Mecanismos ecológicos que determinan los procesos de invasión biológica de leguminosas leñosas a lo largo de gradientes ambientales.
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Date
2024
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Publisher
Universidad de Concepción
Abstract
Las invasiones biológicas se refieren a especies introducidas fuera de su área natural de distribución por acción humana, lo cual tiene un impacto severo en los ecosistemas y la biodiversidad nativa. Para que una especie se convierta en invasora, debe superar diferentes filtros bióticos y abióticos asociados con sus etapas de invasión (transporte, colonización, establecimiento e invasión). En general, el filtrado ambiental determina la colonización de las especies e interfiere significativamente en sus procesos de invasión. Una vez que las especies sobreviven al filtrado ambiental, deben pasar filtros bióticos como la competencia con especies nativas para establecer y generar poblaciones viables. Además, deben superar a las especies nativas para expandirse a nuevas áreas y lograr una invasión exitosa.
Así, i) tener diferencias en la adquisición y uso de recursos en comparación con las especies nativas, ii) presentar diferentes estrategias funcionales dependiendo de los recursos disponibles, iii) tener una alta variabilidad en sus rasgos funcionales, y iv) exhibir rasgos funcionales novedosos permite a las plantas invasoras superar los filtros bióticos y abióticos, facilitando su invasión en diferentes ambientes. En este estudio, elegimos la familia FABACEAE (leguminosas) como modelo de estudio debido a que es una de las familias con mayor número de especies invasoras reportadas a nivel mundial. Específicamente, se enfatiza en especies leñosas invasoras, ya que están experimentando procesos de invasión en todos los continentes y ecosistemas terrestres. El objetivo principal de este estudio fue profundizar en los mecanismos ecológicos que rigen los procesos de invasión biológica de leguminosas leñosas invasoras a lo largo de gradientes ambientales. Este estudio adopta un enfoque novedoso, utilizando la ecología funcional como marco integrador para entender las respuestas de las especies a la variación ambiental. Los dos primeros capítulos del estudio se centran en análisis climáticos y funcionales globales, utilizando la Densidad de Probabilidad de Rasgos (TPD) como método principal de análisis. En los capítulos 3 y 4, se utiliza el gradiente de elevación para comprender las respuestas funcionales a diferentes condiciones ambientales. El capítulo 3 es un análisis regional de la cordillera de los Andes que incluye comparaciones entre comunidades de leguminosas leñosas invasoras y la comunidad local. Finalmente, el capítulo 4 es un estudio local de los ecosistemas andinos de la cordillera de los Andes en Colombia, que incluye la variabilidad intraespecífica de 15 rasgos funcionales de la especie invasora Ulex europaeus a lo largo del gradiente de elevación.
Los hallazgos clave de esta tesis revelan que el filtrado ambiental juega un papel sustancial en los procesos de invasión de las especies de leguminosas leñosas invasoras, con muchas de estas especies mostrando una disociación en las condiciones ambientales entre sus áreas de distribución nativas e introducidas. A escala global, las especies de leguminosas leñosas invasoras parecen tener rasgos funcionales similares a las plantas no invasoras. Sin embargo, al afiliarlas por grupos climáticos basados en cambios en su distribución, se identificaron diferencias funcionales con especies no invasoras, especialmente en nitrógeno foliar y densidad de madera. Estos hallazgos proporcionan nuevos conocimientos sobre la ecología funcional de las leguminosas leñosas invasoras. A escala regional, la comunidad de leguminosas leñosas invasoras mostró variabilidad en sus rasgos funcionales a lo largo de un gradiente de elevación en la cordillera de los Andes, con una combinación de rasgos foliares más conservadores y rasgos de tallo más adquisitivos en altitudes más altas, y exhibió algunas diferencias funcionales con la comunidad local a lo largo del gradiente de elevación. Además, la especie invasora Ulex europaeus mostró variación intraespecífica en rasgos funcionales, principalmente en rasgos de semillas, a lo largo del gradiente de elevación, con semillas menos numerosas, pero más pesadas.
Finalmente, aunque todas las especies están relacionadas filogenéticamente, exhiben comportamientos diferentes asociados con las condiciones ambientales de sus áreas de distribución. Estas mismas condiciones imparten la selección de características funcionales específicas que favorecen a las leguminosas leñosas invasoras, presentando rasgos para una mayor adquisición y uso de recursos que las especies no nativas, independientemente de las limitaciones ambientales, otorgándoles una ventaja competitiva. En el caso de Ulex europaeus, su variabilidad en rasgos de semillas es la estrategia empleada para maximizar su establecimiento en diferentes condiciones ambientales.
Biological invasions refer to species introduced outside their natural distribution area by human action, which severely impacts ecosystems and native biodiversity. For a species to become invasive, it must overcome different biotic and abiotic filters associated with its stages of invasion (transport, colonization, establishment, and invasion). Environmental filtering generally determines species colonization and significantly interferes with their invasion processes. Once species survive environmental filters, they must pass biotic filters, such as competition with native species, to establish and generate viable populations. Additionally, they must outperform native species to spread to new areas and achieve successful invasion. Thus, i) having differences in resource acquisition and use compared to native species, ii) presenting different functional strategies depending on available resources, iii) having high variability in their functional traits, and iv) exhibiting novel functional traits allows invasive plants to overcome biotic and abiotic filters, facilitating their invasion in different environments. In this study, we chose the family FABACEAE (legumes) as the study model because it is one of the families with the highest number of invasive species reported worldwide. Precisely, emphasis is placed on invasive woody species, as they are undergoing invasion processes on all continents and terrestrial ecosystems. The main objective of this study was to delve into the ecological mechanisms that dictate the biological invasion processes of invasive woody legumes across environmental gradients. This study takes a unique approach, using functional ecology as an integrative framework to understand species' responses to environmental variation. The first two chapters of the study focus on global climatic and functional analyses, utilizing the Trait Probability Density (TPD) as the primary method. In chapters 3 and 4, the elevation gradient is used to comprehend functional responses to different environmental conditions. Chapter 3 is a regional analysis of the Andes Mountains that includes comparisons between invasive woody legume communities and the local community. Finally, chapter 4 is a local study of Andean ecosystems of the Andes Mountains in Colombia, which includes intraspecific variability of 15 functional traits of the invasive Ulex europaeus along the elevation gradient. The key findings of this study are significant. They reveal that environmental filtering plays a substantial role in the invasion processes of invasive woody legume species, with many of these species showing a dissociation in environmental conditions between their native and introduced distribution areas. At a global scale, invasive woody legume species appear to have functional traits similar to those of non-invasive plants. However, when classified into climatic groups based on changes in their distribution, functional differences with non invasive species were identified, particularly in foliar nitrogen and wood density. These findings provide novel insights into the functional ecology of invasive woody legumes. At a regional scale, the invasive woody legume community showed variability in its functional traits along an elevation gradient in the Andes Mountains, with a combination of more conservative foliar traits and more acquisitive stem traits at higher altitudes, and exhibited some functional differences with the local community along the elevation gradient. Additionally, the invasive species U. europaeus showed intraspecific variation in functional traits, mainly seed traits, along the elevation gradient, with fewer but heavier seeds. Finally, although all species are phylogenetically related, they exhibit different behaviors associated with the environmental conditions of their distribution areas. These same conditions impart the selection of specific functional characteristics that favor invasive woody legumes, presenting traits for more significant resource acquisition and use than non-native species, regardless of environmental constraints, giving them a competitive advantage. In the case of U. europaeus, its variability in seed traits is the strategy employed to maximize its establishment in different environmental conditions.
Biological invasions refer to species introduced outside their natural distribution area by human action, which severely impacts ecosystems and native biodiversity. For a species to become invasive, it must overcome different biotic and abiotic filters associated with its stages of invasion (transport, colonization, establishment, and invasion). Environmental filtering generally determines species colonization and significantly interferes with their invasion processes. Once species survive environmental filters, they must pass biotic filters, such as competition with native species, to establish and generate viable populations. Additionally, they must outperform native species to spread to new areas and achieve successful invasion. Thus, i) having differences in resource acquisition and use compared to native species, ii) presenting different functional strategies depending on available resources, iii) having high variability in their functional traits, and iv) exhibiting novel functional traits allows invasive plants to overcome biotic and abiotic filters, facilitating their invasion in different environments. In this study, we chose the family FABACEAE (legumes) as the study model because it is one of the families with the highest number of invasive species reported worldwide. Precisely, emphasis is placed on invasive woody species, as they are undergoing invasion processes on all continents and terrestrial ecosystems. The main objective of this study was to delve into the ecological mechanisms that dictate the biological invasion processes of invasive woody legumes across environmental gradients. This study takes a unique approach, using functional ecology as an integrative framework to understand species' responses to environmental variation. The first two chapters of the study focus on global climatic and functional analyses, utilizing the Trait Probability Density (TPD) as the primary method. In chapters 3 and 4, the elevation gradient is used to comprehend functional responses to different environmental conditions. Chapter 3 is a regional analysis of the Andes Mountains that includes comparisons between invasive woody legume communities and the local community. Finally, chapter 4 is a local study of Andean ecosystems of the Andes Mountains in Colombia, which includes intraspecific variability of 15 functional traits of the invasive Ulex europaeus along the elevation gradient. The key findings of this study are significant. They reveal that environmental filtering plays a substantial role in the invasion processes of invasive woody legume species, with many of these species showing a dissociation in environmental conditions between their native and introduced distribution areas. At a global scale, invasive woody legume species appear to have functional traits similar to those of non-invasive plants. However, when classified into climatic groups based on changes in their distribution, functional differences with non invasive species were identified, particularly in foliar nitrogen and wood density. These findings provide novel insights into the functional ecology of invasive woody legumes. At a regional scale, the invasive woody legume community showed variability in its functional traits along an elevation gradient in the Andes Mountains, with a combination of more conservative foliar traits and more acquisitive stem traits at higher altitudes, and exhibited some functional differences with the local community along the elevation gradient. Additionally, the invasive species U. europaeus showed intraspecific variation in functional traits, mainly seed traits, along the elevation gradient, with fewer but heavier seeds. Finally, although all species are phylogenetically related, they exhibit different behaviors associated with the environmental conditions of their distribution areas. These same conditions impart the selection of specific functional characteristics that favor invasive woody legumes, presenting traits for more significant resource acquisition and use than non-native species, regardless of environmental constraints, giving them a competitive advantage. In the case of U. europaeus, its variability in seed traits is the strategy employed to maximize its establishment in different environmental conditions.
Description
Tesis presentada para optar al grado de Doctora en Ciencias Forestales
Keywords
Ecología, Biodiversidad, Invasiones biológicas