Phenotypic Plasticity And Suitable Area Prediction Of Flaveria Bidentis

Yellowtop(Flaveria bidentis)is an annual herbaceous plant in the genus Asteraceae.It is native to South America and has now become one of the seriously invasive plants in China.In this paper,we take the F.bidentis collected in 33 areas as the research object and use field investigation?common garden experiment and natural competition experiment to study the phenotypic variation of F.bidentis from different geographical sources.We also discuss the adaptation counter-strategies of F.bidentis in different habitats.The main conclusions are as follows:1)There are significant differences in the plant height,number of florets,total seed weight,1000-seed weight,seed yield,germination vigor,and germination rate among the 33 F.bidentis populations in the wild.The phenotypic variation among the populations is its main source,and the phenotypic plasticity index of the seed yield is the largest.Correlation analysis of field phenotypic traits and environmental factors in the sampling site showed that the seed yield and plant height of F.bidentis had a significant negative correlation with rainfall;while the principal component analysis showed that the seed yield and plant height of F.bidentis were mainly affected by rainfall.Therefore,it is indicated that phenotypic plasticity may promote the adaptability of F.bidentis in the wild,and thus enhance its invasiveness.2)Under the planting conditions of the common garden experiment in Nanjing,the traits such as seed yield of F.bidentis in 33 populations were not significantly different,which verified that phenotypic plasticity was the main reason for the phenotypic variation of wild F.bidentis,not genetic differentiation.3)We used the ENMeval package in R software to optimize parameters of the MaxEnt model,and simulated suitable cultivation regions of F.bidentis based on geographical distribution records and bioclimatic variables.Percent contribution and permutation importance were applied to evaluate the limiting varables.Finally,the MaxEnt model was constructed with 7 variables and the distribution area of F.bidentis was further predicted.The results showed that the potentially best suitable area for F.bidentis is north-central Henan,the junction of Shandong,Jiangsu and Anhui.Under the RCP4.5 climate background,the best suitable area in the 2030s and 2050s will be further expansion in east China,Yunnan,and Xinjiang.In Nanjing,the natural competition experiment of volunteer seedlings of F.bidentis was used to verify the prediction results of the new model.The results showed that the volunteer seedlings of F.bidentis were weak in the seeding stage.Under artificial weeding,the volunteer seedlings can be grown,but without weeding,it is difficult to grow.This shows that although F.bidentis has the ability to invade Jiangsu Province,it has not yet been able to be introduced into a suitable habitat.Therefore,Jiangsu Province should increase the early warning of F.bidentis.