Alahuhta Janne, Virtala Antti, Hjort Jan, Ecke Frauke, Johnson Lucinda B, Sass Laura, Heino Jani
Geography Research Unit, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland.
Freshwater Centre, Finnish Environment Institute, P.O. Box 413, 90014, Oulu, Finland.
Oecologia. 2017 May;184(1):219-235. doi: 10.1007/s00442-017-3847-y. Epub 2017 Mar 14.
Different species' niche breadths in relation to ecological gradients are infrequently examined within the same study and, moreover, species niche breadths have rarely been averaged to account for variation in entire ecological communities. We investigated how average environmental niche breadths (climate, water quality and climate-water quality niches) in aquatic macrophyte communities are related to ecological gradients (latitude, longitude, altitude, species richness and lake area) among four distinct regions (Finland, Sweden and US states of Minnesota and Wisconsin) on two continents. We found that correlations between the three different measures of average niche breadths and ecological gradients varied considerably among the study regions, with average climate and average water quality niche breadth models often showing opposite trends. However, consistent patterns were also found, such as widening of average climate niche breadths and narrowing of average water quality niche breadths of aquatic macrophytes along increasing latitudinal and altitudinal gradients. This result suggests that macrophyte species are generalists in relation to temperature variations at higher latitudes and altitudes, whereas species in southern, lowland lakes are more specialised. In contrast, aquatic macrophytes growing in more southern nutrient-rich lakes were generalists in relation to water quality, while specialist species are adapted to low-productivity conditions and are found in highland lakes. Our results emphasise that species niche breadths should not be studied using only coarse-scale data of species distributions and corresponding environmental conditions, but that investigations on different kinds of niche breadths (e.g., climate vs. local niches) also require finer resolution data at broad spatial extents.
在同一研究中，很少会考察不同物种的生态位宽度与生态梯度之间的关系，而且，很少有人将物种的生态位宽度进行平均，以解释整个生态群落的变化。我们研究了水生植物群落的平均环境生态位宽度（气候、水质和气候 - 水质生态位）与两大洲四个不同区域（芬兰、瑞典以及美国明尼苏达州和威斯康星州）的生态梯度（纬度、经度、海拔、物种丰富度和湖泊面积）之间的关系。我们发现，在不同研究区域中，平均生态位宽度的三种不同测量方法与生态梯度之间的相关性差异很大，平均气候和平均水质生态位宽度模型常常呈现相反的趋势。然而，也发现了一些一致的模式，比如随着纬度和海拔梯度的增加，水生植物的平均气候生态位宽度变宽，平均水质生态位宽度变窄。这一结果表明，在高纬度和高海拔地区，大型植物物种对于温度变化具有广泛适应性，而在南部低地湖泊中的物种则更为特化。相反，生长在南部营养丰富湖泊中的水生植物在水质方面具有广泛适应性，而特化物种则适应低生产力条件，多见于高地湖泊。我们的研究结果强调，不应仅使用物种分布的粗略数据和相应的环境条件来研究物种的生态位宽度，而且对于不同类型的生态位宽度（例如，气候生态位与局部生态位）的研究还需要在广阔空间范围内获取更精细分辨率的数据。
