Question

What is the number of linkage group founds in honey bees?

Answer 1

Linkage helps to hold the prenatal characters from generation to generation. All the genes present on one chromosome constitute one linkage group. Total Linkage groups in an organism can be calculated by calculating the number of chromosomes in the haploid set.

Complete answer: Linkage is the phenomenon of certain genes staying together during inheritance through generation to generation without any change or separation as they are present on the same chromosomes. It was first discovered by Bateson and Punnett in Lathyrus odoratus. They give the coupling and repulsion phenomenon. Linkage is the exception of independent assortment.
There are two types of linkage:

1. Complete linkage: In this case, the separation of these linked genes is not possible as they are very close to each other. This was reported by Morgan in Drosophila. Gene determining body colour and wing shape are linked genes in drosophila. These genes can be used as markers.
2. Incomplete linkage: In this type, genes are not very close to each other and hence, they can get segregated.
   Linkage groups are exactly the same as the number of chromosomes present in one set of chromosomes.
   Example: In Drosophila, diploid sets of chromosomes contain 8 chromosomes . so its one set contains 4 chromosomes and hence, the total number of linkage groups is 4. But linkage groups in honey bees cannot be derived from this method. They have 32 chromosomes in their diploid set, so as per the rule they should contain 16 linkage groups but in reality, they have 24 linkage groups.

Note: Gene mapping: It is used to study the location of genes. Genes are arranged in a linear fashion on chromosomes. If the distance between the genes is more than the chance of crossing over with another gene will be more, but if they are present very close to each other, there may be chances of linkage.