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COMPETITION Krebs cpt. 12; pages 179-205 Biol 303 Competition.

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Presentation on theme: "COMPETITION Krebs cpt. 12; pages 179-205 Biol 303 Competition."— Presentation transcript:

1 COMPETITION Krebs cpt. 12; pages Biol 303 Competition

2 2. INTRASPECIFIC COMPETITION
1. DEFINITIONS 2. INTRASPECIFIC COMPETITION i. Effects of density on individuals a. growth  Linum usitatissimum  Limpets b. form and reproduction  Corn cockle  Lolium perenne genets and ramets (pages ) ii. Effects of density on populations a. growth (rate)  Law of constant final yield  Growth rate of Rana tigrina b. mortality  3/2 power law of self thinning Biol 303 Competition

3 3. INTERSPECIFIC COMPETITION
i. Theory  Lotka-Volterra (pages )  Tilman (pages ) ii. Examples (pages )  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages ); Paramecium (page 190)  diatoms (Fig. 12.6; page 186) Biol 303 Competition

4 4. CONSEQUENCES OF COMPETITION
i. Ecological a. distribution  barnacles (Fig 7.9; pages 94-95)  Typha ii. Evolutionary a. niche differentiation (pages ; Fig 12.20) b. competitive ability (pages ) c. character displacement (page ) d. competitive release Biol 303 Competition

5 COMPETITION occurs when an organism uses more energy to obtain, or maintain, a unit of resource due to the presence of other individuals than it would otherwise do. Biol 303 Competition

6 COMPETITION ESSENTIAL COMPONENTS:
Two or more organisms that require a single resource that is in short supply. The supply of that resource must be affected by its use by the consumer: Food supply Pollinators Nest space etc. Biol 303 Competition

7 COMPETITION ESSENTIAL COMPONENTS:
Two or more organisms that require a single resource that is in short supply. The supply of that resource must be affected by its use by the consumer: Food supply Pollinators Nest space etc. Biol 303 Competition

8 COMPETITION The contest for that resource reduces the fitness of one or both competitors. Competing organisms may be the: Same INTRASPECIFIC Different INTERSPECIFIC Organisms may compete by: EXPLOITATION INTERFERENCE Biol 303 Competition

9 2. INTRASPECIFIC COMPETITION
1. DEFINITIONS etc. 2. INTRASPECIFIC COMPETITION i. Effects of density on individuals a. growth  Linum usitatissimum  Limpets b. form and reproduction  Corn cockle  Lolium perenne genets and ramets (pages ) ii. Effects of density on populations a. growth (rate)  Law of constant final yield  Growth rate of Rana tigrina b. mortality  3/2 power law of self thinning Biol 303 Competition

10 Flax Biol 303 Competition

11 Balsam Fir Biol 303 Competition

12 Biol 303 Competition

13 Keyhole limpet Biol 303 Competition

14 2. INTRASPECIFIC COMPETITION
1. DEFINITIONS etc. 2. INTRASPECIFIC COMPETITION i. Effects of density on individuals a. growth  Linum usitatissimum  Limpets b. form and reproduction  Corn cockle  Lolium perenne genets and ramets (pages ) ii. Effects of density on populations a. growth (rate)  Law of constant final yield  Growth rate of Rana tigrina b. mortality  3/2 power law of self thinning Biol 303 Competition

15 Corn cockle Biol 303 Competition

16 Ryegrass Biol 303 Competition

17 Ryegrass Biol 303 Competition

18 2. INTRASPECIFIC COMPETITION
1. DEFINITIONS etc. 2. INTRASPECIFIC COMPETITION i. Effects of density on individuals a. growth  Linum usitatissimum  Limpets b. form and reproduction  Corn cockle  Lolium perenne genets and ramets (pages ) ii. Effects of density on populations a. growth (rate)  Law of constant final yield  Growth rate of Rana tigrina b. mortality  3/2 power law of self thinning Biol 303 Competition

19 Bromus (rescue grass) Biol 303 Competition

20 Rana tigrina Biol 303 Competition

21 Buck wheat Biol 303 Competition

22 2. INTRASPECIFIC COMPETITION
1. DEFINITIONS etc. 2. INTRASPECIFIC COMPETITION i. Effects of density on individuals a. growth  Linum usitatissimum  Limpets b. form and reproduction  Corn cockle  Lolium perenne genets and ramets (pages ) ii. Effects of density on populations a. growth (rate)  Law of constant final yield  Growth rate of Rana tigrina b. mortality  3/2 power law of self thinning Biol 303 Competition

23 Biol 303 Competition

24 Biol 303 Competition

25 Biol 303 Competition

26 3. INTERSPECIFIC COMPETITION
i. Theory  Lotka-Volterra (pages )  Tilman (pages ) ii. Examples (pages )  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages ); Paramecium (page 190)  diatoms (Fig. 12.6; page 186) Biol 303 Competition

27 LOTKA - VOLTERRA COMPETITION MODELS
Biol 303 Competition

28 READING FOR THESE LECTURES: Krebs: Scan cpt.11, especially pp. 160-162
Krebs: Cpt. 12, especially Biol 303 Competition

29 Start with the logistic equation
Start with the logistic equation. In populations that have overlapping generations, the logistic curve is described by the logistic equation (Krebs 161): Biol 303 Competition

30 The Lotka-Volterra equations, which describe competition between organisms, are based on the logistic curve. Each of these two equations shows the effect of intra-specific (within a species) competition only. (Krebs 180) Biol 303 Competition

31 (N1 + (N2/10)) species 1 individuals
Suppose 10 individuals of species 2 have the same inhibitory effect on an individual of species 1 as does a single individual of species 1. Then the TOTAL competitive effects ON species 1 (intra and inter-specific) will be equivalent to: (N1 + (N2/10)) species 1 individuals 1/10 (in the case of this example) is the COMPETITION COEFFICIENT and is called . Biol 303 Competition

32 The COMPETITION COEFFICIENT ….
, is the per capita competitive effect ON species 1 OF species 2. , is the per capita competitive effect ON species 2 OF species 1 is. (see footnote in Krebs p182) Biol 303 Competition

33 in which N2 converts N2 to a number of “N1 equivalents”
So the total inhibitory effect of individuals of species 1 (intra-specific force) and species 2 (inter-specific force) on the growth of population 1 will be: in which N2 converts N2 to a number of “N1 equivalents” (Krebs p181, eq. 12.3) Biol 303 Competition

34 Removing the inner brackets:
Krebs p181 Thus there are two “sources of slowing” for the growth of species 1: 1. its own density, and 2. the density of the second species weighted by the second species’ relative impact. Biol 303 Competition

35 For species 2, we have the equivalent formulation:
Krebs p181 These two constitute the Lotka-Volterra model - a logistic model for two species. Biol 303 Competition

36 Now we wish to determine the conditions under which each population would be at equilibrium, that is the conditions under which dN/dt would be zero. In some cases only one population will be able to achieve an equilibrium stable density, and in other cases both can. (Krebs p ) Biol 303 Competition

37 Along the isocline dN1/dt = 0
For Species 1 All the space for species 1 is used up when there are: K1 ind. of sp.1 K1/ ind. of sp. 2 i.e. dN1/dt = 0 Along the isocline dN1/dt = 0 Krebs: Fig 12.1 p182 Biol 303 Competition

38 Along the isocline dN2/dt = 0
For Species 2 All the space for species 2 is used up when there are: K2 ind. of sp.2 K2/ ind. of sp. 1 i.e. dN2/dt = 0 Along the isocline dN2/dt = 0 Krebs: Fig 12.2 p182 Biol 303 Competition

39 Krebs: Fig 12.3 p183 Biol 303 Competition

40 TROUT 2nd species K1 = 400 K2 = 300  = 4  = 0.5 K1 / = 100
Biol 303 Competition

41 TROUT 2nd species K1 = 400 K2 = 300  = 4  = 0.5 K1 / = 100
Biol 303 Competition

42 3. INTERSPECIFIC COMPETITION
i. Theory  Lotka-Volterra (pages )  Tilman (pages ) ii. Examples (pages )  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages ); Paramecium (page 190)  diatoms (Fig. 12.6; page 186) Biol 303 Competition

43 THE RESOURCE RATIO HYPOTHESIS (OF PLANT SUCCESSION)
David TILMAN Biol 303 Competition

44 TILMAN, D. 1985. The resource-ratio hypothesis of plant succession
TILMAN, D The resource-ratio hypothesis of plant succession. American Naturalist 125: READING FOR THESE LECTURES: Krebs: selections from pp Biol 303 Competition

45 Why are there so many kinds of animals?
Evelyn G. HUTCHINSON: Why are there so many kinds of animals? Because there are so many different kinds of food to eat. Why are there so many kinds of plants? Water, CO2, light, nutrients Ratios of resources (light and nitrogen) Biol 303 Competition

46 Why are there so many kinds of animals?
Evelyn G. HUTCHINSON: Why are there so many kinds of animals? Because there are so many different kinds of food to eat. Why are there so many kinds of plants? Water, CO2, light, nutrients Ratios of resources (light and nitrogen) Biol 303 Competition

47 Why are there so many kinds of animals?
Evelyn G. HUTCHINSON: Why are there so many kinds of animals? Because there are so many different kinds of food to eat. Why are there so many kinds of plants? Water, CO2, light, nutrients Ratios of resources (light and nitrogen) Biol 303 Competition

48 Why are there so many kinds of animals?
Evelyn G. HUTCHINSON: Why are there so many kinds of animals? Because there are so many different kinds of food to eat. Why are there so many kinds of plants? Water, CO2, light, nutrients Ratios of resources (light and nitrogen) Biol 303 Competition

49 Why are there so many kinds of animals?
Evelyn G. HUTCHINSON: Why are there so many kinds of animals? Because there are so many different kinds of food to eat. Why are there so many kinds of plants? Water, CO2, light, nutrients Ratios of resources (light and nitrogen) Biol 303 Competition

50 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

51 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

52 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

53 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

54 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

55 R* Species A birth mortality Resource level [1]
Population growth [death] rate mortality R* Resource level [1] Biol 303 Competition

56 OPTIMAL FORAGING Any (plant) species will absorb resources in the proportion by which it is equally limited by them. This proportion is the ratio of the two values of R* R* = the Requirement Value i.e. the level of resource required to hold a population (of a species) at equilibrium: i.e. where birth rate = death rate Biol 303 Competition

57 OPTIMAL FORAGING Any (plant) species will absorb resources in the proportion by which it is equally limited by them. This proportion is the ratio of the two values of R* R* = the Requirement Value i.e. the level of resource required to hold a population (of a species) at equilibrium: i.e. where birth rate = death rate Biol 303 Competition

58 OPTIMAL FORAGING Any (plant) species will absorb resources in the proportion by which it is equally limited by them. This proportion is the ratio of the two values of R* R* = the Requirement Value i.e. the level of resource required to hold a population (of a species) at equilibrium: i.e. where birth rate = death rate Biol 303 Competition

59 R* Species A birth mortality Resource level [2]
Population growth [death] rate mortality R* Resource level [2] Biol 303 Competition

60 R* Species B birth mortality Resource level [1]
Population growth [death] rate mortality R* Resource level [1] Biol 303 Competition

61 1 3 4 2 SPECIES A Population growth [death] rate SPECIES B Resource 1
SPECIES A 1 3 Population growth [death] rate SPECIES B 4 2 Resource 1 Resource 2 Biol 303 Competition

62 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

63 Species A Resource [2] Resource [1] 8 7 6 5
4 3 2 1 Births [A] > Deaths [A] Population increases Resource [2] Zero Net Growth Isocline [ZNGI]: Births = Deaths Births [A] < Deaths [A] Population declines Resource [1] Biol 303 Competition

64 Species B Resource [2] Resource [1] 8 7
6 5 4 3 2 1 Births [B] > Deaths [B] Population increases Resource [2] Zero Net Growth Isocline [ZNGI]: Births = Deaths Births [B] < Deaths [B] Population declines Resource [1] Biol 303 Competition

65 Resource Ratio Hypothesis
One species and one resource One species and two resource Two species and two resources Multiple species and two resources Biol 303 Competition

66 Species A and B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A]
ZNGI [B] Resource [1] Biol 303 Competition

67 Neither species can survive
A B 8 7 6 5 4 3 2 1 Both species can grow A wins Resource [2] ZNGI [A] ZNGI [B] B wins Neither species can survive Resource [1] Biol 303 Competition

68 A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1] Biol 303 Competition

69 Neither species can survive
A B 8 7 6 5 4 3 2 1 A & B coexist A wins Resource [2] ZNGI [A] ZNGI [B] B wins Neither species can survive Resource [1] Biol 303 Competition

70 Neither species can survive
? A B 8 7 6 5 4 3 2 1 A & B coexist A wins Resource [2] ZNGI [A] ZNGI [B] B wins Neither species can survive Resource [1] Biol 303 Competition

71 A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1] Biol 303 Competition

72 A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B]
Resource [1] Biol 303 Competition

73 3. INTERSPECIFIC COMPETITION
i. Theory  Lotka-Volterra (pages )  Tilman (pages ) ii. Examples (pages )  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages ); Paramecium (page 190)  diatoms (Fig. 12.6; page 186) Biol 303 Competition

74 Salamanders in Appalachian Mts. (S. Carolina) p80-81
Plethodon glutinosus Plethodon jordani Biol 303 Competition

75 Galium sylvestre (calcareous) Galium saxatile (acidic)
Bedstraws in Europe Galium sylvestre (calcareous) Galium saxatile (acidic) Biol 303 Competition

76 Krebs Fig. 7.9; p95 Chthamalus Balanus Biol 303 Competition

77 Paramecium Biol 303 Competition

78 GENERAL FEATURES Species do compete in nature
Competition may cause exclusion Competition may lead to coexistence Is frequently asymmetric Biol 303 Competition

79 4. CONSEQUENCES OF COMPETITION
i. Ecological a. distribution a. barnacles (Fig 7.9; pages 94-95) b. Typha c. competitive release ii. Evolutionary a. niche differentiation (pages ; Fig 12.20) b. competitive ability (pages ) c. character displacement (page ; Fig ) Biol 303 Competition

80 Krebs Fig. 7.9; p95 Chthamalus Balanus Biol 303 Competition

81 BullrushCattail Biol 303 Competition

82                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   Biol 303 Competition

83 4. CONSEQUENCES OF COMPETITION
i. Ecological a. distribution barnacles (Fig 7.9; pages 94-95) Typha competitive release ii. Evolutionary a. niche differentiation (pages ; Fig 12.20) b. competitive ability (pages ) c. character displacement (page ; Fig ) Biol 303 Competition

84 Krebs Fig , p198 Biol 303 Competition

85 15 White clover Biol 303 Competition

86 Krebs Fig , p202 Biol 303 Competition

87 Biol 303 Competition

88 Krebs Fig , p202 Darwin’s finches, Geospiza Biol 303 Competition

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