Royer Dana L, Kooyman Robert M, Little Stefan A, Wilf Peter
Department of Earth and Environmental Sciences, Wesleyan University, Middletown, Connecticut 06459 USA.
Am J Bot. 2009 Apr;96(4):738-50. doi: 10.3732/ajb.0800282. Epub 2009 Mar 20.
Teeth are conspicuous features of many leaves. The percentage of species in a flora with toothed leaves varies inversely with temperature, but other ecological controls are less known. This gap is critical because leaf teeth may be influenced by water availability and growth potential and because fossil tooth characters are widely used to reconstruct paleoclimate. Here, we test whether ecological attributes related to disturbance, water availability, and growth strategy influence the distribution of toothed species at 227 sites from Australian subtropical rainforest. Both the percentage and abundance of toothed species decline continuously from riparian to ridge-top habitats in our most spatially resolved sample, a result not related to phylogenetic correlation of traits. Riparian lianas are generally untoothed and thus do not contribute to the trend, and there is little association between toothed riparian species and ecological attributes indicating early successional lifestyle and disturbance response. Instead, the pattern is best explained by differences in water availability. Toothed species' proportional richness declines with proximity to the coast, also a likely effect of water availability because salt stress causes physiological drought. Our study highlights water availability as an important factor impacting the distribution of toothed species across landscapes, with significance for paleoclimate reconstructions.
牙齿状结构是许多叶片的显著特征。植物区系中具齿叶物种的比例与温度呈反比，但其他生态控制因素则鲜为人知。这一差距至关重要，因为叶齿可能受水分供应和生长潜力的影响，还因为化石齿特征被广泛用于重建古气候。在此，我们测试了与干扰、水分供应和生长策略相关的生态属性是否会影响澳大利亚亚热带雨林227个地点具齿物种的分布。在我们空间分辨率最高的样本中，具齿物种的比例和丰度从河岸生境到山脊顶部生境持续下降，这一结果与性状的系统发育相关性无关。河岸藤本植物通常无齿，因此不会导致这种趋势，具齿的河岸物种与表明早期演替生活方式和干扰响应的生态属性之间几乎没有关联。相反，这种模式最好用水分供应的差异来解释。具齿物种的比例丰富度随着靠近海岸而下降，这也可能是水分供应的影响，因为盐胁迫会导致生理干旱。我们的研究强调水分供应是影响具齿物种在景观中分布的一个重要因素，对古气候重建具有重要意义。
