...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution
【24h】

Fossil evidence for Cretaceous escalation in angiosperm leaf vein evolution

机译：化石证据表明被子植物叶脉演化中的白垩纪升级

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The flowering plants that dominate modern vegetation possess leaf gas exchange potentials that far exceed those of all other living or extinct plants. The great divide in maximal ability to exchange CO_2 for water between leaves of nonangiosperms and angiosperms forms the mechanistic foundation for speculation about how angiosperms drove sweeping ecological and biogeo-chemical change during the Cretaceous. However, there is no empirical evidence that angiosperms evolved highly photosyn-thetically active leaves during the Cretaceous. Using vein density (D_v) measurements of fossil angiosperm leaves, we show that the leaf hydraulic capacities of angiosperms escalated several-fold during the Cretaceous. During the first 30 million years of angiosperm leaf evolution, angiosperm leaves exhibited uniformly low vein D_v that overlapped the D_v range of dominant Early Cretaceous ferns and gymnosperms. Fossil angiosperm vein densities reveal a subsequent biphasic increase in D_v. During the first mid-Cretaceous surge, angiosperm D_v first surpassed the upper bound of D_v limits for nonangiosperms. However, the upper limits of D_v typical of modern megathermal rainforest trees first appear during a second wave of increased D_v during the Cretaceous-Tertiary transition. Thus, our findings provide fossil evidence for the hypothesis that significant ecosystem change brought about by angiosperms lagged behind the Early Cretaceous taxonomic diversification of angiosperms.
机译：在现代植被中占主导地位的开花植物具有的叶片气体交换潜力远远超过所有其他有生命或已灭绝植物。非被子植物叶片和被子植物叶片之间最大的以CO_2交换水的能力的巨大分歧，为推测被子植物如何驱动白垩纪整个生态和生物地球化学变化的机理奠定了基础。但是，没有经验证据表明被子植物在白垩纪期间进化出具有高光合活性的叶片。使用化石被子植物叶片的叶脉密度（D_v）测量，我们发现被子植物的叶片水力容量在白垩纪期间上升了几倍。在被子植物叶片进化的前三千万年中，被子植物叶片显示出均匀的低静脉D_v，其与优势白垩纪蕨类和裸子植物的D_v范围重叠。化石被子植物的静脉密度揭示了D_v随后的双相增加。在第一次白垩纪中段增高期间，被子植物D_v首先超过了非小动物精子的D_v上限。然而，现代白热雨林树木典型的D_v上限首先出现在白垩纪-第三纪过渡期间第二次D_v上升。因此，我们的发现为以下假设提供了化石证据：被子植物引起的显着生态系统变化滞后于白垩纪被子植物生物分类的多样化。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号