Question

prnithologists (bird experts) can score the degree of pointedness of a finch's beak numerically. The gene ALX1 was recently found to be important for beak pointedness. Investigators measured the pointedness of 62 finch beaks and determined whether each finch was homozygous for either of two ALX1 alleles B and P, or heterozygous. The averages and ranges of pointedness they recorded for each genotype are reproduced in the figure. While PP birds showed a higher average pointedness compared to BP and BB finches, beak pointedness did not differ significantly from one category to another even though other data clearly point to a role for ALX1 in beak shape. What is your best explanation for why there are overlaps in pointedness among the three categories? P = 8.85 x 10-5 Beak shape score (degree of paintedness) BP Genotype

Answer 1

ALX1 gene is responsible for providing beak pointedness and different shapes to the beaks in birds which has helped the birds in survival during evolution. In the above question as can be seen maximum degree of pointedness is seen for genotype PP, medium pointedness is seen for heterozygoteBP and  minimum is seen for genotype BB though a significant amount of overlapping is seen in three genotypes and from my point of view the most probable reason for this overlap is the degree of recombination. From the above question we know that both B and P are the alleles of ALX1 gene and in comparison to allele B,  allele P might be best fitted for survival and it has evolved during evolution for giving such beakshapes to the birds which has helped them in evolution while passing through difficult stages. But since both B and P are alleles of same gene and allele B has not completly vanished  out and still plays a role in providing beak pointed ness to birds therefore we do see the effect of genotype BB in the figure. Genotype BP is heterozygous made from recombination of allele B and P and have the charactersicts of both allele B and P therefore it has higher degree of pointedness compared to homozygous genotype BB but less then the genotype PP.