From Genes to Shapes: Exploring Local Adaptation in Carpathian Ox‐Eye Daisies

ABSTRACT Aim Historical processes have shaped the Carpathian biogeography, yet ongoing evolutionary forces continue to drive population differentiation. We aimed to test whether local adaptation in the Carpathian subendemic Leucanthemum rotundifolium correlates with genetic, morphological and environmental factors, and to assess how these patterns relate to established taxonomic concepts. Location The Carpathian Mountains, Central Europe. Taxon The genus Leucanthemum (Asteraceae), with a focus on L. rotundifolium . Methods We analysed multiple populations of L. rotundifolium across its Carpathian distribution. Each individual was characterised using a comprehensive set of measures encompassing: (1) genetic variation via SNP, Silico‐DArT and chloroplast markers; (2) morphological traits, including detailed measurements and shape analysis of involucral bracts; and (3) environmental variables such as climate, soil characteristics, topography and indicators of human disturbance. We first evaluated how these data collectively distinguish different Leucanthemum species and align with current taxonomic concepts. Next, we examined how genetic, morphological and environmental factors interact within L. rotundifolium to differentiate individuals and populations. Results Taxonomically recognised species within Leucanthemum were supported by distinct genetic signatures (particularly SNPs), environmental preferences and key morphological traits (notably the measurements of the upper row of involucral bracts). At the intraspecific level, L. rotundifolium populations were primarily differentiated by genetic variation (across all markers) and by environmental factors. In contrast, morphological variability showed no strong spatial signal, though subtle tendencies toward differentiation emerged when morphological traits were interpreted in conjunction with consistent genetic and environmental clustering. Main Conclusions Our findings highlight that the taxonomy of Leucanthemum corresponds closely with genetic, environmental and certain morphological parameters. Within L. rotundifolium , local adaptation is strongly reflected in genetic and environmental divergence, while morphological traits appear more conservative. Nevertheless, subtle morphological shifts may still track underlying genetic and ecological differentiation, revealing a complex interplay of factors shaping the evolutionary trajectory of this Carpathian subendemic.