Evolution and Conservation Biology, Inbios Research Center, University of Liège, Quartier Vallée 1, Chemin de la Vallée 4, B-4000 Liège, Belgium.
Department of Ecology and Evolutionary Biology, 75 North Eagleville Road, University of Connecticut, Storrs, CT 06269, USA.
Mol Phylogenet Evol. 2018 May;122:15-28. doi: 10.1016/j.ympev.2018.01.012. Epub 2018 Jan 31.
Lichen biodiversity and its generative evolutionary processes are practically unknown in the MIOI (Madagascar and Indian Ocean Islands) biodiversity hotspot. We sought to test the hypothesis that lichenized fungi in this region have undergone a rapid radiation, following a single colonization event, giving rise to narrow endemics, as is characteristic of other lineages of plants. We extensively sampled specimens of the lichen genus Sticta in the Mascarene archipelago (mainly Réunion) and in Madagascar, mainly in the northern range (Amber Mt and Marojejy Mt) and produced the fungal ITS barcode sequence for 148 thalli. We further produced a four-loci data matrix for 68 of them, representing the diversity and geographical distribution of ITS haplotypes. We reconstructed the phylogenetic relationships within this group, established species boundaries with morphological context, and estimated the date of the most recent common ancestor. Our inferences resolve a robust clade comprising 31 endemic species of Sticta that arose from the diversification following a single recent (c. 11 Mya) colonization event. All but three species have a very restricted range, endemic to either the Mascarene archipelago or a single massif in Madagascar. The first genus of lichens to be studied with molecular data in this region underwent a recent radiation, exhibits micro-endemism, and thus exemplifies the biodiversity characteristics found in other taxa in Madagascar and the Mascarenes.
在马达加斯加和印度洋岛屿生物多样性热点地区（MIOI），地衣生物多样性及其生成进化过程实际上是未知的。我们试图验证以下假设：该地区的地衣真菌经历了快速辐射，是由单一的定植事件引起的，产生了狭窄的特有种，这是其他植物谱系的特征。我们广泛采集了马卡桑群岛（主要是留尼汪岛）和马达加斯加的地衣属 Sticta 的标本，主要在北部范围（Amber Mt 和 Marojejy Mt）进行采集，并为 148 个叶状体产生了真菌 ITS 条形码序列。我们进一步为其中的 68 个生成了一个四基因座数据矩阵，代表了 ITS 单倍型的多样性和地理分布。我们在该组内重建了系统发育关系，在形态学背景下确定了物种边界，并估计了最近共同祖先的日期。我们的推论确定了一个稳健的分支，包含 31 个来自单一近期（约 1100 万年前）定植事件后的多样化的特有种 Sticta。除了三种之外，所有物种的分布范围都非常有限，仅局限于马卡桑群岛或马达加斯加的单个山脉。该地区第一个用分子数据研究的地衣属经历了近期辐射，表现出微观特有性，因此体现了在马达加斯加和马卡桑群岛的其他分类群中发现的生物多样性特征。
