Download 11.6 Patterns in Evolution

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

Sociocultural evolution wikipedia , lookup

Objections to evolution wikipedia , lookup

Hindu views on evolution wikipedia , lookup

Unilineal evolution wikipedia , lookup

Creation and evolution in public education in the United States wikipedia , lookup

Evidence of common descent wikipedia , lookup

Hologenome theory of evolution wikipedia , lookup

Speciation wikipedia , lookup

Evolution wikipedia , lookup

Creation and evolution in public education wikipedia , lookup

Coevolution wikipedia , lookup

Acceptance of evolution by religious groups wikipedia , lookup

Adaptation wikipedia , lookup

Introduction to evolution wikipedia , lookup

Theistic evolution wikipedia , lookup

Transcript
11.6 Patterns in Evolution
KEY CONCEPT
Evolution occurs in patterns.
11.6 Patterns in Evolution
Evolution through natural selection is not random.
• Natural selection can have direction.
• The effects of natural selection add up over time.
11.6 Patterns in Evolution
• Convergent evolution describes
evolution toward similar traits in
unrelated species.
11.6 Patterns in Evolution
• Divergent evolution describes evolution toward different
traits in closely related species.
kit fox
red fox
ancestor
How do convergent and divergent
evolution illustrate the directional
nature of natural selection?
11.6 Patterns in Evolution
Species can shape each other over time.
• Two or more species can evolve together through
coevolution.
– evolutionary paths become connected
– species evolve in response to changes in each other
11.6 Patterns in Evolution
• Coevolution can occur in beneficial relationships.
11.6 Patterns in Evolution
• Coevolution can occur in competitive relationships,
sometimes called evolutionary.
11.6 Patterns in Evolution
Species can become extinct.
• Extinction is the elimination of a species from Earth.
• Background extinctions occur continuously at a very low
rate.
– occur at roughly the same
rate as speciation
– usually affects a few species
in a small area
– caused by local changes in
environment
11.6 Patterns in Evolution
• Background extinctions occur continuously at a very low
rate.
– occur at roughly the same rate as speciation
– usually affects a few species in a small area
– caused by local changes in environment
11.6 Patterns in Evolution
• Mass extinctions are rare but much more intense.
– destroy many species at global level
– thought to be caused by catastrophic events
– at least five mass extinctions in last 600 million years
11.6 Patterns in Evolution
Speciation often occurs in patterns.
• A pattern of punctuated equilibrium exists in the fossil
record.
– theory proposed by Eldredge and Gould in 1972
– episodes of speciation occur suddenly in geologic
time
– followed by long periods of little evolutionary change
– revised Darwin’s idea that species arose through
gradual transformations
11.6 Patterns in Evolution
• Many species evolve from one species during adaptive
radiation.
– ancestral species diversifies into many descendent
species
– descendent species
usually adapted to
wide range of
environments