Panama

Question 1

History

Answer 1

3Ma
first complete link between the Americas since breakup of Pangea

Question 2

Results of Tectonic Events that pushed them together (3)

Answer 2

Mountains and volcanoes at plate boundaries
major topographic feature of isthmus
barrier to trans-oceanic circulation

Question 3

Ocean Circulation Changes

Answer 3

Tropical circulation of warm water is blocked
warm current deflected north –> Gulf Stream, deflects labrador current
cold current flows north on Pacific side

Question 4

Implications of circulation changes

Answer 4

Increased temperature difference between warm Caribbean and cool Pacific !!
deflection of gulf stream increases moisture in northern latitudes
factor in pleistocene glaciations

Question 5

Changes

Answer 5

island arcs at volcanic plate boundaries (~10MA)

formation of isthmus occurred gradually

Question 6

Lines of evidence for when Isthmus closed

Answer 6

look at the shallow water and the rock record

deeper water organisms would have split earlier as land rose

fossils – molecular clock
shell formations
trade winds, upwellings, nutrients

Question 7

Effects on Biological systems

Answer 7

barrier to ocean dispersal
corridor for land dispersal

Indirect: climate change, geology distribution causing species change

Question 8

Isolation of Marine Biota

Answer 8

isolation across isthmus, speciation results

divergence, selection pressures different

Question 9

Oceanic Ecological changes

Answer 9

Pacific - colder, upwelling of nutrients sometimes, deeper

Caribbean - warmer, shallower (multiple shallow plates together), not as nutrient dense (kept in the organisms instead)

production - pacific, more nutrients
construction - Caribbean (corals), calmer

Question 10

Pre-link fauna (before 3Ma)

Answer 10

both continents had diverse fauna of large and small, filling many niches in different environments

many mammals

(convergent evolution, selection pressures drive evolution in similar directions)

Question 11

Convergent mammals

Answer 11

Placentals in North (camels)
Marsupials in South (lipopterns)

establishment of isthmus allows fauna to move into the other continent. interaction + competition

Question 12

Miocene connections (heralds)

Answer 12

8 Ma
heralds - early colonizers
sloths + raccoons, both good swimmers

Question 13

Legions

Answer 13

3Ma
carnivores moved south, large cats and dogs
some became extinct during pleistocene

smaller animals moved north

Question 14

Legacy of the dinosaurs

Answer 14

Phorusrhachid birds
large flightless predators dominant in south america, dispersed to Florida

Question 15

Aftermath of the exchange

Answer 15

many SA mammals are descendants of NA mammals
major speciation since
several extinction in SA mammals
birds, reptiles, amphibians no as affected

Question 16

Human Changes + side-effects

Answer 16

Isthmus no longer a complete barrier because of panama canal

marine fauna still don’t move across because it goes through Gautan lake which is fresh water – Salinization, drought is an issue now though

increasing pressure for development of rainforest areas

Question 17

Changes in ecosystems

Answer 17

mountain building in Central America
rain shadow, elevation difference in habitat
climate changes during Pleistocene, holocene

different terrestrial boundaries, species adapted to one type of environment

species don’t occur everywhere, continents still quiet distinctive

Question 18

PRISM

Answer 18

model to predict sustainability, environment and economic changes