Reconstruction of the spatio-temporal diversification and ecological niche evolution of Helianthemum (Cistaceae) in the Canary Islands using Genotyping-by-Sequencing data.

BACKGROUND AND AIMS: Several biogeographic models have been proposed to explain the colonization and diversification patterns of Macaronesian lineages. In this study, we calculated the diversification rates and explored what model better explains the current distribution of the 15 endemic species to the Canary Islands belonging to Helianthemum sect. Helianthemum (Cistaceae). METHODS: We performed robust phylogenetic reconstructions based on genotyping-by-sequencing (GBS) data and analysed the timing, the biogeographical history and the ecological niche conservatism of this endemic Canarian clade. KEY RESULTS: Our phylogenetic analyses provide strong support for the monophyly of this clade, and retrieved five lineages not currently restricted to a single island. The pristine colonization event took place in the Pleistocene (c. 1.82 Ma) via dispersal to Tenerife by a Mediterranean ancestor. CONCLUSIONS: The rapid and abundant diversification (0.75-1.85 spp. Ma-1) undergone by this Canarian clade seems the result of complex inter-island dispersal events followed by allopatric speciation driven mostly by niche conservatism, i.e. inter-island dispersal towards niches featuring similar environmental conditions. Nevertheless, significant instances of ecological niche shifts have also been observed in some lineages, remarkably contributing to the overall diversification history of this clade.