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Community and Ecosystem Ecology

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Presentation on theme: "Community and Ecosystem Ecology"— Presentation transcript:

1 Community and Ecosystem Ecology
Chapter 20

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 (+/-)
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 Scavengers
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 Light energy Chemical energy Heat energy Chemical elements
cy cl in g Energy flow Light energy Chemical energy Heat energy Figure A terrarium ecosystem Chemical elements Bacteria, protists, and fungi

25 Energy Flow Ecological Pyramids 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 Figure 20.32 CO2 in atmosphere Burning Photosynthesis
Cellular respiration Higher-level consumers Plants, algae, cyanobacteria Wood and fossil fuels Primary consumers Figure The carbon cycle Decomposition Wastes; death Plant litter; death Decomposers (soil microbes) Detritus Figure 20.32

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