Exam 3 - Ch. 3 and 14

Question 1

*What is meant by the vary phrase “Cambrian Explosion”

Answer 1

“the period of animal evolution”; remarkable pulse of rapid evolution during the Cambrian

Question 2

*What is Ediacaran fauna?

Answer 2

a group of animal species that existed between 575 and 535 million years ago; multicellular organisms that dominated the worlds oceans. some of them gave rise to living lineages of animals while others became extinct

Question 3

*Why is the Burgess Shale fauna significant?

Answer 3

(a lagerstatten) preserved fossils from the Cambrian period

Question 4

*What caused the Cambrian Explosion?

Answer 4

retreat of the glaciers and the rise of oxygen in the ocean

Question 5

*What is an adaptive radiation?

Answer 5

occurs when 1 or few members of a small group of ancestral species rapidly diversifies in large numbers or descendant species occupy many niches
Adaptive radiation: dispersal to new location (often animals) –> reduce competition and increase resources –> adaptive radiation

Question 6

*What triggers adaptive radiations?

Answer 6

ecological opportunity (increase O2 levels and predation - cambrian)
morphological innovation (jointed legs of cambrian arthropods)

Question 7

*What is stasis and what are examples?

Answer 7

no change
examples: fossil gingko, living gingko, horseshoe crabs, white tail deer
classic example: stromatolites

Question 8

*What is the difference between stasis and gradualism?

Answer 8

stasis no change - gradualism gradual change

Question 9

*Why does stasis occur?

Answer 9

no new niches to fill ??? dont really know

Question 10

*What is the relationship between adaptive radiations and mass extinction?

Answer 10

Mass extinction –> reduce competition and increase resources and open niches –> adaptive radiation

Question 11

*What are background extinctions?

Answer 11

extinctions that are not part of mass extinction events; though to be due to typical types and rates of environmental change or species interactions as opposed to the extraordinary environmental changes

Question 12

*When did the big 5 mass extinctions occur?

Answer 12

The Ordovician Event: 443 mya
The Devonian Event: 359 mya
The Permian Event: 252 mya
The Triassic Event: 200 mya
The Cretaceous Event: 65 mya

Question 13

*What is punctuated equilibrium?

Answer 13

a model of evolution that proposes that most species undergo relatively little change for most of their geologic history. these periods of stasis are punctuated by brief periods of rapid change, often associated with speciation events

Question 14

what is the worst possible outcome of global warming

Answer 14

global cooling –> snowball earth

Question 15

mass extinction

Answer 15

mass extinction is a statistically significant departure from background extinction rates that results in a substantial loss of taxonomic diversity