Department of Botany, MRC 166, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560-0166 USA.
Am J Bot. 2001 Aug;88(8):1490-8.
Lichens are intimate and long-term symbioses of algae and fungi. Such intimate associations are often hypothesized to have undergone long periods of symbiotic interdependence and coevolution. However, coevolution has not been rigorously tested for lichen associations. In the present study we compared the nuclear internal transcribed spacer (ITS) phylogenies of algal and fungal partners from 33 natural lichen associations to test two aspects of coevolution, cospeciation and parallel cladogenesis. Since statistically significant incongruence between symbiont phylogenies rejected parallel cladogenesis and minimized cospeciation events, we conclude that switching of highly selected algal genotypes occurs repeatedly among these symbiotic lichen associations.
地衣是藻类和真菌之间的亲密且长期的共生关系。这种亲密的共生关系通常被假设经历了长期的共生相互依存和共同进化。然而，对于地衣共生体是否发生了共同进化还没有进行严格的检验。在本研究中，我们比较了 33 种天然地衣共生体中藻类和真菌伙伴的核内转录间隔区（ITS）系统发育，以检验共同进化的两个方面，即协同进化和并行分支。由于共生体系统发育之间存在统计学上显著的不一致，从而否定了并行分支，同时最小化了协同进化事件，因此我们得出结论，在这些共生的地衣共生体中，高度选择的藻类基因型的转换反复发生。
