Traditional ideas of relatedness among organisms have been revised mainly based on

Answer: Advances in molecular technology

Explanation:

Earlier the phylogenetic relationship among organisms was established based on the physical features and behaviour of the organisms. With the advancement in molecular technology newer tools were developed which allowed to derive the relatedness among the organisms based on their genomic sequences (i. e. molecular characters).

So, the relatedness among organisms has been revised based on the advances in molecular technology.