Historical Biogeography

Question 1

T/F
The Quaternary has been a time of biogeographic upheaval

Answer 1

true
because earth has passed through repeated cycles of glaciation

Question 2

What era, period, and epoch are we currently in?

Answer 2

era: Cenozoic
period: quaternary
epoch: Holocene
- present interglacial epoch, started 12,000 years ago

Question 3

Our current quaternary period is broken down into 2 epochs. What are they? When did each begin?

Answer 3

Pleistocene
- began 2.5mya
- glacial

Holocene (current)
- began 12,000yrs ago
- interglacial

Question 4

What are the 3 models of Change over Earth’s History

Answer 4

1. Predictable rules govern climate change: directional change, stable climate
2. Random, abrupt, catastrophic events cause climate change (eg. asteroid impacts)
3. The climate alternates between alternate stable states (eg. glacial/interglacial periods)

Question 5

List up to 8 drivers of change on earth

Answer 5

• changing solar output
• tectonic and volcanic activity
• asteroid impacts
• methane clathrate releases
• orbital patterns (Milankovitch)
• changing ocean circulation
• changing sea levels
• humans

Question 6

During the Pleistocene epoch, what were the 6 main climate forcing factors?

Answer 6

• Variation in the geometry of Earth’s orbit (Milankovitch)
• Variation in solar insolation emitted by the sun
• Plate tectonic processes: altered atmospheric and oceanic circulation and positions of continents
• Atmospheric absorptivity/reflectivity: Impact of volcanos
• Earth surface albedo (eg snow vs water vs soil vs vegetation)
• Feedback effects and interactions

Question 7

Which epoch does this describe:

Period of gradual cooling during the mid-Cenzoic, followed by period
of dramatic climatic reversals

Answer 7

Pleistocene

Question 8

During the pleistocene cooling, what was the consequence for plants and animals?

Answer 8

Regional assemblages of plants and animals that had co-evolved
during the warmth of Paleogene and Neogene were subject to
disruption and displacement

Question 9

Ice extent during the last glacial maximum occurred approx. _____-_____ years ago

Answer 9

26,500-19,000 years ago

Question 10

During the LGM, there were expansive ice sheets across much of both hemispheres. Which ice sheets remain today?

Answer 10

only greenland and antarctica

Question 11

During the LGM, the average air temperatures over land were __-__C _____(warmer/cooler) than during interglacial periods

Answer 11

4-8C cooler

Question 12

During the LGM, the ocean surface temperatures were __-__C ____ (warmer/colder) thank during interglacial periods

Answer 12

2-3C colder

Question 13

During the LGM, was it on average drier or wetter compared to interglacial?

Answer 13

drier during LGM

Question 14

generally, climatic zones shifted toward ___ ______ during glacial periods

Answer 14

the equator

Question 15

during interglacial periods, climatic zones generally shift ____

Answer 15

poleward

Question 16

the presence of ice during glacial periods also creates micro_____. Give 2 examples of these

Answer 16

microclimates

1. air masses descending ice sheets would undergo adiabatic warming; makes glacial winters less severe & glacial summers colder/ less prone to heat waves
2. some areas were wetter: eg. south of North America’s glaciers –> prevailing westerlies brought moisture from oceans = more water in American southwest lakes

Question 17

How does moisture level generally shift during glacial periods?

Answer 17

Reduced solar heating= reduced evaporative input of water into the atmosphere
regional to global aridification and expansion of deserts and other xeric ecosystems
ie DRIER

Question 18

Pluvial Lakes=

Answer 18

Formation of large lakes due to low
evaporation and high precipitation rates (in certain areas), fueled by prevailing winds carrying moisture from the ocean

Question 19

give 3 examples of pluvial lakes

Answer 19

• remnants of one formed the great salt lake in utah
• death valley was a pluvial lake basin! now desert
• mojave desert (california)

Question 20

In the deep past, were sea levels much higher or lower?

Answer 20

higher

Question 21

Glacial/ interglacial periods can be interpreted from the ___ ____ at the time

Answer 21

sea level

lower sea level= glacial period because the water is locked up in ice sheets

higher sea level= interglacial

Question 22

What are the 2 types of sea level changes? Define each

Answer 22

• Isostatic sea level changes –rising or lowering of the land surface relative to sea level
  through movement of Earth’s crust
• Eustatic sea level changes – alteration of the level of sea itself

Question 23

eustatic changes lag ____ ____ and isostatic changes lag _____ changes

Answer 23

climate warming

eustatic changes

Question 24

give an example of isostatic rebound

Answer 24

hudson bay:
was covered in ice during last ice age
- ice started to melt, releasing lots of weight from the earth, so it started to rebound (post-glacial crustal rebound)
- hudson bay will be above sea level by the time it stops isostatically rebounding!

Question 25

biogeographic dynamics of Pleistocene biotas are triggered by 3 changes:

Answer 25

1. Changes in the location, extent, and configuration of biota prime habitats 2. Changes in the nature of climatic and environmental zones 3. Formation and dissolution of dispersal routes

Question 26

Vegetation zones tended to shift toward the ____(or to ____ elevations) during glacial periods and toward the ___(or ____elevations) during inter-glacials

Answer 26

equator lower poles higher

Question 27

During the LGM, there was _____ (south/north) expansion of boreal forest and tundra deep into the North American interior and along the Appalachians

Answer 27

southward

Question 28

T/F Generally, tundra, boreal forest, scrub retreated during LGM at the expense of more closed canopies (deciduous forest, evergreen forest)

Answer 28

false expanded , not retreated it was at the expense of more closed canopies though

Question 29

in terms of elevational shifts in vegetation, what complicated the shifts in climatic zones/ biomes?

Answer 29

local micro-climates! eg. SW America was cooler & wetter at LGM, and veg zones were displaced 500-1000m below present limits

Question 30

Explain the elevational shifts in the Andes following the LGM

Answer 30

the zones shift all together, but upper zones become narrower as they shifted to higher elevations in response to global warming

Question 31

Are changes in marine enviros more or less pronounced than in terrestrial enviros? Why? Where were the most substantial shifts?

Answer 31

Less pronounced than terrestrial because of the high specific heat capacity of water * More substantial shifts at mid-latitudes

Question 32

Pleistocene glaciation lowered sea levels by __-__m below their current level

Answer 32

100-135m

Question 33

Many terrestrial regions and associated biota that are now isolated by oceanic barriers were _____during LGM. Give 2 examples

Answer 33

connected (ie land/ ice bridges) eg beringia (connected Siberia and Alaska) eg british isles and europe were connected

Question 34

what happened to sea levels as the earth came out of the LGM?

Answer 34

they rapidly rose marine waters spilled onto low-lying regions of the continents

Question 35

glacial periods allowed for _____ taxa to disperse across hemispheres. Why?

Answer 35

stenothermal = organisms that can only tolerate a small range of temperatures So, they were forced to disperse if they wanted to survive

Question 36

Mammals have been widespread across all major landmasses (except ____)until:

Answer 36

Antarctica until pleistocene and early holocene

Question 37

T/F Range shifts of mammals fit fairly simple predictions of southern/ northern movement with glaciation/ deglaciation

Answer 37

false it's much more complicated than just moving north or south

Question 38

Did communities migrate together? give examples

Answer 38

Yes! eg. collared lemmings, eastern chipmunks, gophers, etc

Question 39

As a result of individualistic differences in the extent & direction of range shifts during the Holocene, species that co-occurred during the LGM often exhibit ____ ranges today

Answer 39

disjunct

Question 40

Refugia=

Answer 40

areas to which species were displaced during glacial episodes, generally with the connotation that such refugia involved smaller, often subdivided ranges

Question 41

t/f many species that were unable to disperse with their shifting habitats persisted and even diversified in these refugia

Answer 41

true!

Question 42

What are nunataks? What are they an example of?

Answer 42

=exposed portions of ridges, mountains, or peaks not covered with ice or snow within (or at the edge of) an ice field or glacier example of refugia

Question 43

Megafaunal collapse occurred during the last stages of the _____and/or during the early ______

Answer 43

Pleistocene Holocene

Question 44

Extinctions of mammals in the late Pleistocene and early Holocene were biased; targeted the _____mammals, sparing the ____size classes

Answer 44

largest smaller

Question 45

Why were the largest vertebrates at a disadvantage under climate change (ie why were they targeted during Pleistocene extinctions?)

Answer 45

Hypothesized that fragmentation of once-expansive ecosystems required by these mega-herbivores and their predators are the cause

Question 46

T/F 1. Extinctions were not synchronous across the planet 2. Extinctions occurred during a stage when climate change was especially severe

Answer 46

1. true Megafaunal collapse occurred at different times on different continents 2. false they did not necessarily

Question 47

During the Pleistocene extinction, most of the large vertebrates in ____ were spared but disappeared across all other landmasses. Why?

Answer 47

Africa Possibly because of their co-evolution with our ancestors?

Question 48

When did humans disperse from Africa?

Answer 48

mostly during the Pleistocene

Question 49

Collapse of megafaunal assemblages was asynchronous across the planet but all began soon after the arrival of ____

Answer 49

humans

Question 50

In Africa, where ecologically significant humans first evolved, the native biota had an opportunity to ____ with humans

Answer 50

co-evolve

Question 51

Did the spread of humans lead to Pleistocene megafaunal extinctions?

Answer 51

Extinction patterns are consistent with anthropogenic history of hominids across continents

Question 52

Extinctions were: * ______severe in regions where megafauna coevolved with hominids (Africa) * ______in regions whose megafauna experienced archaic homids before being colonized by humans * _____severe in regions where H. sapiens were the first to colonize the region and encountered the ecologically naïve biota * Megafaunal extinctions appear to be _____(related/unrelated) to climate change across continents

Answer 52

* Least * Intermediate * Most * unrelated

Question 53

* _____causes have emerged as a leading hypothesis for Pleistocene megafaunal extinctions

Answer 53

anthropogenic

Question 54

biologically, as humans, we are a product of the ____ and our civilization is a more recent product of the _____

Answer 54

Pleistocene Holocene

Question 55

wherever humans have travelled, they have often been followed by a wave of ____ (particularly ___ ____) Human impacts on the biosphere may be older than commonly thought

Answer 55

extinctions large animals