Pure polyploidy: Closing the gaps in autopolyploid research

Polyploidy (whole-genome duplication, WGD) is an integral feature of eukaryotic evolution with two main forms typically recognized, autopolyploidy and allopolyploidy. In plants, a growing body of research contradicts historical assumptions that autopolyploidy is both infrequent and inconsequential in comparison to allopolyploidy. However, the legacy of these assumptions still persists through a lack of research on central facets of autopolyploid evolution. This review highlights recent research that has significantly increased scientific understanding of autopolyploidy. Key advances include: 1) unreduced female gametes contribute disproportionally to polyploidization through the formation of triploids, 2) niche divergence in autopolyploids can occur immediately or gradually after WGD through a diverse set of mechanisms, but broad niche overlap is also common between diploids and autopolyploids, and 3) the degree of genomic and transcriptomic changes following WGD is lower in autopolyploids than allopolyploids, but is highly variable both within and between species in both types of polyploids. We discuss the implications of these and other recent findings, present promising systems for future research, and advocate for expanded research in diverse areas of autopolyploid evolution.