The goal of this short course is to introduce the notions of orthology and paralogy, their theoretical grounds and their practical implications. In addition, I will focus on the different strategies that one might use to predict orthologs and paralogues among completely sequenced genomes.
We will survey what are the different assumptions by each method so that their weaknesses and strengths are understood. We will see in practice how to
obtain reliable sets of orthologs by using methods and databases that can be accessed on-line.