Submitted:
30 December 2025
Posted:
01 January 2026
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Abstract
The Balkan Peninsula is a biodiversity hotspot where topographic and habitat heterogeneity have shaped genetic differentiation. Polyploidization significantly contributes to diversification within plant lineages, including the allopolyploid Veronica austriaca complex. We sampled 751 individuals from 50 Balkan and Central European populations belonging to the hexaploid V. austriaca and its putative diploid (V. dalmatica) and tetraploid progenitors. Diversity patterns were investigated through microsatellite markers (SSRs), plastid DNA sequences, ploidy estimations, morphological data and climatic niche differentiation analysis. Five lineages were detected within the complex according to nuclear DNA data. The plastid DNA haplotypes form two main groups that overall match those detected by SSRs data and could suggest that the hexaploid V. austriaca resulted from two different allopolyploid events. Our analyses evidence rapid and recent colonization of diverse mesic grassy habitats by an allopolyploid perennial herb across a large European scale. The enhanced dispersal abilities of the hexaploid V. austriaca (compared to its lower ploidy relatives) seem to result from higher genetic diversity and ecological niche differentiation, which may also be related to slight morphological differences of potential functional significance. Style length is a crucial character to distinguish diploids from polyploids, which may affect pollination biology within the complex.
