The role of environment and mid-domain effect on moth species richness along a tropical elevational gradient
The role of environment and mid-domain effect on moth species richness along a tropical elevational gradient
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DOI：
10.1111/j.1466-8238.2006.00281.x
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发表时间：
2007-03-01
影响因子：
6.4
通讯作者：
Kluge, Juergen
中科院分区：
文献类型：
--
作者：
Brehm, Gunnar;Colwell, Robert K.;Kluge, Juergen
目的首次在完整的热带海拔梯度上研究鳞翅目几何蛾的生物多样性。描述了这些模式，并探讨了几何约束和环境因素的作用。研究沿着Barva样带（北纬10度，西经84度）进行，该样带位于哥斯达黎加Braulio Carrillo国家公园及其邻近地区，海拔高度从40到2730米不等。方法于2003年和2004年在12个热带雨林站点采用2根15w紫外荧光管的“光塔”人工取样。我们使用基于丰度的稀疏、真实丰富度的统计估计（Chao 1）、地理插值的观察丰富度和Fisher’s alpha作为本地多样性的度量。结果共采集标本13765份，种类739种。在海拔500 ~ 2100 m之间，四种测量结果均呈驼峰状分布。这两个亚科的丰富度和多样性在海拔较低（尺蠖科）或较高（尺蠖科）的高度均高于整体的尺蠖科。在4个环境因子中，相对湿度在样带上与基于稀疏度的丰富度估计值的相关性最高，与整个尺蠖科和大蠹科的真实物种丰富度估计值的相关性也最高，而降雨量解释了尺蠖科丰富度的最大变化。飞蛾丰富度的海拔分布与温度和树种丰富度都不一致。在逐步多元回归中，所有环境因子的组合产生了较高的r(2)值。通过将几何约束与观测到的插值丰富度进行比较，研究了几何约束的潜在影响（mid-domain effect， MDE）。总的来说，模型对整个尺蠖科和尺蠖科的拟合非常好，但对尺蠖科的拟合就不那么好了。与大范围物种相比，小范围物种与模型预测的偏差更大，并且在两个亚科之间存在显著差异，表明环境因素对小范围物种的影响更为显著。我们假设小范围的物种（至少是小鱼科的）可能倾向于成为寄主专家，而大范围的物种往往是多食的。根据插值范围，这些飞蛾的平均海拔范围随着海拔的增加而增大，符合Rapoport的海拔规则，尽管采样效应可能夸大了这种模式。潜在的机制仍然未知，因为拉波波特的“拯救”假说无法解释观察到的模式。结论该地区飞蛾多样性呈驼峰型分布。然而，在分类单元和范围大小方面存在显著差异。环境因素和几何因素都可能对观测到的模式有所贡献。
Aim The biodiversity of geometrid moths (Lepidoptera) along a complete tropical elevational gradient was studied for the first time. The patterns are described, and the role of geometric constraints and environmental factors is explored.Location The study was carried out along the Barva Transect (10 degrees N, 84 degrees W), a complete elevational gradient ranging from 40 to 2730 m a.s.l. in Braulio Carrillo National Park, Costa Rica, and adjacent areas.Methods Moths were sampled manually in 2003 and 2004 at 12 rain forest sites using light 'towers', each with two 15 W ultraviolet fluorescent tubes. We used abundance-based rarefaction, statistical estimation of true richness (Chao 1), geographically interpolated observed richness and Fisher's alpha as measures of local diversity.Results A total of 13,765 specimens representing 739 species were analysed. All four measures showed a hump-shaped pattern with maxima between 500 and 2100 m elevation. The two subfamilies showed richness and diversity maxima at either lower (Ennominae) or higher (Larentiinae) elevation than Geometridae as a whole. Among the four environmental factors tested, relative humidity yielded the highest correlation over the transect with the rarefaction-based richness estimates as well as with estimated true species richness of Geometridae as a whole and of Larentiinae, while rainfall explained the greatest variation of Ennominae richness. The elevational pattern of moth richness was discordant with both temperature and with tree species richness. A combination of all environmental factors in a stepwise multiple regression produced high values of r(2) in Geometridae. The potential effects of geometric constraints (mid-domain effect, MDE) were investigated by comparing them with observed, interpolated richness. Overall, models fitted very well for Geometridae as a whole and for Ennominae, but less well for Larentiinae. Small-ranged species showed stronger deviations from model predictions than large-ranged species, and differed strikingly between the two subfamilies, suggesting that environmental factors play a more pronounced role for small-ranged species. We hypothesize that small-ranged species (at least of the Ennominae) may tend to be host specialists, whereas large-ranged species tend to be polyphagous. Based on interpolated ranges, mean elevational range for these moths was larger with increasing elevation, in accordance with Rapoport's elevational rule, although sampling effects may have exaggerated this pattern. The underlying mechanism remains unknown because Rapoport's 'rescue' hypothesis could not explain the observed pattern.Conclusions The results clearly show that moth diversity shows a hump-shaped pattern. However, remarkable variation exists with regard to taxon and range size. Both environmental and geometric factors are likely to contribute to the observed patterns.