Botany Unit, Finnish Museum of Natural History, University of Helsinki, P.O. Box 7, 00014, Helsinki, Finland.
Senckenberg Forschungsinstitut und Naturmuseum Frankfurt, Senckenberganlage 25, 60325, Frankfurt am Main, Germany.
Sci Rep. 2022 Jun 30;12(1):11048. doi: 10.1038/s41598-022-14970-9.
We show that obligate lignicoles in lichenized Micarea are predominately asexual whereas most facultative lignicoles reproduce sexually. Our phylogenetic analyses (ITS, mtSSU, Mcm7) together with ancestral state reconstruction show that the shift in reproduction mode has evolved independently several times within the group and that facultative and obligate lignicoles are sister species. The analyses support the assumption that the ancestor of these species was a facultative lignicole. We hypothezise that a shift in substrate requirement from bark to wood leads to differentiation in reproduction mode and becomes a driver of speciation. This is the first example of lichenized fungi where reproduction mode is connected to substrate requirement. This is also the first example where such an association is demonstrated to spark lichen speciation. Our main hypothesis is that obligate species on dead wood need to colonize new suitable substrata relatively fast and asexual reproduction is more effective a strategy for successful colonization.
我们表明，共生地衣中的专性木质者主要是无性繁殖，而大多数兼性木质者则进行有性繁殖。我们的系统发育分析（ITS、mtSSU、Mcm7）以及祖先状态重建表明，在这个群体中，繁殖模式的转变已经独立进化了多次，并且兼性木质者和专性木质者是姐妹种。这些分析支持了这样一种假设，即这些物种的祖先为兼性木质者。我们假设，从树皮到木材的基质需求的转变导致了繁殖模式的分化，并成为物种形成的驱动因素。这是共生真菌中繁殖模式与基质需求相关的首例例子。这也是首次证明这种关联会引发地衣物种形成的例子。我们的主要假设是，死木上的专性物种需要相对较快地占领新的适宜基质，无性繁殖是成功占领的更有效策略。
