Evolution and Descent with Modification

• Speciation


  The process by which new species form from an ancestral species. It involves the splitting of a single ancestral lineage into two or more genetically distinct descendant lineages.
• Allopatric speciation


  When populations are separated by a geographic barrier like a mountain range or body of water, preventing gene flow between them. They evolve independently.
• Peripatric speciation


  A small peripheral population becomes isolated from the main larger population. This smaller isolated group can rapidly evolve reproductive isolation.
• Parapatric speciation


  Populations are separated by environmental gradients or habitat preferences rather than geographic barriers. Gene flow is possible but still limited.
• Sympatric speciation


  Populations become reproductively isolated while still occupying the same geographic region, often through disruptive selection or polyploidy events.
• Adaptive radiation


  The diversification of numerous species from a common ancestor to adapt to different ecological niches, like Darwin's finches.
• Role of speciation


  Speciation allows lineages to undergo "descent with modification" from common ancestors, producing the biodiversity of life seen today.
• Speciation


  The process by which new species form from an ancestral species. It involves the splitting of a single ancestral lineage into two or more genetically distinct descendant lineages.
• Speciation process


  1. Variation within a population

  2. Isolation preventing interbreeding

  3. Natural selection acts differently on isolated groups
• Allopatric speciation


  When populations are separated by a geographic barrier like a mountain range or body of water, preventing gene flow between them. They evolve independently.
• Peripatric speciation


  A small peripheral population becomes isolated from the main larger population. This smaller isolated group can rapidly evolve reproductive isolation.
• Parapatric speciation


  Populations are separated by environmental gradients or habitat preferences rather than geographic barriers. Gene flow is possible but still limited.
• Sympatric speciation


  Populations become reproductively isolated while still occupying the same geographic region, often through disruptive selection or polyploidy events.
• In what year did Charles Darwin publish On the Origin of Species

  1859
• What sparked Charles Darwin's ideas on evolution?

  His fascination with the "endless forms most beautiful" and diversity of life he observed during his voyage on the HMS Beagle.
• What was Darwin's main hypothesis?

  That Earth's many species have descended with modification from common ancestors through the process of natural selection.