Evolution of Neuroplastin-65

Variation in the protein neuroplastin-65, encoded by the NPTN gene, correlates with intelligence in humans, but how did it evolve? This study investigated how this gene’s evolution differed between various organisms. A phylogenetic tree of the gene was created to trace the evolution. We hypothesized that the pattern of mutations in the gene would mostly correlate to the accepted evolution of animals, especially among primates where intelligence is under significant selective pressure. The data used forty-eight different organisms’ gene sequences. Analysis produced a phylogenetic tree that reasonably matched the hypothesis. Neuroplastin evolved along with individual species, as evidenced by correlations between the neuroplastin tree and other researchers’ phylogenetic species trees. Among primates, the data suggest the gene was under purifying pressure, as hypothesized. However, the impact of this conclusion is limited because the primate subtree branches are poorly supported. Interestingly, among bony fish, there appears to be either positive or no selective pressure on the NPTN gene. Furthermore, fish neuroplastin genes may be experiencing convergent evolution with mammal neuroplastin genes.