PLB 115 1st EditionCommunity Interactions Lecture 18Previous Notes’ OutlineI. Interpreting BehaviorII. AnthropomorphismIII. Instinctive and Learned BehaviorIV. The Nature of Instinctive BehaviorV. Stimulus and ResponseVI. Instinctive Behavior Cannot Be ModifiedVII. Instinctive Behavior Can Be ComplexVIII. Nature of Learned BehaviorIX. Kinds of LearningX. Types of AssociationXI. Instinct and Learning in the Same AnimalXII. Human BehaviorXIII. Social BehaviorXIV. AltruismCurrent Notes’ OutlineI. Communitya. Complexity & StabilityII. Dynamic CommunitiesIII. The Niche ConceptIV. The Habitat ConceptV. Kinds of Organism InteractionsVI. CompetitionVII. Competition & Natural SelectionVIII. Examples of Competitive ExclusionIX. PredationX. Predation’s Effects on PreyXI. Symbiotic RelationshipsXII. ParasitismXIII. Styles of ParasitismXIV. Parasitic Life CyclesXV. CommensalismXVI. MutualismXVII. Types of CommunitiesXVIII. Biomes of the WorldThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.XIX. Temperate Deciduous ForestXX. Temperate Grassland (Prairie)XXI. Temperate RainforestXXII. Boreal Coniferous ForestXXIII. TundraXXIV. Mediterranean Shrublands (Chaparral)XXV. DesertXXVI. SavannaXXVII. Tropical Dry ForestXXVIII. Tropical RainforestXXIX. Influence of Precipitation & Temperature on VegetationXXX. The Relationship Between Elevation and ClimateCommunity InteractionsCommunity: All of the populations of different species that interact in a particular location- Before an ecologist can study a community, the community boundaries must be definedComplexity and Stability- The interactions between species in a community involve a number of food chainso food chains interconnect as a food webComplexity and stability are directly correlated- More complex communities with more species that interact are more stable- Simpler communities that have been influenced by humans tend to be less stableCommunities Are Dynamic- Although over periods of years communities can be reasonably stable, they are still dynamic- Individual organisms are being born while others are dying- The processes of photosynthesis, respiration, decomposition, predation, parasitism, etc.,are occurring- Populations change size- If one particular species increases or decreases significantly, the community as a whole will be affectedThe Niche ConceptAn organism’s niche is its specific functional role in the community- Involves the organism’s impact on the biotic and abiotic elements of the community- Involves how the abiotic and biotic elements in a community impact that organismAffected by characteristics of the soil (abiotic)o Soil particle size, pH, soil moisture, etc. Affects soil composition by burrowing through soil (abiotic) Loosens soil and allows air and water to penetrate the soil Incorporates organic matter into soil- Impacts other organisms (biotic interactions)- Eaten by animals- Affected by parasitesThe Habitat Concept- The habitat of an organism is the kind of place or community where it lives- Habitats are described in terms of typical features of an organism’s surroundingso Prairie dog habitat is grasslandso Tuna habitat is the open oceano Cactus habitat is desertKinds of Organism Interactions- An important aspect of an organism’s niche is how it interacts with other species in the community- Some interactions are positive, some are negative, and some are neutralCompetition- Competition is an interaction between organisms in which both organisms are harmed- The most common interaction- Occurs when two organisms need a vital resource that is in short supplyo Can be food, water, shelter, nesting sites, mates, etc.- Intraspecific competition occurs between members of the same specieso Pine seedlings competing for sunlight- Interspecific competition occurs between members of different specieso Vultures and lions competing for foodCompetition and Natural SelectionCompetition is a force for natural selection- In a competitive relationship, one of the two organisms is harmed less and “wins” the competition- The winner has greater access to the limited resource- The competitive exclusion principle states that no two species can occupy the same niche at the same time- The more similar organisms are, the more intense the competition will be between them- If two organisms occupy the same niche, the competition will be so intense thato One of the two species will migrate to a different area One of the two species will become extinct One of the two species will evolve to occupy a slightly different nicheExamples of Competitive ExclusionWarblers feed on insects but occupy different niches- Different species of warblers feed on similar organisms, but do so in different parts of treesDifferent species of flowering plants compete for pollinators but occupy different niches- Some have tubular flowers attract humming birds- Some produce foul odors and attract flies and beetles- Some bloom at night and attract moths or bats- Some even mimic the female of certain insects which the male insects attempt to mate with and pollinate flowers in the processPredation- Predation occurs when one organism is captured, killed, and eaten by another- The predator is the killer and the prey is killed- Predators have evolved specific methods for capturing preyo Chase and kill (leopards, lions, etc.)o Camouflage, wait and strike (frogs, lizards, etc.)o Use tools to capture and kill (spiders and webs)Predation’s Effects on Prey- Prey populations are controlled by predators- Predators act as selecting agents on prey populations by eliminating less well-adapted prey individuals. - Predators remove sick and injured prey, which can control the spread of disease in the prey populationSymbiotic RelationshipsSymbiosis means “living together”- Describes situation in which members of two species live in close physical relationshipo Not always positive for both speciesSymbiosis includes- Parasitism- Mutualism- CommensalismParasitism- Involves one organism living in or on another living organism in order to obtain nutrients- The parasite benefits and the host is harmed- Parasites usually do not kill their host immediately because they need nutrients from it- However, as the parasite drains nutrients from the host, the host is weakened and may dieo Ex: viruses, protists, plants, fish, insects, worms, mites, and ticks - There