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

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 117-119) 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. INTERSPECIFIC COMPETITION i. Theory  Lotka-Volterra (pages 180-182)  Tilman (pages 182-185) ii. Examples (pages 185-199)  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages 187-189); Paramecium (page 190)  diatoms (Fig. 12.6; page 186)   Biol 303 Competition

4. CONSEQUENCES OF COMPETITION i. Ecological a. distribution  barnacles (Fig 7.9; pages 94-95)  Typha ii. Evolutionary a. niche differentiation (pages 190-192; Fig 12.20) b. competitive ability (pages 199-201) c. character displacement (page 201-202) d. competitive release Biol 303 Competition

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

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

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

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

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 117-119) 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

Flax Biol 303 Competition

Balsam Fir Biol 303 Competition

Biol 303 Competition

Keyhole limpet Biol 303 Competition

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 117-119) 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

Corn cockle Biol 303 Competition

Ryegrass Biol 303 Competition

Ryegrass Biol 303 Competition

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 117-119) 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

Bromus (rescue grass) Biol 303 Competition

Rana tigrina Biol 303 Competition

Buck wheat Biol 303 Competition

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 117-119) 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

Biol 303 Competition

Biol 303 Competition

Biol 303 Competition

3. INTERSPECIFIC COMPETITION i. Theory  Lotka-Volterra (pages 180-182)  Tilman (pages 182-185) ii. Examples (pages 185-199)  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages 187-189); Paramecium (page 190)  diatoms (Fig. 12.6; page 186) Biol 303 Competition

LOTKA - VOLTERRA COMPETITION MODELS Biol 303 Competition

READING FOR THESE LECTURES: Krebs: Scan cpt.11, especially pp. 160-162 Krebs: Cpt. 12, especially 180-184 Biol 303 Competition

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

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

(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

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

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

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

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

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 p182-183) Biol 303 Competition

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

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

Krebs: Fig 12.3 p183 Biol 303 Competition

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

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

3. INTERSPECIFIC COMPETITION i. Theory  Lotka-Volterra (pages 180-182)  Tilman (pages 182-185) ii. Examples (pages 185-199)  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages 187-189); Paramecium (page 190)  diatoms (Fig. 12.6; page 186) Biol 303 Competition

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

TILMAN, D. 1985. The resource-ratio hypothesis of plant succession TILMAN, D. 1985. The resource-ratio hypothesis of plant succession. American Naturalist 125:827-852 READING FOR THESE LECTURES: Krebs: selections from pp. 182-186 Biol 303 Competition

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

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

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

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

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

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

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

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

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

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

R* Species A birth mortality Resource level [1] Population growth [death] rate mortality 0 1 2 3 4 5 6 7 8 9 10 R* Resource level [1] Biol 303 Competition

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

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

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

R* Species A birth mortality Resource level [2] Population growth [death] rate mortality 0 1 2 3 4 5 6 7 8 9 10 R* Resource level [2] Biol 303 Competition

R* Species B birth mortality Resource level [1] Population growth [death] rate mortality 0 1 2 3 4 5 6 7 8 9 10 R* Resource level [1] Biol 303 Competition

1 3 4 2 SPECIES A Population growth [death] rate SPECIES B Resource 1 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 SPECIES A 1 3 Population growth [death] rate 0 1 2 3 4 5 6 7 8 9 10 0 1 2 3 4 5 6 7 8 9 10 SPECIES B 4 2 Resource 1 Resource 2 Biol 303 Competition

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

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 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

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 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

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

Species A and B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

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 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

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 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

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 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

A B Resource [2] Resource [1] 8 7 6 5 4 3 2 1 ZNGI [A] ZNGI [B] 0 1 2 3 4 5 6 7 8 9 10 Resource [1] Biol 303 Competition

3. INTERSPECIFIC COMPETITION i. Theory  Lotka-Volterra (pages 180-182)  Tilman (pages 182-185) ii. Examples (pages 185-199)  salamanders (pages 80-81)  bedstraws  barnacles(Fig 7.9; pages 94-95)  Yeast (pages 187-189); Paramecium (page 190)  diatoms (Fig. 12.6; page 186)   Biol 303 Competition

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

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

Krebs Fig. 7.9; p95 Chthamalus Balanus Biol 303 Competition

Paramecium Biol 303 Competition

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

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 190-192; Fig 12.20) b. competitive ability (pages 199-201) c. character displacement (page 201-202; Fig. 12.23) Biol 303 Competition

Krebs Fig. 7.9; p95 Chthamalus Balanus Biol 303 Competition

BullrushCattail Biol 303 Competition

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  Biol 303 Competition

4. CONSEQUENCES OF COMPETITION i. Ecological a. distribution barnacles (Fig 7.9; pages 94-95) Typha competitive release ii. Evolutionary a. niche differentiation (pages 190-192; Fig 12.20) b. competitive ability (pages 199-201) c. character displacement (page 201-202; Fig. 12.23) Biol 303 Competition

Krebs Fig. 12.20, p198 Biol 303 Competition

15 White clover Biol 303 Competition

Krebs Fig. 12.22, p202 Biol 303 Competition

Biol 303 Competition

Krebs Fig. 12.23, p202 Darwin’s finches, Geospiza Biol 303 Competition