7226079
Description
Flashcards by Shareef Akbari, updated more than 1 year ago
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Created by Shareef Akbari
over 7 years ago
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| Question | Answer |
| As you go down in the taxon hierarchy, is it easier or harder for each taxon to go extinct? Why? | As you go down, it is easier to become extinct, simply because there are less organisms in each taxon as you go down the hierarchy. |
| How do taxon survival times change as you go down a taxon? | it is takes 10^3 times less time for a taxon to go extinct than the one above it (i.e. Genus can last 10^3 times longer than a species) |
| What is Darwin's reason for extinction? | Environmental changes occur, and species were not adapted to the new environment. Therefore, they die (bad genes) |
| What are the characteristics that increase extinction risk and which is the most important? | 1. Small population size (most important) 2. Small range size 3. Small population density 4. low carrying capacity 5. high trophic level 6. increased body size |
| What is population shochasticity? | Random fluctuations in population |
| What is the equation for the probability of extinction? | |
| What is the equation for the probability of extinction when birth and death rate are the same? What is its significance? | Because the denominator will always be bigger than the numerator, the number will always be less than 1, and so as population size rises, the probability of extinction will decrease exponentially |
| Is there still a risk of extinction at very very high population sizes? Why (not)? | Yes, because of population stochasticity |
| What is the relationship between population range and the probability of extinction? Why? | They are inversely proportional. It is much easier to kill all individuals in a population if they are all in the same place. Environmental stochasticity has a greater effect on population numbers. |
| How many mass extinctions have there been? Which was the worst? | 5 Late permian |
| What proportion of families and species were lost during the Late Permian mass extinction? | Families: 82% Species: 95% |
| What is the effect of mass extinctions on the course of evolution? | Can alter the course of evolution depending on what organisms are left after the extinction, as whatever will come after will stem from these organisms. |
| What are the two possible causes of the Late Permian mass extinction and define them? | 1. Bolide impact: something from space hitting the earth. 2. Volcanic activity |
| What are the results of massive volcanic activity? | Global atmospheric changes Water acidification Increase in the amount of sulphur dioxide in the atmosphere, which decreases temperature by reflecting sunlight back into space and acidifies water. |
| What evidence is there for a bolide impact causing the Late Permian mass extinction? | The iridium anomaly: There is a much higher amount of iridium in the part of the geological record that corresponds to the late Permian than is normally present in the earth. Indicates that something from outside the earth may have contributed to this, maybe a bolide impact. |
| What are the potential reasons for the extinction of large mammals after recent ice ages? Which one contributed more and how do we know this?? | Climate change Overkill: Contributed more because extinctions only occurred when humans arrived and there were no plant extinctions, just mammals. May have hunted them to extinction. |
| What is the equation for the relationship between species loss and loss of evolutionary history? What are the assumptions we have to make for this equation to be correct? |
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