I believe that the most common antibody switch is from IgM to IgG.
Class switching occurs by a mechanism called the class switch recombination binding. It is a biological mechanism that allows the class of antibody produced by an activated B cell to change during a process known as isotype or class switching. The mechanism changes a B cell's production of antibodies from one form to another, such as from the isotype IgM to the isotype IgG.
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations.
