Divergence – (Speciation) And Convergence
Divergence:
-The process in which populations develop
differently from a common ancestral form.
Speciation: -The end result of divergence; when
two species have slowly evolved from one.
For speciation to officially take place, the final two
populations must have changed so much that they
no longer interbreed.
Adaptive Radiation:
-The evolution of one species into many different
species.
- Example : The 14 species of finches on the
Galapagos.
- Example of Divergence:
REPTILE ANCESTOR
Speciation  Lizard
Ancestor
Alligator
Ancestor
Dinosaurs Snake Lizard Crocodiles Alligators
Speciation as well
YOUTUBE Clip:
http://www.youtube.com/watch?v=PjcFSy1KCTI
Convergence:
-Process in which two or more groups
develop and adapt to their environments so
that they become more alike in their
structures or other features. They may have
little or no phylogenetic ties.
-Note: They can never be so similar as to
allow mating and reproduction between the
two species.
Ex: Kangaroo and Deer (same facial features)
Ex: Tasmanian wolf and Timber wolf
- How could two such unrelated (Tasmanian
Wolf is a marsupial) animals come to
resemble each other so closely?
- The selective pressures on the ancestors of
both wolves may have been so similar, that
only those members with these structural
adaptations could survive. Thus, the same
kinds of traits would be favored in both
populations.
- Over time, selection tended to remove some
traits while favoring others.
There is a striking resemblance between these
two animals. This similarity occurs even
though they are not closely related in a
genetic sense.
Placental Ancestor
Pouched Ancestor
Convergence
Timber : Tasmanian
Wolf : Wolf
Other Examples :
Hedgehog
Spiny Anteater