Slide 1Slide 2Objectives ICompetition: use or defense of a limiting resource that reduces availability to othersSlide 5Types of competition:Competition may occur through exploitation (indirect) of shared resources or (direct) interference (individuals defend resources actively).Allelopathy: chemical (interference) competition.Types of ResourcesIntraspecific competition + density-dependent population regulationDensity-dependent regulation (via intraspecific competition) of growth. ***Summarize 2 conclusions.Density-dependent regulation of time to reach sexual maturity. ***Does age or weight determine sexual maturity? Explain.Density-dependent regulation of birth rateSlide 14Logistic growth modelLogistic equation is based on intraspecific competition depressing r, the per capita population growth rate; population size continues to increase until N = K.Slide 17*** How much is K of sp 1 reduced by one individual of competing sp 2? By all individuals?Lotka-Volterra addition of interspecific competition to logistic equation:***What is  (competition coefficient) for the effect of 1 ind. of sp. 2 (N2) on sp. 1 (N1) or equivalence of sp. 2 for sp. 1?Objectives IINiche:From 1 to n niche axes --> hypervolume of niche spaceNiche metricsIntraspecific competition: creates selective pressure for broader resource use.Niche breadth decreases with interspecific competition..Slide 27‘Ghost of competition past’: What evidence is used to deduce that interspecific competition has occurred in the past?1) Niche separation via resource partitioning among related species.1) Niche separation via resource partitioning2) Habitat shift: Use of habitat often changes depending on presence or absence of closely related species. Expand habitat when other species absent.3) Character displacement when in sympatry.3) Character displacement: Morphological traits and food selection of species shift depending on presence or absence of closely related species.4. Competitive Exclusion Hypothesis: 2 species can’t coexist on the same limiting resource.Slide 355) Competitive release: Densities of organisms often increase when densities of competing species are reduced.Slide 37Field Experiments: How can we demonstrate competition is occurring?Question 1: ButtercupsFigure for preceding ? Draw the contrasting curves for species 1 and 2.Question 2. Observation: zones of sp. B + C do not overlap. What are two alternative hypotheses / predictions? Experimental design?What explains zonation of barnacles?Question 3: Galium sp. + Common garden experiment to study interspecific competition:Slide 44Question 5: 2 grasses Observation: An area of serpentine rock is adjacent to an area of granite rock. Grass 1 on granite soil is replaced abruptly by Grass 2 on serpentine soil.Results:***Design two experiments to determine whether competition limits the distribution of these two grasses.Results:Fall 2010 IB Workshop Seriessponsored by IB academic advisorsUndergraduate ResearchTuesday, Oct. 124:00-5:00pm 1038 FLBLearn why this experience is so valuable, how to go about finding a faculty member with whom to work, and how to use this experience to apply for graduation with distinction. Fellow IB students who have done IB 390 or 490 will share their experiences as well.Chapter 16To what extent does competition controlspecies’ presence and abundance?Objectives I •Define competition•Types of competition•Types of resources• D-D regulation via intraspecific competition• Plant responses• Animal responses•Competition added to logistic growth modelsCompetition: use or defense of a limiting resource that reduces availability to othersSuperior competitors can persist at lower resource levels.Types of competition:•Exploitation vs. interference•Intraspecific vs. interspecificCompetition may occur through exploitation (indirect) of shared resources or (direct) interference (individuals defend resources actively).exploitinterfereAllelopathy: chemical (interference) competition.•This plant distribution is caused by:•H1: Allelopathy•H2: Seed predation by small mammals •No resolution: need experiment considering both simultaneously.Types of Resources• Plants• abiotic• biotic• Animals• abiotic• bioticIntraspecific competition + density-dependent population regulation•Negative responses:• Growth is….• Sexual maturity is….• Birth rate is …• Death rate is…Density-dependent regulation (via intraspecific competition) of growth. ***Summarize 2 conclusions.Figure 1Density-dependent regulation of time to reach sexual maturity. ***Does age or weight determine sexual maturity? Explain. Figure 2Density-dependent regulation of birth rateFigure 3Intraspecific competition contributes to density-dependent birth and death rates; hence to regulation of population size.Figure 5Logistic growth model•dN/dt = r N(K - N)/K)•As N approaches K, intraspecific competition increases.•Population growth slows.Logistic equation is based on intraspecific competition depressing r, the per capita population growth rate; population size continues to increase until N = K.Interspecific competition reduces equilibriumlevel of population below carrying capacity.At equilibrium, each competing species reduces Kfor the other species.*** How much is K of sp 1 reduced by one individual of competing sp 2? By all individuals? K1Figure 6Lotka-Volterra addition of interspecificcompetition to logistic equation:•(dN/dt) = rN[(K-N)/K] becomes:•(dN1/dt) = r1N1[(K1 -N1 - 1,2N2)/K1]1,2 = competition coefficient• effect of each individual of sp 2 on sp 1• effect of sp 2 on sp 1’s growth rate•Similarly, for species 2:• (dN2/dt) = r2 N2[(K2 -N2 - 2,1N1)/K2]***What is  (competition coefficient) for the effect of 1 ind. of sp. 2 (N2) on sp. 1 (N1) or equivalence of sp. 2 for sp. 1?K1Figure 7Objectives II•Niche concepts•Interspecific competition•‘Ghost of competition past’: how deduce today whether competition in past?•Classic experiments• Competitive exclusion hypothesis•Field experimental studies: how document that competition is occurring?Niche: •Ecological role of species in community•Ranges of conditions and resource qualities within which the species persists•Often conceived as a multi-dimensional space (hypervolume)From 1 to n niche axes --> hypervolume of niche spaceNiche metricsIntraspecific competition: