Space explorer: floral evolution and lineage diversification of the Neotropical Sapranthinae clade (Annonaceae)

Résumé fourni par la source

Floral morphology influences angiosperm diversification, yet many lineages maintain ancestral traits due to selection pressures. Although ecological speciation can generate novel floral morphologies, such innovations rarely become widespread. Understanding how floral traits persist, shift, or re-emerge offers crucial insights into the evolutionary patterns that reflect the balance between conservation and innovation in plant diversification. Here, we examine the evolutionary dynamics of floral morphology in the Neotropical Sapranthinae clade (Annonaceae, Magnoliidae) using a phylogenomic framework based on hundreds of nuclear loci. We reconstruct species-level relationships, estimate divergence times, and quantify floral morphospace across the clade. Through multivariate and comparative analyses, we assess floral disparity, convergence, and trait evolution, and evaluate their statistical association with diversification rates. Our analyses recovered three monophyletic genera within the Neotropical Sapranthinae-Desmopsis, Sapranthus, and Tridimeris-with divergence times spanning from the Eocene to the Pliocene. We identified seven distinct floral morphs, each defined by unique morphological features. Ancestral state reconstruction indicates the Desmopsis-type flower as the ancestral condition, with six major transitions and two convergence events contributing to floral disparity. Evolutionary modelling supports multiple adaptive optima, while temporal patterns in floral disparity suggest an early burst of floral innovation followed by episodic shifts coinciding with changes in diversification rates. Sapranthinae illustrates dynamic morphospace exploration within Magnoliidae and highlights the macroevolutionary significance of floral disparity in shaping angiosperm diversity.

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