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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????