Slide Set 9 Flashcards
what are the 3 related concepts influencing why some species have very restricted distribution patterns and thus are considered to be endemic?
- failure to expand beyond place of origin
- relict populations and role of refugia
- disjunct distributions
neoendemic plant
- failure to disperse very far
- dispersal ability is limited by narrow habitat requirements, and mode of reproduction
what is the case study of tree groundsels
each mountain 2 or 3 endemic species found in east africa
- each group isolated with altitude and distance
- within each group, different ecological tolerances
- dispersal between mountains unlikely
- autochthonous neoendemic species
taxonomic relicts
sole survivors of once diverse groups
bio geographic relicts
endemic survivors of once wide spread taxa
what is the case study of tuatara?
exists on on a small island near the coast of new zealand, is cosnidered to be allochthonous endemic having originated in a location different from where it now survives
Pleistocene glaciations
repeated cycles of glaciation, interspersed with warm inter glacial periods in northern hemisphere
- shifted polar areas by 10-20 degrees
- reduced in tropics, increased grassland areas
- obvious effects on N hemisphere
describe pleiostone glaciations in SE asia
in past was normal, combination of evergreen forests, open woodland, shrubland, and grasslands when sea levels were lower
what is an example of a climatic relict
SE Asian species of termites as indicator for areas where rain forest stayed stable despite glaciation related climate change
Glacial relicts are?
cold adapted species whose distribution has been modified by the most recent glacial advances or glacial retreats
post glacial relicts
species whose current distributions were driven by climate changes since the last glacial retreat
the longer an area has been isolated the greater the number of endemic species and the _______ the taxonomic rank of its endemics
higher
what is the ratite story?
- ratites do not share a common flightless ancestor
- the putative common ancestor was a ground feeder could run well and also could fly
- dispersal led to seperate land masses preceeded flightlessness
what is wgeners theory?
alfred wagner a meterologist, proposed idea of supercontinent pangea.
- continents were a single land mass during the paleazoic era
what is some modern evidence of pangea?
- convection currents and seafloor spreading
- divergence of africa from south africa during the Jurassic period
describe ridges and trenches
submarine volcanic chains, spreading ridges, source of new oceanic crust material
- regions on either side move away from ridge
- mid atlantic ridge responsible for the formation and separation of ___________ from _________
s america from africa
ridges are ___________
interconnected
trenches are zones of _________
subduction, old material descends into the mantle and is consumed
generally ocean floor older than 180 My has been consumed in _______ trenches
subduction
transform faults
other motions of tectonic plates
- plates can rotate past each other
tectonic plates ________ continents
support
plate tectonics
continous movement, regeneration and destruction of ocean floor
______ ________ move the tectonic plates
convection currents
___________ in the mantle supplies the energy for convection currents
radioactivity
describe the cambrian period
- hard shelled marine animals
- shallow seas and bordering land masses
- warm climate
Devonian period
pre pangea
- age of fishes and freshwater species
- plants took over land
carboniferous period
another ice house
- ice cap at south pole
- equatorial coal swamps
permian and triassic periods
pangea supercontinant formed around 300 mya
- role of subduction and role of superplume
Paleocene land patterns
shallow seas and warm waters, extensive marine life, moderation of climate in centre of continents, tethys ocean, warm equitorial westward current
paleocene ocean patterns
warm water flows westward around the globe along the equator, warm winds bring moisture to the high arctic, warm currents moderate temperature of antarctic and australia
paleocene climate patterns
- Overall, global climate ~60 Mya was much warmer than today
- Warm temperate climate over most of northern hemisphere
- Cool temperate climate near the poles
oligocene ocean patterns
- Tethys Sea, and great warm equatorial current, have both disappeared
- Altered currents in the Indian Ocean and eastern Pacific
- Antarctica encircled by a cold current
oligocene climate patterns
30 mya, wide arid belts, central asia cooler and drier, increased seasonality in india , antarctica isolated and glaciated
miocene land patterns
mountain building in western in western N america blocked or deflected westerly winds
- tectonic activity has raised sea levels greater flooding of continental shelves, mediterranean
miocene oceanic patterns
- gyres well formed in both north and south atlantic and pacific oceans
- extensive areas of upwelling and downwelling to form bottom water
- reduced water flow from eastern pacific into the indian ocean
miocene climate patterns
- Cool temperate regions have expanded in northern hemisphere
- Polar regions are both cold
- Australia starts to become hotter & drier, especially in west & interior
pliocene oceanic patterns
- More extensive regions of downwelling
- Strengthening of Antarctic current
- S America approached N America – reducing that oceanic connection
