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Overview Ch 13,14, 15: Intro to relationships

Definitions of terms applying to relationships.

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Overview Ch 13,14, 15: Intro to relationships

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    1. Overview Ch 13,14, &15: Intro to relationships     tropic                        non tropic interactions     herbivory                   Commensalism    grazing & browsing    competition     frugivory                    Amensalism     seed predation           neutralism     predation                    Mutualsim     parasitism                   Mycorrhizae    saprobism                   Pollination

    2. Definitions of terms applying to relationships      Trophic terms: hebivory, (know terms from video), carnivore, omnivore                      parasitism   - 1 benefits (P); 1 is harmed (host) competition  - both species are harmed, fewer resources   predation   - 1 benefits (predator); 1 is harmed (prey) saprobism    - eating dead material; no impact      

    3. Definitions con’t Amensalism: A symbiotic relationship between organisms in which one species is harmed or inhibited and the other species is unaffected. - Mutualism - Both species benefit by the interaction between the two species. Ex. Pollination Commensalism - ‘at table together'. This is a symbiotic relationship between two species in which one species benefits and the has no effect. neutralism - 2 species exist in same area with no impact on each other

    4. Introduction to relationships  Haskell’s Gain-Loss Matrix               Effect on weak species                                              -                        0                        + effect on                      -    competition         amensalism          parasitism strong species           0    amensalism         neutralism           commensalism                              +    Predation            commensalism     mutualism

    5. Competition Chapter 13

    6. Modes of Competition Interference: Direct aggressive interaction between individuals. Intraspecific: Competition with members of own species. Interspecific: Competition between individuals of two species - reduces fitness of both.

    7. Types of competition con’t Scramble -Food resources Contest Head to head battles Mates Territory Physical contest, visual, odor cues

    8. Interspecific Competition Among Herbaceous Plants Self-Thinning Plant growth rates and weights have been found to increase in low density populations. Competition is more intense at higher pop densities. mortality among competing plants.

    9. Interspecific Competition Among Herbaceous Plants

    10. Lotka Volterra In general, LV predicts coexistence of two species when, for both species, interspecific competition is weaker than intraspecific competition. Predict population growth for the two species will stop when: N1=K 1-?12 N2 and N2 = K 2- ?21 N1 Zero Growth Isoclines Above: Population increasing Below: Population decreasing Coexistence of two species is only possible when isoclines cross.

    11. Lotka Volterra Effect of interspecific competition on population growth of each species: dN1 / dt = rm1N1 ((K1-N1-?12N2) / K1) dN2 / dt = rm2N2 ((K2-N2-?21N1) / K2) ?12: Effect of individual of species 2 on rate of pop. growth of species 1. ?21: Effect of individual of species 1 on rate of pop. growth of species 2.

    12. Lotka Volterra

    13. Niches Niche: Summarizes environmental factors that influence growth, survival, and reproduction of a species. Type of food eaten, area it lives in.

    14. Niches Hutchinson defined niche as: n-dimensional hyper-volume n equates the number of environmental factors important to survival and reproduction of a species. Fundamental niche = hypervolume = many env factors considered such as food, nest sites, mating strategies. Realized niche (also called ecological niche) includes interactions such as competition that may restrict environments where a species may live. Includes inter and intra specific competition

    15. Feeding Niches of Galapagos Finches Grant found differences in beak size among ground finches translates directly into diet. Size of seeds eaten can be estimated by measuring beak depths. Individuals with deepest beaks fed on hardest seeds. After 1977 drought, the remaining seeds were very hard. Thus, mortality was most heavy in birds with smaller beaks.

    16. Feeding Niches of Galapagos Finches

    17. Gause: Principle of Competitive Exclusion Two species with identical niches cannot coexist indefinitely. One will be a better competitor and thus have higher fitness and eventually exclude the other. 4 C rule (Complete Competitors Cannot Coexist Compare niches of 5 species of woodpeckers

    18. Paramecia Lab Experiments Gause demonstrated resource limitation with Paramecium caudatum and Paramecium aurelia in presence of two different concentrations of Bacillus pyocyaneus. When grown alone, carrying capacity determined by intraspecific competition. When grown together, P. caudatum quickly declined. Reduced resource supplies increased competition.

    19. Paramecia Lab Experiments

    20. Competition and Niches Competition can restrict species to their realized niches. But if competitive interactions are strong and pervasive enough, they may produce an evolutionary response in the competitor population. Changes fundamental niche.

    21. Niche Overlap and Competition Between Barnacles Connell discovered interspecific competition in barnacles. Balanus plays a role in determining lower limit of Chthamalus within intertidal zone. Did not account for all observed patterns. Predation by starfish

    23. Competition and Niches of Small Rodents Brown studied competition among rodents in Chihuahuan Desert. Predicted if competition among rodents is mainly for food, then small granivorous rodent populations would increase in response to removal of larger granivorous rodents. Insectivorous rodents would show little or no response. Results supported hypothesis.

    24. Competition and Niches of Small Rodents

    25. Character Displacement & resource partitioning degree of competition depends on degree of niche overlap, interspecific competition is predicted to lead to directional selection for reduced niche overlap. Resource Partioning – ex. beaks of finches Compare 5 types of beaks in Darwin’s finches

    26. Character Displacement

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