Speciation network in Laurasiatheria: retrophylogenomic signals

Rapid species radiation due to adaptive changes or occupation of new ecospaces challenges our understanding of ancestral speciation and the relationships of modern species. At the molecular level, rapid radiation with successive speciations over short time periods—too short to fix polymorphic alleles—is described as incomplete lineage sorting. Incomplete lineage sorting leads to random fixation of genetic markers and hence, random signals of relationships in phylogenetic reconstructions. The situation is further complicated when you consider that the genome is a mosaic of ancestral and modern incompletely sorted sequence blocks that leads to reconstructed affiliations to one or the other relative, depending on the fixation of their shared ancestral polymorphic alleles. The laurasiatherian relationships among Chiroptera, Perissodactyla, Cetartiodactyla, and Carnivora present a prime example for such enigmatic affiliations. We performed whole-genome screenings for phylogenetically diagnos...

因适应性演化或开拓新生态位而引发的快速物种辐射（rapid species radiation），极大地阻碍了学界对祖先物种形成过程与现生物类群亲缘关系的认知。在分子层面，短时间尺度内发生连续物种形成的快速辐射事件——其时间跨度过短，以至于无法完成多态性等位基因的固定——被定义为不完全谱系分选（incomplete lineage sorting）。不完全谱系分选会导致遗传标记发生随机固定，进而在系统发育重建中产生随机的亲缘关系信号。当考虑到基因组实为祖先与现代未完全分选序列片段构成的镶嵌体时，问题将进一步复杂化：此类镶嵌结构会使得根据共享祖先多态性等位基因的固定情况，重建出与某一类或另一类群的亲缘关联。翼手目（Chiroptera）、奇蹄目（Perissodactyla）、鲸偶蹄目（Cetartiodactyla）与食肉目（Carnivora）之间的劳亚兽总目（Laurasiatheria）类群亲缘关系，便是这类神秘亲缘关联模式的典型案例。我们针对系统发育诊断性的...开展了全基因组筛选