Biogeographic divergence in leaf traits of Sapindus mukorossi and Sapindus delavayi and its relation to climate

To explore differences in leaf morphology between Sapindus mukorossi and Sapindus delavayi,and how the environment might drive these differences,80 germplasm samples from the Sapindus germplasm nursery in Fujian Province were selected.The study revealed a wide variation and diversity in 16 germplasm traits,both within and between species grown under the same conditions.On average,the relative contribution of intraspecific variability to total variability was more important(83%) than the relative contribution of interspecific variability(17%).PERMANOVA analysis showed differences in leaflet thickness,length,perimeter,length to width ratio,and leaf hairs or trichome density.Correlation analyses between leaf morphological traits and environmental variables indicated that leaves tended to be larger,longer,and thicker in wetter,warmer,and low-altitude conditions.Our analysis of the relationship between climate and leaf morphology revealed that S.mukorossi had a greater sensitivity to climate variation,particularly in response to mean temperatures of the coldest and warmest seasons,which led to differences in leaf traits and the distribution of the two species.These findings contribute to the understanding of leaf morphology variations in S.mukorossi and S.delavayi,and provide a basis for the collection of Sapindus germplasm resources,their cultivation and use to help address climate change.