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Chapter 11


p. 236


Within a population, how many different kinds of genes are there?  Population = individuals from same species  High genetic diversity means lots of different genes 

Same species, many different genes


Mutations - random changes in genes  Migration 

 Individuals move, they

move their genes.  Bigger affect with rarer genes  

Sexual reproduction Population size  Smaller populations

more vulnerable to change

Selective breeding  Remember Botany of

Desire?


Measures number of different species in an area  Counting number of taxonomies = taxonomic richness  1.4 million species discovered 

 More discovered each

year  Probably a lot more


History  Ex – equatorial regions

not affected by glaciers in last Ice Age 

Migration  Could increase or

decrease diversity  

Size of area Human activity


How many different kinds of ecosystems are in an area? ď‚Ą Ecosystem is not a biome ď‚Ą


239


Ecosystems provide free services  Usually not directly part of the economy 

 No one pays for them or

sells them  Examples?


  

Agriculture Forestry Fishery

Depend on environment  Sustainable?  Billions of dollars at stake 


Do all species have intrinsic value?  Is human-driven extinction worse than other extinctions?  Is experiencing nature a right?  Experiences influence opinion 


242-253


Cause of 80-90% of threatened species  Even fragmented habitats cause species loss 

Causes:  Farming  Forestry  Grazing  Modification of aquatic

habitats  Conversion to urban


Deforestation  Clear-cutting  Patchwork clear-cutting  Selective removal  Replanting

Farming  Conversion of land  Overgrazing


Taking and using organisms faster than they can reproduce  Great concern in fisheries  Aguaculture (fish farming) increasing to relieve pressure 

 There are problems 


Introduced purposely or accidentally  Exotic pets that escape  Trapped in/on cargo  Use for agriculture

Invasive when they take over native wildlife


We actively try to get rid of some species  Mosquitos  Rats

Effort to eliminate predators that fed on livestock  Bears

 Mountain lions


Some species highly sensitive to change  Domino effect of changes 

 Due to

interconnectedness


Practice