The monophyletic group Caniformia (dog-like carnivores) in the order Carnivora comprises 9 families. However, the interfamilial relationship of Caniformia, particularly the phylogenetic placement of Ursidae, remains a controversial issue among researchers.

A research group headed by academician ZHANG Yaping from Kunming Institute of Zoology, Chinese Academy of Sciences made a study on phylogenetic utility of nuclear introns using a data set comprising > 22 kb of 22 nuclear intron loci from 16 caniformian species.

The study result supports the view that Ailuridae should classified as the sister taxon to a clade containing Procyonidae and Mustelidae, with Mephitinae as the sister taxon to all of them. It also shows that all the newly developed intron data partitions exhibit Intra-Individual Allele Heterozygotes (IIAHs).

The study not only resolves some of the ambiguous relationships in Caniformia phylogeny, but also shows that the noncoding nuclear markers can offer powerful complementary data for estimating the species tree. In addition, the incorporation of IIAHs into phylogenetic analysis not only provides insights into the interfamilial relationships of Caniformia, but also identifies two potential hybridization events occurred within Ursidae and Otariidae respectively.

Its relevant paper has been published in Systematic Biology (2011, 60: 175-187). “This study provides a nice empirical contribution to the utility of large-scale intron data for mammalian systematics with a detailed account of the pros and cons of using such phylogenetic markers”, reputed reviewer of the paper.