Dataset obtained for the preparation of the manuscript "Strong floral morphology conservatism during the rapid diversification of the genus Helianthemum" based on the analysis of 1122 flowers and 83 Helianthemum taxa

Abstract

Premise: Divergence of floral morphology and breeding systems are often expected to be linked to angiosperm diversification and environmental niche divergence. However, available evidence for such relationships remain idiosyncratic, due to different taxonomic, geographical and time scales. The Palearctic genus Helianthemum shows the highest diversity of the family Cistaceae in terms of breeding systems, floral traits and environmental conditions, resulting from three recent evolutionary radiations occurred since the Late Miocene. Here, we investigate the tempo and mode of evolution of floral morphology in the genus, and its link with species diversification and environmental niche divergence. Methods: We quantified eighteen floral traits from 83 taxa and applied phylogenetic comparative methods using a robust phylogenetic framework based on genotyping by sequencing data. Results: The results revealed three different floral morphologies, putatively related to three different breeding systems: (i) type I, characterized by small flowers without herkogamy and low pollen to ovule ratio; (ii) type II, represented by large flowers with approach herkogamy and intermediate pollen to ovule ratio; and (iii) type III, featured by small flowers with reverse herkogamy and the highest pollen to ovule ratio. Each morphology has been highly conserved across each radiation and has evolved independently of species diversification and ecological niche divergence. Conclusions: The combined results of trait, niche and species diversification ultimately recovered a pattern of potentially non-adaptive radiations in Helianthemum and highlight the idea that evolutionary radiations can be decoupled from floral morphology evolution even in lineages that diversified in heterogeneous environments as the Mediterranean Basin.