Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, 15260.
Department of Biology, University of Virginia, Charlottesville, VA.
Am J Bot. 2018 Apr;105(4):700-710. doi: 10.1002/ajb2.1046. Epub 2018 Apr 2.
Polyploids are predicted to have greater niche breadth and larger ranges than diploids because of higher ecological tolerances, self-compatibility, and increased genetic variation. However, empirical support for this prediction is mixed, and most studies compare diploids and polyploids, rather than accounting for quantitative variation in ploidy. We test the prediction that species of higher ploidy have greater range breadth and abiotic breadth than those of lower ploidy.
We estimate range breadth (latitudinal range, altitudinal range, and range size) and abiotic breadth (range in temperature, precipitation, and ultraviolet-B irradiance) for 109 species in the Potentilleae tribe of Rosaceae. We assess the contribution of ploidy to variation in range breadth, while accounting for shared evolutionary history and time of species divergence using phylogenetic comparative methods.
Ploidy varied widely among species from 2× to 12×. Phylogenetic relatedness explained little of the variation in ploidy, range breadth, and abiotic breadth. Transitions to higher ploidy were associated with reduced latitudinal and altitudinal ranges, smaller overall range size, and reduced abiotic breadth for temperature and UV-B.
In contrast to predictions, this study shows that transitions to higher ploidy are associated with reduced range size and abiotic breadth. It also highlights the importance of considering continuous variation in ploidy when evaluating ecological correlates with ploidy. We discuss how genome duplication may contribute to the observed negative relationship between ploidy and range breadth.
由于生态容忍度、自交亲和性和遗传变异增加，多倍体被预测比二倍体具有更大的生态位宽度和更大的范围。然而，这一预测的实证支持是混杂的，大多数研究比较的是二倍体和多倍体，而不是考虑到倍性的定量变化。我们检验了这样一个预测，即较高倍性的物种比较低倍性的物种具有更大的范围广度和非生物广度。
我们估计了蔷薇科缬草族 109 个物种的范围广度（纬度范围、海拔范围和范围大小）和非生物广度（温度、降水和紫外线-B 辐射范围）。我们使用系统发育比较方法，评估了倍性对范围广度变异的贡献，同时考虑了共同的进化历史和物种分化时间。
物种的倍性从 2×到 12×变化很大。系统发育关系解释了倍性、范围广度和非生物广度变异的很小一部分。向更高倍性的转变与纬度和海拔范围的缩小、总范围大小的缩小以及温度和 UV-B 的非生物广度的缩小有关。
与预测相反，本研究表明，向更高倍性的转变与范围大小和非生物广度的缩小有关。它还强调了在评估与倍性相关的生态相关性时考虑倍性连续变化的重要性。我们讨论了基因组加倍如何导致观察到的倍性与范围广度之间的负相关关系。
