Plant Conservation and Population Biology, Department of Biology, KU Leuven, Heverlee, Belgium.
Ann Bot. 2020 Nov 24;126(7):1203-1214. doi: 10.1093/aob/mcaa142.
The geographical distribution of plant species is linked fundamentally not only to environmental variables, but also to key traits that affect the dispersal, establishment and evolutionary potential of a species. One of the key plant traits that can be expected to affect standing genetic variation, speed of adaptation and the capacity to colonize and establish in new habitats, and therefore niche breadth and range size, is the plant mating system. However, the precise role of the mating system in shaping range size and niche breadth of plant species remains unclear, and different studies have provided contrasting results. In this study, we tested the hypothesis that range size and niche breadth differed with mating system in the orchid genus Epipactis.
We modelled the ecological niches of 14 Epipactis species in Europe using occurrence records and environmental satellite data in Maxent. Niche breadth and niche overlap in both geographic and environmental space were calculated from the resulting habitat suitability maps using ENMTools, and geographic range was estimated using α-hull range definition. Habitat suitability, environmental variable contributions and niche metrics were compared among species with different mating systems.
We did not detect significant differences in niche breadth, occurrence probability or geographical range between autogamous and allogamous Epipactis species, although autogamous species demonstrated notably low variation in niche parameters. We also found no significant differences in niche overlap between species with the same mating system or different mating systems. For all Epipactis species, occurrence was strongly associated with land cover, particularly broad-leafed and coniferous forests, and with limestone bedrock.
These results suggest that the mating system does not necessarily contribute to niche breadth and differentiation, and that other factors (e.g. mycorrhizal specificity) may be more important drivers of range size and niche breadth in Epipactis and orchids in general.
植物物种的地理分布不仅与环境变量密切相关，还与影响物种传播、建立和进化潜力的关键特征有关。其中一个关键的植物特征，预计会影响物种的遗传变异、适应速度以及在新栖息地的殖民和建立能力，从而影响生态位广度和分布范围大小，是植物的交配系统。然而，交配系统在塑造植物物种的分布范围和生态位广度方面的确切作用仍不清楚，不同的研究得出了相互矛盾的结果。在这项研究中，我们检验了交配系统是否会影响orchid 属 Epipactis 物种的分布范围和生态位广度的假设。
我们使用 Maxent 中的物种出现记录和环境卫星数据，对欧洲的 14 种 Epipactis 物种的生态位进行建模。使用 ENMTools 从生成的栖息地适宜性图中计算地理和环境空间中的生态位广度和生态位重叠，并使用α-壳范围定义来估计地理范围。比较了不同交配系统的物种之间的栖息地适宜性、环境变量贡献和生态位指标。
我们没有发现自交和异交 Epipactis 物种之间的生态位广度、出现概率或地理范围有显著差异，尽管自交物种的生态位参数变化显著较低。我们还发现，同交配系统或不同交配系统的物种之间的生态位重叠没有显著差异。对于所有 Epipactis 物种，出现都与土地覆盖，特别是阔叶林和针叶林，以及石灰岩基岩密切相关。
这些结果表明，交配系统不一定会导致生态位广度和分化，而其他因素（例如菌根特异性）可能是 Epipactis 物种和一般兰花分布范围和生态位广度的更重要驱动因素。
