Discuss what Darwin observed during his voyage on the Beagle. How did those observations lead to his theory about common descent with modification

While on his voyage on the Beagle,while in Galapagos Island he observed  that Finches(birds) across the island are similar but different in the structure of their beaks. This mystified him and he puzzled on thus on why there were differences in the beaks shapes.

He therefore postulated from the observation that  beak shapes  of these birds must be responsible for  the adaptation to their habitats.Thus these birds must have come from common ancestors,(and the need to survive by adaptations to different environments is responsible for the beak shapes). The driving force  for these phenomena  is Natural selection.Therefore,where the size of beaks is the needed adaptation for survival,birds with larger sizes will be selected over those with smaller beaks for eating Feeds(selection pressure) and therefore will be  better adapted  and naturally selected  than smaller birds.

Darwin predicted that the dormant traits(large beaks) will remain in the population as the parents pass these to their offspring from generation to generation,while the  population smaller beaks which could not resist the selection pressure will fizzled  out.

Thus the better adapted larger beak population will dominate and evolved after a long period of time.Thus all organisms with adaptations and naturally selected on earth must have evolved from a common ancestor.

Although Darwin proposed these,he lacks knowledge of genetics,therefore he could not explain  how dominant traits for adaptation are inherited from one generation to another.However,mutation which gives rise to variations  is  driving  force  for the changes in structural characteristic for adaptation.Gene flow,gene drifts,together with natural selection are the driving forces.

Explanation:

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