w9 by nicole

8/7/2019 W9 by Nicole

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CLIMATE CHANGE:

Global temperatures over the last 65 Myr. Indicate that we are currently in arelatively “cool period”

• Quarternary climate cycles are natural experiments• Late Pleistocene climate change

o Pleistocene glaciation ~18,000 years agoo “younger dryas and bolling allerod”

o “Medieval warming” occurred ~800-110 years ago• FUTURE WARMING:



o Decreasing the pika population size causes a decrease in genetic

variation, few individuals cannot maintain the same level of geneticdiversity

Easier to lose than to gain genetic diversity (mutation takessome time to accumulate)

• Red squirrels are giving birth earlier in response to more food availability atthat time (just before a species expands its range)

• Species can show a decrease in body size in response to warmingo In CA, the Mediterranean climate can be difficult

Ground squirrels are more affected by precipitation than bytemperature (larger due to increased precip. in norcal)

The CA situation (in which temperature and precipitation arenot correlated allows for interesting study design)

o Increaing glaciers are not due to colder temperatures, but ratherincreased precip.

• Body size of the pack rat decreases with increasing temperature• Many species expand poleward (in some cases equatorial contraction)

o Gross majority of species are moving north with decreasing glaciationo Mountain beaver (last species in the genus) is restricted to coastal Pac.

Northwest Douglas fir forestso Nine-banded armadillo is limited by the # of freeze days (max=2

weeks), moving north as climate warmso Dormouse is not able to remain in hibernation because it is awoken

due to warmth, dies because it doesn't have enough resources tosustain the hibernation if it wakes

o Ecological niche modeling: determining what the range of species willbe

o Range contraction of the flying squirrel as a result of the forest die-off (pine beetle is limited by freezing days, so during warm times it eatsmore pine)



o Future contraction of the grizzly bear is may also be related to tree die-off since the mothers must accumulate fat from pine cones beforehibernation; conifer presence is a source of carbs

o Due to range expansion, grizzly bears are now encountering polarbears pizzly bears

• Great American Biotic Interchangeo Tectonic movement caused uplift of the Panamanian isthmus causing

N. American species to move south and S. American species to movenorth

o N. American species that went south were more successful than the S.American species that went north

Most originally s. American species went extinct• We are currently facilitating global invasion

o 71% of Patagonia species came from the Great American BioticInterchange

o 15% from endemic mammalian specieso 19% due to anthropogenic causes

• Human expansion:o Genetic evidence indicates that there was coastal colonization from

north to south from Asiao Ice-free corridor east of the Rocky Mountains may have been another

way that humans colonized• Pleistocene-Holocene Transition:



o We replaced many of the larger animals, cause of extinction Most of the extinctions occurred at the bimodal peak for

mammal body size; most were mammals, herbivores We caused dramatic changes in geographic range of plants and

animalso

CA condor had a large range/distribution, present along the coast,scavenges for preyo The extinction event occurred earlier in Australia than in N. America

• 2008-1/4 of all mammal species are threatenedo Extinction can happen quickly, while speciation cannot (the average

mammalian species takes 2-5 myr to evolve)

o Warming also caused changes to mammalian ecosystem rise of C4grasses (which do better in arid conditions)

Led to decrease in mammalian browsers and increase inmammalian grazers

w9 by nicole

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