Tracing the evolutionary history of the genus hellianthenum and the radiation in Macaronesia

Spanish National Plan for R+D+i (CGL2017-82465-P). PI: A. Aparicio. 2018-2020.

Tracing the evolutionary history of species requires the estimation of divergence times along with phylogenetic and ancestral area reconstructions and the study of functional traits evolution. The genus Helianthemum is integrated by three cohesive Clades whose differentiation started in the Miocene about 7.8 Mya which nowadays are distributed and concentrated in different areas around the Mediterranean Basin and have different ecological preferences. One such areas of high diversity is the Canary archipelago where the two Macaronesian lineages of Helianthemum (i. e. sect. Eriocarpum and sect. Helianthemum) show a significantly different level of differentiation with 3 and 14 species respectively, probably originated by a recent (0.4 Mya) and explosive burst of diversification within the sect. Helianthemum, and a high degree of endemicity (15 out of 16 species). In this project we consider two general objectives designed with different taxonomical and geographical scales: (i) to trace the evolutionary history of Helianthemum assessing the phylogenetic relationships, divergence times and ancestral area reconstruction (c. 130 taxa, Old World), and, once defined and detected the sister lineages of the Macaronesian species, (ii) to disentangle their biogeographic history (divergence times, colonization history, patterns of endemicity and diversification boosters). To do so, our first objective is to complete a well-resolved phylogenetic reconstruction based in GBS sequences (genotyping-by-sequencing) derived from Next-generation sequencing molecular techniques as the framework to explore biogeographic events (i. e. extinction, vicariance, dispersal, duplication). Nested with the previous taxonomic and geographic scale we aim to characterize the evolutionary history of the two Macaronesian (Canary Islands and Cape Verde) lineages by inferring, on the one hand, the number of colonization events and their temporal and geographical origins and, on the other, assessing diversification rates and genome size, hypothesizing an increase of diversification rates an a reduction of genome size of the Macaronesian endemics compared their non Macaronesian relative sister species. We also aim to assess if the fact that most Canarian species are critically endangered is consequence of recent species formation (i. e. early stages of range expansion) or, contrarily, the last stages of ancient species due to recurrent population extinction. This last approach would further enhance this project under a conservation biology perspective.