Ecological and evolutionary consequences of ploidy-driven trait variation: Insights from Saxifraga oppositifolia L.

Abstract

The ecological and evolutionary consequences of ploidy-driven trait variation, particularly for autopolyploids, remain poorly understood. <i>Saxifraga oppositifolia</i> L. (purple saxifrage), is a highly successful arctic-alpine plant species with significant genetic and phenotypic variation potentially related to autopolyploidy. Over the past decade, we have accumulated knowledge of <i>S. oppositifolia</i> through student projects at the University Centre in Svalbard. Building on this knowledge, we initiated the long-term “SO-field study” in 2018 including 768 permanently tagged plants screened for ploidy level, trait variation and environmental associations. Here we summarize main findings from unpublished student projects, consolidating and extending these findings with the available data from the ongoing SO-field study, containing 63% diploids, 16% triploids, and 21% tetraploids. Our results support that Svalbard is a mixed-ploidy contact zone, where ploidy is strongly associated with certain traits, including growth form, leaf mass area, flower investment, seed production and habitat. Autopolyploidy has significantly influenced both ecology and evolution of <i>S. oppositifolia </i>and needs to be accounted for when autopolyploids are used as a study species or evaluated for management purposes. Our findings suggest considerable re-interpretation of former research and pave the way for new inquiries and hypotheses to be tested within this framework.