Flashcards in Lecture 18 - Extinctions & Adaptive Radiations Deck (16):
What does the history of life reveal?
the rise and fall of major groups of organisms
What are the 3 factors that major changes can be attributed to?
1. plate tectonics/continental drift
2. mass extinctions
3. adaptive radiations
What was the formation of countries originally called?
How many times has Pangea formed?
come together and shifted apart 3 times
How many mass extinction events occurred?
How many of earth's species became extinct during these mass extinctions?
More than 50%
What was the Permian extinction?
-loss of 95% of marine species
-largest extinction ever
-caused by volcanoes
What was the Cretaceous extinction?
-loss of mammals
-probably caused by meteor (65 mya)
-loss of dinosaurs
What is evidence of a meteorite?
The Chicxulub crater off the coast of Mexico
Why could we be in the midst of the 6th mass extinction?
-more species than ever
-extinction rates are extremely high
What are 3 taxonomic issues why current species estimates are bad?
1. lumpers vs. splitters
2. different species definitions
3. hard to distinguish hybrids from distinct species
What are 5 types of reasons that explain why current species estimates are bad?
1. taxonomic issues
2. geographic biases
3. taxonomic biases
4. taxonomists are going extinct
5. difficulty of documenting extinction
What are 3 reasons why past species estimates are bad?
1. fossilization is rare
2. fossils are nearly impossible to ID to species
3. fossil record is biased
What is the fossil record bias toward?
-large, widespread organisms
When can adaptive radiations occur? (3)
1. when organisms colonize a new habitat
2. when groups go extinct
3. when key innovations evolve