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EVOLUTION (descent with modification (the Darwinian revolution (scala…

- - - - descent with modification --> diversity of life
        
        unity of life: all organisms descend from common ancestor
      - artificial selection - selective breeding caused by humans
        observation #1: members of pop vary in traits
        observation #2: all species produce more offspring than environment can support, some do not survive and reproduce
        inference #1: indivs w/ traits that increase probability of survival and reproducing leave more offspring
        inference #2: leads to more of favorable traits in pop
  - - - homologous structures - variations on structure from common ancestor, adapted for different functions
        ex. bones in arms, forelegs, flippers, wings
        homologous genes - found in very different species, can have new functions or the same
        ex. genes to code for protein synthesis
      - convergent evolution - evolution of similar traits but no common descent
        analogous features - similar function, no common ancestry
- - - - paleozoic era
        
        cambrian explosion - 535 mya, many present-day phyla first appear; larger organisms with hard bodies
        
        500 mya: colonization of land
      - mesozoic era
        
        age of reptiles
      - cenozoic era
  - - - Permian - 251 mya, b/w paleozoic and mesozoic era
        
        dramatically changed life in ocean and on land
      - Cretaceous - 65.5 mya, b/w mesozoic & cenozoic era
        
        killed all dinosaurs, 1/2 of marine species
        
        possibly caused by asteroid/comet collision
- - - - reinforcement - stronger reproductive barriers
      - fusion - weaker reproductive barriers
      - stability - continued production of hybrids
- - - - founder effect - indivs with diff allele frequencies isolated from larger pop
      - bottleneck effect - pop decreases suddenly, allele freq changes, decreases genetic diversity
      - effects of genetic drift:
        
        greatly affects small pops
        
        causes random changes in allele frequencies
        
        can lead to decreased genetic variation
        
        can cause harmful alleles to become fixed