Within a population of colorful parrots, birds carry single dominant alleles cod

Question

Within a population of colorful parrots, birds carry single dominant alleles coding for red, blue, or green coats of feathers. A pirate ship visits this population and carries off as many blue parrots as they can in honor of their captain, Bluebeard. Years later, sailors visiting Bluebeard’s former lair are impressed by the overwhelmingly blue-coated birds living there. Question: Which force of evolution does the above scenario depict? Please identify and define the force, then explain why the above scenario fits its description.

Explanation / Answer

The birds in the original population were colourful having single dominant alleles coding for red, blue, or green colours of feathers. It tells us that the population had species richness and genetic variety for the feather colour in parrots. When the pirate ship carries off as many blue parrots as they can, a selective force acts on this population. Since only the blue coloured birds are selected, there is genetic drift in the new population growing at Bluebeard's lair. The alleles red, blue and green were all individually dominant therefore only one allele can show the characteristic colour phenotype. A blue bird will have only dominant blue phenotype and no red or green colour. So, when only blue birds are taken the red and green alleles are lost from the population as both male and female birds are blue and so their offsprings will also be blue.

Years later the former lair will have only blue birds although the original population would still have all three coloured birds. This effect is known as Founder Effect.

The founder effect occurs when a small group (blue parrots) are separated from one large population (red, blue, green parrots) and forms a new population in a different geographic location. This new population's allelic frequency is probably different from the original population's, and will change certain allelic ratios are in the populations. The founders of the population will determine the genetic makeup of the future generations.

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