Polyploidy—whole genome duplication—is widely acknowledged to have played an important role in the evolution and diversification of vascular plants. However, the influence of genome duplication at the community level remains unclear. In part, this is due to persistent uncertainties over the extent of polyploid phenotypic variation, and the interactions between polyploids and co-occurring species. We investigated community-level patterns of phylogenetic relatedness between diploids and polyploids and how these relationships might influence population-level species interactions. Focusing on two plant families in which polyploidy has evolved multiple times, Brassicaceae and Rosaceae, we build upon the hypothesis that the greater allelic and phenotypic diversity of polyploids allows them to successfully exploit novel ecological niches. Using a phylogenetic framework, we specifically test (1) whether polyploid species are more distantly related to diploids within the same community than co-occurring diploids are to one another, and (2) whether non-native polyploid species are more abundant in communities, consistent with successful establishment and with polyploid species exhibiting greater adaptability than diploids.
Results/Conclusions
Our results suggest that the effects of genome duplication on community structure are not clear-cut. We find that polyploid species tend to be more distantly related to co-occurring diploids than diploids are to each other, but this varies across lineages. We also do not find a consistent pattern of non-native polyploid species being more abundant than diploid species, consistent with polyploids being no more likely than diploids to exploit novel habitat. While polyploidy appears to have some important influences on species co-occurrence in Brassicaceae and Rosaceae communities, our study highlights the paucity of available data on intraspecific ploidal variation. The increased use of high-throughput methods to identify ploidal variation, such as flow cytometry and whole genome sequencing, will greatly aid our understanding of how such a widespread, radical genomic mutation influences the evolution of species and those around them.