Evolution | Encouragement to Beneficial Genes | Bomp-4 gene | Natural Selection | Darwin's finches

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Natural selection encourages conservation and multiplication of those genes and genotypes that assure the highest level of adaptive efficiency to the population in its existing environment. It means when two or more gene combinations are present, selection favours increased reproduction of the gene combination which is most suitable under the existing environmental conditions. Therefore, natural selection brings about improved adaptive relations between organisms and environment. 

How natural selection favours beneficial genes and gene combinations can be illustrated by the following example:


# Example: Changes in Beak Size, Beak Shape, and Body Size in Galapagos Finches.

Peter and Rosemary Grant studied changes in the beak size, beak shape, and body size in the populations of Darwin's finches on the Daphine Major Island of Galapagos Islands from 1973 onward. There was drought on the island in 1977. Grant's team compared the population of finches before and after the drought and found that:

• Birds that survived the drought had deeper beaks than the birds that died, because during this draught period finches could get only tough shelled seeds which could be cracked by large and deep beaks.

• In 1983, when environment changed and small, soft seeds were available in plenty, small finches with small, pointed beaks became more numerous.

# At molecular level - At molecular level, the recent work of Abzhanov et.al on the development of beak size and shape in finches at Galapagos Islands showed that variation in beak size is controlled by the degree of expression of a single gene, Bomp-4. The expression of this gene is influenced by the type of food available.

source: Organic Evolution (Evolutionary Biology), 13th edition, Medtech, by Veer Bala Rastogi , pg 300 -301

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