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Transcript
Community Ecology CH 20 Species Interactions • • • • • Predation Parasitism Competition Mutualism Commensalism Predation • • • • Helps shape community Predator: eats another Prey: gets eaten Natural selection favors adaptations that help predator efficiency and prey avoidance mechanisms Predator avoidance Camouflage Chemical warfare Warning coloration Mimicry Deceptive looks Deceptive behavior Antipredator defense • Mimicry: organism looks like a poisonous one (Monarch & Viceroy butterfly) What can a plant do? • Deterrents to herbivores: spines, thorns, thick leaves, serrated edges, secondary compounds (poison etc.) • • • • • Symbiotic Relationships: 1. Parasitism +/Harms one (host) & helps the other (parasite) Usually doesn’t kill host Ectoparasite: external (tick, leech, mosquito) Endoparasite: internal (tapeworm, malaria parasite) • • • Symbiotic Relationships: 2. Mutualism +/+ Both species benefit from each other Pollination - bird gets food, plant gets pollination service • • Symbiotic Relationships: 3. Commensalism +/0 One species benefits and the other is not affected (or the 2nd benefit hasn’t been discovered yet) Ø Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Commensalism Ø Organism is not affected + + Organism benefits Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. Competition • • Results from fundamental niche overlap Competitive exclusion principle: one species eliminates the other (one uses resources better and has a reproductive advantage) Competition Character Displacement • • • Natural Selection favors differences in competitors Niche overlap may lead to differences Darwin’s finches (beak size is different when there is competition on the island) Resource Partitioning • • • When species use the same resources, they use only part of them Different warblers feeding in different parts of a tree Reduces competition Resource Partitioning Properties of Communities • • • Species richness: The number of different species a community contains Species Evenness: relative abundance of each species Species diversity: Relationship between richness & evenness Patterns of richness • Varies w/ latitude - closer to equator = more species • Why? Less disturbed b/c ice age didn’t affect them • more stable climate • more plants = more food Species Area Effect • • Larger areas usually more diverse, more diversity of habitats Humans destroy habitats and diversity goes with them Succession • Gradual, sequential regrowth of species in an area Types of Succession • • • Primary: The area has never had life - new island, bare rock…is 1st (or primary time) for life to succeed Secondary: The existing community was disturbed - fire, logging, human activity (gets a 2nd chance to succeed) Pioneer species - first to arrive, small, fast-growing, good disperser • • • • • Primary Succession Very slow Have to create the soil Proceeds from lichens & mosses to climax community Takes hundreds of years Each stage paves the way for the next Secondary Succession • • • Varies where it starts, depending on level of disturbance May take 100 years Short-lived grass, long-lived grass, shrubs, trees Fire Succession • Needed for: – Reproduction – Clearing out competitors Complexity of Succession • Climax community - stable end point • There may be no such thing • Too complex to predict Major Biomes = CH 21 • Terrestrial (land) ecosystems • Tundra • Tropical forest • Temperate forest • Taiga • Temperate grassland • Savanna • Chaparral • Desert • Tundra Major Biomes • Cold • Permafrost under the surface of the ground • Lacks trees • Forests • Tropical: • abundant rainfall, stable & warm temps., high species diversity • Temperate • Coniferous (conebearing) or deciduous (lose their leaves) trees • Taiga Major Biomes • Cold, warmer than tundra • More precip. Than tundra • Mostly coniferous forests • Grasslands • Tropical aka Savanna: • Alternating wet/dry seasons • Warm year-round • Herds of grazing animals • Temperate • Cold winter & hot summer • Grasses • Herds of grazing animals Major Biomes • Deserts • Less than 25 cm (10 inches) rain/yr • Inhabitants have adaptations to conserving water • Nocturnal • Light color • Leaves spines Ocean Zones • • • Photic zone: shallow enough to receive sunlight (photosyn.) unlike aphotic zone Zones determined by location Intertidal • Btwn high and low tide • Animals must tolerate drying out & wave action • Ocean Zones Neritic zone: • Receives nutrients from bottom of ocean (upwelling) and from land • Richest zone in # of species & # of individuals • Ocean Zones Oceanic zone: • Far from land • Productivity limited by lack of nutrients • Estuaries: Ocean Zones • Rivers flow into ocean • Very productive nutrients from land • Freshwater Zones Lakes & Ponds: • Oligotrophic: low nutrients, clear water • Eutrophic: high nutrients, cloudy water • Freshwater Zones Rivers & Streams • Flow down an elevation gradient • Freshwater Wetlands • Marshs & swamps • Very “productive” • Covered w/ water at least part of the year SCAVENGER HUNT Animals = Ch 35, 36, 40 Arthropod-invertebrate with exoskeleton, jointed appendages and segmented body Amphibian-frogs, toads, salamanders; metamorphose from juvenile water-breather to adult air-breather Mollusk-snails, slugs, squid, octopus; mantle used for breathing and excretion Plants = Ch 28-30 Dicot plant-2 seed flowering plant Monocot plant-1 seed flowering plant Alga- singular for algae; autotrophic, photosynthetic; seaweed Gymnosperm Angiosperm Bryophyte Fern Sporophyte and gametophyte Renewable resource= water, oxygen, timber, fruits, meat, wind, solar power Nonrenewable resource= coal, oil, gas, copper Habitat fragmentation= when native is cleared for human activities for agriculture, rural or urbanization Humans & the Environment = CH 22 This is Fresh Kills Landfill in NY…..it covers 8 square miles and receives 34 million pounds of garbage each DAY! Earth’s Layers • Biosphere includes: • Geosphere: rock/land – important to biogeochemical cycles • Hydrosphere: water • Oceans cover 70% of surface • Freshwater <3% (mostly inaccessible) • Atmosphere: mixture of gases (air) • Atmosphere includes: • Greenhouse gas layer trap heat on Earth – in “troposphere” • Ozone Layer protects Earth from harmful UV radiation – in “stratosphere” • Ozone means “to smell” Ozone Thinning •O3 layer in upper atmosphere – helpful •Ozone layer lies 11-16 miles above Earth’s surface •Screens harmful UV radiation that causes skin cancer…absorbs 99% of radiation •CFC’s (chloroflouorocarbons) chemicals that break down ozone come from A/C, aerosol cans, refrigerators etc. Ozone Thinning •CFC’s banned in 1995 •1 CFC may destroy 100,000 ozone molecules •Biggest hole over Antarctica •May take 50-100 yrs to rebuild •@ ground level, ozone irritates nasal passages, throat, lungs Global Warming • • • • • CO2 and water vapor trap heat = greenhouse effect CO2 does trap more solar energy Increased CO2 from burning fossil fuels (coal, oil, natural gas) Increasing CO2 levels correlate w/ increase in temp. Earth has raised 1° F since 1860; May raise 3-8° F by 2100 = melt polar ice caps (hottest year on record is 1998 then 2003) Global Warming •Implications -Shift agricultural regions -Disrupt aquatic & terrestrial ecosystems -Rising sea levels -More extreme weather events Greenhouse Effect -Gases trap heat near planet’s surface just as glass panes found in a greenhouse Greenhouse Effect -4 gases: carbon dioxide, CFC’s, methane, nitrous oxide -Every 1% drop in ozone will lead to 6% increase in skin cancer and will also reduce # of certain marine algae = fewer producers Global Warming Facts 1. “Global warming is caused by depletion of the ozone layer”— THIS IS NOT TRUE---DON’T SAY! 2. W/OUT GASES, SCIENTISTS ESTIMATE THE EARTH’S AVG TEMP TO BE 0 DEGREES 3. Economics of Global Warming: -What happens if we continue to have storms and earthquakes? - More Pollution Issues • • Smog Acid Precipitation • Organisms are adapted to specific pH-tied to H20 cycle • Pollutants in air can change the pH and lead to problems • Land & water pollution • • • • Sewage Industries Burning fossil fuels Biological magnification • Chemicals move through the food chain becoming more concentrated the higher up you are • Ex: DDT, mercury • • Removing DDT in US has helped save bald eagle pop Dichlorodiphenyltrichloroethane = P ESTICIDE Ecosystem Disruption •Humans simplify ecosystems • ex: farmland, urban areas •Extinction •20% of species may be extinct in next 50 yrs •Biggest threat’s:habitat destruction, invasive species, overharvesting, hunting •1/2 of rainforests may be gone by 2020 Keystone Species • • • One who affects many others Maintains richness in a community If it disappears, the stability comes apart • Otters/sea urchins/giant kelp Community Stability • • How does the community respond to disturbance More species = greater stability Human Resource Use •Humans use 10 – 55% of Earth’s primary productivity •Ecological Footprint: analysis of your resource use; analyze people’s use of food/natural resources •Sustainability: meet the needs of a population indefinitely—need to close the gap b/n renewable and nonrenewable resources Human Resource Use -Need to work on: -energy production -transportation -agriculture -housing -waste disposal -slow human population growth -decrease the consumption of resources Environmental Solutions •Conservation: maintain & protect natural areas •Restoration: trying to return an area to natural conditions •Ex: drained wetlands •Bioindicators: use as early warning system b/c are especially sensitive to ecological changes •Ex: Rainbow trout, mussels, frogs and their mating calls Saving Biodiversity •Debt for nature swap: Money is given to developing countries to save their biodiversity (instead of converting it to farmland etc.) •Ecotourism: helps preserve nature and educate people •Laws: •1970 = Environmental Protection Agency created (EPA) •1973 = Endangered Species Act •1990 = Clean Air Act Restoration Case Study = p 451 •Florida Everglades •Army Corps of Engineers diverted water from Lake Okeechobee for cities and agriculture – previously would go to Kissimmee River to oceans making extensive wetlands •Devastated the natural ecosystem – pesticide and fertilizer runoff, heavy metals, reduction in water = increase salinity •Army corps responsible for long-term restoration, most ambitious in U.S. History Restoration Case Study = p 447 -Before 1870, whooping cranes migrated b/n Canada and Gulf Coast -Hunters killed whoopers for feathers and drained marshes for land -in 1937, only 15 whoopers left so US govt regulated hunting of birds and started a captive breeding program -negative impacts of captivity: -don’t know how to migrate or do courtship dance Captive Breeding Programs 1. 2. 3. 4. Boost #’s Species live somewhere else until habitat improves Inbreeding is prevented Learn immense amount of detail about population