Marine macroalgal genus richness [data used in Keith et al. 2014]

This dataset consists of an ESRI shapefile showing genus richness counts of 3 macroalgal clades (Rhodophyta, Chlorophyta, Phaeophyceae) at 367 sites used in the analyses of Keith et al (2014)Data extent: latitude 70S - 70NProjection: World Equidistant Cylindrical.Abstract [Related Publication]:Aim: Marine macroalgae provide an excellent opportunity to test hypotheses about latitudinal diversity gradients because macroalgal richness decreases towards the tropics, contrary to classic patterns, and because three evolutionarily distinct macroalgal clades (Rhodophyta, Chlorophyta, Phaeophyceae) have converged ecologically. Specifically, we determine the extent to which environmental conditions can predict genus richness in macroalgae. We also evaluate whether the magnitude or direction of the effect of environmental factors, or their ability to explain variation in macroalgal diversity, varies geographically.Location: Global oceans.Methods: We formulated and fitted global spatial regression models and geographically weighted regression (GWR) models to determine the extent to which environmental conditions could predict genus richness in macroalgae. GWR allowed us to determine how the role of environmental conditions varied amongst geographical regions.Results: The global regression model showed that sea surface temperature and nutrients were important predictors of macroalgal genus richness at a global scale. However, GWR revealed that environmental factors explained less variability in richness in the tropics than elsewhere.Main conclusions: Our results show that whilst environmental conditions influence marine macroalgal diversity, the strength of this influence shows considerable geographical variation. In particular, environmental conditions explain more of the observed variation in diversity at high latitudes than at low latitudes. This finding is consistent with the hypothesis that environmental tolerances influence species distributions more strongly at high latitudes, whereas other factors, such as biotic interactions, play a more prominent role in the tropics.The full methodology is available in the publication shown in the Related Publications link below.

本数据集包含一份ESRI形状文件（ESRI shapefile），展示了用于Keith等人（2014）分析的367个样点处3个大型藻类分支的属丰富度计数，这3个分支分别为红藻门（Rhodophyta）、绿藻门（Chlorophyta）及褐藻纲（Phaeophyceae）。
数据范围：南纬70°至北纬70°
投影：世界等距圆柱投影（World Equidistant Cylindrical）。

摘要[相关文献]：
研究目标：海洋大型藻类为验证纬度多样性格局假说提供了绝佳研究契机，其丰富度随向热带区域趋近而逐渐降低，这与经典多样性格局截然相反；同时三个演化上独立的大型藻类分支（红藻门、绿藻门、褐藻纲）已发生生态趋同。本研究旨在明确环境条件可在多大程度上预测大型藻类的属丰富度。此外，我们还评估了环境因子的效应强度、方向，抑或其解释大型藻类多样性变异的能力，是否存在地理变异。
研究区域：全球海洋。
研究方法：我们构建并拟合了全球空间回归模型与地理加权回归（Geographically Weighted Regression, GWR）模型，以探究环境条件对大型藻类属丰富度的预测能力；其中地理加权回归（GWR）可用于解析环境条件的作用在不同地理区域间的差异。
研究结果：全球回归模型显示，海表温度与营养盐是全球尺度下大型藻类属丰富度的重要预测因子。然而地理加权回归（GWR）分析表明，热带区域的丰富度变异被环境因子解释的比例低于其他区域。
主要结论：本研究结果表明，尽管环境条件会对海洋大型藻类的多样性产生影响，但该影响的强度存在显著的地理变异。具体而言，环境条件对高纬度区域多样性变异的解释度高于低纬度（热带）区域。这一发现与下述假说相符：环境耐受性对高纬度地区物种分布的影响更为强烈，而在热带区域，生物相互作用等其他因素则发挥更为主导的作用。
完整研究方法可参见下文相关文献链接中的出版物。