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  • Video ReviewsWolves of YellowstoneStonefliesInvasive speciesWildlife corridorsFlying foxesDung beetlesSea OttersSea lampreyAnts and acacia tree

  • Community EcologyAP Environmental ScienceMilton High School

  • Habitat fragmentation causes significant decline in species diversityReduce species richnessReduce amount of functional habitatCause isolation of a speciesPossibility of genetic drift or inbreeding

  • Edge Effects Associated with Habitat Fragmentation Can Reduce BiodiversityMakes many species vulnerable to stresses such as predators and firesCreates barriers that can prevent some species from colonizing new areas and finding food and mates

  • Edge effect

  • Conservation Biologists Protect BiodiversityPreserving large areas of habitatUsing migration corridors to link smaller habitat patches

  • Tunnels under roadsBridges over roads

  • Who benefits from wildlife corridors?

  • Species diversitySpecies richness number of different speciesSpecies evenness abundance of individuals within each of those species

  • The Most Species-rich EnvironmentsTropical forestsCoral reefsDeep seaLarge tropical lakes

  • Three Major Factors Affect Species DiversityLatitude (distance from equator)Depth (aquatic systems)Pollution (aquatic systems)

  • Number of Species Found on an Island Determined by a Balance Between:Rate at which new species immigrate to the islandThe rate at which species become extinct on the island

  • Two features of an island which affects its immigration and extinction rateIslands size

    Islands distance from the mainland

  • Canary ArchipelagoWhat can you predict about how each island was colonized by wild species?

  • The closer the island is to another land mass, the higher the probability of colonization.

    2) The older the island, the more likely it will be colonized.

    3) The larger the island, the more species are likely to be established.

    4) The geographic isolation reduces gene flow between populations.

    5) Over time, colonial populations become genetically divergent from their parent population due to natural selection, mutation, and/or genetic driftGeneral principles of island colonization

  • Explain Robert MacArthur and E.O. Wilsons Theory of Island Biogeography? How is this theory applied to the management of National Parks?Island Biogeography

  • Critical Roles of Keystone SpeciesPollination of flowering plant speciesDispersion of seeds by fruit-eating animalsHabitat modification (Gopher tortoise)Predation by top carnivores to control populations of various speciesImproving the ability of plant species to obtain soil minerals and waterEfficient recycling of animal wastes

  • Sea Otter: A keystone species

  • Sea otters feed on the sea urchin which eats the base of the kelp plants (killing the kelp plants)

  • The Dodo bird inhabited the island of Mauritius in the Indian Ocean

  • In 1505, the Portuguese became the 1st humans to set foot on Mauritius Dodo bird source of food for the sailors

    Dutch used the island as a penal colony and brought pigs and monkeys which ate the eggs of the dodo bird

  • A combination of human exploitation and introduced species significantly reduced the dodo populationThe last dodo bird was killed in 1681

  • Scientists discovered a certain species of tree was becoming quite rare on Mauritius. All of the remaining trees of their species were about 300 years old and no new trees had germinated since the late 1600s.

  • Was it coincidence that the tree had stopped reproducing 300 years ago and that the dodo bird had become extinct 300 years ago?

  • The dodo ate the fruit of the tree and the seed only became active and could grow after passing through the digestive tract of the dodo bird.Scientists discovered the turkeys digestive tract accomplishes the same task and they are now using turkeys to begin a new generation of the tree - Tambalacoque

  • Biological indicator species are unique environmental indicators as they offer a signal of the biological condition of a particular habitatUsing bioindicators as an early warning of pollution or degradation in an ecosystem can help sustain critical resources

  • Fish are an excellent indicator of watershed health because:Live in water all of their lifeDiffer in their tolerance levels to amount and types of pollutionAre easy to collectLive for several yearsAre easy to identify

  • Benthic macroinvertebrates are good indicators because:Live in water for all or most of their lifeStay in areas suitable for their survival Are easy to collectDiffer in their tolerance to amount and types of pollutionAre easy to identifyOften live for more than one yearHave limited mobilityAre integrators of environmental condition

  • Possible Causes of Amphibian DeclinesLoss of habitatProlonged droughtPollution (pesticides, nitrates, pH)Increases in ultraviolet radiationIncrease parasitismOverhuntingEpidemic diseasesImmigration or introduction of alien predators and competitors

  • What is the disadvantage?

  • Five Basic Types of Interactions Between SpeciesInterspecific competitionIntraspecific competitionPredationParasitismMutualismcommensalism

  • CommensalismRemorasucking disc does not harm shark

  • Bacteria in your intestines

  • Significant Niche Overlap one of the competing species mustMigrate to another areaShift its feeding habits or behavior through natural selection or evolutionSuffer a sharp population declineBecome extinct in that area

  • How Species Avoid PredatorsRun, swim, fly fastHighly developed sense of smell or sightProtective shellsThick barkSpinescamouflageParts that break offChemical warfareWarning colorationBehavioral strategiesPuffing upMimicrySchoolingLiving in large groupsSpreading their wings

  • Avoiding predators

  • Examples of Primary SuccessionBare rock exposed by glacial retreat or severe soil erosionNewly cooled lavaAn abandoned highway or parking lotNewly created shallow pond or reservoir

  • Pioneer species start soil formation process by:Trapping wind-blown soil particles and tiny pieces of detritusProducing tiny bits of organic matterSecreting mild acids that slowly fragment and break down the rockLichen

  • Examples of Secondary SuccessionAbandoned farmlandsBurned or cut forestsHeavily polluted streamsLand that has been dammed or flooded

  • Three Aspects of StabilityPersistence resist disturbance

    Constancy keep within limits

    Resilience bounce back

  • The End

  • Role of positive and negative feedback loops in the stability of an ecosystemNegative feedback loops promote stability in a dynamic systemPositive feedback loops usually leads to one or more populations being wiped out (local extinction)Positive feedback loop = causes a system to change further in the same direction (positive refers to the direction of change, rather than desirability of the outcome)

    Negative feedback loop = causes a system to change in the opposite direction

  • Positive feedback loopA warmer atmosphere will melt ice and this changes the Earths albedo which further warms the atmosphereAn increase in temperature will melt the permafrost in the tundra causing a release of trapped carbon dioxide and methane (both are greenhouse gases)

  • Negative feedback loopPredator-prey relationship

    The moose population will rise and fall in response to the wolf population

  • Positive and negative feedback loops coupled together The settlers of Easter Island found plenty of natural resources The Islanders had many children and the population went up The islands tree and soil resources were used faster than they could be renewed Without trees Islanders could not build traditional seagoing canoes All of the islands natural resources were used up Both the population and the civilization collapsed

  • Example of negative feedback loopAn example of negative feedback is body temperature regulation. If blood temperature rises too high, this is sensed by specialized neurons in the hypothalamus of the brain. They signal other nerve centers, which in turn send signals to the blood vessels of the skin. As these blood vessels dilate, more blood flows close to the body surface and excess heat radiates from the body. If this is not enough to cool the body back to its set point, the brain activates sweating. Evaporation of sweat from the skin has a strong cooling effect, as we feel when we are sweaty and stand in front of a fan. Read more: Homeostasis - Biology Encyclopedia - cells, body, examples, function, human, process, system, organisms, blood

  • Example of positive feedback loopAn example of its beneficial effect is seen in blood clotting. Part of the complex biochemical pathway of clotting is the production of an enzyme that forms the matrix of the blood clot, but also speeds up the production of still more thrombin. That is, it has a self- catalytic , self-accelerating effect, so that once the clotting process begins, it runs faster and faster until, ideally, bleeding stops. Thus, this positive feedback loop is part of a larger negative feedback loop, one that is activated by bleeding and ultimately works to stop the bleeding. Read more: Homeostasis - Biology Encyclopedia - cells, body, examples, function, human, process, system, organisms, blood

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