Resumen de Reconciling standardized inventories and dna barcoding to infer diversity paterns in iberian spider communities
Unveiling the patterns and identifying the factors that drive community assembly are key questions in ecology and evolution, especially in the current state of climate change and biodiversity loss. Because of its particular location, its geological and climatic history, and its complex relief, the Iberian provides an excellent arena for the study of past and present patterns of biodiversity and its drivers. In this thesis, we aim at revealing patterns of taxonomic, functional and phylogenetic diversity and the determinants of community assembly in spiders from white-oak forests across the Iberian Peninsula. We generated more than 3,200 DNA barcodes from 371 species, which greatly increased the DNA barcode reference library of Iberian spiders for future studies. We also combined morphological and molecular species delimitation methods to identify instances of overlooked diversity, which allowed us to discover and describe a new species and to detect an instance of introgression between closely related species. We also revealed that certain functional traits of spiders are related to high levels of population structure, which can help us to characterise those groups that might be more vulnerable to local extinctions. We investigated the impact of adding information of juvenile spiders, which are usually discarded because they are not morphologically identifiable to species level, on diversity estimates by means of metabarcoding approaches. We found that they contribute a large proportion of extra diversity, and that they can change our interpretations of the differences among communities based on species composition. We further determined that metabarcoding approaches, if properly corrected, may also contribute abundance information to diversity estimates. Estimating the phylogenetic diversity of a community requires building a robust tree for the species of interest. We decided to investigate some of the variables that may influence the estimation of phylogenetic diversity. We found that combining at least one mitochondrial and one nuclear genes of the species of interest and including a backbone with additional species and genes had the greatest impact in phylogenetic inference, followed by the incorporation of time information and by enforcing a topological. We assessed the alpha taxonomic, functional and phylogenetic diversity of Iberian spider communities, and we found that they provide different yet complementary information, which is fundamental for designing effective conservation strategies. We uncovered the importance of past climatic conditions to explain the levels of phylogenetic diversity of the communities but not those of functional diversity. Differences in environmental variables among communities, on the other hand, did not explain the variation observed in functional and phylogenetic diversity, most likely because of both the high habitat type similarity and the relatively narrow geographic scope of the study.
