Gradualism suggests that change is gradual with the accumulation of unique morphological adaptation....
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Transcript of Gradualism suggests that change is gradual with the accumulation of unique morphological adaptation....
Gradualism suggests that change is gradual with the accumulation of unique morphological adaptation.
Punctuated Equilibrium suggests that rapid change occurs, with a new species “erupting” from the ancestral lineage and then staying the same
thereafter.
Gra
du
alis
m The evolution of new species by gradual accumulation
of small genetic changes over long periods of time
Slow and steady change in an organism
Over a short period of time it is hard to notice
Gra
du
alis
m Current living zebras (top), extinct quaggas (bottom)
Gra
du
alis
m
Gra
du
alis
m
Pu
nct
uat
ed E
qu
ilib
riu
m Stable periods of no change (genetic equilibrium)
interrupted by rapid changes involving many different lines of descent
Rare, rapid events of branching speciation
Pu
nct
uat
ed E
qu
ilib
riu
m Horseshoe crabs have changed little
since their first appearance in the fossil record.
They are in a state of equilibrium
Pu
nct
uat
ed E
qu
ilib
riu
m
Pu
nct
uat
ed E
qu
ilib
riu
m
Pu
nct
uat
ed E
qu
ilib
riu
m
Gra
du
alis
m
vs
Pu
nct
uat
ed
Similar to gradualism
Similar to punctuated evolution