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ThedeephistoryoftheSouthwest
• Whichgeologicaleventshaveshapedthisregion?
• Howhasthefloraandfaunachangedover8me?
Biomes:ecosystemsoflargegeographicareasthataredeterminedbyclima8cfactorssuchas
temperatureandprecipita8on.
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Classified in terms of vegetation.
Biomes
Clima8cfactorssuchastemperatureandprecipita8onaredeterminedbyla8tudeandeleva8on.Some8mesalsoaffectedbywindandfire.
Altitudinal climatic changes
Al8tudinalBiodiversityGradient
La8tudinalclima8cchanges La8tudinalBiodiversityGradient
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Examples
Ants
Mammals Fishes
NotBees!
La8tudinalgradient:someexplana8ons
• Climatestabilityhigherintropics• Netprimaryproduc8vity(photosynthesis)ishigherinthetropics.
• Spa8al/areahypothesis:thetropicsarethelargestbiome.
• Bio8cinterac8onshypothesis:Strongerinterac8onsintropicspromotehigherpar88onofresources.
La8tudinalclima8cchanges
BiomesinNorthAmerica Biomesofthesouthwest
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Biomes:Tundra
• Thehighesteleva8onbiome.
• SanFranciscopeaks(12,600feet)
• Extremelycoldwinters,waterheldasice,highwinds)
• Ground-huggingwoodyshrubs.
• Notrees,noannuals.• Lowspeciesdiversity
VertebratesinTundra• Pika
Least chipmunk
Yellow-bellied marmot
Montane shrew(white-tailed ptarmigan)
Biomes:Coniferousforest• Coldandwetforests.• Dominatedbycone-bearingtrees.
Subalpineconiferforest
• Fromabove7,200feetto8mberline(11,000f.).
• 25tomorethan39in.ofprecipita8on.Muchofthisprecipita8onfallsassnow.
(Engelman spruce)
Corkbark fir
Lepus americanus (Snowshoe hare)
Blue grouse Sapsucker
Woodpecker
LekkingBehavior• Sites where males display to the females. • The purpose of the display is to attract females and defend
territories. • The males whose display is most attractive to the female, will get
to mate with her.
http://www.youtube.com/watch?v=LcnnkyGidzo
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Cold-temperateconiferforests• Between6,900and
7,950^.• Mixedconiferseries:
Douglasfir,Whitefir,Limberpine,andaspen.
• Ponderosapineforest
Pseudosuga menziesii (Douglas fir)
Pinus flexilis (Limber Pine)
Abies concolor (White fir)
Pinus ponderosa
Populus tremuloides (Aspen)
IncreaseinDiversity• Bats:Southwesternmyo6s,Long-
earedMyo6s,Long-leggedMyo6s,Bigbrownbat.
• Shrews:Vagrant,dwarf,Merriam.• Chipmunks:Colorado,Gray-collared,
Grayfooted,Uinta.• Voles:Montane,Long-tailed,
Mexican.• CoFontails:Eastern,NuFal’s.• Squirrels:Goldenmantled,Tassel-
eared.• Porcupine.• White-taileddeer,Muledeer.• RockyMountainelk• Merriamelk,GrayWolf(gone)• Skinks:Southern,many-lined,
Westernslink.• WesternraFlesnake,Twin-spoFed
raFlesnake.
• Owls:Flammulated,Pygmy,SpoFed,Saw-whet.
• Warblers:Yellow-rumped,Grace’s,Red-faced.
• Goshawk• Broad-tailedhummingbird.• Westernandpineflycatchers.• Stellerjay• Browncreeper.• WesternTanager.• Warblingvireo,Solitaryvireo.• Eveninggrosbeak.• Wildturkeys.• Aztecthrush.• Tigersalamander.• Lizards:Short-horned,Strippedplateau,
Bunchgrass,andArizonaalligator.• Gophersnake.• Sonoranmountainkingsnake
Biomes:Woodland• Mildwinters,wetsummers.
• AlligatorBarkJunipers,andPines(5400-7200f).
• Evergreenoaks(4500-5400f).
Elaphe triaspis (green rat snake)
Lampropeltis pyromelana(Mountain Kingsnake)
Sceloporus virgatus (Striped plateau lizard)
Phrynosoma ditmarsi, (Ditmar’s Horned Lizard)
Eumeces callicephallus (Mountain skink)
Crotalus lepidus(Rock rattlesnake)
C. pricei (Twin-spotted rattlesnake)
Thamnophis eques (Mexican garter snake)
Chaparral• 3,150-6,000f.• Shrubsthathavedense,
compactcrownsandsmallevergreensclerophyllousleaves.
• Mostplantspecieshaveextensiverootsystemsandregeneratea^erburning.
Biomes:Grassland• 3,300-4,200f,9mmto18
in.ofrain.• Warm,humidsummers
(moderaterain)andcold,drywinters.
• Grassisthedominantlifeform.
• Alsoannuals,scrubs,andgeophytes.
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Desert
• Extremearidity.
Biomes:Thornscrub• Intermediatebetween
desertandtropicalforestbiomes.
• 12-20in.ofrain,mostfallsbetweenJulyandSeptember.
• Shorttrees,shrubs,andcac8.
• Soilshaveo^enlowdrainage.
Biomes:Tropicaldryforest
• Determined by the absence of freezing temperatures.
• Dry season that can last up to 8 months.
• It supports a high diversity of animals and plants.
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Bursera speciesThehistoryofEarth
• Earthisabout4.5billionyearsold(basedonabsoluteda8ngofEarthandmeteoriterocks).
• The arrangement of seas and continents has changed enormously because of plate tectonics.
Platetectonics• TheEarthhasmany
layers.• It has an iron-nickel core with a temperature of 13,000 degrees F,
• a mantle,• and the crust.
• Theearth’slithosphereconsistsofplatesabout100kmthick.
• Twokindsofplates:Con8nentalandOceanicplates.
• Theplatesdri^allovertheglobe.Some8mestheyseparatefromoneanother,orcollide,slippastoneanother,orsliplaterally.
Platemovement• Whenathin,oceanicplatecollides
withathickcon8nentalplate,theoceanicplateisforcedunderthecon8nentalplate;thisphenomenoniscalledsubduc8on.
• Whentwocon8nentalplatescollide,mountainrangesarecreatedasthecollidingcrustiscompressedandpushedupwards.
• Whentwoplatesmovesidewaysagainsteachotherthereisatremendousamountoffric8onwhichmakesthemovementjerky.Whenthepressureisreleasedsuddenly,andtheplatessuddenlyjerkapart,thisisan earthquake.
earthquake
Subduc8on
Rocky Mountainshttp://www.youtube.com/watch?v=0mWQs1_L3fA
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Platemovements• 200-240millionyearsago
(Triassicperiod)allofthepresent-daycon8nentscombinedtoformasupercon8nentcalledPangaea.
• TheclimatewashotandhumidalthoughtherewereglaciersinsouthernPangaea.
• Theworldhadexperiencedamajormassex8nc8on.
• InthelateTriassicAfricaandAsiastartedtoseparate
140 million years ago (Early Cretaceous; Beginning of diversification of flowering plants)
150 million years ago(Jurassic; radiation of dinosaurs)
65 million years ago (Late Cretaceous; mass extinction, end of dinosaurs, mammals begin radiation ) Today
• SantaRitamountains,southernArizona,UpperCretaceousrockshaveremainsofthecarnivorousdinosaurGorgosaurus.
Araucaria trees
54.9-36.6millionyearsago(Eocene)• Aperiodofglobalwarming.
Temperaturesofar6coceansatleast15degreeshigherthantoday.
• Almostnola6tudinalstra6fica6onofvegeta6on.
• BytheendoftheEocene,deciduoustreesbecomeincreasinglyabundantacrossNorthAmerica,thefirstindica6onofdryseasons.
• Noevidenceforaregionaldesertclimateinthesouthwestyet.
Fossil sycamore leaf
36-6to23.7mya(Oligocene)
• BythemiddleOligoceneaseriesofenormousvolcanicerup6onsgaveanotherupli_totheRockymountainsandtheSierramadreoccidental.
• Changeofmarinecurrents.
• Coolertemperatures.
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BasinandrangetopographyHeating from below (30 mya)
Volcanism (25 mya)
Basin and range faulting (12-6 mya)
Today- basins filled with sand, and clay
Basin and range disturbance
Basin and range province 23.7to5.3mya(Miocene)• Asclimatechangedand
mountainswereli^ed,themodernNorthAmericanbiomesareestablished.
• Clima8cla8tudinalgradientsareestablished.
• Increasingtrendsinaridity.
15-8mya(middleMiocene)
• Forma8onoftheSonoranDesertandotherNorthAmericanDeserts.
15-5mya(lateMiocene)
• Forma8onoftheBajaCaliforniaPeninsula
West coast of Mexico
GeologicTimeScale
1.8mya(Pleistocene)
• TheEarthenteredanewclima8ceracharacterizedbyglacialandinterglacialperiods.
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Glacia8onsandtheSouthwest
• PlantremainsinfossilPackratmiddensdocumentanexpansionofwoodlandtreesandshrubsintoareasthathadbeendesert.
Neotoma sp. (Packrat)
Hola!
“garbage pile”
Fossilpackratmiddens• Packratshaveanaffinityfor
collec8ngtrinkets(piecesofplants,bones,socks).
• Theyproduceaveryviscousurinewhichtheyusetomarkitsterritoryandnest.
• Whenurinecrystallizesitactsasglue,holdingallthegarbagetogether.
• Debrisheldinmiddenbecomemummifiedandpreservedasfossils.
Yuccabrevifolia
Pinus monophylla
Quercus turbinellaJuniperus spp.
11,000years-today(Holocene)
• Presentinterglacialperiod.• Two-thirdsofthelargemammalsofNorthAmericawentex8nct.
For the last 20 MY, until 11,000 years ago, North America was teeming with wildlife. AMERICAN MASTODON
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SABER-TOOTHED CAT
CAMEL (evolved in North America!) DIRE WOLF
GIANT SLOTH HORSE (evolved in North America!)
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SomenowpersistinCentralorSAmerica
Smaller animals survived
Humans invade the New World
The Clovis people
The“overkill”ofnaïveanimalshypothesis.
Animals had not had any experience with humans before
Evidencefortheoverkillhypothesis
• Soona^erhumansreachedAustraliaandNewGuinea40,000yearsago,themegafaunawentex8nctthere.
• Humancoloniza8onofNewZealand,MadagascarandHawaiiallresultedinex8nc8onofbiganimals.
• Intheabsenceofhumans,biganimalsremaintame.
Butwhyaretheres8llbigmammalsinAfrica?
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Quaternaryex8nc8onofmammals
• The“overkill”ofnaïveanimalshypothesis.
• Theclimatechangehypothesis.
• Extraterrestrialeventcausedclimatechange,theYoungerDryas(dryandcold).CausedbytheimpactofaseriesofcometsinNA
• ✔The“overkill”ofnaïveanimalshypothesis.
• Theclimatechangehypothesis.
• ETcause????