@ Schmalhausen Institute of Zoology, Ukraine
Heterochrony as a driver of cetacean evolution
Fully aquatic cetaceans (whales and dolphins) evolved from semi-aquatic ancestors nearly 45 million years ago and gave a broad diversity of forms. Much of this development can be explained as heterochronies, with paedomorphosis leading as to diminishing, as to increase in body size, and peramorphosis expressing itself in bizarre structures. Initially, paedomorphosis could develop as a factor facilitating suction feeding or social interactions, whereas peramorphosis could be driven by sexual selection. A possible genomic mechanism for heterochrony may be positive selection in regulatory genes.