Polyploidization is an important mechanism that has caused many rapid speciation events and it increases genetic diversity of both plants and animals. Polyploidization occurs rarely in animals, especially in vertebrates. So far, little is known about the extent of multiple autopolyploid origins in vertebrates. 

Using both mitochondrial (mtDNA) and nuclear DNA sequences from up to 1202 individuals, Prof. ZHANG Yaping’s research team (Kunming Institute of Zoology. CAS) collaborated with Yunnan University explored the origin, tempo and frequency of polyploidization in Chinese and Japanese goldfish. 

The results confirmed the recurrent autoploidization within the Carassius auratus species complex (Cypriniformes, Cyprinidae). The Chinese and Japanese goldfish experience polyploidization events more frequently than any other vertebrates, which make the species of the genus Carassius an ideal model system for the study of recurrent polyploidization and the evolution of genomic complexity. 

Their findings have been published in Heredity (http://www.nature.com/hdy/journal/v112/n4/abs/hdy2013121a.html).