Question

A. Which type of mutation do you feel would be most likely to be influenced by natural selection, those that result in changes of the third codon position, or those that result in changes of the first codon position? Explain your reasoning. B. In many animals inbreeding among close relatives reduces the ability of their offspring to survive. Explain why this occurs.

Answer 1

Non synonymous mutations bring about a change in the sequence which is translatable and thus only these are subject to natural selection in a variable environment. A mutation in the third codon is synonymous and doesn't produce any change in the amino acid sequence . However, a mutation in the first position of codon will produce a non synonymous change and will produce a changed protein which will be subject to natural selection.

B. This is because of the same gene pool. Recessive disorders are usually lethal and rare. Having children within the same gene pool i.e. between relatives would bring recessive alleles together in an offspring developing lethal recessive disorders, reducing the survival of the offsprings.