BIO 105 1st Edition Lecture 3 Communities Community all the populations that live together in a habitat Competition Between Species Interspecific competition between DIFFERENT species Interspecific Interaction Competition Mutualism Predation Herbivory Parasites and pathogens Effect on Species 1 Negative Positive Positive Positive Positive Effect on Species 2 Negative Positive Negative Negative Negative Commensalism Positive Unaffected 0 Example Weeds in garden Bees and flowers Lion and antelopes Caterpillars and leaves Heartworm and dogs Salmonella and humans 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 community Ex 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 organisms 90 95 of all species that have ever lived are now extinct Lecture 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 Curves o Type I fewer offspring few die young most individuals survive until old age Ex humans Remember we are 1 so it is Type 1 o Type 2 chance of death pretty similar in young and older slanted lie death rate consistent over time Ex Songbirds lizards o Type 3 produce a lot of offspring many individuals die early if survive to adultgood chance to live Ex oysters fish Exponential Growth J shaped Population size expands by ever increasing increments during successive intervals hence the 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 curve Q We live in a developed country our population growth is not accelerating this is becauseA Our birth and death rates are fairly equal