| To adapt to diverse stresses or disturbances,plants develop various ecological strategies by changing a series of functional traits and resource allocation patterns.The studies on plant ecological strategies have great significance to answer the frontier hot issues of ecology,such as vegetation succession,biodiversity protection,ecosystem function maintenance and response to global environmental change.However,previous studies mostly focused on the macro analysis of plant interspecific level,and there were relatively few studies on the genetic and environmental mechanisms underlying plant ecological strategies variation,especially for the phylogenetic history of intraspecific genetic lineages,which limited the mechanistic exploration and potential application of ecological strategies.In this study,combined with field surveys and multi-year common garden experiments,we measured plant functional traits such as shoot height,leaf length and photosynthetic efficiency,and analyzed the genetic variation of P.australis using 2 chloroplast DNA fragments and 11 nuclear microsatellite markers(SSR).The functional traits and CSR(competitor,stress-tolerator and ruderal)ecological strategies were compared among P.australis genotypes from different origins.Eventually,we explored the relationships among functional traits,ecological strategies and climatic environmental factors,and revealed the effects of phylogenetic history of P.australis on its functional traits,ecological strategies and climatic niches.The results of this study are as follows:(1)There were significant differences in some functional traits including shoot height and leaf thickness of P.australis,between different origins in the field,but these differences disappeared or reversed in the common garden environment,suggesting that the functional traits of P.australis changed due to the direct influence of the environment.Meanwhile,the differences in the basal diameter and leaf length between different origins were consistent in the two environments(field and commom garden),suggesting that the genetic factors of P.australis played an important role in the intraspecific variation of functional traits.Compared with P.australis from the Yellow River Delta,the S score of P.australis in Ningxia Plain was significantly higher and the C score was lower,which might be due to the precipitation differention between two origins.The results revealed that environmental and genetic factors jointly affected the functional traits and ecological strategies of P.australis.The functional traits within the same organ,between different organs,and the whole plant were closely related.Through the synergy or trade-off relationship between traits,plants could quickly adjust their ecological strategies to adapt to the environment.(2)According to the correlation analysis between climatic environmental factors including annual average temperature,annual precipitation and precipitation seasonality,and the functional traits and ecological strategies of P.australis,the study showed that the annual average temperature and annual precipitation significantly affected the functional traits of P.australis such as basal diameter,leaf length,shoot number,and CSR scores.These results suggest climatic adaptation is a signficiant evolutionary mechanism of CSR ecological strategies in P.australis.Under the climatic conditions with sufficient water and heat,plants tended to increase the investment in C-related traits(e.g.shoot hight)and reduce the investment in R-related traits and S-related traits(e.g.shoot number and specific leaf area).Annual average temperature and annual precipitation were important climatic factors affecting plant functional traits and ecological strategies of P.australis.(3)The result of SSR genetic molecular marker analysis displayed that the collected P.australis from China in this study were mainly from two lineages.One lineage was dominated by haplotype P,and the other lineage was dominated by haplotype O.The phylogenetic conservation analysis for functional traits of P.australis in the common garden found that most of the functional traits were less restricted by the phylogenetic history of the intraspecific lineages,suggesting the traits were mainly affected by the environment.That is to say,the similar environments could shape the same type of ecological strategies in different lineages.However,the phylogenetic conservation analysis of the climatic niche revealed genotypes of P.australis with close genetic relatedness tended to survive under similar climatic conditions and have similar climatic niches.(4)A variety of ecological strategy types of P.australis were discovered by the CSR ecological strategies analysis method based on leaf traits,mainly concentrated in the S-C region.With the increase of leaf thickness/leaf area,shoot height and shoot number,the corresponding S score,C score and R score significantly increased,respectively,indicating that the CSR scores from StrateFy based on leaf traits could well predict the change of the ecological strategies of the whole plant.The results suggested that the leaf trait-based analysis method could be applied to ecological strategy differences within P.australis as well as other widespread plant species.Our study compared the genetic variation,functional traits and ecological strategies of P.australis from different origins,and explored synergy and trade-off relationship between functional traits.The results highlighted the significant roles of genetic and environmental factors in the evolution of ecological strategies,and verified a good applicability of the CSR ecological strategies analysis method based on leaf traits in intraspecific analysis of ecological strategies.These results could offer solid scientific basis for the germplasm assessment and selection,for the wetland conservation and restoration,and for the ecological engineering plant allocation,and had significant implications for the prediction of plant distribution pattern and ecosystem response under global climate change. |
