Processes of SpeciationSections
11.5 and 11.6
Genetic IsolationWhenever genetic information ceases to transfer between two populations, they
are considered isolated
Reproductive IsolationIsolation caused when members of different
populations can no longer produce offspring that can survive and reproduce.
A mule is a combination between a horse and a donkey. While they can produce offspring, the offspring are infertile.
Behavioral Isolation
They have bazaar courtship rituals that are very unique to different species
Isolation caused by the differences in courtship and mating behaviors…remember the birds of paradise.
Geographic Isolation
Isolation due to physical barriers including rivers,
oceans , and mountains…island
s are a great example
Temporal Isolation
These frog species mate at different times and may be the reason for speciation
Isolation due to the timing of
reproductive and courtship
periods…temporal is all about timing!
Patterns in Evolution
Evolution through the process of natural selection is not random. Instead, it has a direction based on environmental factors.
Its important to distinguish that this does not mean that there is intent in the process!
Convergent Evolution
Marine mammal (whales)
Swimming ability
Dorsal fin
Broad flat tail
Sleek body shape
Marine fishes
Swimming ability
Dorsal Fin
Broad flat tail
Sleek body shape
Evolution towards similar characteristics
among unrelated species due to similar
environmental conditions
Convergent evolution
Whales Sharks
Convergent evolution
Bats Birds
Divergent EvolutionWhen closely related species evolve to
become more and more different over time
Ancestral Bat
Fruit Bat
Vampire Bat
Divergent Evolution
Vampire Bat
Click HERE to see video #1
Fruit Bat
Click HERE to See video #2
Coevolution
These fish both benefit from this relationship
The evolution of two species in
response to each other
Can be both beneficial and competitive
Coevolution
Cheetah
Click HERE to watch video #1
Gazelle
Click HERE to watch video #2
Coevolution
In the case of the Gazelle and the Cheetah, both are extremely fast in order to survive.
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