Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced range.Local adaptation of introduced species has frequently been observed at the continent scale,...Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced range.Local adaptation of introduced species has frequently been observed at the continent scale,particularly in response to latitudinal climatic variation.However,significant environmental heterogeneity can also exist at the landscape scale.A small number of studies have provided evidence that introduced species may also be capable of phenotypic and genetic differentiation at much smaller spatial scales.For example,previously we found US agricultural and non-agricultural populations of Sorghum halepense(Johnsongrass)to be phenotypically and genetically distinct.in this study,we inves-tigated whether this phenotypic differentiation of agricultural and non-agricultural populations of S.halepense is the result of fine-scale local specialisation.Methods We surveyed a nationally collected S.halepense germplasm panel and also collected neighbouring agricultural and non-agricultural sub-populations of S.halepense at four sites throughout Western Virginia,USA,raising seedlings in common conditions mimicking both agricultural and non-agricultural habitats.Important Findings At the national scale,we found evidence of habitat differentiation but not specialisation.However,at the local scale,we found evi-dence of specialisation in two of the four local populations to non-agricultural habitat,but no evidence of specialisation to agricultural habitat.These results show that local specialisation is a possible,but not guaranteed consequence of kilometre-scale habitat heterogen-eity in invasive species.This finding contributes to a growing aware-ness of the importance of fine-scale local adaptation in the ecology and management of introduced and weedy species.展开更多
Aims Invasive species often have higher relative growth rates(RGR)than their native counterparts.Nutrient use efficiency,total leaf area and specific leaf area(SLA)are traits that may confer RGR differences between na...Aims Invasive species often have higher relative growth rates(RGR)than their native counterparts.Nutrient use efficiency,total leaf area and specific leaf area(SLA)are traits that may confer RGR differences between natives and invasives,but trait differences are less prominent when the invasive species belongs to the same plant functional type as the dominant native species.Here,we test if traits displayed soon after germination confer an early size advantage.Specifically,we predicted that invasive species seedlings grow faster than the natives because they lack trade-offs that more strongly constrain the growth of native species.Methods We quantified plant morphological and physiological traits and RGR during early seedling growth at high and low nutrient levels in three dominant perennial native C_(4) grasses:Panicum virgatum L.(switchgrass),Schizachyrium scoparium(Michx.)Nash(little bluestem)and Andropogon gerardii Vitman(big bluestem);and a perennial C_(4) exotic invasive grass,Sorghum halepense(L.)Pers.(Johnsongrass).Important Findings After 2 weeks of growth,Johnsongrass seedlings had greater biomass,SLA and photosynthetic nitrogen use efficiency,but lower leaf N concentrations(%leaf N)and root:shoot ratio than natives.As growth continued,Johnsongrass more quickly produced larger and thicker leaves than the natives,which dampened the growth advantage past the first 2 to 3 weeks of growth.Investment in carbon gain appears to be the best explanation for the early growth advantage of Johnsongrass.In natives,growth was constrained by an apparent trade-off between allocation to root biomass,which reduced SLA,and production of leaves with high N content,which increased carbon gain.In Johnsongrass,root:shoot ratio did not interact with other traits,and%leaf N was decoupled from RGR as a result of a trade-off between the positive indirect association of%leaf N with RGR and the negative direct association of%leaf N with RGR.展开更多
文摘Aims As an exotic species colonises a new continent,it must overcome enormous environmental variation in its introduced range.Local adaptation of introduced species has frequently been observed at the continent scale,particularly in response to latitudinal climatic variation.However,significant environmental heterogeneity can also exist at the landscape scale.A small number of studies have provided evidence that introduced species may also be capable of phenotypic and genetic differentiation at much smaller spatial scales.For example,previously we found US agricultural and non-agricultural populations of Sorghum halepense(Johnsongrass)to be phenotypically and genetically distinct.in this study,we inves-tigated whether this phenotypic differentiation of agricultural and non-agricultural populations of S.halepense is the result of fine-scale local specialisation.Methods We surveyed a nationally collected S.halepense germplasm panel and also collected neighbouring agricultural and non-agricultural sub-populations of S.halepense at four sites throughout Western Virginia,USA,raising seedlings in common conditions mimicking both agricultural and non-agricultural habitats.Important Findings At the national scale,we found evidence of habitat differentiation but not specialisation.However,at the local scale,we found evi-dence of specialisation in two of the four local populations to non-agricultural habitat,but no evidence of specialisation to agricultural habitat.These results show that local specialisation is a possible,but not guaranteed consequence of kilometre-scale habitat heterogen-eity in invasive species.This finding contributes to a growing aware-ness of the importance of fine-scale local adaptation in the ecology and management of introduced and weedy species.
文摘Aims Invasive species often have higher relative growth rates(RGR)than their native counterparts.Nutrient use efficiency,total leaf area and specific leaf area(SLA)are traits that may confer RGR differences between natives and invasives,but trait differences are less prominent when the invasive species belongs to the same plant functional type as the dominant native species.Here,we test if traits displayed soon after germination confer an early size advantage.Specifically,we predicted that invasive species seedlings grow faster than the natives because they lack trade-offs that more strongly constrain the growth of native species.Methods We quantified plant morphological and physiological traits and RGR during early seedling growth at high and low nutrient levels in three dominant perennial native C_(4) grasses:Panicum virgatum L.(switchgrass),Schizachyrium scoparium(Michx.)Nash(little bluestem)and Andropogon gerardii Vitman(big bluestem);and a perennial C_(4) exotic invasive grass,Sorghum halepense(L.)Pers.(Johnsongrass).Important Findings After 2 weeks of growth,Johnsongrass seedlings had greater biomass,SLA and photosynthetic nitrogen use efficiency,but lower leaf N concentrations(%leaf N)and root:shoot ratio than natives.As growth continued,Johnsongrass more quickly produced larger and thicker leaves than the natives,which dampened the growth advantage past the first 2 to 3 weeks of growth.Investment in carbon gain appears to be the best explanation for the early growth advantage of Johnsongrass.In natives,growth was constrained by an apparent trade-off between allocation to root biomass,which reduced SLA,and production of leaves with high N content,which increased carbon gain.In Johnsongrass,root:shoot ratio did not interact with other traits,and%leaf N was decoupled from RGR as a result of a trade-off between the positive indirect association of%leaf N with RGR and the negative direct association of%leaf N with RGR.
基金We are grateful for the Weed Science Society of America for funding to W.K.,and Virginia Tech College of Agriculture and Life Sciences and grants from the National Institute of Food and Agriculture grants nos.2015-68004-23492 and 2013-67013-21306 to J.N.B.
基金This work was funded by the Project for High-level Talents of Basic and Applied Basic Research(Natural Science)in Hainan(2019RC280)the Key Research and Development Project of Hainan(ZDYF2019055)the Central Public-interest Scientific Institution Basal Research Fund for Chinese Academy of Tropical Agricultural Sciences(630042019014 and 1630042017017).
