Vulnerability to Extinction

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Vulnerability to Extinction
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Rare species are most vulnerable to
extinctionTypes of rarity
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Restricted range
Ambystoma tigrinum stebbinsi
San Rafael Valley Arizona
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Restricted habitat type
Spartina putens
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Small populations
Mediterranean monk seal
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• Madagascar
• worlds 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.j
sp
Source USGS
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Endemism depends on isolation
14 endemic plants
80 endemic plants
What features of the landscape can lead to
isolation ? endemism?
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Vulnerability

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

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Dispersal in metapopulations
rescue effect
anti-rescue effect
spreads disease/parasites limits
adaptation synchronizes dynamics
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• 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

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Why are weedy species less likely to face high
risks of extinction?
In groups, design a organism that would be highly
resistant to extinction riskis it similar to any
organisms that you know about?
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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 Morans I to estimate
  the taxonomic autocorrelation of extinction risk

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How would this information inform conservation
decisions?
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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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