Researchers studying dog size variation identified a polymorphism associated with the size phenotype in either small or large breeds but found no link to medium breeds. The study also explored left-handedness in humans, suggesting that neutral evolution, in the presence of frequency-dependent selection, likely played a role in its maintenance.

1. Extra credit: Scientists working on dog size variation research discovered a polymorphism
aseociated with ail dog treeds sharing which size phenotype? small breeds large breeds they were
unable to find an association between a single nucleotide polymorphisn and any specific sue
claty medium breed neutral evolution is the mechanism most likely to have maintained left-
handedness in humans despite is sigrifant fitres com negative freyusncy-dependent selection
linkage diseguilibrium stabilizang sciection positive trequency-dependent selection