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58 Cards in this Set
- Front
- Back
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Extinction is the _______ of all ________. |
Fate of all Species |
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Does extinction occur when anagenesis occurs? |
Yes; the ancestral form still disappears. |
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Is extinction common? |
Yes |
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Is extinction well documented in the fossil record? |
Yes |
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What did Cuvier's study of fossils confirm? |
Many fossils came from animals that no longer existed, so extinction is clearly real. |
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What did the fossil record show about speed of extinction? |
It showed that species are disappearing at low levels all the time. |
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Is the extinction of clades random or are some clades prone to persistence? Ex: If a clade has made it through a past challenge is it more likely to survive future challenges than new clades are? |
Past performance does not appear to predict future results. If this theory had been true then there would be a steep drop near 0 showing that new clades die quickly and then a flatter right side of the graph showing that once you survive to a certain age you are more likely to keep surviving. We see a straight line showing that clade age has no effect on probability of extinction. |
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Are some life history characteristics correlated with long survival? |
Mollusks with planktonic development of larvae persist longer than those without. Why? 1. Broad dispersal to seed in new habitats (insurance against local catastrophe). 2. Large overall population sizes 3. More general habitat requirements |
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Mass Extinction |
A statistically significant increase above the background extinction rate. |
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What are 3 characteristics of a Mass Extinction? |
1. Global in extent 2. Involves a broad range of organisms 3. Rapid effect relative to expected taxa lifespans |
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How many mass extinctions have their been so far? |
5 |
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There is a general incline/decline of extinction rate over time. |
Decline |
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Why would extinction rate be declining? |
Selection on lineages with high extinction rates go extinct, but then are not replaced with lineages with high extinction rates, so the average lineage is getting more persistent over time. |
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Biota |
The animal and plant life of a particular region, habitat, or geological period. |
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Possible Causes of the Ordovician Extinction |
Glacial/interglacial episodes Uplift and weathering of Appalachians affecting atmosphere and ocean chemistry Less CO2 lowered average global temperatures (ice age) |
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Possible Causes of the Devonian Extinction |
Global cooling followed by warming because of diversification of land plants changing the environment and causing a fall in CO2. Less oxygen in water. Maybe an asteroid? |
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Possible Causes of the Permian Extinction |
Volcano Global Warming Too little oxygen in deep water Too much hydrogen sulfide and CO2 for marine and terrestrial realms. Ocean acidification. |
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Possible Causes of the Triassic Extinction |
Elevated CO2 levels increases global temperatures and leading to calcification crisis in oceans. |
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Possible Causes of the Cretaceous Extinction |
Impact in the Yucatan resulting in global cataclysm that caused rapid cooling. Volcano releasing CO2 leading to warming, tectonic uplift changing biogeography, and accelerating erosion harming the oceans also were probably happening before the impact. |
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What can mass extinction result from? |
Climate change! |
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How did climate change cause the Devonian extinction? |
Large forests drove greenhouse gases down = global cooling |
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How does moving of continents effect climate? |
Large landmasses can have extreme temperature fluctuations. |
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How do todays extinction rates compare to fossil record and to future rates. |
Todays rates are 1000 times higher than fossil record and future rates are predicted to be 10 times higher than current rates. |
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Why can we not totally trust todays evolution rate comparison? |
Fossil data is best for mollusks, while present data is best for birds and mammals, so the extinction rates do not totally align. |
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Current threats to threatened or endangered species: (4) |
1. Habitat loss 2. Overexploitation 3. Invasive species/pathogens also climate change's broad effects. |
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Coevolution |
Reciprocal evolutionary change between interacting species, driven by natural selection. |
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How are interactions between animals classified? |
By impact of one species on the other's fitness/population density. |
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Example of +/+ Relationship |
Zebra and its gut bacteria. |
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Example of +/- Relationship |
Lion and zebra. |
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When interactions between species are strong enough they... |
create selection pressure on each party. |
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What is the incentive behind +/- interactions? |
+/- interactions give one species incentive to strengthen the interaction at the other's expense. This is antagonistic coevolution. |
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Antagonistic coevolution is... |
+/- coevolution; the red queen hypothesis. |
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What can antagonistic coevolution lead to? |
Extreme specialization. |
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Example of Extreme Specialization |
Some garter snakes can eat newts that would kill any other predator. |
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Strength of interaction often varies a great deal ________. This creates a ________ _______. |
spatially; geographic mosaic
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3 Examples of things that can Weaken +/- coevolution: |
1. If predator has alternate prey 2. If prey has refuge from predator 3. If the costs of the coevolution are large (expensive toxin, resistance, etc.) |
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What can provide fuel to coevolution? |
Gene flow from hotspots can provide variation to fuel coevolution in other places. |
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Geographic Mosaic |
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Coevolution in Predator/Prey Interactions: What kind of selection occurs? |
Reciprocal Selection |
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Coevolution in Predator/Prey Interactions: How is the fitness of the victim individuals increased? |
By not interacting with the exploiter. |
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Coevolution in Predator/Prey Interactions: How is the fitness of the exploiter individuals increased? |
By interacting with the victim. |
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Coevolution in Predator/Prey Interactions: What does reciprocal selection favor? |
Victim traits that decrease the efficacy or frequency of interaction, but exploiter traits that increase the efficacy or frequency of the interaction. |
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Coevolution in Predator/Prey Interactions: Phenotype Graph |
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A Mutualistic Relationship is a _ / _ relationship. |
+ / + |
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An obligate mutualist relationship is the result of... |
extreme specialization. |
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Fig and Wasp Mutualism Example |
Fig flowers develop within the fruit. Wild figs are all pollinated by wasps that parasitize flowers. Female wasps hatch, collect pollen from unparasitized flowers, and eventually pollinate and lay their eggs in another fruit. The wasps only reproduce in figs, and figs are only pollinated by these wasps. Without one, the other party would go extinct. |
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In a mutualist relationship, each party has incentive to ___________ the relationship. This can lead to _______ _________. |
strengthen; extreme specialization |
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Why not cheat in a mutualistic relationship? |
Cooperation is maintained as an ESS because it benefits each individual wasp and fig to do so. |
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__________ is critical to the stability of cooperative behavior. |
Enforcement |
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Enforcement in the Wasp/Fig Relationship |
Wasps could stop visiting figs (pollinating them) if the figs are not providing protective galls for the larvae. Figs could drop fruit if wasps don't take or deliver pollen and just drop off their eggs. |
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Mutualism Mosaic |
Geographic mosaics also occur with mutualistic interactions. |
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Mutualistic Mosaic Example |
Fly proboscis lengths vary with flower depths across sites. When the interaction is strong, fly has incentive for long proboscis to gain access to all flowers. Flower has incentive for long tube to force fly to brush anthers and get pollen on them. There is a trade off for the fly though since a long proboscis is expensive and hard to maneuver. Result: flowers make tubes no longer than necessary and flies match this tube length to get pollen but not overexert themselves. |
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Pattern of Character Displacement |
Two species are more similar when they occur in different locations rather than in the same locations. |
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Why do distinct phenotypes arise when species are in the same location? |
Selection to avoid competition pushes phenotypes apart. |
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What kind of interaction is competition and what does this mean each party wants to do? |
-/- interaction, so each party has incentive to weaken the interaction. |
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Alternate Explanation for Character Displacement Pattern |
Lack of genetic variation, different seeds available, etc. (?) |
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Process of Character Displacement = |
Competing species with a big overlap in phenotype evolve more distinct phenotypes when you but them in the same location. |
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Testing Character Displacement |
Take three kinds of finches and have them interact for a couple generations. Some beaks get smaller and some get bigger = character displacement. |
