What are the two causes of extinction and what do they lead to?
Biotic (competition with other species) and abiotic. Both lead to inability to adapt to changing environments.
What two things does extinction depend on?
How fast the change occurs Whether there's genetic variation to help the species adapt.
What are the two possibilities for measuring the rate of extinction? Which is correct?
Older lineages have a slower rate of extinction (curved line) Age independent (straight line)
Age independent is correct.
What percentage of all extinctions are background extinctions?
96%. The other 4% are mass extinctions.
What are the basic characteristics of background extinctions?
Slope is linear and age independent risk of extinction. Natural selection cannot predict environmental changes/extinction rates. Rate of extinction varies across species groups. Species with smaller home range have a higher risk
Let's say we have two species of gastropods. One has planktonic development and the other has direct development. Which has the higher risk of extinction?
Direct development has a much higher risk. Smaller geographical range.
What are the main characteristics of mass extinctions?
Huge impact High extinction rates Global effect Very rapid
What caused the Permian-Triassic extinction?
Decline in O2 levels and increase in CO2 levels. Primarily due to volcanic activity.
What directly caused the K-T extinction? What proof do we have?
Huge meteor (10 km in diameter) off Yucatan peninsula. High levels of iridium (only found in outer space objects) and shocked quartz (only found due to high impact)
What effects did the cause of the K-T extinction have?
Lots of acid rain. Massive tidal waves. Earthquakes. Volcanoes. Fires. Darkness because of dust cloud for 1 year. Temperature changes. Decalcification of shells of oceanic animals.
What are the biological changes because of mass extinctions?
Sudden extinction of many taxa New adaptive radiations Slow recovery (5-10 million years) with low diversity at first.
____ hotspots with _____ % of the land have ____% of all vascular plants and ____% of all vertebrate species nowadays.
25 hotspots. 1.4% 44% 35%
What are the main causes of contemporary extinctions?
Climate change/pollution Invasive species Habitat deforestation/fragmentation Hunting/overhavesting
How many species risk of extinction increases if temperature increases by 1 degree C? By 3 degrees C?
1 degree C: 25-30% all species. 3 degrees C: 40$ of all species.
Name two examples of invasive species and what they do.
Zebra mussels - come in on hulls of ships to Great Lakes and spread. Attack all sorts of species. Kudzu - engulfs all vegetation around it.
Half of all endangered species are endangered because of ______.
Why is habitat deforestation and fragmentation a problem?
Limits ability to move around Results in isolation
What is the difference between mass extinctions and contemporary extinctions concerning: Threat?
Mass: Extrinsic Contemporary: Intrinsic.
What is the difference between mass extinctions and contemporary extinctions concerning: Scale?
Mass: Global Contemporary: Relatively patchy
What is the difference between mass extinctions and contemporary extinctions concerning: Speed?
Mass: Fast (wipe out major lineages) Contemporary: Slower to develop
What is the difference between mass extinctions and contemporary extinctions concerning: Impact?
Mass: Broad. Contemporary: More due to loss of declining lineages...
What is the difference between mass extinctions and contemporary extinctions concerning: Recovery?
Mass: 5-10 million years. Contemporary: ???? Depends on human activity.
Contemporary extinctions are ____ to _____ times higher than normal background extinctions.
100-1000 times higher.
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