Nargar Katharina, O'Hara Kate, Mertin Allison, Bent Stephen J, Nauheimer Lars, Simpson Lalita, Zimmer Heidi, Molloy Brian P J, Clements Mark A
Australian Tropical Herbarium, James Cook University, Cairns, QLD, Australia.
National Research Collections Australia, Commonwealth Industrial and Scientific Research Organisation (CSIRO), Canberra, ACT, Australia.
Front Plant Sci. 2022 Jun 29;13:912089. doi: 10.3389/fpls.2022.912089. eCollection 2022.
Australia harbours a rich and highly endemic orchid flora with over 90% of native species found nowhere else. However, little is known about the assembly and evolution of Australia's orchid flora. Here, we used a phylogenomic approach to infer evolutionary relationships, divergence times and range evolution in Pterostylidinae (Orchidoideae), the second largest subtribe in the Australian orchid flora, comprising the genera and . Phylogenetic analysis of 75 plastid genes provided well-resolved and supported phylogenies. Intrageneric relationships in were clarified and monophyly of eight of 10 sections supported. was found to not form part of Pterostylidinae and instead merits recognition at subtribal level, as Achlydosinae. Pterostylidinae were inferred to have originated in eastern Australia in the early Oligocene, coinciding with the complete separation of Australia from Antarctica and the onset of the Antarctic Circumpolar Current, which led to profound changes in the world's climate. Divergence of all major lineages occurred during the Miocene, accompanied by increased aridification and seasonality of the Australian continent, resulting in strong vegetational changes from rainforest to more open sclerophyllous vegetation. The majority of extant species were inferred to have originated in the Quaternary, from the Pleistocene onwards. The rapid climatic oscillations during the Pleistocene may have acted as important driver of speciation in Pterostylidinae. The subtribe underwent lineage diversification mainly within its ancestral range, in eastern Australia. Long-distance dispersals to southwest Australia commenced from the late Miocene onwards, after the establishment of the Nullarbor Plain, which constitutes a strong edaphic barrier to mesic plants. Range expansions from the mesic into the arid zone of eastern Australia (Eremaean region) commenced from the early Pleistocene onwards. Extant distributions of Pterostylidinae in other Australasian regions, such as New Zealand and New Caledonia, are of more recent origin, resulting from long-distance dispersals from the Pliocene onwards. Temperate eastern Australia was identified as key source area for dispersals to other Australasian regions.
澳大利亚拥有丰富且高度特有的兰花植物群，超过90%的本土物种在其他地方都找不到。然而，对于澳大利亚兰花植物群的组装和进化却知之甚少。在这里，我们采用系统基因组学方法来推断澳大利亚兰花植物群中第二大亚族——鸟巢兰亚族（兰科）的进化关系、分歧时间和分布范围演变，该亚族包括多个属。对75个质体基因的系统发育分析提供了分辨率高且得到支持的系统发育树。明确了某些属内的关系，并支持了10个组中8个组的单系性。发现某属不属于鸟巢兰亚族，而是应在亚族级别上被认可为无柱兰亚族。推断鸟巢兰亚族在渐新世早期起源于澳大利亚东部，这与澳大利亚从南极洲完全分离以及南极绕极流的开始同时发生，这导致了全球气候的深刻变化。所有主要谱系的分歧发生在中新世期间，伴随着澳大利亚大陆干旱化和季节性增强，导致植被从雨林向更开阔的硬叶植被发生强烈变化。推断大多数现存物种从更新世开始的第四纪起源。更新世期间快速的气候振荡可能是鸟巢兰亚族物种形成的重要驱动力。该亚族主要在其祖先分布范围即澳大利亚东部经历了谱系多样化。从中新世晚期开始，在纳拉伯平原形成后，向澳大利亚西南部的远距离扩散开始，纳拉伯平原对中生植物构成了强大的土壤障碍。从更新世早期开始，从中生地带向东澳大利亚干旱区（厄勒曼地区）的分布范围扩张开始。鸟巢兰亚族在其他澳大拉西亚地区（如新西兰和新喀里多尼亚）的现存分布起源较晚，是从上新世开始远距离扩散的结果。澳大利亚东部温带地区被确定为向其他澳大拉西亚地区扩散的关键源区。
