Lec 20: Case Study - Panama Flashcards
when was the isthmus of panama created?
3 MYA
how did tectonic events at the isthmus of panama affect climate?
topographic features (mountains, volcanoes) affect
- global climate (CO2 absorption)
- local climate (wind patterns blocked)
how did the formation of the isthmus affect ocean circulation changes?
- warm gulf stream deflected north
- increased temp difference between carribean and Pacific
- increased moisture in northern latitudes
how do we know that the isthmus formed gradually?
fossil evidence of shallow water organisms
what are the direct effects of the isthmus on biota?
land bridge as a BARRIER and CORRIDOR for dispersal
What are the ecological changes related to the isthmus as a barrier?
- pacific side is much deeper
- coral reefs on carribean plate side (more biodiversity), pacific side pelagic
- upwelling of cold water on pacific side, redistribution of nutrients
- speciation
describe the pre-link fauna in North and South America
Both continents had diverse fauna, but had different species filling similar niches, due to convergent evolution.
name some convergent mammals
- saber-toothed cats and marsupials
- camels and lipopterns
- rhinos and toxontids
who were some heralds of the north and south? When did they arrive to their respective locations?
8 Ma, during the Miocene
- sloths, S –> N
- raccoons, N –> S
what happened to legions of the north?
many became extinct in the north
which proportion of South American mammals are descnedants of North american ancestors
50%
what is vegetation like on either side of the isthmus?
- NA: grassland, desert, scrub forest
- SA: Rainforest
Why is the isthmus no longer a complete barrier? Why doesn’t fauna move across despite this?
- the panama canal connects the atlantic and pacific
- fauna dont move across because Gatun Lake is a freshwater barrier
