Patterns of abiotic niche shifts in allopolyploids relative to their progenitors.

Polyploidy has extensive genetic, physiological, morphological, and ecological ramifications. While the patterns underlying the genetic and morphological consequences of polyploidy are being rapidly elucidated, the effects on ecological niche are still largely unknown. This study investigated 13 allopolyploid systems in North America (10 ferns and three angiosperms) using digitized natural history museum specimens. The abiotic niches of the allopolyploids were compared with those of their diploid progenitors using ecological niche modeling, niche analyses, and multivariate analyses. We identified four patterns of niche shifts through our analyses: niche expansion, niche contraction, niche intermediacy, and niche novelty. The classification of these shifts depended on the amount of niche overlap and breadth between the polyploid and progenitors. The most common niche shift was niche intermediacy in which the polyploid inhabited a geographic range between that of the progenitors and had a high degree of niche overlap. Each polyploid had at least partial geographic sympatry and abiotic niche overlap with one of its progenitors, suggesting that biotic and/or microclimate factors may play a larger role in polyploid establishment than previously hypothesized. This study provides a baseline for future comparisons of the diverse outcomes of genome merger and duplication on abiotic niche preference.