Pinniped and cetacean leptin sequences clade within the Carnivora and Cetartiodactyla respectively.

<p>Neighbour-joining (NJ) analysis, using the Tamura 3-parameter method with 1000 replicates, comparing diverse nucleotide sequences of mammalian leptin sequences with the sequences isolated in this study (underlined). The tree was rooted at the midpoint and support for each node (expressed as a percentage) is shown when >50%. The rodent, primate and lagomorphs clades have been collapsed for clarity. Evidence of positive selection was detected along the branch leading to the phocids indicated with ‘*’. Consistent topologies were predicted using Neighbour-joining and Maximum Likelihood methods (data not shown – see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035395#s4" target="_blank">Methods</a> for description).