Kellogg Biological Station, Department of Plant Biology, Michigan State University, Hickory Corners, Michigan 49060, USA.
Ecology. 2011 Nov;92(11):2096-107. doi: 10.1890/10-1023.1.
Our planet shows striking gradients in the species richness of plants and animals, from high biodiversity in the tropics to low biodiversity in polar and high-mountain regions. Recently, similar patterns have been described for some groups of microorganisms, but the large-scale biogeographical distribution of freshwater phytoplankton diversity is still largely unknown. We examined the species diversity of freshwater phytoplankton sampled from 540 lakes and reservoirs distributed across the continental United States and found strong latitudinal, longitudinal, and altitudinal gradients in phytoplankton biodiversity, demonstrating that microorganisms can show substantial geographic variation in biodiversity. Detailed analysis using structural equation models indicated that these large-scale biodiversity gradients in freshwater phytoplankton diversity were mainly driven by local environmental factors, although there were residual direct effects of latitude, longitude, and altitude as well. Specifically, we found that phytoplankton species richness was an increasing saturating function of lake chlorophyll a concentration, increased with lake surface area and possibly increased with water temperature, resembling effects of productivity, habitat area, and temperature on diversity patterns commonly observed for macroorganisms. In turn, these local environmental factors varied along latitudinal, longitudinal, and altitudinal gradients. These results imply that changes in land use or climate that affect these local environmental factors are likely to have major impacts on large-scale biodiversity patterns of freshwater phytoplankton.
我们的星球在动植物物种丰富度上表现出显著的梯度变化，从热带地区的高生物多样性到极地和高山地区的低生物多样性。最近，一些微生物群体也呈现出类似的模式，但淡水浮游植物多样性的大规模生物地理分布仍然很大程度上未知。我们研究了从美国大陆 540 个湖泊和水库中采集的淡水浮游植物的物种多样性，发现浮游植物生物多样性存在强烈的纬度、经度和海拔梯度，表明微生物在生物多样性方面可以表现出显著的地域差异。使用结构方程模型的详细分析表明，这些淡水浮游植物多样性的大规模生物多样性梯度主要是由当地环境因素驱动的，尽管纬度、经度和海拔仍有直接影响。具体来说，我们发现浮游植物物种丰富度是湖泊叶绿素 a 浓度的递增饱和函数，随着湖泊面积的增加而增加，可能随着水温的升高而增加，类似于生产力、栖息地面积和温度对宏观生物多样性模式的影响。反过来，这些当地环境因素沿着纬度、经度和海拔梯度发生变化。这些结果表明，影响这些当地环境因素的土地利用或气候变化很可能对淡水浮游植物的大规模生物多样性模式产生重大影响。
