Novel genomic insights into body size evolution in cetaceans and a resolution of Peto’s Paradox

Cetaceans (whales, dolphins, and porpoises) have undergone a radical transformation from the typical terrestrial mammalian body plan to a streamlined one while exhibited dramatic inter-specific size ranges. However, the molecular mechanisms underlying the diversifying evolution of cetacean body size are largely unknown. Here, by using genome and phenotypic data from 22 cetaceans, we seek to investigate the genome-wide gene-phenotype correlation and to explore the genetic basis under the high diversity of body size in cetaceans. Results of the functional enrichment showed that body size-related genes in cetaceans were enriched in pathways associated with immunity, cell growth, and metabolism, suggesting their potential roles in the diversifying evolution of body size in cetaceans. A series of genes was also found coevolution with body size that are mainly involved in immune surveillance, tumor suppression function, and development of ‘cheater’ tumors. This in turn suggests that the genes...