What are three alternative fates of a new gene duplicate? What is the evidence that gene duplication has been the source of the α and β gene families for human hemoglobin? DNA-sequencing studies for a gene in two closely related species produce the following numbers of sites that vary:

Synonymous polymorphisms                50

Nonsynonymous polymorphisms        20

Synonymous species differences         18

Nonsynonymous species differences    2

Does this result support neutral evolution of the gene? Does it support an adaptive replacement of aminoacids? What explanation would you offer for the observations?