Polyploidization is a major source of diversification among plants, particularly during cladogenesis, but most evidence involves herbaceous temperate species. The prevalence of polyploidy among woody taxa is largely unknown, especially among tropical groups.

Ms. Chen Sichong of Xishuangbanna Tropical Botanical Garden (XTBG), under the guidance of her supervisor Chuck Cannon, examined genome size variation globally and at several taxonomic levels within the Fagaceae, a large, diverse, and widely distributed woody plant family.

In the study, the researchers performed the first extensive survey of genome size variation in Fagaceae, sampling among and within six genera for which the phylogenetic relationships were known. To investigate the stability and variation of genome size within and among genera and across biotic zones in the Fagaceae, they directly measured nuclear DNA content for 171 individuals from 47 tropical Chinese species, including three separate genera and the tropical subgenus Cyclobalanopsis within the genus Quercus.

They found no evidence that whole genome duplication or polyploidization played a major role in species diversification among the Fagaceae genera. Overall, their survey of genome size in the Fagaceae, across taxonomic levels and geographic scales, strongly supported the hypothesis that woody taxa rarely experienced polyploidization.

The study entitled “Genome size variation in the Fagaceae and its implications for trees” has been published online in Tree Genetics & Genomes.