Ecological factors correlate with genome size variation of Acanthocalyx (Caprifoliaceae) in the Hengduan-Himalaya Mountains.

While the genome sizes of flowering plants vary c. 2400-fold, it remains little known what factors may have driven the variation. In this study, we investigated the spatial pattern of the genome size of 54 populations of Acanthocalyx, which is found in the Hengduan-Himalaya Mountains. Our results showed that the red-flowered lineage of Acanthocalyx had significantly larger genomes (ranging from 1.9 to 2.5 Gb) compared to the white-flowered lineage, which had an average genome size of 1.27 Gb. This difference in genome size can be attributed to particular environmental factors. Within the red-flowered lineage, the genome size was positively correlated with soil nitrogen content and mean diurnal range. On the other hand, the genome size of the whiteflowered lineage, Acanthocalyx alba was negatively correlated with latitude which aligns with the population dynamics of this species during the Pleistocene. Overall, our findings highlight the influence of abiotic factors and geography in regulating the genome size of Acanthocalyx species. This study contributes to our understanding of the evolution of alpine plants in the Hengduan-Himalaya Mountains. [ABSTRACT FROM AUTHOR]