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Chapter 20 Community and Ecosystem Ecology. Community Ecology Species living in same vicinity Potential interactions will occur Interspecific interactions.

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Presentation on theme: "Chapter 20 Community and Ecosystem Ecology. Community Ecology Species living in same vicinity Potential interactions will occur Interspecific interactions."— Presentation transcript:

1 Chapter 20 Community and Ecosystem Ecology

2 Community Ecology Species living in same vicinity Potential interactions will occur Interspecific interactions Interactions between species Classified according to effect on populations Helpful (+) Harmful (-)

3 Community Interactions Occurs in a few ways: Competition Mutualism Predation Herbivory Parasites and pathogens

4 1. Competition (-/-) Occurs when members of two different species try to utilize the same resource Competitive Exclusion Principle: No two species can occupy the same ecological niche at the same time

5 Competition Between Two Species of Barnacles

6 Competition Competition can lead to resource partitioning decreases competition between the two species Character displacement is often viewed as evidence that competition and resource partitioning have taken place

7 2. Mutualism (+/+) Both members of the association benefit

8 3. Predation (+/-) Predator Prey 2 ways this regulates population growth: A. Predator-Prey Population Dynamics B. Antipredator Defenses

9 3. Predation A. Predator-Prey Population Dynamics Cycling of predator and prey populations Occurs when either predators overkill prey, or when prey overuse resources and their numbers crash In either case, predator numbers also decrease from a decrease in food source

10 Predatory-Prey Cycling of a Lynx and a Snowshoe Hare

11 Coevolution Evolutionary change in one species results in an evolutionary change in the other Organisms in symbiotic associations are especially prone to the process of coevolution Also occurs between predators and prey Example: Cheetah sprints forward to catch prey, and this behavior might be selective for those gazelles that jump high in the air

12 3. Predation B. Antipredator Defenses Cryptic coloration Camouflage Warning coloration Association with undesirable consequences

13 3. Predation B. Antipredator Defenses Mimicry One species resembles another species Can help capture food or avoid being preyed upon Batesian Mimicry A prey that is not harmful mimics another species that has a successful antipredator defense Warning colorations Mullerian mimicry Species that resemble each other all have successful defenses

14 Mimicry Among Insects Mullerian Batesian

15 Coral snake vs. Milk snake

16 4. Herbivory (+/-) Consumption of plants by an animal Plant must expend energy to regenerate Evolved defenses

17 5. Parasites & Pathogens (+/-) Parasite Lives on or in a host Endoparasite Ectoparasite Pathogens Disease-causing microorganisms

18 Trophic Structures Feeding relationships among species in a community Determines the passage of energy and nutrients Sequence of food transfer is a food chain Unbranched

19 Trophic Structure Autotrophs (producers) Require an energy source and inorganic nutrients to produce organic food molecules Manufacture organic nutrients for all organisms Green plants and algae carry on photosynthesis

20 Trophic Structure Heterotrophs (consumers) Need a preformed source of organic nutrients Herbivores Graze directly on plants or algae Carnivores Feed on other animals Omnivores Feed on both plants and animals

21 Trophic Structure Heterotrophs Decomposers Heterotrophic bacteria and fungi Break down nonliving organic matter They release inorganic matter to be used by producers Scavengers Feed on dead remains

22 Ecosystem

23 Ecosystem Ecology Possesses both abiotic and biotic components Biotic The various populations of organisms that form a community Abiotic Includes resources such as sunlight, inorganic nutrients, soil, water, temperature and wind Two major processes sustain all ecosystems: Energy flow passage of energy through the components of the ecosystem Chemical cycling use and reuse of chemical elements within the ecosystem

24 Energy flow Light energy Bacteria, protists, and fungi Chemical elements Chemical energy Heat energy Ch e m i c al cy cl in g

25 Energy Flow Biomass Mass of living organic material in ecosystem Ecological Pyramids only about 10% of the energy of one trophic level is available to the next trophic level Producers at the base Most available energy Energy is given off in less usable forms as producers are eaten by primary consumers, etc.

26 Chemical Cycling Biogeochemical cycles Biotic and abiotic components of the chemical cycles in an ecosystem 3 main cycles: Carbon cycle Phosphorus cycle Nitrogen cycle

27 CO 2 in atmosphere Burning Cellular respiration Wood and fossil fuels Decomposition Wastes; death Decomposers (soil microbes) Detritus Plant litter; death Primary consumers Higher-level consumers Plants, algae, cyanobacteria Photosynthesis Figure 20.32

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