BIO 105 1st EditionLecture 3Communities Community-all the populations that live together in a habitat Competition Between Species- Interspecific- competition between DIFFERENT speciesInterspecific Interaction Effect on Species 1 Effect on Species 2 ExampleCompetition Negative (-) Negative (-) Weeds in gardenMutualism Positive (+) Positive (+) Bees and flowersPredation Positive (+) Negative (-) Lion and antelopesHerbivory Positive (+) Negative (-) Caterpillars and leavesParasites and pathogens Positive (+) Negative (-) Heartworm and dogs, Salmonella and humansCommensalism Positive (+) Unaffected (0) Barnacles on a whale- Intraspecific- between members of the SAME species Competitive Exclusion Principle- Two species compete for IDENTICAL RESOURCES, one will be more successful and will eventually eliminate the other**Remember the key words compete and exclude Resource Partitioning- minimizes competition and allows coexistence Keystone Species- exerts an important regulating effect on other species in a communityEx: An otter is a keystone species, if otters are removed; the community structure is greatly affected**Remember: The key to survival is this specie  Prey Defenses- Camouflage/ melansim- Ex: Stripes on a Tiger helps him blend in with his surroundings- Warning coloration-Ex: Blue colored frogs lets predators know he is dangerous- Mimicry-Ex: Leaf Bug pretends to be a leaf - Moment of truth defenses-Ex: When a skunk is approached by a predator he sprays his odor Parasitism- predation- Endoparasites- live inside the host (tapeworm) **Remember Endo- like indoor - Ectoparasites – live on the surface of the host (mosquito) Primary Succession- Glacier Retreat, Lava Bed- Species colonize barren habitants (like rock where glacier pulls back or after volcano eruption)- Mosses, lichens, & small plants with brief life cycles grow in first Secondary Succession- After Fire- Grasses grow in first, then trees and other organisms90-95% of all species that have ever lived are now extinctLecture 6- Population Population- a group of individuals of the same species occupying a given area- Clumped- dispersion is when individuals aggregate in patches-Ex: fish, humans- Uniform- dispersion is when individuals are evenly spaced –Ex: penguins- Random- dispersion, the position of each individual is independent of the others-Ex: forests Life History Patterns- set of adaptations that influence survival, fertility, and age at first reproduction- Summarized in- Survivorship Curveso Type I- fewer offspring- few die young- most individuals survive until old ageEx: humans**Remember we are #1 so it is Type 1o Type 2- chance of death pretty similar in young and older-slanted lie- death rate consistent over timeEx: Songbirds, lizardso Type 3- produce a lot of offspring, many individuals die early-if survive to adult- good chance to liveEx: oysters, fishExponential Growth- J shaped-Population size expands by ever increasing increments during successive intervals, hencethe “j” shape-Doubling time- time it takes for a population to double in size-Impact of death on growth- death slows rate of increase but does not prevent exponential growth- just shifts it to the right Biotic Potential- maximum rate of increase per individual under ideal conditions- Assumes adequate shelter, food, and resources with no predators, pathogens or pollutants- Ex: human females are biologically equipped to bear 20 or more children but in each generations many females do not reproduce at all- The Duggars- In nature, biotic potential is rarely reached because of Limiting Factors Limiting Factors- All limiting factors acting on a population dictate sustainable population size- keep from reaching biotic potential- Ex: Food, Mineral ions, Refuge from predators, living space, pollution free habitats Carrying Capacity (K)- maximum number of individuals that can be sustained in a particular habitat- Logistic growth- “S” shaped curveQ: We live in a developed country, our population growth is not accelerating- this is because- A: Our birth and death rates are fairly