Green T G A, Budel B, Heber U, Meyer A, Zellner H, Lange O L
Department of Biological Sciences, The University of Waikato, Private Bag, Hamilton, New Zealand.
Julius-von-Sachs-Institut für Biowissenschaften der Universiät Würzburg, Mittlerer Dallenbergweg 64, D-97082 Würzburg, Federal Republic of Germany.
New Phytol. 1993 Dec;125(4):723-731. doi: 10.1111/j.1469-8137.1993.tb03921.x.
Photosymbiodemes are lichens which contain a single mycobiont but have cyanobacteria and green algae as primary photobionts in different parts of the thallus. Members of a photosymbiodeme can be found as separate, free-living lichen species. The photosynthesis of the components of two Pseudocyphellaria photosymbiodemes were studied in the natural forest environment in New Zealand. It was found that the green algal component had a large photosynthetic advantage when thallus water contents were low and the thalli were in equilibrium with atmospheric humidity. The cyanobacterial components were at an advantage when thallus water contents were very high. The environment in which photosymbiodemes are found, forest margins in high humidity areas, seems to provide the correct combination of thallus water contents so that neither component has a major advantage. The photosymbiodemes appear to be models, preserved by the special habitat and showing a possible early stage in the evolution before the definite separation of ecologically specialised green algal and cyanobacterial species.
光合共生群落是指那些含有单一真菌共生体，但在叶状体不同部位分别以蓝细菌和绿藻作为主要光合共生生物的地衣。光合共生群落的成员可以作为独立的、自由生活的地衣物种被发现。在新西兰的天然森林环境中，对两种拟杯点衣光合共生群落的组成部分的光合作用进行了研究。研究发现，当叶状体含水量较低且叶状体与大气湿度处于平衡状态时，绿藻成分具有较大的光合优势。当叶状体含水量非常高时，蓝细菌成分则具有优势。光合共生群落所处的环境，即高湿度地区的森林边缘，似乎提供了叶状体含水量的正确组合，使得两种成分都不具有主要优势。光合共生群落似乎是由特殊栖息地保存下来的模型，展示了生态上特化的绿藻和蓝细菌物种明确分离之前进化过程中可能的早期阶段。
