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12 Cards in this Set
- Front
- Back
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Rapoport's rule |
Annual climatic stability creates a latitudinal trend in species range size - latitudinal gradient in species richness is a consequence - Species can have narrow tolerances in more stable climates, leading to smaller ranges, and allowing coexistence of more species - Condition to rule: organisms that avoid seasonality are not expected to follow it or show latitudinal gradients |
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Problems with Rapoport's rule |
- whenyou use seasonal variability in climate to predict species richness there isnot a reliable relationship to be observed (species richness and climatic condition does not show a relationship) - empirical inconsistencies (bad evidence) - sampling artefact (less tropical sampling= small ranges... might have no looks hard/far enough) |
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Conclusion on Rapoport's rule |
It exists but is not universal and does not explain latitudinal diversity |
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Glacial retreat |
- Recovery of species after glaciation - Richness recovered quickly - Footprints of glaciations fade quickly in terms of species number but not species composition |
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Refugia |
Pocket population that survives through unfavourable conditions (ex. glaciation) |
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Species richness |
- Energy explain variability in species richness - Heat interacts with water and appears to generate global patterns of plant diversity - Habitat heterogeneity- increase habitat variation - Climate (energy and water) provide best explanation for species richness |
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Extinction risk |
1. Small population size (endangered species in small populations will go extinct) 2. Small range size (substantial environment disturbances) 3. Low population density or size/ low carrying capacity/ high trophic level/ large body size (species are susceptible to substantial alterations in biotic conditions- fitness may drop quickly) |
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Mass extinctions |
- redirect evolution down pathway defined by diversity of survivors - bolide impact (big pieces of space debris) - volcanism (extended periods of acid rain and climate warming) |
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Post- glacial extinctions common because: |
- Overkill hypothesis - Climate change hypothesis |
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Loss of evolutionary history |
- 79% of evolutionary history remains - potential to rebound from mass extinctions remains |
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Random extinctions |
- more threatened than expected - higher taxonomic levels more rarely disappear |
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Massive ecological problems |
- climate change - 6th mass extinction - invasive species - emerging pathogens - ozone depletion - loss of ecosystem services |
