Cenozoic formation and colonisation history of the New Zealand vascular flora based on molecular clock dating of the plastid <i>rbcL</i> gene

A colonisation history for 411 extant genera and 477 lineages of the vascular flora of New Zealand was constructed using the plastid <i>rbcL</i> gene. Molecular clock crown ages suggest that the Eocene-Oligocene transition extinction at 33.9 Ma was critical to the development of the extant flora as few lineages, mostly ferns and conifers, predate this event. Based on crown dates, almost all extant angiosperm lineages have established after the Eocene-Oligocene transition extinction. The Oligocene marine transgression had little discernible impact on the formation of the extant flora, as at the culmination of the inundation (22.0–25.0 Ma) fifty extant lineages of vascular plant were present and another eight lineages originated during this time. The majority of extant species (89%) originated after the end of the Miocene Thermal Optimum at about 15.0 Ma. Nearly 50% of the extant species have evolved during mountain uplift and glaciation of the late Pliocene-Pleistocene (0–4.99 Ma). Therefore, despite a residual contribution from the Eocene, Oligocene and early to mid Miocene periods, the New Zealand vascular flora essentially originated in the late Miocene and after.本研究依托质体rbcL基因（plastid rbcL gene），构建了新西兰411个现存属、477个维管植物支系的定殖历史。分子钟冠群年龄分析显示，发生于33.9 Ma的始新世-渐新世过渡灭绝事件对现存植物区系的形成至关重要：仅有极少数类群（多为蕨类与针叶树）早于该事件出现。基于冠群定年结果，几乎所有现存被子植物支系均形成于始新世-渐新世过渡灭绝事件之后。渐新世海侵对现存植物区系的形成几乎无显著影响，在海侵鼎盛期（22.0–25.0 Ma），新西兰已有50个现存维管植物支系，另有8个支系在此期间起源。绝大多数现存物种（89%）起源于约15.0 Ma的中新世气候适宜期结束之后。近50%的现存物种是在上新世晚期-更新世（0–4.99 Ma）的山地隆升与冰川作用期间演化而来。综上，尽管始新世、渐新世及中新世早中期仍有少量类群留存，但新西兰维管植物区系本质上形成于中新世晚期及之后。