Upload
ruth-burns
View
214
Download
0
Tags:
Embed Size (px)
Citation preview
Community EcologyCommunity Ecology
AP Environmental AP Environmental ScienceScience
Milton High SchoolMilton High School
Species diversitySpecies diversity
Species richness Species richness – – number of different number of different speciesspecies
Species evenness Species evenness – – abundance of abundance of individuals within individuals within each of those specieseach of those species
Habitat fragmentation causes Habitat fragmentation causes significant decline in species significant decline in species diversitydiversity Reduce species richnessReduce species richness Reduce amount of functional habitatReduce amount of functional habitat Cause isolation of a speciesCause isolation of a species Possibility of genetic drift or inbreedingPossibility of genetic drift or inbreeding
Edge Effects Associated Edge Effects Associated with Habitat Fragmentation with Habitat Fragmentation Can Reduce BiodiversityCan Reduce Biodiversity Makes many species vulnerable Makes many species vulnerable
to stresses such as predators and to stresses such as predators and firesfires
Creates barriers that can prevent Creates barriers that can prevent some species from colonizing new some species from colonizing new areas and finding food and matesareas and finding food and mates
Edge effect
Conservation Conservation Biologists Protect Biologists Protect BiodiversityBiodiversity Preserving large areas of habitatPreserving large areas of habitat Using migration corridors to link Using migration corridors to link
smaller habitat patchessmaller habitat patches
Tunnels under roads
Bridges over roads
Who benefits from wildlife corridors?
The Most Species-rich The Most Species-rich EnvironmentsEnvironments Tropical forestsTropical forests Coral reefsCoral reefs Deep seaDeep sea Large tropical lakesLarge tropical lakes
Three Major Factors Three Major Factors Affect Species Affect Species DiversityDiversity Latitude (distance from equator)Latitude (distance from equator) Depth (aquatic systems)Depth (aquatic systems) Pollution (aquatic systems)Pollution (aquatic systems)
Number of Species Found Number of Species Found on an Island Determined by on an Island Determined by a Balance Between:a Balance Between: Rate at which Rate at which
new species new species immigrate to immigrate to the islandthe island
The rate at The rate at which species which species become extinct become extinct on the islandon the island
Two features of an island Two features of an island which affects its which affects its immigration and extinction immigration and extinction raterate Island’s sizeIsland’s size
Island’s Island’s distance distance from the from the mainlandmainland
Canary Archipelago
What can you predict about how each island was
colonized by wild species?
1) 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 drift
General principles of General principles of island colonizationisland colonization
Critical Roles of Critical Roles of Keystone SpeciesKeystone Species Pollination of flowering plant speciesPollination of flowering plant species Dispersion of seeds by fruit-eating Dispersion of seeds by fruit-eating
animalsanimals Habitat modification (Gopher tortoise)Habitat modification (Gopher tortoise) Predation by top carnivores to control Predation by top carnivores to control
populations of various speciespopulations of various species Improving the ability of plant species to Improving the ability of plant species to
obtain soil minerals and waterobtain soil minerals and water Efficient recycling of animal wastesEfficient recycling of animal wastes
Sea Otter: Sea Otter: A keystone speciesA 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 population
The 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 1600’s.
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
turkey’s 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 Biological indicator species are unique environmental indicators as unique environmental indicators as they offer a signal of the biological they offer a signal of the biological
condition of a particular habitatcondition of a particular habitat
Using bioindicators as an early warning of pollution or
degradation in an ecosystem can
help sustain critical resources
Fish are an excellent Fish are an excellent indicator of watershed indicator of watershed
health because:health because: Live in water all of their Live in water all of their
lifelife Differ in their tolerance Differ in their tolerance
levels to amount and levels to amount and types of pollutiontypes of pollution
Are easy to collectAre easy to collect Live for several yearsLive for several years Are easy to identifyAre easy to identify
Benthic macroinvertebrates Benthic macroinvertebrates are good indicators are good indicators
because:because: Live in water for all or most of their Live in water for all or most of their
lifelife Stay in areas suitable for their Stay in areas suitable for their
survival survival Are easy to collectAre easy to collect Differ in their tolerance to amount Differ in their tolerance to amount
and types of pollutionand types of pollution Are easy to identifyAre easy to identify Often live for more than one yearOften live for more than one year Have limited mobilityHave limited mobility Are integrators of environmental Are integrators of environmental
conditioncondition
Possible Causes of Possible Causes of Amphibian DeclinesAmphibian Declines Loss of habitatLoss of habitat Prolonged droughtProlonged drought Pollution (pesticides, nitrates, pH)Pollution (pesticides, nitrates, pH) Increases in ultraviolet radiationIncreases in ultraviolet radiation Increase parasitismIncrease parasitism OverhuntingOverhunting Epidemic diseasesEpidemic diseases Immigration or introduction of alien Immigration or introduction of alien
predators and competitorspredators and competitors
What is the disadvantage?
Five Basic Types of Five Basic Types of Interactions Between Interactions Between SpeciesSpecies Interspecific competitionInterspecific competition PredationPredation ParasitismParasitism MutualismMutualism commensalismcommensalism
Commensalism
Remora
“sucking” disc does not harm shark
Bacteria in your intestines
Significant Niche Overlap – Significant Niche Overlap – one of the competing one of the competing species mustspecies must Migrate to another areaMigrate to another area Shift its feeding habits or Shift its feeding habits or
behavior through natural behavior through natural selection or evolutionselection or evolution
Suffer a sharp population declineSuffer a sharp population decline Become extinct in that areaBecome extinct in that area
How Species Avoid How Species Avoid PredatorsPredators
Run, swim, fly fastRun, swim, fly fast Highly developed Highly developed
sense of smell or sense of smell or sightsight
Protective shellsProtective shells Thick barkThick bark SpinesSpines camouflagecamouflage
Parts that break offParts that break off Chemical warfareChemical warfare Warning colorationWarning coloration Behavioral Behavioral
strategiesstrategies– Puffing upPuffing up– MimicryMimicry– SchoolingSchooling– Living in large groupsLiving in large groups– Spreading their wingsSpreading their wings
Avoiding predators
Examples of Primary Examples of Primary SuccessionSuccession Bare rock exposed by glacial Bare rock exposed by glacial
retreat or severe soil erosionretreat or severe soil erosion Newly cooled lavaNewly cooled lava An abandoned highway or parking An abandoned highway or parking
lotlot Newly created shallow pond or Newly created shallow pond or
reservoirreservoir
Pioneer species start Pioneer species start soil formation process soil formation process by:by: Trapping wind-blown soil particles and tiny Trapping wind-blown soil particles and tiny
pieces of detrituspieces of detritus Producing tiny bits of organic matterProducing tiny bits of organic matter Secreting mild acids that slowly fragment Secreting mild acids that slowly fragment
and break down the rockand break down the rock
Lichen
Examples of Secondary Examples of Secondary SuccessionSuccession Abandoned farmlandsAbandoned farmlands Burned or cut forestsBurned or cut forests Heavily polluted streamsHeavily polluted streams Land that has been dammed or Land that has been dammed or
floodedflooded
Three Aspects of Three Aspects of StabilityStability Persistence – resist disturbancePersistence – resist disturbance
Constancy – keep within limitsConstancy – keep within limits
Resilience – bounce backResilience – bounce back
Role of positive and negative Role of positive and negative feedback loops in the stability of an feedback loops in the stability of an ecosystemecosystem
Negative feedback loops promote Negative feedback loops promote stability in a dynamic systemstability in a dynamic system
Positive feedback loops usually leads Positive feedback loops usually leads to one or more populations being to one or more populations being wiped out (local extinction)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 loopPositive feedback loop
A warmer atmosphere will melt ice and this
changes the Earth’s albedo which
further warms the atmosphere
An 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 Negative feedback looploop
Predator-prey relationship
The moose population will rise and fall in
response to the wolf population
Positive and negative feedback loops coupled together
1. The settlers of Easter Island found plenty of natural resources2. The Islanders had many children and the population went up3. The island’s tree and soil resources were used faster than they could be
renewed4. Without trees Islanders could not build traditional seagoing canoes5. All of the island’s natural resources were used up6. Both the population and the civilization collapsed
Example of negative Example of negative feedback loopfeedback loop
An 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 http://www.biologyreference.com/Ho-La/Homeostasis.html#ixzz11mSI4EzD
Example of positive Example of positive feedback loopfeedback loop
An 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 http://www.biologyreference.com/Ho-La/Homeostasis.html#ixzz11mSpKQyy
The End