Diversidad de hongos endófitos asociados al frailejón (Espeletia hartwegiana) en un marco de cambio climático, páramo de Romerales, Quindío, Colombia

Debido al aumento global de las temperaturas impulsado por el cambio climático de origen antropogénico, y a la poca información que se tiene sobre hongos endófitos en especies de los páramos, esta investigación buscó identificar y caracterizar la diversidad de hongos endófitos del frailejón Espeletia hartwegiana. Esta especie habita en los páramos desde 3000 a 5000 metros de lo que la hace una especie más vulnerable a los aumentos de temperatura que se pronostican para el año 2100 de hasta 2.5°C. La identificación y caracterización de los hongos endófitos se realizó por medio de técnicas filogenia molecular basado en datos de secuencias de genes múltiples de las regiones espaciadoras transcritas internas (ITS), en donde se encontraron un total de 15 géneros de endófitos como Nigrospora, Trichoderma y Diaporthe con un total de 35 especies. Los hongos endófitos encontrados podrían tener un rol vital en la supervivencia de esta especie de frailejón mediando la forma en cómo responde al estrés abiótico producido por el cambio climático como aumento de la temperatura, cambio en las precipitaciones y sequías, además del estrés biótico como virus, baterías, insectos y hongos fitopatógenos

Ecological Niches, Species Distributions, And Biogeographic Processes In Rodents On Neotropical Sky Islands

This dissertation focused on the methodological and theoretical improvement of correlative ecological niche models (ENMs) to better understand the processes governing species distributions and associated evolutionary divergence in rodents inhabiting mesic conditions in the Neotropics. Focusing on a widespread rodent from northern South America (Heteromys anomalus), in the first chapter I proposed and tested a methodological approach to surmount the challenge of incorporating environmental information from the margins of species geographic ranges into ENMs. In so doing, I argue how populations that exist on the borders of species\u27 local ranges (spatial margins) can lead to exaggerated estimates of their niches and potential geographic distributions due to issues of variable choice and resolution. In the second chapter, I demonstrated how the approach developed in Chapter 1 improved the ability of ENMs to detect an obvious environmental barrier fostering isolation and potential divergence between continental and peninsular populations in three rodent lineages in northern South America: Proechimys guairae, Rhipidomys venezuelae, and the Heteromys anomalus/H. oasicus species pair. In the third chapter, I integrated ENMs with molecular data to test the effect of the climatic oscillations of the late Quaternary Period in two species of rodents restricted to the sky islands of Costa Rica and western Panama: Reithrodontomys creper and Nephelomys devius. Overall, results revealed how, despite sharing similar distribution patterns, niche differences in these species resulted in idiosyncratic responses to past climate change that match currently observed patterns of genetic diversity. Finally, in the fourth chapter, I developed a perspective of the ecological niche concept that takes into account the responsiveness of phenotypes and the variability of ecological strategies that a species can perform. Integrating these aspects into niche theory leads to a more holistic perspective that reduces conflict between niche definitions, dissolves existing paradoxes, and has multiple implications for the study of niches, their evolution, and their effect on lineage divergence. Overall, this dissertation contributes to the conceptual and methodological development of correlative approaches for modeling species Grinnellian niches and their associated potential geographic distributions; the understanding of how these relate to the evolutionary history of Neotropical montane taxa with regards to past climate change; and finally, to a more holistic perspective of the niche concept that has multiple implications for the study of niches in general, as well as our understanding of how they evolve and affect lineage divergence