Parallel bursts of recent and rapid radiation in the Mediterranean and Eritreo‐Arabian biodiversity hotspots as revealed byGlobulariaandCampylanthus(Plantaginaceae)

Abstract

AbstractAimMolecular phylogenetic inferences have been important to test hypotheses of the temporal and geographical origin of plant lineages from the Mediterranean region (MR) and their rates of diversification. However, comparisons are still rare between well‐sampled and closely related clades from within and outside theMR. Here, we compare the biogeographical histories and diversification rates between two main genera of woody perennial Plantaginaceae with highest species diversities in theMR(Globularia) and the Eritreo‐Arabian region (EAR;Campylanthus).LocationMediterranean Basin and adjacent regions; Eritreo‐Arabian region.MethodsWe estimated a time‐calibrated phylogeny of theGlobularia+Poskea–Campylanthusclade based on combined nuclear (ITS) and chloroplastDNAsequences for ancestral area reconstructions and within‐ and among‐clade diversification rate analyses.ResultsThe presently disjunct ranges betweenGlobulariaandCampylanthusmost likely reflect dispersal/migration from theEARinto theMRbetween the mid‐early Miocene (c. 9.6 Ma) and the late Pliocene (c. 3.3 Ma). The subsequent diversification ofGlobulariacoincides with that ofCampylanthus(c. 3.5 Ma), with similar rates of constant lineage accumulation in both genera. While the MacaronesianGlobulariaspecies are recent (Late Pleistocene) colonists, most likely from theMR, neither late Plio‐/Pleistocene vicariance nor dispersal‐mediated range evolution can be refuted for Macaronesian versusEARCampylanthus.Main conclusionsThe coupling between low‐ and high‐latitude climate shifts likely triggered the simultaneous diversification at comparable rates ofCampylanthusandGlobulariain, respectively, theEARandMRat the end of the Pliocene. In the extensive and ecogeographically complexMR,Globulariaexperienced increased diversification rates likely triggered by glacial cycles and resulting in adaptive species formation. In contrast, increased diversification rates inCampylanthuslikely were triggered by aridity cycles and resulted in geographical speciation.