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Population Regulation The logistic equation suggests that factors - - PowerPoint PPT Presentation
Population Regulation The logistic equation suggests that factors - - PowerPoint PPT Presentation
Population Regulation The logistic equation suggests that factors limiting growth exert stronger effects on mortality and fecundity as a pop. grows. What are these factors, and how do they operate? Many things influence rates of pop. growth,
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What are these factors, and how do they operate?
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Many things influence rates
- f pop. growth, but only
density-dependent factors are thought to be able to regulate the size of a pop.
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Conceptually . . .
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What about density- independence?
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Regiona Percentage of females pregnant Embryos per female Corpora lutea per ovary Western 94 1.71 1.97 Catskill periphery 92 1.48 1.72 Catskill central 87 1.37 1.72 Periphery 86 1.29 1.71 Adirondack center 79 1.06 1.11
Reproductive of white-tailed deer in 5 regions of New York State, 1939-1949.
aRegions arranged by decreasing suitability of range.
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Region Percentage of females pregnant Embryos per female Corpora lutea per ovary Western 94 1.71 1.97 Catskill periphery 92 1.48 1.72 Catskill central 87 1.37 1.72 Periphery 86 1.29 1.71 Adirondack center 79 1.06 1.11
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Region Percentage of females pregnant Embryos per female Corpora lutea per ovary Western 94 1.71 1.97 Catskill periphery 92 1.48 1.72 Catskill central 87 1.37 1.72 Periphery 86 1.29 1.71 Adirondack center 79 1.06 1.11
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Percentage of females pregnant Embryos per female Corpora lutea per ovary 1939-1943 (prehunting) 57 0.71 0.60 1947 (after heavy hunting) 100 1.78 1.86
Reproduction of white-tailed deer in the Debar Mountain area of the Adirondack Mountains of New York before and after hunting.
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What about density independence?
Commercial catch Locality Before After % decline Matagorda 16,919 1,089 98.6 Aransas 55,224 2,552 95.4 Lagunda Madre 2,016 149 92.6
Cold weather caused fish kills on the Texas Gulf Coast in winter, 1948.
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Some Review Questions
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When a population of
- rganisms is just starting to
fill up its habitat, the growth rate is nearly purely exponential.
- a. True
- b. False
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- a. inbreeding may lead to increased homozygosity
and loss of fertility
- b. mature individuals may have difficulty finding mates
- c. when N is large, growth is slow
- d. at very low N, population growth is highest
- e. r is a constant
Probably the most serious
- versimplification inherent
within the logistic growth model is:
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As population density increases, there is a tendency for the individual birth rates to decline and the individual death rates to increase. This change in either b or d, or in both, is known as:
- a. intraspecific competition
- b. interspecific competition
- c. density dependence
- d. density independence
- e. optimal functioning
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What would a graph of independent and dependent birth rates look like if you plotted pop. size on the horizontal axis and birth rate (per individual) on the vertical axis?
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What would a graph of independent and dependent death rates look like if you plotted pop. size on the horizontal axis and death rate (per individual) on the vertical axis?
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Which of the following situations is the best example of density independent population changes.
Time 1 Time 2 N Birth rate Death rate N Birth rate Death rate 100 0.3 0.1 500 0.1 0.1 50 3.0 2.0 300 3.0 2.0 500 0.4 0.4 100 0.6 0.3 25 1.0 0.1 200 1.0 0.5 200 0.3 0.2 50 0.6 0.2 A B C D E
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