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Extinctions and how to change diversity 1. Sepkoski’s Curves and others. 2. How to change diversity 3. Models of div

Extinctions and how to change diversity 1. Sepkoski’s Curves and others. 2. How to change diversity 3. Models of diversity increase 4. Perturbations to the curves 5. End Permian event 6. End Cretaceous event. 1a. Sepkoski’s Curves and others. Family diversity. Time. Orders.

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Extinctions and how to change diversity 1. Sepkoski’s Curves and others. 2. How to change diversity 3. Models of div

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  1. Extinctions and how to change diversity 1.Sepkoski’s Curves and others. 2. How to change diversity 3. Models of diversity increase 4. Perturbations to the curves 5. End Permian event 6. End Cretaceous event

  2. 1a. Sepkoski’s Curves and others Family diversity Time Orders 200 100 Time Different taxonomic levels affect the shape of the curves

  3. 1b. Sepkoski’s Curves and others Marine invertebrates Vascular land plants Families Species 600 1000 400 500 200 End Ordovician End Permian End Ordovician End Permian Insects Terrestrial tetrapods Families Families 300 600 100 200 End Permian End Ordovician End Permian End Ordovician

  4. 2. How to change diversity Diversity = origination - extinction Diversity Diversity increases by a. Higher origination rates b. Lower extinction rates Diversity decreases by a. Lower origination rates b. Higher extinction rates Time Origination - Darwinian evolution. Changes of shape with time. Extinction - consequence of competition, selective or general

  5. 3. Models of diversity increase Diversity Logistic - ecosystems ‘fill’ Additive Exponential - ecosystems don’t ‘fill’ Time Additive model implausible. Implies slower rates of evolution with time. Others both have merit. Logistic curve is a good fit for marine invertebrates Exponential curve is a good fit for non-marine tetrapods. Both may be correct in some circumstances. Or just hard to tell apart in early stages (a scale effect)

  6. 4. Perturbations to the curves Mass extinctions Diversity Mass extinctions perturb system. Reset curves. Time Mass extinctions reset diversity curves. They are major events in the history of life. Fast recovery from these events may suggest a generally logistic model of diversification.

  7. 5. End Permian event Pangaea 60% families extinct 95% species extinct Marked end of Palaeozoic fauna Trilobites, rugose, tabulate corals extinct. Difficult to attribute cause May be related to odd tectonic configuration Sea level rise Reefs Fungal spike Deep marine anoxia Siberian trap eruptions Shallow marine anoxia Mid Permian Late Permian Early Triassic Terrestrial tetrapods Marine benthos ?Two extinctions

  8. 6. End Cretaceous event 30% families extinct 65% species extinct Dinosaurs, marine and flying reptiles, ammonites extinct. Two likely causes - a. Meteorite impact b. Deccan Trap volcanism

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