Resumen de New insights on Spatial and Evolutionary patterns in the Iberian vascular fora: Novel methodologies and applications in biogeography and conservation
The Iberian Peninsula is one of the most diverse regions in the Mediterranean Basin hotspot, sheltering around 6,500 vascular plant species and subspecies, of which nearly one third are endemic to the region. Positioned at the convergence of the Mediterranean Sea and the Atlantic Ocean, and characterized by a varied array of topographic landforms and other climatic and edaphic factors, the region exhibits a remarkable diversity of environments. These features have prompted, on the one hand, a notable diversification of plant lineages, and, on the other hand, have favored the colonization and settlement of a great number of species from different origins, thus contributing to the outstanding plant diversity that characterizes the Iberian Peninsula.
The general objective of this thesis was characterizing the distribution patterns of the Iberian flora at the regional scale, evaluating its taxonomic and phylogenetic structure, and identifying priority areas for conservation. To do so, the following specific objectives were pursued: a) compiling a chorological database including distribution information for the Iberian flora at the finest possible scale (10x10 km); b) designing a generalized workflow to expand incomplete phylogenies; c) evaluating the impact of contrasting floristic elements (endemic taxa versus the entire flora), phylogenetic information, and spatial resolution on bioregionalization analyses, and d) identifying areas of the Iberian Peninsula encompassing significantly high values of threatened phylogenetic diversity to inform a list of priority areas for conservation.
In an early stage of the dissertation, information from research papers, regional atlases and global biodiversity repositories was gathered and curated to create the AFLIBER database. This dataset comprises taxonomic and chorological information for the entire vascular plant flora of the Iberian Peninsula, including 6,456 species and subspecies of plants, of which 2,142 are endemic to the region. For each taxon, distributional information using 10-km-side grid cells was recorded. This lookup was performed using both automatic and manual quality filters, and the resultant distribution maps were visually checked by experts. The distribution dataset relies on nearly 2.8 million records, of which 1.8 million correspond to unique occurrences. As a second step in the dissertation, the randtip framework to expand incomplete phylogenies using non-molecular information was created and implemented in an R package. The software uses taxonomic information to designate the phylogenetic segments that most certainly contain phylogenetically uncertain taxa (PUTs) and to bind them below the corresponding clades at a randomly selected point. Beyond providing a comprehensive toolkit of functions to optimally expand incomplete phylogenies, potential pitfalls and opportunities to optimize parameter determination for PUT binding were disclosed.
Equipped with AFLIBER and randtip, the focus was on assessing the importance of i) using distinct floristic elements (endemic taxa versus entire flora), ii) including phylogenetic information, and iii) the spatial resolution, for bioregionalization analyses, identifying which environmental variables more significantly drove each scheme. Endemic species yielded a more topography-driven regionalization, while the whole flora produced bioregions more aligned with other environmental variables, and both taxonomically and phylogenetically informed analyses led to similar bioregionalization schemes. Lastly, we explored the spatial distribution of angiosperm phylogenetic diversity and provided a priority list of areas for conservation using a complementarity analysis. To do so, the evolutionary distinctiveness of the species and their probability of becoming extinct based on global threat assessments were combined into an integrative analysis that revealed 21 complementary areas for conservation, some of which extend beyond currently protected areas.
This doctoral dissertation establishes a foundational framework for exploring spatial and evolutionary dimensions of the flora of the Iberian Peninsula. The incorporation of innovative methodologies developed here offers opportunities for reassessing various macroecological and biogeographic enquiries, including bioregion delimitation and the identification of critical areas for biodiversity conservation. In summary, the materials and methodologies presented here, alongside the obtained results, represent a fresh perspective in the field of plant biogeography, providing a highly valuable framework for analyzing biogeographic and evolutionary patterns, as well as conservation imperatives, in diverse ecosystems and floras worldwide.
