The contribution of the edaphic factor as a driver of recent plant diversification in a Mediterranean biodiversity hotspot

1. The high diversification rates of plant lineages in the Mediterranean
Basin hotspot have been linked to a complex interaction of climatic
stressors, geographic isolation and soil type, but the question remains as
to which of these factors has been the most significant environmental
driver of recent speciation. 2. Here, we draw on distributional data for
the entire endemic flora of the Iberian Peninsula, together with DNA-based
phylogenies and spatial phylogenetic methods, to explore patterns of
relative phylogenetic endemism at different spatial resolutions and
phylogenetic scales (superclades) and assess how environmental factors
contribute to explain these patterns. 3. We found that recent
diversification of angiosperms as a whole, and particularly of eudicots,
has been boosted by environmental stressors including high values of soil
pH and dry-seasonal climatic conditions, while diversification of monocots
has not been associated with soil conditions but with high elevation and
less seasonal climate. 4. Synthesis. These results provide robust insights
into the environmental factors driving recent plant diversification in the
Mediterranean Basin, including a role of soil properties that had not been
quantified before. The contrasting environmental drivers of
diversification in Eudicots and Monocots highlight the importance of
analyzing spatial phylogenetic patterns at multiple phylogenetic scales to
get a better understanding of the processes that shape biodiversity.