Many examples of convergent evolution exist in insects in terms of developing resistance at a molecular level to toxins. One well-characterized example is the evolution of amino acid substitutions at well-defined positions in the structure of the Na,K-ATPase α-subunit spanning 15 genera and 4 orders. The synergistic relationship between the Q111 and N122 substitutions are highlighted. Convergent evolution in this case does not depend on the type of selection or time frame in which it can occur, but has more to do with the co-evolutionary relationship causing a sort of soft selection between cardenolide-producing plants and the insects that prey on them.