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Vulnerability to Extinction

Vulnerability to Extinction. Rare species are most vulnerable to extinction Types of rarity…. Restricted range. Ambystoma tigrinum stebbinsi. San Rafael Valley Arizona. Restricted habitat type. Spartina putens. Small populations. Mediterranean monk seal. Madagascar

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Vulnerability to Extinction

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  1. Vulnerability to Extinction

  2. Rare species are most vulnerable to extinctionTypes of rarity…

  3. Restricted range Ambystoma tigrinum stebbinsi San Rafael Valley Arizona

  4. Restricted habitat type Spartina putens

  5. Small populations Mediterranean monk seal

  6. Madagascar • world’s fourth largest island • more than 200,000 species of plants and animals • high proportion of endemism – isolation • 85 percent of the population is employed in some form of food production • Agricultural products account for 45 percent of the gross domestic product and nearly 80 percent of all export income • slash and burn agriculture Source : http://www.fao.org/forestry/fo/fra/maps.jsp Source: USGS

  7. Endemism depends on isolation 80% endemic plants 14% endemic plants What features of the landscape can lead to isolation  endemism?

  8. Vulnerability • Small populations • Sparse populations • Large animals • Specialized • Homogenous (genetic) • Economic importance • Dead clade walking • Low or high dispersal

  9. Dispersal in metapopulations “rescue effect” “anti-rescue effect” spreads disease/parasites limits adaptation synchronizes dynamics

  10. Littorina saxatilis (perwinkle) • Different ecotypes • Upper shore populations ridged to protect from crab predation • Lower shore smaller and smooth to protect from wave action • Low dispersal/assortative mating critical to species survival • Hadramphus spinipennis (weevil) • restricted to two outlying islands of the Chatham Islands group, New Zealand • dynamics characterized by frequent local extinctions • increased connectivity of populations following deforestation increased local extinction rates

  11. Why are weedy species less likely to face high risks of extinction? In groups, design a organism that would be highly resistant to extinction risk…is it similar to any organisms that you know about?

  12. Taxonomic distribution of extinction • Spatial autocorrelation measures the tendency of similar items to be near each other • Taxonomic autocorrelation measures the tendency of traits to be near each other on a phylogenetic tree. • Lockwood et al. 2002 use Moran’s I to estimate the taxonomic autocorrelation of extinction risk

  13. How would this information inform conservation decisions?

  14. Freshwater mussels (Phylum Mollusca, Class Bivalvia) Vulnerabilities: sensitive to pollution and sedimentation, require fish for dispersive life stage, habitat alteration, invasive molluscs Asian clam Zebra mussel

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