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Speciation
This is the formation of new species.
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Allopatric speciation
- - New species are formed by reproductive isolation ( meaning you can only make an off spring with it’s
- opulqtion)
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Forms of reproductive isolation
- - biochemistry- sperm not compatible with egg
- - the physical hardware does not match up
- - behavioural ( specific courtships )
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3 step process of Allopatric speculation
- - physical barrier - that separates singe populations.
- - Natural selections work on the separated groups independently
- - over the time changes are so great that they are unable to be sexually compatible
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what are the rates of evolution?
- - theory of gradualism
- theory of punctuated equilibrium
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Theory of Gradualism
- - speciation takes place at a slow rate, at a steady pace with transition species.
- - the fossil records are supporting this theory
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Theory of punctuated equilibrium
- - speciation can appear abruptly
- Like 100,000 years and then little change is seen over a long period of time
- - getting the best version of the organism first try randomly and does not alter its form.
- - no transitional fossils
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Punctuated equilibrium assertions
- - they evolve rapidly in evolutionary time
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- - it occurs in small isolated populations so a fossil record would be rare
- - they do not change significantly for a long period of time
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Divergent evolution
- - this is the evolution of one species into many different species by developing different traits.
- - leads to homologs structures
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Convergent evolution
- - this is the process by which organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.
- - leads to Analogous structures
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