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Evolution Adaptive Radiation Adaptive Radiation • The speciation and adaptation of an array of species • Species show different morphological and physiological traits Galapagos Darwin’s Finches • Darwin noticed varieties of finches on the Galapagos • Kept specimens, but didn’t record which islands they came from • Back in England, recognized they were closely related, but different species • Finches evolved from an ancestor that came from mainland S.America Darwin’s Finches Convergent and Divergent Evolution Convergent • Pattern of evolution in which similar traits arise because different species have independently adapted to similar conditions Divergent • Pattern of evolution in which species that were once similar to an ancestral species diverge, or become more distinct Convergent Divergent Mass Extinctions Mass Extinctions • Large scale dying out of a large percentage of all living organisms in an area over a relatively short period of time • There have been 5 global mass extinctions The Big 5 Era Time Extinction Cause Cretaceous – Tertiary 65.5 Ma 50% of all Genera, 75% of all species Dinos killed off, mammals and bird evolved as dominant Asteroid or Comet, volcanic events TriassicJurassic 205 Ma 48% of all Genera Large amphibians, other non-dinos Dinos evolved as dominant (no competition) Small impacts, gradual climate change, massive volcanic eruptions PermianTriassic 251 Ma 83% of all Genera Many insects killed off, Archosaurs become dominant Mother of all mass extinctions Impact? Volcanism, climate change, Combination? Late Devonian 360-375 Ma 50% of all Genera Many causes, ocean anoxia, global cooling caused by ocean volcanism 57% of all Genera Many invertebrates extinct Movement of Gondwana Ordovician- 440-450 Silurian Ma Co-evolution Coevolution • The change of a species triggered by the change of a related object
