Unit 4: Mechanisms of Evolution Animations   Study Guide

Chapter 24 The Origin of Species Review
  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.
     
     
     
     
    • Chromosomal changes such as in plants, can lead to reproductive isolation and speciation.
       
       
       
       
    • selection can also result in nonrandom mating and speciation.
       
       
       
       
    • Some isolation barriers may weaken over time and result in and allow two species to merge into one. 
     
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