Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 27 Community Characteristics Why do organisms compete? Food, resources and reproduction.

Similar presentations

Presentation on theme: "Chapter 27 Community Characteristics Why do organisms compete? Food, resources and reproduction."— Presentation transcript:


2 Chapter 27 Community Characteristics

3 Why do organisms compete? Food, resources and reproduction

4 27.1 Biotic Factors Nutritional Relationships *Predator-prey relationship *Interspecies Competition *Intraspecies Competition Symbiotic Relationships *Mutualism (+,+) *Parasitism (+, -) *Commensalism (+,0)

5 SPECIES A SPECIES B PositiveNegativeNeutral Positive Negative Neutral

6 SPECIES A SPECIES B PositiveNegativeNeutral Positivemutualism Predation (Species A is prey) Parasitism (Species A is host) Competitive exclusion of Species A commensalism Negative Predation (Species A is predator) Parasitism (Species A is parasite) Competition Limiting resources -- Neutral commensalism --Resource partitioning

7 2. Symbiotic Relationships Different organisms may live together in a close association. This is known as symbiosis. There are three types: 1. Commensalism 2. Mutualism 3. Parasitism KEY: + = benefits - = harmed o = not affected

8 Commensalism (+, o) In this relationship, one organism benefits and the other is not affected. Ex: barnacles on a whale

9 Commensalism (+, o) Epiphytes (mosses, orchids, ferns, bromeliad ) attach themselves to tree bark and obtain their nutrients without harm to the trees.

10 Mutualism (+, +) In this relationship both organisms benefit from each other. Ex: protozoan living in the digestive tract of termites. Wood eaten by termites is digested by the protozoan. The nutrients released supply both organisms.

11 Mutualism (+, +) In this relationship both organisms benefit from each other. Ex:

12 Mycorrhizae (+, +) In this relationship both organisms benefit from each other. Ex: Red Cedar and mycorrhizal fungi.

13 Parasitism (+, - ) In this relationship, the parasite benefits at the expense of the host. Ex: athletes foot fungus on humans tapeworm and heartworm in dogs.

14 Parasitism (+, - ) Pathogens (disease causing agents) are parasites that often cause the death of its host. Crown gall disease in plants.

15 Parasite/Host Relationship Guinea worm/Human

16 Parasite/Host Relationship Sea Lamprey/Fish

17 Parasitism Parasite/Host Relationship Varroa mite/Honeybee Tracheal mites

18 Do Now: Define keystone species and discuss two examples of organisms that are keystone species.

19 Keystone species These determine the nature and structure of an entire ecosystem. Usually found in small numbers but have a key influence. Examples: Wolves, Fig Trees

20 27.4 Predator/Prey Relationships!

21 27.4 Predator-Prey Cycles

22 27.7 Predator/Prey Relationships Data collected from fur pelts from the Hudson Bay Company

23 Studies have shown that Endocrine changes in populations may produce behavioral changes which tend to limit population growth. Therefore all population changes may not be due to predator/prey relationships alone.

24 Case Study "The Effects of Coyote Removal in Texas: A Case Study in Conservation Biology" by Margaret Carroll Department of Biology Framingham State College

25 Case Study The Wolf, the Moose, and the Fir Tree: Who Controls Whom on Isle Royale? A case study of trophic interactions by Gary M. Fortier Department of Small Animal Science Delaware Valley College

26 The Data

27 Fig. 1. Population parameters of the Isle Royale ecosystem from Shaded areas signify periods of forage suppression that may be connected to interactions between herbivores and carnivores. Population size of wolves each winter (based on aerial counts). Population size of moose each winter (based on aerial counts and skeletal remains). Ring-widths from the west end of Isle Royale, N=8. Ring-widths from the east end of Isle Royale, N=8. Actual evapotranspiration rates (AET), annual calculations based on data from April-October at a weather station 20 km from Isle Royale. AET is an approximation of primary productivity, it represents water availability as a function of temperature and rainfall.

28 Energy Flow Relationships For an ecosystem to be self- sustaining, there must be a flow of energy between organisms. The pathway of energy flow through the living components of an ecosystem are represented by food chains and food webs.

29 Nutritional Relationships Involves the transfer of nutrients from one organism to another within an ecosystem. In terms of nutrition, organisms are either autotrophs or heterotrophs

30 Energy Flow through a food Chain

31 Energy Losses The mouse receives energy from the food it eats. Cells extract the food's energy for growth, acquiring food, escaping enemies lost as heat. Some lost in the mouse's waste (feces). The remaining energy is stored in the mouse's body and is available to the organism that preys on it. About 90% of the energy is used or lost, only 10% is available to predators.

32 Energy Flow

33 Biological Magnification A nondegradable or slowly degradable substance That becomes more and more concentrated in the tissues of organisms at higher trophic levels of a food web. –* Dichloro-Diphenyl-Trichloroethane (DDT) –* Polychlorinated biphenyls (PCBs)

34 DDT in Food Webs

35 DDT

36 PCBs in Food Webs PCB concentrations in animal tissue can be magnified up to 25 million times. Microscopic organisms pick up chemicals from sediments Consumed in large numbers by filter feeding zooplankton. Mysid shrimp then consume zooplankton fish eat the mysid and so on up the food web to the herring gull. (Figure and caption from Our Stolen Future, p. 27)

37 Fig. 41-7, p.736 DDT residues Why was there never a concern for the Ring-billed gulls?

38 DDT Detection In 1962, Rachel Carson, a former U.S. Fish and Wildlife Service (USFWS) scientist and writer, published Silent Spring, outlining the dangers of DDT Fig. 41-8, p.736

39 DDT in Food Webs Heinz Meng Responsible for the reintroduction of the Peregrine Falcon.

40 27.3 Competitive Interactions Exploitative competition: species do not interact directly but compete for resources Competitive exclusion: both species require same resource

41 27.3 Competitive Interactions WAYS TO AVOID COMPETITION ??? Over abundance or resources Resource Partitioning

42 27.3 Natural selection can favor Resource Partitioning: differences in resource use among species.

43 The diagram represents a tree containing three different species of warbler, A, B, and C. Each species occupies a different niche. A fourth species, D, which has the same environmental requirements as species B, enters the tree at point X. Members of species B will most likely (1.) live in harmony with species D (2.) move to a different level and live with species A or species C (3.) stay at that level but change their diet (4.) compete with species D

44 Effect of community complexity on Species richness

45 41.8 Ecological Succession Succession is a process of ecological change in which a series of natural communities are established and then replaced over time. Two kinds of succession:. –Primary succession takes place on an area that is originally completely empty of life. flow of lava has, for a time, no life at all on it. Over a period of time, however, various kinds of organisms begin to grow in the area. Over time, the variety of life-forms changes as succession continues. –Secondary succession is far more common. It occurs in an area where life once existed but has then been destroyed. –a forest that has been destroyed by a wildfire. –For a period of time, no living organisms may exist in the area. Before long, however, certain types of plants begin to reappear. And, as with primary succession, the nature of the plant communities gradually change over time.

46 41.8 Ecological Succession Pioneers Organisms -lichen -grasses Climax Community

47 United streaming video Biologix: Interactions and Relationships among Organisms E05F2A25&blnFromSearch=1&produ ctcode=US# A-4EFD E05F2A25&blnFromSearch=1&produ ctcode=US#

Download ppt "Chapter 27 Community Characteristics Why do organisms compete? Food, resources and reproduction."

Similar presentations

Ads by Google