Macroevolution

Macroevolution/Speciation

Speciation - when a new species arises from an ancestral species. 

  • Speciation events are accelerated with prolonged & extreme environmental pressures which lead to an accumulation of extreme descendants with modifications or a NEW SPECIES. 

Members of the SAME species can mate & produce fertile offspring

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Speciation -  creation of one species from a pre-existing species. A speciation event is proof of macroevolution. 

Artificial selection - humans select the favorable traits, notnature. 

Exs: with Wild Mustard Plants

  • Broccoli - suppression of flower development

  • Cabbage - suppression of internode length

  • Kale - enlargement of leaves

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Divergent evolution - creates new species that share a COMMON ANCESTOR. The more recent the ancestor, the more closely related the species. Proof- Homologous Structures. 

Homologous structures - are the same structures seen in different species due to a common ancestor. 

  • These same structures are used for different functions

Geographic Isolation - physical barriers that prevent members of a population from being able to meet & mate

Sexual Isolation - usually  follows georgraphic isolation, physcial seperation prevents mating, and new enviorments select for new favorable adaption, the accumulation of new favorable adaptations over thousands of years can prevent the mating and production of fertile offspring. 

  • Different mating calls, different mating times

Evolutionary Arms Race ---> Coevolution

  • Two species evolving together

Adaptive Radiation - create 3 or more new species that all share a COMMON ANCESTOR

Convergent Evolution - type for macroevolution where newly formed species closely resemble each other due to a  shared environment and or shared environmental role. But their similarities are NOT due to a shared common ancestor. 

Vestigial Structures -  Unused structures or organs, that give evidence of a common ancestor. 

Tempos of Speciation 

Gradualism -  Slow & Steady speciation events, usually due to an environment that does NOT undergo rapid change. 

Punctuated Equilibrium- speciation events that occur relatively rapidly & are followed by periods of no speciation (equilibrium) . PE is spurred on by an environment that alters frequently & rapidly.  

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Symbiotic Relationships

💀  &  +  = Prey/Predator

  +    &  -   = Parasite

  +    &  +  =  Mutualism : Birds + Flowers

  +    &  O = Commensalism: orchid + tree

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MACROEVOLUTION

  1. Artificial Selection 

   

  1. Humans select favorable traits
    1. Divergent Evolution 

   

  1. Homologous structures 
  2. Is lead to from geographic isolation  &  sexual isolation
    1. Coevolution

   

  1. “Evolutionary Arms Race”
  2. Happens or is driven by symbiotic relationships 
    1. Adaptive Radiation 

   

  1. Type of divergent where 3 or more species
    1. Convergent Evolution 

   

  1. Analogous structures