nemesia_plate_smallOur ability to recognize species and correctly assign individuals to them, are fundamental to the basic understanding of biodiversity and have broad implications for efforts ranging from biological conservation to comparative genomics. Species are heterogeneous evolving entities, which delimitation requires the integration of multiple lines of evidence. Recent technological and theoretical advances have renewed biologists’ interest in the issue of delimiting species. In this project, we propose to investigate species boundaries in two highly diverse, yet taxonomically difficult spider genera with contrasting evolutionary patterns. The Canarian woodlouse-hunter spiders (Dysdera) provide a spectacular example of species diversification on islands, where phenotypic differentiation has most likely outpaced random genetic differentiation. Mediterranean Nemesia, on the other hand, includes species with little morphological differentiation but deep genetic structure over short distances. Here, we aim to delimit species and infer drivers and mechanisms of diversification in these two spider groups by integrating genetic, phenotypic and ecological evidence. Up until now, the application of state of the art multilocus approaches to species delimitation and species tree inference in non-model organisms was hampered by the lack of genomic information. We will circumvent this limitation by using Next Generation Sequencing tools for developing novel markers and sequencing them in hundreds of taxa. Moreover, we will use geometric morphometrics and species distribution modelling techniques to seamless integrate morphological and ecological evidence with the information provided by molecules. Armed with these tools, we will further test specific hypotheses regarding the evolutionary processes behind the diversification of both genera. In Dysdera, we will investigate if the observed changes in mouthparts morphology are the result of dietary specialization (oniscophagy) and if ecological segregation has accelerated diversification rates. In Nemesia, we will disentangle the role of environmental variables, historical factors and dispersal capability in limiting species geographical ranges and will test if burrow architecture explains local patterns of species co-occurrence. Finally, as an example of the far-reaching relevance of the project, we will elaborate a prioritized list of relevant areas for conservation in the Iberian peninsula based on the endemism-richness and phylogenetic diversity of Nemesia. The genus is well suited as a bioindicator because of its poor dispersal capabilities and life cycle features