Biogeographical Evidence of Evolution

• The Science of Biogeography

  • Vicariance
  • Dispersal
• Dispersal

  • refers to when a population moves across a geographical barrier in order to settle in a new location.
• Vicariance

  • refers to when a barrier appears which isolates two populations of the same species that were once connected.
• Dispersal

  • Initial dispersal of a portion of the population.
  • Dispersed population starts to diverge from original population.

  A) Ancestral Population

  B) Geographic Isolation

  C) Isolation

  
• Vicariance

  • Isolation of population due to geographic barrier.

  A) Vicariance

  
• Phenomena That Shape Biogeographical Patterns

  1. Continental Drift Theory
  2. Climate and Sea Level Change
  3. Migration
  4. Geographical Barriers
  5. Center of Origin
• The Continental Drift Theory

  • Alfred Wegener proposed this theory.
  • It suggests that most of today's continents were once connected.
  • Further evidence can be seen in the fossil assemblages found in different continents.
• Climate and Sea Level Change

  • This affected the amount of land available for organisms to thrive in.
  • These patterns may have affected how species were dispersed and how they interacted with each other.
  • The dip in sea levels also meant that land bridges- a stretch of land that connected areas in times when sea levels were low- became exposed from underwater.
• Migration

  • Emigration - the movement of a population away from an area.
  • Immigration - refers to the movement of a population into an area.
• Geographical Barriers

  • these are mountains and valleys, or bodies of water like rivers and oceans.
  • It divides the organisms.
• Center of Origin

  • a geographic location where multiple species have been proven to have acquired distinct characteristics that may have led to speciation.
  • The East Indies- SEA countries -is where diversification of many marine species occurred and spread out to colonize other areas.