The origin, dynamics, and molecular evolution of transmissible cancers

Abstract

Three transmissible cancers are known to have emerged naturally in the wild: canine transmissible venereal tumor (CTVT); Tasmanian devil facial tumor disease (DFTD); and a recently discovered leukemia-like cancer in soft-shell clams (Mya arenaria). These cancers have all acquired the ability to pass between individuals. DFTD emerged approximately 20 years ago and has decimated the Tasmanian devil population. CTVT arose over 10,000 years ago in an ancient breed of dog. The clam cancer is believed to have evolved at least 40 years ago. In this manuscript, we review CTVT and DFTD, the two transmissible mammalian cancers, and provide an overview of the leukemia-like cancer of clams. We showcase how genetics and genomics have enhanced our understanding of the unique biology, origins, and evolutionary histories of these rare cancers.