The adaptive value of heterospory: Evidence from Selaginella
The adaptive value of heterospory: Evidence from Selaginella
复制标题
DOI：
10.1111/evo.13484
复制
发表时间：
2018-05
期刊：
影响因子：
3.3
通讯作者：
Kurt B. Petersen;M. Burd
中科院分区：
文献类型：
--
作者：
Kurt B. Petersen;M. Burd
异孢子生殖是陆生植物进化的一个关键创新，但它为什么进化一直不清楚。我们使用了114种异孢石松卷柏的地理分布，探讨小孢子和大孢子大小的功能生态学，性状，将与一个物种的再生生态位的许多方面。我们在全球范围内使用叶面积指数（LAI）和净初级生产力（NPP）来表征栖息地，叶面积指数是衡量树叶密度和遮荫的指标，净初级生产力是衡量生长潜力的指标。小孢子大小随着生境LAI和NPP的增加而趋于减小，这一趋势可能与抗干燥性或叶片表面对风载颗粒的过滤有关。大孢子的大小往往会增加物种之间的居住区的高叶面积指数，但有一个重要的相互作用与净初级生产力。这种地理格局表明，较大的大孢子提供了一个建立的优势，在阴影的栖息地，虽然在开放的栖息地，那里的光是限制较少，较高的生产力的环境似乎给一个优势，以较小的大孢子的物种。这些结果支持以前的理论论点，异孢子生殖最初是一种适应的高度和密度的泥盆纪的营养冠层，伴随着多样化的维管植物的叶子。
Heterospory was a pivotal evolutionary innovation for land plants, but it has never been clear why it evolved. We used the geographic distributions of 114 species of the heterosporous lycophyte Selaginella to explore the functional ecology of microspore and megaspore size, traits that would be correlated with many aspects of a species’ regeneration niche. We characterized habitats at a global scale using leaf area index (LAI), a measure of foliage density and thus shading, and net primary productivity (NPP), a measure of growth potential. Microspore size tends to decrease as habitat LAI and NPP increase, a trend that could be related to desiccation resistance or to filtration of wind‐borne particles by leaf surfaces. Megaspore size tends to increase among species that inhabit regions of high LAI, but there is an important interaction with NPP. This geographical pattern suggests that larger megaspores provide an establishment advantage in shaded habitats, although in open habitats, where light is less limiting, higher productivity of the environment seems to give an advantage to species with smaller megaspores. These results support previous theoretical arguments that heterospory was originally an adaptation to the increasing height and density of Devonian vegetative canopies that accompanied the diversification of vascular plants with leaves.