthe S (Sigmoidal) curve? • All populations have some limits. • Reading a S curve can reveal those limits or at least give you an idea that are limits to look for. What limited our growth for so long????

  17. Objective #3 • Who was Thomas Malthus and what did he say about population growth?

  18. Thomas Malthus • 18th century Economist link to article • “Elevated as man is above all other animals by intellectual faculties, it is not to be supposed that the physical laws to which he is subjected should be essentially different from those which are observed to prevail in other parts of animated nature. He may increase slower than most other animals, but food is equally necessary to his support; and if this natural capacity of increase be greater than can be permanently supplied with food from a limited territory, his increase must be constantly retarded by the difficulty of procuring the means of subsistence’. “

  19. Population Oscillations

  20. So what did he say? • Populations are cyclic • They will flux with the environment • Famine, disease, war…all affect population

  21. Europe: 0-2000

  22. And the US?

  23. Populations go thru one of two types of growth: Irruptive or Malthusian Growth (unstable) Peaks, diebacks OR Logistic growth (stable) Constantly changing rate Be able to discuss the pros and cons of each.

  24. Objective #4 • Discuss environmental resistance and discuss how it can lead to logistic or stable growth

  25. Malthusian Strategies • Low tropic levels, pioneer species, primary succession • Move into disturbed environs, mature early, make many offspring, don’t care for them, rely on sheer numbers • Insects, rodents, parasites, annual plants • Limited by predators, overshoot/diebacks, adapt quickly • Extrinsic characteristics (pg. 129)

  26. Logistic Strategies • Larger, live longer, mature more slowly, produce less offspring, have fewer predators, care for offspring longer • Wolves, elephants, bears, primates • intrinsic characteristics (pg. 129)

  27. Objective #5 • Define fecundity, fertility, birth rates, life expectancy, death rates, survivorship

  28. Fecundity • The physical ability to reproduce

  29. Natality • Producing of new individuals through hatching, birth, germination or cloning

  30. fertility • A measure of the offspring produced

  31. Birth Rates • Crude birth rates for many countries is declining…..

  32. Life expectancy Life expectancy calculator Living to 100

  33. Death rates • Causes of  Death Number of Deaths Rate per 100,000  • 15-24 years • All causes 32,699 • Accidents and adverse effects 13,872 • Motor vehicle accidents 10,624 • All other accidents and adverse effects 3,248  • Homicide and legal intervention 6,548  • Suicide 4,369 • Malignant neoplasms, including neoplasms of lymphatic and hematopoietic tissues1,642 • Diseases of heart 920  • Human immunodeficiency virus infection 420  • Congenital anomalies 387  • Chronic obstructive pulmonary diseases and allied conditions 230  • Pneumonia and influenza 197 • Cerebrovascular diseases 174 • All other causes (Residual) 3,940 • More death rate statistics  • Countries death rates

  34. survivorship • The percentage of offspring born at the same time that survives to a certain age

  35. Objective #6 • Compare and contrast density dependent and density independent population processes

  36. Density-Independent Factors • Abiotic components of the ecosystem

  37. Density-Independent Factors • Natural disasters or extreme weather events can help or hurt a population

  38. What effect did this eruption have on the habitat? The organisms?

  39. Weather Patterns with a Global Impact!

  40. Do these occurrences really REGULATE the population?

  41. Density-Dependent Factors • Reduce the population size • Drop in natality or increase mortality • HOW? Either: • Intraspecific interactions • Interspecific interactions

  42. Predator-Prey cyclic relations

  43. Who do I prey on?

  44. What might cause this change?

  45. Stress and Crowding

  46. The Summary The summary is very good. A must read for all.

More Related