Bio1151 Chapter 24 The Origin of Species
  1. A             species is a group of organisms whose members can interbreed in nature and produce          offspring under natural conditions.







     
     
     
     
  2. Reproductive           can prevent interbreeding and result in reproductive            .

     
     
     
     
    • Prezygotic barriers prevent the formation of          , and include          ,           ,             ,             , and          isolation.

       
       
       
       
    • Postzygotic barriers prevent the         from developing into a fertile adult, and include reduced hybrid            , reduced hybrid            , and hybrid            .


     
     
     
     
  3. Speciation can occur by             ("Other Country") speciation, or by            speciation.





     
     
     
     
    • Sympatric speciation may also result from
       
       
       
       
      • chromosomal changes such as             that leads to reproductive isolation.





         
         
         
         
      •         selection that leads to nonrandom mating.


     
     
     
     
  4. Some isolation barriers may weaken over time and result in         and allow two species to merge into one.