Chapter 13, Problem 6A

Summary Introduction

To discuss:

The way selective breeding is affected due to polygenic inheritance.

Introduction:

The process by which desired traits of certain plants and animals are selected and passed on to their future generations is called selective breeding. This can be achieved through hybridization and inbreeding. Some phenotypic traits are due to interaction of multiple pairs of genes. Such traits are called polygenic traits.

Answer to Problem 6A

Polygenic inheritance makes selection of organisms with desired traits difficult for selective breeding.

It takes several generations to get the desired combination of characters due to which it is time consuming.

Explanation of Solution

Some phenotypic traits are due to interaction of multiple pairs of genes. Such traits are called polygenic traits. Examples are traits like skin color, eye color, hair color, height, and finger print pattern. A number of intermediate phenotypes result due to multiple pairs of genes than only extreme phenotypes. Hence there would be a variety of phenotypes.

If selective breeding of polygenic traits is carried out, it would take several generations to get the desired combination of characters. It will be time consuming and expensive as extreme care is needed to select and successfully cross organisms to yield right combination of traits from both parents. Since a variety of phenotypes would be available in case of polygenic inheritance, it would be difficult to select the right organisms with desired traits.