Ecological and evolutionary consequences of variation in aristolochic acids, a chemical resource, for sequestering specialist Troidini butterflies

Plant-insect interactions provide an opportunity to examine fundamental ecological and evolutionary processes, including mechanisms of species cooccurrence and adaptations to herbivory and predation. An example is the interaction between butterflies in the Troidini tribe (Papilionidae), a group that sequesters chemical defenses from its host plants in the genus Aristolochia (Aristolochiaceae). In this dissertation, I examined the ecological and evolutionary consequences of variation in aristolochic acids, the chemical compounds sequestered by Troidini from it host plants, through a combination of observational, experimental and laboratory studies. I conducted studies at several sites throughout the Americas where different levels of knowledge about this interaction are available. These differences allowed me to ask specific questions in areas where there is ample background information (i.e. North America) and to ask more general, but fundamental questions in areas where little is known (i.e. South America). In North America, I showed for a Troidini species, Battus philenor, that larvae preferentially fed on less tough, younger leaves, and found no evidence that aristolochic acid content influenced larval foraging. For these herbivores, mechanical resistance might be a more important determinant of larval foraging behavior and development compared to plant chemical defenses. In another study in North America, with data from three consecutive seasons, I found that larger egg clutches of B. philenor suffer less predation compared to small clutches. This study suggests that, for eggs protected with toxic chemicals, there is a clear benefit in laying eggs in large clusters in areas with high levels of predator threat. In Iguazú National Park, Argentina, little is known about Troidini- Aristolochia interaction; therefore I studied general and specific aspects of this interaction. Our main finding, in contrast to what has been reported in North America, is that many Aristolochia and Troidini are not defended with aristolochic acids, contrary to the currently accepted paradigm that all Troidines are toxic. Studying these species in areas where they are understudied and reach higher diversity gives a more complete picture of this plant-butterfly interaction. My results contribute to furthering our understanding of the role of chemical ecology in shaping evolutionary dynamics and ecological processes

Not all toxic butterflies are toxic: high intra- and interspecific variation in sequestration in subtropical swallowtails

Many herbivorous insects make use of plant secondary metabolites by consuming and storing these toxic compounds in their body tissue or integument, thereby obtaining chemical defense against their natural enemies. Swallowtail butterflies in the tribe Troidini (Papilionidae) sequester toxic alkaloids (aristolochic acids, AAs) from their host plants in the genus Aristolochia. Troidine butterflies have been a model group for development of theory on host plant chemical sequestration, but most studies on this group have been limited to a single species in North America. These studies have led, in part, to the paradigm that troidine butterflies are toxic, thereby explaining the numerous mimicry relationships that exist throughout most of their range. Herein, we present one of the first comparative studies in a single location of a community of troidine butterflies. We examined the AA content of five co-occurring troidine butterfly species and their two Aristolochia host plants. We found that one Aristolochia species, A. triangularis, was preferred in choice assays and did not possess quantifiable levels of AA. We also found that most troidine butterflies did not possess quantifiable levels of AAs, but larvae have the ability to sequester AAs when it is present in their diet. A larval preference experiment showed that host plant AA concentration did not influence larval feeding choice. A performance experiment showed that higher levels of AAs in the diet increased larval mortality, which might indicate a cost associated with sequestration of the chemical defense and also might shed some light on why so many troidine butterflies in this community have little or no AAs. We propose that automimicry might be operating in this system and many putative models of this paradigmatic system might not possess plant-derived defensive chemistry

Insectos de importancia económica y sanitaria “La hormiga cortadora de hojas”, Acromyrmex lobicornis

Acromyrmex lobicornis es la hormiga cortadora que posee la distribución más extensa de Argentina y que alcanza las latitudes más australes del mundo. En Patagonia, la herbivoría por hormigas cortadoras, aunque de menor magnitud que en el noreste del país, es un problema en los estadios iniciales de las forestaciones, y con vista a incrementarse si el área forestada aumenta.Estación Experimental Agropecuaria BarilocheFil: Dimarco, Romina Daniela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. Grupo de Ecologia de Poblaciones de Insectos; Argentin

Invasive Species: To eat or not to eat, that is the question

Managing invasive species is a current challenge for biodiversity conservation. A recurring recent suggestion is that by harvesting nonnatives for human consumption, people can control invasive populations. Even though humans may be able to control or eradicate certain populations of nonnative species by harvesting them as food sources, several caveats should be considered before starting these programs. A prominent problem is that creating a market engenders pressure to maintain that problematic species. Also, if the target species becomes an economic resource, people may try to recreate that market in previously uninvaded regions. Using invasive species as an economic resource may trigger the local community to protect these harmful species, to facilitate their incorporation into the local culture, and can generate severe management problems. As with other management programs, managers must know if the harvest actually reduces the target population. Mortality could produce a reduction in the population size or growth, or it could be compensatory, in which case removal of the harvested individuals would not affect population growth. However, in addition to possible control, there may be several benefits of this approach, including an opportunity for public outreach. Projects aiming at controlling invasives through human consumption should be carefully examined, as they may produce results opposite to those proposed.Fil: Nuñez, Martin Andres. University of Tennessee; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Kuebbing, Sara. University of Tennessee; Estados UnidosFil: Dimarco, Romina Daniela. University of Tennessee; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Simberloff, Daniel. University of Tennessee; Estados Unido

What can possibly go wrong? The risks of introducing soil microorganisms from Antarctica into South America = ¿Qué puede salir mal? : Los riesgos de introducir microorganismos del suelo de la Antártida en América del Sur

Endophytic fungi form mutualistic associations with plant roots which can increase plant survival and resistance to stress. Recently, it has been proposed that endophytic fungi from Antarctica should be used to facilitate reintroduction and establishment of native plants in xeric environments of northern Chile. In this note, we suggest this is a risky proposition and may lead to biological invasions. It is difficult to predict which endophytic fungi will become invasive, where they will invade, or what their impacts will be. Organisms that move across continents may or may not become invasive depending on the interaction between the species and the invaded community; unexpected outcomes may occur due to adaptation and novel interactions of the introduced species in the new environment. The fact that these endophytes are mutualistic does not imply that they will not have negative effects on the recipient community, since they might promote invasion of other non-native species or may change the competitive relationships among native species. Further, taxonomically uncharacterized fungal isolates from plant roots are likely to contain non-beneficial species. The fact that these endophytic fungi species are from Antarctica does not ensure that they cannot invade elsewhere. It should be recognized that invasive microorganisms are extremely difficult to control. We strongly suggest that the further translocation, use and spread of endophytes from Antarctica should be halted until a risk assessment is undertaken. Biosecurity measures must be taken when considering transcontinental experiments. Based on previous experiences, it is likely that the risk and potential costs of introducing these new species significantly exceed any potential benefits of their introductionsLos hongos endófitos forman asociaciones mutualísticas con raíces de plantas y pueden mejorar la sobrevivencia y resistencia al estrés. Recientemente se ha propuesto usar hongos endófitos de la Antártida para facilitar la reintroducción y establecimiento de plantas nativas en formaciones xerofíticas del norte de Chile. En esta nota se sugiere que aquello es una propuesta riesgosa y puede conducir a invasiones biológicas. Es difícil predecir qué especies se convertirán en invasoras, dónde lo harán o cuáles serán sus efectos. Los organismos transportados entre continentes pueden o no convertirse en invasores, según las interacciones entre especies y con la comunidad invadida, y pueden ocurrir resultados inesperados debido a adaptaciones de especies invasoras al nuevo ambiente y a novedosas interacciones con especies introducidas en el nuevo ambiente. Estos endófitos mutualistas pueden tener efectos negativos en la comunidad receptora, como promover invasiones de otras especies exóticas o cambiar relaciones de competencia entre especies nativas. Los hongos endófitos de la Antártida no garantizan que no puedan invadir otros lugares. La falta de identificación taxonómica de tales hongos impide saber si estos inóculos contienen especies no beneficiosas, como patógenos del suelo. Los microorganismos invasores son extremadamente difíciles de controlar. Por ello, se recomienda que la translocación, uso y dispersión de hongos endófitos antárcicos debiera detenerse hasta tener una evaluación del riesgo de su introducción. Medidas de bioseguridad deben tomarse en experimentos transcontinentales. Según experiencias anteriores, el riesgo y costos potenciales de introducir estas especies pueden superar ampliamente cualquier beneficio potencial de su uso.Fil: Nuñez, Martin A. Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad del Comahue. INIBIOMA. Grupo de Ecología de Invasiones; ArgentinaFil: Dimarco, Romina Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas-Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; ArgentinaFil: Dickie, Ian A. Lincoln University. Bio-Protection Research Centre; Nueva ZelandaFil: Pauchard, Anibal. Universidad de Concepción. Facultad de Ciencias Forestales. Laboratorio de Invasiones Biolóogicas; Chile. Institute of Ecology and Biodiversity (IEB); Chil

Herbivory patterns of six woody species from the temperate forest of South America : preliminar evidence to the carbon–nutrient balance hypothesis

La hipótesis del balance carbono-nutrientes (HBCN) explica las variaciones intraespecíficas en los niveles de herbivoría sugiriendo que, cuando una planta adquiere recursos que exceden la demanda de crecimiento (e.g., luz), dichos recursos son derivados a la producción de defensas químicas. Nosotros documentamos las variaciones intraespecíficas de los niveles de herbivoría en seis especies leñosas del bosque templado de América del Sur para determinar si dichas variaciones apoyan lo esperado por la HBCN. Para todas las especies, las plantas ubicadas en sitios con mayor disponibilidad de luz tuvieron entre 1.2-5 veces menor porcentaje de daño foliar que aquellas ubicadas en sitios con menor disponibilidad de luz. Estos resultados, aunque preliminares, apoyan la HBCN. Futuros estudios deberían determinar si los mecanismos responsables de este patrón coinciden con los propuestos por esta hipótesis.The carbon-nutrient balance hypothesis (CNBH) explains the intraspecific variation in herbivory levels suggesting that, when plants acquire resources in excess of growth demands (e.g., light), these resources are shunted into production of chemical defenses. We documented the intraspecific variation of herbivory levels in six woody plant species from the South American temperate forest to determine whether these patterns support the predictions of the CNBH. For all the species studied, plants located in sites with high light availability showed between 1.2-5 times less foliar damage than those located in sites with low light availability. These results, although preliminary, support the CNBH. Future studies could test whether the mechanisms responsible for this pattern are those proposed by the CNBH

Exotic Mammals Disperse Exotic Fungi That Promote Invasion by Exotic Trees

Biological invasions are often complex phenomena because many factors influence their outcome. One key aspect is how non-natives interact with the local biota. Interaction with local species may be especially important for exotic species that require an obligatory mutualist, such as Pinaceae species that need ectomycorrhizal (EM) fungi. EM fungi and seeds of Pinaceae disperse independently, so they may use different vectors. We studied the role of exotic mammals as dispersal agents of EM fungi on Isla Victoria, Argentina, where many Pinaceae species have been introduced. Only a few of these tree species have become invasive, and they are found in high densities only near plantations, partly because these Pinaceae trees lack proper EM fungi when their seeds land far from plantations. Native mammals (a dwarf deer and rodents) are rare around plantations and do not appear to play a role in these invasions. With greenhouse experiments using animal feces as inoculum, plus observational and molecular studies, we found that wild boar and deer, both non-native, are dispersing EM fungi. Approximately 30% of the Pinaceae seedlings growing with feces of wild boar and 15% of the seedlings growing with deer feces were colonized by non-native EM fungi. Seedlings growing in control pots were not colonized by EM fungi. We found a low diversity of fungi colonizing the seedlings, with the hypogeous Rhizopogon as the most abundant genus. Wild boar, a recent introduction to the island, appear to be the main animal dispersing the fungi and may be playing a key role in facilitating the invasion of pine trees and even triggering their spread. These results show that interactions among non-natives help explain pine invasions in our study area.Fil: Nuñez, Martin Andres. University Of Tennessee; Estados Unidos; . Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Hayward, Jeremy. State University Of New York; Estados UnidosFil: Horton, Thomas R.. State University Of New York; Estados UnidosFil: Amico, Guillermo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación en Biodiversidad y Medioambiente; ArgentinaFil: Dimarco, Romina Daniela. University Of Tennessee; Estados Unidos;Fil: Barrios Garcia, M. Noelia. University Of Tennessee; Estados UnidosFil: Simberloff, Daniel. University Of Tennessee; Estados Unidos

Sheep feeding preference as a tool to control pine invasion in Patagonia: influence of foliar toughness, terpenoids and resin content

Herbivores modulate the structure and composition of plant communities, including plant invasions. This is conditioned by plant palatability which can be reduced by its chemical or physical traits. The effects that ungulates browsing has on pine invasions are variable and the empirical evidence on the causes of this variability is scarce. We experimentally explored how sheep browsing preference varies between seedlings of pine species with different invasiveness; Pinus contorta (high invasiveness), P. ponderosa (medium invasiveness), P. radiata (medium invasiveness) and P. jeffreyi (low invasiveness). Secondly, we quantified anti-herbivory chemical compounds and physical traits of these species and related them with sheep preference observed. The browsing incidence of P. contorta was 68%, P. ponderosa 58%, P. radiata 29%, and P. jeffreyi 84%. Among anti-herbivory traits analyzed, α-pinene concentration had a negative effect on the probability of a terminal bud being browsed and on browsing intensity. Meanwhile, foliar toughness was negatively related to browsing intensity and water concentration was positively related to browsing intensity. Also, the most invasive species, P. contorta, was highly damaged. Thus, sheep herbivory could be slowing pine invasion rate; suggesting that could be considered a tool to control early invasions, especially for this particular species.Fil: Zamora Nasca, Lucía Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Dimarco, Romina Daniela. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; ArgentinaFil: Nassini, Daniela. Comisión Nacional de Energía Atómica. Gerencia Complejo Tecnológico Pilcaniyeu; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alvear, Pablo Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Mayoral, Ariel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Nuñez, Martin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Relva, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Think globally, measure locally: The MIREN standardized protocol for monitoring plant species distributions along elevation gradients

Climate change and other global change drivers threaten plant diversity in mountains worldwide. A widely documented response to such environmental modifications is for plant species to change their elevational ranges. Range shifts are often idiosyncratic and difficult to generalize, partly due to variation in sampling methods. There is thus a need for a standardized monitoring strategy that can be applied across mountain regions to assess distribution changes and community turnover of native and non-native plant species over space and time. Here, we present a conceptually intuitive and standardized protocol developed by the Mountain Invasion Research Network (MIREN) to systematically quantify global patterns of native and non-native species distributions along elevation gradients and shifts arising from interactive effects of climate change and human disturbance. Usually repeated every five years, surveys consist of 20 sample sites located at equal elevation increments along three replicate roads per sampling region. At each site, three plots extend from the side of a mountain road into surrounding natural vegetation. The protocol has been successfully used in 18 regions worldwide from 2007 to present. Analyses of one point in time already generated some salient results, and revealed region-specific elevational patterns of native plant species richness, but a globally consistent elevational decline in non-native species richness. Non-native plants were also more abundant directly adjacent to road edges, suggesting that disturbed roadsides serve as a vector for invasions into mountains. From the upcoming analyses of time series, even more exciting results can be expected, especially about range shifts. Implementing the protocol in more mountain regions globally would help to generate a more complete picture of how global change alters species distributions. This would inform conservation policy in mountain ecosystems, where some conservation policies remain poorly implemented.EEA BarilocheFil: Haider, Sylvia. German Centre for Integrative Biodiversity Research; AlemaniaFil: Haider, Sylvia. Martin Luther University. Institute of Biology. Geobotany and Botanical Garden; AlemaniaFil: Lembrechts, Jonas Johan. University of Antwerp. Centre of Excellence Plants and Ecosystems (PLECO); BélgicaFil: McDougall, Keith. Department of Planning, Industry and Environment; AustraliaFil: Pauchard, Aníbal. Universidad de Concepción. Facultad de Ciencias Forestales. Laboratorio de Invasiones Biológicas; ChileFil: Pauchard, Aníbal. Institute of Ecology and Biodiversity (IEB); ChileFil: Alexander, Jake M. Institute of Integrative Biology; SuizaFil: Barros, Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico. Instituto Argentino de Nivología y Glaciología y Ciencias Ambientales (IANIGLA); ArgentinaFil: Cavieres, Lohengrin A. Universidad de Concepción. Facultad de Ciencias Naturales y Oceanográficas. Departamento de Botánica; ChileFil: Cavieres, Lohengrin A. Institute of Ecology and Biodiversity (IEB); ChileFil: Rashid, Irfan. University of Kashmir. Department of Botany; IndiaFil: Rew, Lisa J. Montana State University. Department of Land Resource and Environmental Sciences; Estados UnidosFil: Aleksanyan, Alla. Institute of Botany aft. A.L. Takhtajyan NAS RA. Department of Geobotany and Plant Ecophysiology; ArmeniaFil: Aleksanyan, Alla. Armenian National Agrarian University. Chair of Biology and Biotechnologies; ArmeniaFil: Dimarco, Romina Daniela. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. Grupo de Ecología de Poblaciones de Insectos; ArgentinaFil: Dimarco, Romina Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. Grupo de Ecología de Poblaciones de Insectos; ArgentinaFil: Dimarco, Romina Daniela. University of Houston. Department of Biology and Biochemistry; Estados UnidosFil: Seipel, Tim. Montana State University. Department of Land Resource and Environmental Sciences; Estados Unido

Global Invader Impact Network (GIIN): toward standardized evaluation of the ecological impacts of invasive plants

Terrestrial invasive plants are a global problem and are becoming ubiquitous components of most ecosystems. They are implicated in altering disturbance regimes, reducing biodiversity, and changing ecosystem function, sometimes in profound and irreversible ways. However, the ecological impacts of most invasive plants have not been studied experimentally, and most research to date focuses on few types of impacts, which can vary greatly among studies. Thus, our knowledge of existing ecological impacts ascribed to invasive plants is surprisingly limited in both breadth and depth. Our aim was to propose a standard methodology for quantifying baseline ecological impact that, in theory, is scalable to any terrestrial plant invader (e.g., annual grasses to trees) and any invaded system (e.g., grassland to forest). The Global Invader Impact Network (GIIN) is a coordinated distributed experiment composed of an observational and manipulative methodology. The protocol consists of a series of plots located in (1) an invaded area; (2) an adjacent removal treatment within the invaded area; and (3) a spatially separate uninvaded area thought to be similar to pre-invasion conditions of the invaded area. A standardized and inexpensive suite of community, soil, and ecosystem metrics are collected allowing broad comparisons among measurements, populations, and species. The method allows for one-time comparisons and for long-term monitoring enabling one to derive information about change due to invasion over time. Invader removal plots will also allow for quantification of legacy effects and their return rates, which will be monitored for several years. GIIN uses a nested hierarchical scale approach encompassing multiple sites, regions, and continents. Currently, GIIN has network members in six countries, with new members encouraged. To date, study species include representatives of annual and perennial grasses; annual and perennial forbs; shrubs; and trees. The goal of the GIIN framework is to create a standard yet flexible platform for understanding the ecological impacts of invasive plants, allowing both individual and synthetic analyses across a range of taxa and ecosystems. If broadly adopted, this standard approach will offer unique insight into the ecological impacts of invasive plants at local, regional, and global scales.Fil: Barney, Jacob N. Virginia Tech. Department of Plant Pathology, Physiology, and Weed Science; Estados UnidosFil: Tekiela, Daniel R. Virginia Tech. Department of Plant Pathology, Physiology, and Weed Science; Estados UnidosFil: Barrios Garcia Moar, Maria Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. CENAC-APN; ArgentinaFil: Dimarco, Romina Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas-Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Grupo de Ecología de Poblaciones de Insectos; ArgentinaFil: Hufbauer, Ruth A. Colorado State University. Department of Bioagricultural Sciences and Pest Management and Graduate Degree Program in Ecology; Estados UnidosFil: Leipzig-Scott, Peter. Colorado State University. Department of Bioagricultural Sciences and Pest Management and Graduate Degree Program in Ecology; Estados UnidosFil: Nuñez, Martin A. Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad del Comahue. INIBIOMA. Laboratorio de Ecotono; ArgentinaFil: Pauchard, Anibal. Universidad de Concepción. Facultad de Ciencias Forestales. Laboratorio de Invasiones Biolóogicas; Chile. Institute of Ecology and Biodiversity (IEB); ChileFil: Pysek, Petr. The Czech Academy of Sciences. Institute of Botany. Department of Invasion Ecology; República Checa. Charles University in Prague. Faculty of Science. Department of Ecology; República ChecaFil: Viıtkov, Michaela. The Czech Academy of Sciences. Institute of Botany. Department of Invasion Ecology; República ChecaFil: Maxwell, Bruce D. Montana State University. Department of Land Resources and Environmental Sciences; Estados Unido