D. Coevolution E. Gradualism
Transcript of D. Coevolution E. Gradualism
Patterns of Evolution
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Patterns of Evolution:
A. Mass Extinctions
B. Adaptive RadiationC. Convergent EvolutionD. Coevolution
E. GradualismF. Punctuated Equilibrium
Patterns of Evolution
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A. Mass Extinctions:
Over the past 540 million years, life on Earth has passed through five great mass extinction's.
1. Late Ordovician
2. Late Devonian
3. EndPermian (sometimes called Permian Triassic)
4. EndTriassic
5. EndCretaceous (Cretaceous Tertiary or KT)
Patterns of Evolution
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A. Mass Extinctions:
Over the past 540 million years, life on Earth has passed through five great mass extinction's.
1. Late Ordovician
440 MYA86% of life on earth was wiped out
2. Late Devonian
365MYA 75% of species
land plants: nutrients from roots went into oceanalgae bloom lack of oxygen
volcanic ash
3. EndPermian (sometimes called Permian Triassic)
245251 MYA
96% lost
volcanic eruption?
4. EndTriassic
200214 MYA wed dinosaurs to dominate
5. EndCretaceous (Cretaceous Tertiary or KT)
65MYAextinction of dinosaurs
6. Holocene Extinction
present
caused by human activity
Patterns of Evolution
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Patterns of Evolution:
A. Mass Extinctions
B. Adaptive RadiationC. Convergent EvolutionD. Coevolution
E. GradualismF. Punctuated Equilibrium
Patterns of Evolution
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B. Adaptive Radtion (Divergent Evolution)
• The evolution of an ancestral species, which was adapted to a particular way of life, into many diverse species, each adapted to a different habitat
• Many new species diversify from a common ancestor .
• The branching out of a population through variation.
• The new species live in different ways than the original species did.
Hawaiin honeycreepers
Beak color,shape and size is different for different habitats and nutrition.
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C. Convergent Evolution:
• Opposite of divergent evolution (adaptive radiation)
• Unrelated organisms independently evolve similarities when adapting to similar environments, or ecological niches
• Analogous structures are a result of this process (same function, different species)
• Example: penguin limb/whale flipper/fish fin
• The wings of insects, birds, pterosaurs, and bats all serve the same function and are similar in structure, but each evolved independently
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D. Coevolution:
• The mutual evolutionary influence between two species
• When two species evolve in response to changes in each other
• They are closely connected to one another by ecological interactions (have a symbiotic relationship) including:> Predation: Predator/prey> Parasitism: Parasite/host > Mutualism: Plant/pollinator
• Each party exerts selective pressures on the other, thereby affecting each others' evolution
• Commensalism is not coevolution because one party is unaffected.
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E. Gradualism
• The evolution of new species by gradual accumulation of small genetic changes over long periods of time
• Emphasizing slow and steady change in an organism
• Occurs at a slow but constant rate
• Cannot see this over a short period of time.
Top: current living zebras
Bottom: extinct quaggas
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F. Punctuated Equilibrium
• Stable periods of no change (genetic equilibrium) interrupted by rapid changes involving many different lines of descent
• Opposite of gradualism
• It is rare, rapid events of branching speciation
• Characterized by long periods of virtual standstill ("equilibrium"), "punctuated" by episodes of very fast development of new forms