Abstract:
Specific ecological conditions in the high mountain environment exert a selective pressure that often leads to convergent trait evolution. Reticulations induced by incomplete lineage sorting and introgression can lead to discordant trait patterns among gene and species trees (hemiplasy/xenoplasy), providing a false illusion that the traits under study are homoplastic. Using phylogenetic species networks, we explored the effect of gene exchange on trait evolution in Soldanella, a genus profoundly influenced by historical introgression. At least three features evolved independently multiple times: the single-flowered dwarf phenotype, dysploid cytotype, and ecological generalism. The present analyses also indicated that the recurring occurrence of stoloniferous growth might have been prompted by an introgression event between an ancestral lineage and a still extant species, although its emergence via convergent evolution cannot be completely ruled out. Phylogenetic regression suggested that the independent evolution of larger genomes in snowbells is most likely a result of the interplay between hybridization events of dysploid and euploid taxa and hostile environments at the range margins of the genus. The emergence of key intrinsic and extrinsic traits in snowbells has been significantly impacted not only by convergent evolution but also by historical and recent introgression events.
摘要:
高山环境中的特定生态条件会施加选择性压力,这通常会导致收敛性状的进化。由不完全谱系分类和基因渗入诱导的网织可导致基因和物种树之间的不一致性状模式(半生体/异种体),提供了一种错误的错觉,即所研究的特征是同质的。利用系统发育物种网络,我们探索了基因交换对Soldanella性状进化的影响,一个深受历史渗入影响的属。至少有三个特征独立进化多次:单花矮人表型,异倍体细胞型,生态概括性。目前的分析还表明,在祖先谱系和仍然存在的物种之间发生渗入事件可能会促使雌雄同体生长的反复发生。尽管不能完全排除它通过趋同进化的出现。系统发育回归表明,雪铃中较大基因组的独立进化很可能是异倍体和整倍体类群的杂交事件与该属范围边缘的敌对环境之间相互作用的结果。雪铃中关键内在和外在特征的出现不仅受到趋同进化的影响,而且受到历史和最近的渗入事件的影响。