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Heinz Mullerscharer - One of the best experts on this subject based on the ideXlab platform.
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the population genetics of the fundamental cytotype shift in invasive centaurea stoebe s l genetic diversity genetic differentiation and small scale genetic structure differ between cytotypes but not between ranges
Biological Invasions, 2016Co-Authors: Walter Durka, Christoph Rosche, Isabell Hensen, Heinz Mullerscharer, Patrik Mraz, Matthias Hartmann, Susanne LachmuthAbstract:Polyploids are overrepresented in invasive species. Yet, the role of genetic diversity and drift in colonization success of polyploids remains unclear. Here, we investigate genetic diversity, genetic differentiation and small-scale genetic structure in our model system, the three geo-cytotypes of Centaurea stoebe: monocarpic diploids and polycarpic (allo)tetraploids coexist in the native range (Eurasia), but only tetraploids are reported from the invasive range (North America). For each geo-cytotype, we investigated 18–20 populations varying in size and habitat type (natural vs. Ruderal). Population genetic analyses were conducted at eight microsatellite loci. Compared to diploids, tetraploids revealed higher genetic diversity and lower genetic differentiation, whereas both were comparable in tetraploids between both ranges. Within spatial distances of a few meters, diploid individuals were more strongly related to one another than tetraploids. In addition, expected heterozygosity in diploids increased with population size and was higher in natural than in Ruderal habitats. However, neither relationship was found for tetraploids. The higher genetic diversity of tetraploid C. stoebe may have enhanced its colonization abilities, if genetic diversity is correlated with fitness and adaptive capabilities. Furthermore, the inheritance of a duplicated chromosome set as well as longevity and frequent gene flow reduces drift in tetraploids. This counteracts genetic depletion during initial introductions and in subsequent phases of small or fluctuating population sizes in Ruderal habitats. Our findings advocate the importance of studying colonization genetic processes to gain a more mechanistic understanding of the role of polyploidy in invasion dynamics.
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adaptation of senecio vulgaris asteraceae to Ruderal and agricultural habitats
American Journal of Botany, 2001Co-Authors: Kirsten A Leiss, Heinz MullerscharerAbstract:Adaptation of the annual plant Senecio vulgaris to Ruderal and agricultural habitats was investigated. We expected S. vulgaris to be adapted to the agricultural habitat through nutrient-specific differentiation of relatively few genotypes responding to the generally high homogenous nutrient levels at the agricultural habitat caused by constant fertilization. To assess adaptation of S. vulgaris, vegetative and reproductive responses of seed families from various populations of agricultural and Ruderal habitats, grown in the greenhouse at high and low nutrient levels, were compared. Data were analyzed with a three-level nested ANOVA based on the levels habitat, population, and family. A significant habitat effect indicated that S. vulgaris from Ruderal and agricultural habitats were genetically different with plants from the agricultural habitat having larger leaves and a higher reproduction. A significant habitat by nutrient effect showed a stronger response of reproduction to nutrients at the agricultural habitat, suggesting that genetic differentiation among habitats is nutrient-specific. Contrary to expectations, only the agricultural habitat showed genetic diversity of S. vulgaris. Results suggest that nutrient levels at the agricultural habitat are more heterogeneous as generally proposed leading to a relatively high genetic variation.
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performance of reciprocally sown populations of senecio vulgaris from Ruderal and agricultural habitats
Oecologia, 2001Co-Authors: Kirsten A Leiss, Heinz MullerscharerAbstract:Senecio vulgaris from Ruderal habitats may colonise crop fields and persist in the new environment. Persistence may occur through phenotypic plasticity or genetic differentiation. In the presence of genetic variation, differential responses of life history traits to selection may lead to local adaptation. A reciprocal seed transplant experiment was conducted to determine environmental and genetic variation of life history traits in S. vulgaris from Ruderal and agricultural habitats, and whether infection by the rust Puccinia lagenophorae is a selection factor in S. vulgaris populations. Emergence, growth and fecundity showed environmental as well as genetic variation, as shown by a significant site and origin effect. However, there was no evidence of local adaptation, as indicated by the absence of significant origin by site interactions. Genetic variation in emerging seedling numbers seems to be important for S. vulgaris, an annual plant which has no means other than seed production for propagation. Seedling survival was solely under environmental control stressing the importance of stochastic events for plant mortality. Most S. vulgaris from Ruderal sites showed reduced growth, but still reached reproduction, suggesting that S. vulgaris is following the plastic strategy of a stress tolerator to endure unfavourable environments. Plants at most agricultural sites behaved like r-strategists, exploiting a productive environment for rapid plant growth and maximising reproduction. Emergence, survival, growth and fecundity were higher at the agricultural sites. Infection by the rust occurred at all sites, with the highest incidence at the agricultural sites, and was solely determined by the environment. A higher incidence did not result in an increased disease impact on plant growth and reproduction nor did it affect survival of S. vulgaris. Although the majority of life-history traits studied showed phenotypic and genetic variation, which can both be subject to natural selection, no adaptation of S. vulgaris to its local environment was detected.
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population dynamics of the annual plant senecio vulgaris in Ruderal and agricultural habitats
Basic and Applied Ecology, 2001Co-Authors: Kirsten A Leiss, Heinz MullerscharerAbstract:Summary The annual plant Senecio vulgaris has migrated from Ruderal to agricultural habitats resulting in weed populations. The population dynamics of S. vulgaris and its naturally associated rust fungus Puccinia lagenophorae were investigated as a basis for the biological control of S. vulgaris with the rust. A detailed basic study at a single Ruderal site and a parallel investigation at each five Ruderal and five agricultural sites were conducted from April to November 1997. During the whole period of study the spatial distribution of plants was aggregated and plants showed a relatively large size hierarchy as indicated by mean values of the Gini coefficient higher than 0.5. Seedling establishment appeared to be a major factor influencing the dynamics of S. vulgaris . The importance of seedling establishment, together with the observed short generation time of 5 weeks and the broad range of plant sizes at reproduction classifies S. vulgaris as a Ruderal strategist. The population dynamics of S. vulgaris differed between the Ruderal and the agricultural habitat. Plants of S. vulgaris at the Ruderal habitat survived over winter, resulting in greater population sizes (0.1 to 1 of the maximum) and a majority of plants in flower and seed set (81.9%) in spring. At the agricultural habitat, where only a few S. vulgaris winter due to weed control measures, population sizes in spring were smaller (0 to 0.16 of the maximum) with mainly vegetative plants (66.7%). The limited number of suitable hosts at the agricultural habitat in spring lead to a delay of rust infection until August, in contrast to the Ruderal habitat where the rust was already present in April. In both habitats mature plant stages were more susceptible to rust infection than vegetative stages. Manipulating the dynamics of the host over winter may enhance rust epidemics in spring serving as biological control of S. vulgaris . S. vulgaris und ihres naturlich vorkommenden Rostpilzes Puccinia lagenophorae in bezug auf die biologische Kontrolle von S. vulgaris mit dem Rost untersucht. Es wurden eine detailierte Basisstudie an einem Ruderalen Standort sowie parallel dazu verlaufende Untersuchungen an je funf Ruderalen und landwirtschaftlichen Standorten von April bis November 1997 durchgefuhrt. Wahrend des gesamten Beobachtungszeitraumes war die raumliche Verteilung der Pflanzen aggregiert, und die Pflanzen wiesen eine relative starke Grosenhierarchie, angezeigt durch Durchschnittswerte des Gini Koeffizienten groser als 0.5, auf. Die Etablierung von Keimlingen scheint ein wichtiger Fakor fur die Populationsdynamik von S. vulgaris zu sein. Die Bedeutung der Etablierung von Keimlingen, sowie die beobachtete kurze Generationszeit von funf Wochen, und die breite Streuung der Pflanzengrose zu Beginn der Reproduktion klassifizieren S. vulgaris als einen r-Strategen. Die Populationsdynamik von S. vulgaris zwischen dem Ruderalen und dem landwirtschaftlichen Habitat war unterschiedlich. Pflanzen von S. vulgaris im Ruderalen Habitat uberwinterten, was eine grosere Population (0.1 bis 1 des Maximums) sowie eine Mehrzahl an bluhenden und Samen bildenden Pflanzen (81.9%) im Fruhjahr zur Folge hatte. Im landwirtschafltichen Habitat konnte S. vulgaris aufgrund von Unkrautkontrollmasnahmen kaum uberwintern, so dass die Populationen im Fruhjahr kleiner waren (0 bis 0.16 of des Maximums) mit der Mehrzahl der Pflanzen im vegetativen Stadium (66.7%). Im landwirtschaftlichen Habitat fuhrte die geringe Anzahl geeigneter Wirtspflanzen im Fruhjahr zu einer Verzogerung des Auftretens von Rostinfektionen bis August, im Gegensatz zum Ruderalen Habitat, wo der Rost bereits im April anwesend war. In beiden Habitaten waren reproduktive Pflanzenstadien anfalliger fur eine Infektion mit dem Rost als vegetative Stadien. Die Manipulation der Wirtspflanzendynamik uber Winter konnte die Entwicklung von Rostepidemien im Fruhjahr fordern und als biologische Unkrautkontrollmasnahme gegen S. vulgaris eingesetzt werden.
Kirsten A Leiss - One of the best experts on this subject based on the ideXlab platform.
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adaptation of senecio vulgaris asteraceae to Ruderal and agricultural habitats
American Journal of Botany, 2001Co-Authors: Kirsten A Leiss, Heinz MullerscharerAbstract:Adaptation of the annual plant Senecio vulgaris to Ruderal and agricultural habitats was investigated. We expected S. vulgaris to be adapted to the agricultural habitat through nutrient-specific differentiation of relatively few genotypes responding to the generally high homogenous nutrient levels at the agricultural habitat caused by constant fertilization. To assess adaptation of S. vulgaris, vegetative and reproductive responses of seed families from various populations of agricultural and Ruderal habitats, grown in the greenhouse at high and low nutrient levels, were compared. Data were analyzed with a three-level nested ANOVA based on the levels habitat, population, and family. A significant habitat effect indicated that S. vulgaris from Ruderal and agricultural habitats were genetically different with plants from the agricultural habitat having larger leaves and a higher reproduction. A significant habitat by nutrient effect showed a stronger response of reproduction to nutrients at the agricultural habitat, suggesting that genetic differentiation among habitats is nutrient-specific. Contrary to expectations, only the agricultural habitat showed genetic diversity of S. vulgaris. Results suggest that nutrient levels at the agricultural habitat are more heterogeneous as generally proposed leading to a relatively high genetic variation.
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performance of reciprocally sown populations of senecio vulgaris from Ruderal and agricultural habitats
Oecologia, 2001Co-Authors: Kirsten A Leiss, Heinz MullerscharerAbstract:Senecio vulgaris from Ruderal habitats may colonise crop fields and persist in the new environment. Persistence may occur through phenotypic plasticity or genetic differentiation. In the presence of genetic variation, differential responses of life history traits to selection may lead to local adaptation. A reciprocal seed transplant experiment was conducted to determine environmental and genetic variation of life history traits in S. vulgaris from Ruderal and agricultural habitats, and whether infection by the rust Puccinia lagenophorae is a selection factor in S. vulgaris populations. Emergence, growth and fecundity showed environmental as well as genetic variation, as shown by a significant site and origin effect. However, there was no evidence of local adaptation, as indicated by the absence of significant origin by site interactions. Genetic variation in emerging seedling numbers seems to be important for S. vulgaris, an annual plant which has no means other than seed production for propagation. Seedling survival was solely under environmental control stressing the importance of stochastic events for plant mortality. Most S. vulgaris from Ruderal sites showed reduced growth, but still reached reproduction, suggesting that S. vulgaris is following the plastic strategy of a stress tolerator to endure unfavourable environments. Plants at most agricultural sites behaved like r-strategists, exploiting a productive environment for rapid plant growth and maximising reproduction. Emergence, survival, growth and fecundity were higher at the agricultural sites. Infection by the rust occurred at all sites, with the highest incidence at the agricultural sites, and was solely determined by the environment. A higher incidence did not result in an increased disease impact on plant growth and reproduction nor did it affect survival of S. vulgaris. Although the majority of life-history traits studied showed phenotypic and genetic variation, which can both be subject to natural selection, no adaptation of S. vulgaris to its local environment was detected.
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population dynamics of the annual plant senecio vulgaris in Ruderal and agricultural habitats
Basic and Applied Ecology, 2001Co-Authors: Kirsten A Leiss, Heinz MullerscharerAbstract:Summary The annual plant Senecio vulgaris has migrated from Ruderal to agricultural habitats resulting in weed populations. The population dynamics of S. vulgaris and its naturally associated rust fungus Puccinia lagenophorae were investigated as a basis for the biological control of S. vulgaris with the rust. A detailed basic study at a single Ruderal site and a parallel investigation at each five Ruderal and five agricultural sites were conducted from April to November 1997. During the whole period of study the spatial distribution of plants was aggregated and plants showed a relatively large size hierarchy as indicated by mean values of the Gini coefficient higher than 0.5. Seedling establishment appeared to be a major factor influencing the dynamics of S. vulgaris . The importance of seedling establishment, together with the observed short generation time of 5 weeks and the broad range of plant sizes at reproduction classifies S. vulgaris as a Ruderal strategist. The population dynamics of S. vulgaris differed between the Ruderal and the agricultural habitat. Plants of S. vulgaris at the Ruderal habitat survived over winter, resulting in greater population sizes (0.1 to 1 of the maximum) and a majority of plants in flower and seed set (81.9%) in spring. At the agricultural habitat, where only a few S. vulgaris winter due to weed control measures, population sizes in spring were smaller (0 to 0.16 of the maximum) with mainly vegetative plants (66.7%). The limited number of suitable hosts at the agricultural habitat in spring lead to a delay of rust infection until August, in contrast to the Ruderal habitat where the rust was already present in April. In both habitats mature plant stages were more susceptible to rust infection than vegetative stages. Manipulating the dynamics of the host over winter may enhance rust epidemics in spring serving as biological control of S. vulgaris . S. vulgaris und ihres naturlich vorkommenden Rostpilzes Puccinia lagenophorae in bezug auf die biologische Kontrolle von S. vulgaris mit dem Rost untersucht. Es wurden eine detailierte Basisstudie an einem Ruderalen Standort sowie parallel dazu verlaufende Untersuchungen an je funf Ruderalen und landwirtschaftlichen Standorten von April bis November 1997 durchgefuhrt. Wahrend des gesamten Beobachtungszeitraumes war die raumliche Verteilung der Pflanzen aggregiert, und die Pflanzen wiesen eine relative starke Grosenhierarchie, angezeigt durch Durchschnittswerte des Gini Koeffizienten groser als 0.5, auf. Die Etablierung von Keimlingen scheint ein wichtiger Fakor fur die Populationsdynamik von S. vulgaris zu sein. Die Bedeutung der Etablierung von Keimlingen, sowie die beobachtete kurze Generationszeit von funf Wochen, und die breite Streuung der Pflanzengrose zu Beginn der Reproduktion klassifizieren S. vulgaris als einen r-Strategen. Die Populationsdynamik von S. vulgaris zwischen dem Ruderalen und dem landwirtschaftlichen Habitat war unterschiedlich. Pflanzen von S. vulgaris im Ruderalen Habitat uberwinterten, was eine grosere Population (0.1 bis 1 des Maximums) sowie eine Mehrzahl an bluhenden und Samen bildenden Pflanzen (81.9%) im Fruhjahr zur Folge hatte. Im landwirtschafltichen Habitat konnte S. vulgaris aufgrund von Unkrautkontrollmasnahmen kaum uberwintern, so dass die Populationen im Fruhjahr kleiner waren (0 bis 0.16 of des Maximums) mit der Mehrzahl der Pflanzen im vegetativen Stadium (66.7%). Im landwirtschaftlichen Habitat fuhrte die geringe Anzahl geeigneter Wirtspflanzen im Fruhjahr zu einer Verzogerung des Auftretens von Rostinfektionen bis August, im Gegensatz zum Ruderalen Habitat, wo der Rost bereits im April anwesend war. In beiden Habitaten waren reproduktive Pflanzenstadien anfalliger fur eine Infektion mit dem Rost als vegetative Stadien. Die Manipulation der Wirtspflanzendynamik uber Winter konnte die Entwicklung von Rostepidemien im Fruhjahr fordern und als biologische Unkrautkontrollmasnahme gegen S. vulgaris eingesetzt werden.
Pierre Baduel - One of the best experts on this subject based on the ideXlab platform.
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genetic basis and evolution of rapid cycling in railway populations of tetraploid arabidopsis arenosa
PLOS Genetics, 2018Co-Authors: Pierre Baduel, Ben Hunter, Sarang Yeola, Kirsten BombliesAbstract:Spatially structured plant populations with diverse adaptations provide powerful models to investigate evolution. Human-generated Ruderal habitats are abundant and low-competition, but are challenging for plants not adapted to them. Ruderal habitats also sometimes form networked corridors (e.g. roadsides and railways) that allow rapid long-distance spread of successfully adapted variants. Here we use transcriptomic and genomic analyses, coupled with genetic mapping and transgenic follow-up, to understand the evolution of rapid cycling during adaptation to railway sites in autotetraploid Arabidopsis arenosa. We focus mostly on a hybrid population that is likely a secondary colonist of a railway site. These mountain railway plants are phenotypically similar to their cosmopolitan cousins. We thus hypothesized that colonization primarily involved the flow of adaptive alleles from the cosmopolitan railway variant. But our data shows that it is not that simple: while there is evidence of selection having acted on introgressed alleles, selection also acted on rare standing variation, and new mutations may also contribute. Among the genes we show have allelic divergence with functional relevance to flowering time are known regulators of flowering, including FLC and CONSTANS. Prior implications of these genes in weediness and rapid cycling supports the idea that these are "evolutionary hotspots" for these traits. We also find that one of two alleles of CONSTANS under selection in the secondary colonist was selected from rare standing variation in mountain populations, while the other was introgressed from the cosmopolitan railway populations. The latter allele likely arose in diploid populations over 700km away, highlighting how Ruderal populations could act as allele conduits and thus influence local adaptation.
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a ticket to ride allele delivery by rail in secondary Ruderal colonization by arabidopsis arenosa
bioRxiv, 2017Co-Authors: Pierre Baduel, Ben Hunter, Sarang Yeola, Kirsten BombliesAbstract:Human-generated Ruderal habitats are abundant, but challenging for plants. Some Ruderal habitats, however, provide networked corridors (e.g. roadsides and railways) that can facilitate rapid long-distance spread of successfully adapted variants. Here we use transcriptomic and genomic analyses, coupled with genetic mapping and transgenics to understand adaptation to railways in Arabidopsis arenosa. We show normally perennial A. arenosa switched to rapid cycling, a common adaptation for Ruderal plants, at least twice upon railway colonization. We further show substantial gene flow from a widely distributed railway colonist likely contributed to secondary colonization by a non-Ruderal type, highlighting how connectivity can affect adaptability. We find loss of expression of the reproductive repressor FLOWERING LOCUS C (FLC) is likely primarily responsible for rapid cycling in the widely distributed railway variant. However, a second railway colonist in the Alps also cycles rapidly, but retains high FLC. Some alleles in this population encode non-functional proteins, suggesting FLC has started to decay, but most are functional. Instead, this population likely circumvents FLC via a derived allele of CONSTANS (CO), which shows strong evidence of selection in this population. Importantly, we find this CO allele arrived via gene flow from the widespread Ruderal, where it was also previously under selection. This suggests Ruderal adaptation may have been progressive, perhaps in both cases, with FLC-circumvention arising first, and FLC loss arising later but ultimately obscuring its earlier circumvention. These snapshots of railway adaptation highlight that gene flow from widespread Ruderals can provide opportunities for subsequent adaptation by local genotypes.
L. A. Hermanutz - One of the best experts on this subject based on the ideXlab platform.
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Agroecotypes or phenotypic plasticity? comparison of agrestal and Ruderal populations of the weed Solanum ptycanthum
Oecologia, 1996Co-Authors: L. A. Hermanutz, S. E. WeaverAbstract:To test if the high nutrient inputs of agroeosystems select for specialized agroecotypes or for phenotypic plasticity, Ontario populations of the northwardly migrating annual weed Solanum ptycanthum from Ruderal (beach) and agricultural habitats were compared over a nutrient gradient. Temporal variation of total available nitrogen was determined in both types of habitats. As gene flow via seed contamination of tomato transplants from S. United States was detected, variation in response to nutrient (N) levels was also compared between agrestal populations from the northern (Ontario) and southern (Georgia) ends of the species range. Five families from six populations (two northern agrestal, two northern Ruderal and two southern agrestal) were grown in the greenhouse at low, medium and high nutrient levels, and plant growth and traits associated with reproductive success measured. All populations displayed significant levels of plasticity in the majority of vegetative and reproductive traits. There were no detectable differences over the levels of nutrients tested between individuals sampled from northern agrestal and Ruderal populations, even though variation in available nitrogen is greater in agroecosystems. Southern agrestal populations were genetically differentiated from the northern populations, and exhibited almost twice the overall plasticity of northern populations, measured by the Mahalanobis distance. Canonical discriminant analysis showed complete overlap in the northern populations over all nutrient levels, suggesting that colonization of new habitats is via a general-purpose genotype, rather than by selection for specialized agroeotypes.
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outcrossing in the weed solanum ptycanthum solanaceae a comparison of agrestal and Ruderal populations
American Journal of Botany, 1991Co-Authors: L. A. HermanutzAbstract:Levels of outcrossing, using a Pgm polymorphism, were estimated for individuals from Ruderal and agrestal populations of the predominantly monomorphic weed Solanum ptycanthum, at the northern edge of its range, and compared to agrestal populations sampled from the southern portion ofits distribution. Individuals were grown in agricultural habitats in Ontario. Outcrossing estimates ofthe northern agrestals were very low (< 3%) and did not differ from Ruderal estimates. Southern agrestals exhibited much higher outcrossing rates (10/0%-17%). Of the floral traits measured, degree of stigma exsertion and style position showed interpopulation variation and correlated with outcrossing rate. Outcrossing in northern individuals was largely precluded by the complete overlap in female and male functions and stigmatic surfaces that were in direct contact with anther sacs as the flower opened. The observed flexibility in mating system may have played an important role in colonization success of S. ptycanthum.
Joshua S Caplan - One of the best experts on this subject based on the ideXlab platform.
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functional morphology underlies performance differences among invasive and non invasive Ruderal rubus species
Oecologia, 2013Co-Authors: Joshua S Caplan, Alan J YeakleyAbstract:The ability of some introduced plant species to outperform native species under altered resource conditions makes them highly productive in ecosystems with surplus resources. However, Ruderal native species are also productive when resources are available. The differences in abundance among invasive and non-invasive Ruderal plants may be related to differences in ability to maintain access to or store resources for continual use. For a group of Ruderal species in the Pacific Northwest of North America (invasive Rubus armeniacus; non-invasive R. ursinus, R. parviflorus, R. spectabilis, and Rosa nutkana), we sought to determine whether differences in functional morphological traits, especially metrics of water access and storage, were consistent with differences in water conductance and growth rate. We also investigated the changes in these traits in response to abundant vs. limited water availability. Rubus armeniacus had among the largest root systems and cane cross-sectional areas, the lowest cane tissue densities, and the most plastic ratios of leaf area to plant mass and of xylem area to leaf area, often sharing its rank with R. ursinus or Rosa nutkana. These three species had the highest water conductance and relative growth rates, though Rubus armeniacus grew the most rapidly when water was not limited. Our results suggest that water access and storage abilities vary with morphology among the Ruderal species investigated, and that these abilities, in combination, are greatest in the invasive. In turn, functional morphological traits allow R. armeniacus to maintain rapid gas exchange rates during the dry summers in its invaded range, conferring on it high productivity.
