Biogeographic patterns of polyploidy in the spleenwort: bridging divergent perspectives over the evolutionary consequences of polyploidy

Abstract

Abstract Despite substantial progress in genomic and phenotypic research on polyploidy, its broader eco-evolutionary implications remain elusive. We thus focused on spleenworts as a model system to investigate the impact of polyploidy on their biogeographic patterns. Contrary to the conventional expectation that polyploids would be more common at higher latitudes, our findings showed a higher prevalence in tropical regions, with their dominance gradually decreasing toward the poles. Both diploid and polyploid species richness in spleenworts displayed similar responses to biogeographic factors such as elevation and isolation from waterbodies that serve as indicators of stress tolerance. This suggested that the potential evolutionary advantages associated with polyploidy at the individual level may not necessarily translate to higher organizational levels. Instead, regional disparities in polyploid formation and extinction rates, particularly influenced by ecological interactions among species, may play a critical role in determining global biogeographic patterns. Our study therefore underscores the importance of understanding the geographic contexts in which polyploidy can either pose an evolutionary risk or contribute to success in plant diversification.