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1、国外动物学39 Still waters run deep.流静水深流静水深,人静心深人静心深 Where there is life,there is hope。有生命必有希望。有生命必有希望Earth Environment-OverviewlWater has physical properties critical to life on earth.lThe steady supply of sunlight maintains a suitable range of temperatures for life metabolism.lLiving matter requires a
2、supply of major and minor elements available on earth.lThe earths gravity is strong enough to hold an extensive gaseous atmosphere.lThe environment is modified by organisms.lOrganisms are adapted by evolution to the environment.lThe earth is an open system with a continuous supply of energy.lBuildin
3、g materials for life come from producers and are cycled through consumers.lLife is part of a cycle of life-death-decay-recycling.Earth EnvironmentEarth EnvironmentlThe primitive earth of 4.5 billion years ago had a reducing atmosphere of ammonia,methane,and water and was fit for pre-biotic synthesis
4、 of early living forms.lThis early atmosphere would be fatal to todays organisms.lThe appearance of free oxygen in the atmosphere is an example of the reciprocity of life and the earth.lLiving organisms produce changes in their environment and must adapt and evolve.BiospherelThe biosphere is the thi
5、n outer layer of the earth capable of supporting life.lIncludes living organisms as well as the physical environments.Biosphere-SubdivisionslLithosphere rocky material of the earths outer shell.lSource of mineral elements required for life.lHydrosphere water on or near the earths surface.lAtmosphere
6、 the gaseous component of the biosphere.lAtmospheric oxygen is produced by photosynthesis.Greenhouse EffectlMaterials in the atmosphere,such as CO2 and water vapor retain heat,raising atmospheric temperature.lGreenhouse effectlBurning fossil fuels increases CO2 in the atmosphere.Greenhouse EffectlTh
7、e greenhouse effect provides conditions essential for life on Earth.lHumans are increasing this effect.lIncreased temperatures could lead to a rise in sea level as polar ice melts.BiomeslVarying combinations of both biotic and abiotic factors determine the nature of Earths many biomes.lBiomes are th
8、e major types of ecological associations that occupy broad geographic regions of land or water.BiomeslEach biome grades into the next without sharp boundaries.lBoundary areas are called ecoclines.Terrestrial BiomeslClimate is particularly important in determining why particular terrestrial biomes ar
9、e found in certain areas.lTemperaturelRainfalllSolar radiationTerrestrial BiomeslThe suns rays strike higher latitudes at a lower angle.lAtmospheric heating is less.Terrestrial BiomeslAir warmed at the equator rises and moves toward the poles.lReplaced by cold air moving away from the poles.lRotatio
10、n of the earth complicates this pattern.lThree latitudinal cells result.Terrestrial BiomeslHot,moist air rises at equator,cools,condenses and provides rainfall(tropical forests).lWarm air flows northward,and sinks at 20-30 latitude dry.lAir heats,absorbs moisture(desert areas),then the air flows tow
11、ard the equator again.The Distribution of Major Terrestrial BiomesGeneral Features of Terrestrial BiomeslVertical stratification is an important feature of terrestrial biomes.lCanopylLow-treelShrub understorylGround layerlForest floor(litter layer)Temperate Deciduous ForestlTemperate deciduous fores
12、ts receive rain year-round.lCold winters and hot,humid summers.lAnimals may migrate,hibernate,or survive on scarce available food or stored fat through the winter.Coniferous ForestlConiferous forests,or taiga,are common in the northern hemisphere.lEvergreens dominantlColder,less rain than temperate
13、forests.Coniferous ForestlMammals that inhabit coniferous forests include deer,moose,elk,snowshoe hares,wolves,foxes,lynxes,weasels,bears.lAdapted for long,snowy winters.Tropical ForestlTropical rain forests receive lots of rain and are generally warm year-round.lStratifiedlDiverseTropical ForestlCa
14、nopy insectivorous birds and bats fly above the canopy.lFruit bats,canopy birds,and mammals live in the canopy eating leaves&fruit.lMiddle zones are home to arboreal mammals(monkeys,sloths),birds,bats,insects,amphibians.lClimbing animals move along the tree trunks feeding at all levels.lGround level
15、 contains larger mammals(capybara,paca,agouti,pigs)as well as a variety of reptiles and amphibians.Tropical ForestlNutrients in a tropical forest are tied up in living organisms.lSoil is poor.lSlash and burn agriculture involves removing vegetation to grow crops but the soil is so poor that the fiel
16、ds must be moved often.GrasslandlTemperate grasslands receive seasonal precipitation and have cold winters and hot summers.lPrairieGrasslandlGrasses and herds of large grazing mammals are dominant.lJackrabbits,prairie dogs,and ground squirrels are common.lPredators include coyotes,cougars,bobcats,ra
17、ptors,badgers,and ferrets.GrasslandlSavannas are tropical grasslands with seasonal rainfall.GrasslandlChaparral receives highly seasonal rainfall.lShrubs and small trees are common.lAdaptations to fire.TundralTundra has a permanently frozen layer of soil called permafrost that prevents water infiltr
18、ation.lVery cold,short growing season.lLittle rainTundralTundra is often covered with bogs,marshes,or ponds.lGrasses,sedges,and lichens may be common.lLemmings,caribou,musk-oxen,arctic foxes,arctic hares,ptarmigans and other migratory birds.DesertlDeserts have very low precipitation less than 30 cm/
19、yr.lVariable temperatures.lAnimals often nocturnal and live in burrows.lReptiles and small mammals are common.Aquatic BiomesAquatic BiomeslAquatic biomes account for the largest part of the biosphere in terms of area.lCan contain fresh or salt water.lOceans cover about 75%of Earths surface.lHave an
20、enormous impact on the biosphere.Inland WaterslOnly about 2.5%of the earths water is fresh.lMuch of that is found in polar ice caps or underground aquifers.Inland WaterslLotic,or running water habitats include streams and rivers.lMore oxygenlLentic,or standing water habitats include lakes and ponds.
21、lLess oxygenInland WaterslOligotrophic lakes nutrient poor&oxygen rich.lEutrophic lakes nutrient rich&sometimes oxygen poor.lEutrophicationAn oligotrophic lakeA eutrophic lakeLAKESInland WaterslStreams and rivers have a current.STREAMS AND RIVERSInland WaterslAnimals living in vegetation or debris o
22、f the bottom(benthos)are called benthic.lSnails,mussels,crustaceans,insects.lAnimals up in the water column are pelagic.lSwimming animals are called nekton.lFloating or weak swimmers are called plankton.WetlandslWetlands include areas that are able to support aquatic plants.lMay be freshwater or mar
23、ine.WETLANDSEstuarieslEstuaries are transition areas between river and sea.lSalinity varies from nearly fresh to the salinity of seawater.ESTUARIESAquatic BiomeslMany aquatic biomes are stratified into zones or layers defined by light penetration,temperature,and depth.lThe photic zone is the most pr
24、oductive.Rocky Intertidal ZonelThe rocky intertidal zone is alternately submerged and exposed by the tides.lUpper zones are exposed to air longer.lPhysical stress(desiccation,waves,temp,salinity),predation,and competition produce distinct bands.Rocky Subtidal ZonelKelp forests dominated by brown sea
25、weeds occupy shallow subtidal waters.lGrazing urchins and molluscs are common.lPredators include sea stars,fishes,and otters.Rocky Subtidal ZonelCoral reefs are limited to the photic zone in tropical marine environments with high water clarity.lHighly diverseCORAL REEFSNearshore Soft SedimentslInter
26、tidal and subtidal environments with soft sediments include beaches,mudflats,salt marshes,sea-grass beds,and mangrove communities.Nearshore Soft SedimentslSalt marsh habitat includes grasses,mussels,crabs,shrimp,and polychaetes.lBurrowing organisms.lDeposit or filter feeders.lSmall fishes and birds
27、that feed on them are common.Nearshore Soft SedimentslCalm,tropical,coastal areas support mangrove communities.lMangrove trees grow submerged in soft sediments.lRich community of detritus feeders(oysters,crabs,shrimp).lMany fishes often used as a nursery ground.Deep-Sea SedimentslThe deep sea includ
28、es the continental slope,continental rise,and abyssal plain.lSand where there are currents,fine mud where currents are weak.lSuspension feeding invertebrates are common.lDeposit feeders found in muddy areas.Hydrothermal VentslHydrothermal vents occur on the abyssal plain in areas of submarine volcan
29、ic activity.lArchaebacteria that derive energy by oxidizing sulfides form the basis of the food chain.lGrazed by bivalves,limpets,and crabs.lOther organisms,like tube worms,have symbiotic archaebacteria.Pelagic RealmlThe pelagic realm includes the open ocean area.lHigh oxygen,low nutrient levels.lAr
30、eas of upwelling bring nutrients up from the sea floor.OCEANIC PELAGIC BIOMEPelagic RealmlEpipelagic surface waterslMesopelagic twilight zone,supports a varied community of animals.lDeep sea forms depend on a rain of organic debris from above.ZoogeographylZoogeography describes patterns of animal di
31、stribution and species diversity.lWhy species and species diversity are distributed as they are.ZoogeographylThe history of an animal species must be documented before we can understand why it lives where it does.lCamels originated in North America and spread to Eurasia,Africa,and South America.lCam
32、els went extinct in North America 10,000 years ago.lToday,we see true camels in Eurasia&Africa and camel descendents(llamas,alpacas etc)in South America.ZoogeographylGeologic change is responsible for much of the alteration in animal distribution.ZoogeographylPhylogenetic systematics allows us to re
33、construct histories of animal distributions.lGeographical distributions of closely related species are mapped onto a cladogram to generate hypotheses of the geographic history.ZoogeographylDisjunct distributions are closely related species that live in widely separated areas.lDispersal a population
34、moves to a new location.lVicariance environmental changes break up a once continuous population into small pockets.Distribution by DispersallDispersal involves emigration from one region and immigration into another.lOne way outward movement.lDifferent from a periodic movement back&forth.lActive or
35、passivelCenter of originlExplains movement of animal populations into favorable habitats adjacent to the place of origin.Distribution by VicariancelAreas once joined may become separated by barriers.lPopulation becomes fragmented into smaller,isolated populations.lLava flowslContinental driftlEmerge
36、nce of mountain rangesDistribution by VicariancelVicariance by continental drift helps to explain the disjunct distribution of ratite birds.lAncestral species widespread throughout Southern Hemisphere.Distribution by VicariancelAs the continents moved apart,the ancestral species was fragmented into
37、disjunct populations that evolved independently producing the diversity seen today.Continental DriftlThe concept of continental drift was proposed by Alfred Wegener in 1912.lNot fully accepted until the mechanism was found.Continental DriftlPlate tectonics is the mechanism of continental drift.lThe
38、earths surface is composed of 6-10 rocky plates which shift position on a more malleable underlying layer.Continental DriftlPangaea the single great landmass broke up 200 million years ago.lTwo supercontinents resulted:lLaurasia North America,Eurasia,GreenlandlGondwana South America,Africa,Madagasca
39、r,Arabia,India,Australia,New Guinea,AntarcticaContinental DriftlContinental drift explains several puzzling distributions of animals.lSimilarity between some organisms in South America and Africa.Continental Drift-The Case of Marsupial EvolutionlMarsupials appeared about 100 million years ago in Sou
40、th America.lThey spread through Antarctica and Australia that were at that time joined together.Continental Drift-The Case of Marsupial EvolutionlMarsupials encountered placental mammals in North America,could not compete,and became extinct.lThe modern opossums are recent arrivals from South America
41、.lThe placental mammals expanded into South America,but the marsupials were well established there.lAbout 50 million years ago,Australia drifted apart from Antarctica and remained in isolation with only marsupials to diversify on the continent.Wallaces LinelWallaces line represents a geographic sepa
42、ration between Asian and Australian faunas.lA collision of tectonic plates brought formerly distant land masses closer together.Temporary Land BridgeslTemporary land bridges have been important pathways for dispersal.lLand bridge connected Asia and North America across the Bering Strait.lToday,a lan
43、d bridge connects North and South AmericaClimatic Cycles and VicariancelGlacial cycles have occurred with durations of 20,000 to 100,000 years within the past three million years.lTaxa sharing the same areas typically differ greatly in evolutionary age and in phylogenetic branching pattern.Climatic Cycles and VicariancelCycling temperatures interact with the habitat requirements of animals.