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Evolution by Stages

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notes

EVOLUTION BY STAGES:-

Evolution takes place in stages.

(i) Fitness advantage:-

Evolution of eyes: evolution of complex organs is not sudden. It occurs due to minor changes in the DNA, however takes place bit by bit over generations.

-Flat worm has rudimentary eyes.

-Insects have compound eyes

-humans have binocular eyes

(ii) Functional advantage:

Evolution of feathers: Feathers provide insulation in cold weather but later they might become useful for flight.

e.g. Dinosaurs had feathers but could not fly.

Birds later adapted the feathers for flight.

 

MOLECULAR PHYLOGENY:-

Molecular phylogeny is how the molecular structures are used for gaining data or information about the evolutionary relationship of an organism.
One of the most common approaches, in this case, is how homologous genetic sequences are compared by using a sequence alignment process.

Evolution by artificial selection:-

-That idea was that changes in DNA during reproduction are the basic events in evolution
-From wild cabbage many varieties like broccoli, cauliflower, red cabbage, kale, Cabbage and kohirabi were obtained by artificial selection.

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Shaalaa.com | Heredity and evolution part 18 (Evolution by stages)

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Heredity and evolution part 18 (Evolution by stages) [00:08:42]
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