Historical biogeography and evolutionary diversification of Lilium(Liliaceae): New insights from plastome phylogenomics

Here, we infer the historical biogeography and evolutionary diversification of the genus Lilium. For this purpose, we used the complete plastomes of 64 currently accepted species in the genus Lilium(14plastomes were newly sequenced) to recover the phylogenetic backbone of the genus and a timecalibrated phylogenetic framework to estimate biogeographical history scenarios and evolutionary diversification rates of Lilium. Our results suggest that ancient climatic changes and geological tectonic activities jointly shaped the distribution range and drove evolutionary radiation of Lilium, including the Middle Miocene Climate Optimum(MMCO), the late Miocene global cooling, as well as the successive uplift of the Qinghai-Tibet Plateau(QTP) and the strengthening of the monsoon climate in East Asia during the late Miocene and the Pliocene. This case study suggests that the unique geological and climatic events in the Neogene of East Asia, in particular the uplift of QTP and the enhancement of monsoonal climate, may have played an essential role in formation of uneven distribution of plant diversity in the Northern Hemisphere.

Cenozoic plant diversity of Yunnan： A review

Yunnan in southwestern China is renowned for its high plant diversity.To understand how this modern botanical richness formed,it is critical to investigate the past biodiversity throughout the geological time.In this review,we present a summary on plant diversity,floristics and climates in the Cenozoic of Yunnan and document their changes,by compiling published palaeobotanical sources.Our review demonstrates that thus far a total of 386 fossil species of ferns,gymnosperms and angiosperms belonging to 170 genera within 66 families have been reported from the Cenozoic,particularly the Neogene,of Yunnan.Angiosperms display the highest richness represented by 353 species grouped into 155 genera within 60 families,with Fagaceae,Fabaceae,Lauraceae and Juglandaceae being the most diversified.Most of the families and genera recorded as fossils still occur in Yunnan,but seven genera have disappeared,including Berryophyllum,Cedrelospermum,Cedrus,Palaeocarya,Podocarpium,Sequoia and Wataria.The regional extinction of these genera is commonly referred to an aridification of the dry season associated with Asian monsoon development.Floristic analyses indicate that in the late Miocene,Yunnan had three floristic regions:a northern subtropical floristic region in the northeast,a subtropical floristic region in the east,and a tropical floristic region in the southwest.In the late Pliocene,Yunnan saw two kinds of floristic regions:a subalpine floristic region in the northwest,and two subtropical floristic regions separately in the southwest and the eastern center.These floristic concepts are verified by results from our areal type analyses which suggest that in the Miocene southwestern Yunnan supported the most Pantropic elements,while in the Pliocene southwestern Yunnan had abundant Tropical Asia(Indo e Malaysia)type and East Asia and North America disjunct type that were absent from northwestern Yunnan.From the late Miocene to late Pliocene through to the present,floristic composition and vegetation types changed markedly,presumably in response to altitude changes and coeval global cooling.An integration of palaeoclimate data suggests that during the Neogene Yunnan was warmer and wetter than today.Moreover,northern Yunnan witnessed a pronounced temperature decline,while southern Yunnan experienced only moderate temperature changes.Summer precipitation was consistently higher than winter precipitation,suggesting a rainfall seasonality.This summary on palaeoclimates helps us to understand under what conditions plant diversity occurred and evolved in Yunnan throughout the Cenozoic.

Involucre fossils of Carpinus,a northern temperate element,from the Miocene of China and the evolution of its species diversity in East Asia

East Asia has long been recognized as a major center for temperate woody plants diversity.Although several theories have been proposed to explain how the diversity of these temperate elements accumulated in the region,the specific process remains unclear.Here we describe six species of Carpinus,a typical northern hemisphere temperate woody plant,from the early Miocene of the Maguan Basin,southwestern China,southern East Asia.This constitutes the southernmost,and the earliest occurrence that shows a high species diversity of the genus.Together with other Carpinus fossil records from East Asia,we show that the genus had achieved a high diversity in East Asia at least by the middle Miocene.Of the six species here described,three have become extinct,indicating that the genus has experienced apparent species loss during its evolutionary history in East Asia.In contrast,the remaining three species closely resemble extant species,raising the possibility that these species may have persisted in East Asia at least since the early Miocene.These findings indicate that the accumulation of species diversity of Carpinus in East Asia is a complex process involving extinction,persistence,and possible subsequent speciation.

Cenozoic plants from Tibet:An extraordinary decade of discovery,understanding and implications

Plant fossils play an important role in understanding landscape evolution across the Tibetan Region,as well as plant diversity across wider eastern Asia.Within the last decade or so,paleobotanical investigations within the Tibet Region have led to a paradigm shift in our understanding of how the present plateau formed and how this affected the regional climate and biota.This is because:(1)Numerous new taxa have been reported.Of all the Cenozoic records of new plant fossil species reported from the Tibet(Xizang)Autonomous Region 45 out of 63(70%)were documented after 2010.Among these,many represent the earliest records from Asia,or in some cases worldwide,at the genus or family level.(2)These fossils show that during the Paleogene,the region now occupied by the Tibetan Plateau was a globally significant floristic exchange hub.Based on paleobiogeographic studies,grounded by fossil evidence,there are four models of regional floristic migration and exchange,i.e.,into Tibet,out of Tibet,out of India and into/out of Africa.(3)Plant fossils evidence the asynchronous formation histories for different parts of the Tibetan Plateau.During most of the Paleogene,there was a wide east-west trending valley with a subtropical climate in central Tibet bounded by high(>4 km)mountain systems,but that by the early Oligocene the modern high plateau had begun to form by the rise of the valley floor.Paleoelevation reconstructions using radiometrically-dated plant fossil assemblages in southeastern Tibet show that by the earliest Oligocene southeastern Tibet(including the Hengduan Mountains)had reached its present elevation.(4)The coevolution between vegetation,landform and paleoenvironment is evidenced by fossil records from what is now the central Tibetan Plateau.From the Paleocene to Pliocene,plant diversity transformed from that of tropical,to subtropical forests,through warm to cool temperate woodland and eventually to deciduous shrubland in response to landscape evolution from a seasonally humid lowland valley,to a high and dry plateau.(5)Advanced multidisciplinary technologies and novel ideas applied to paleobotanical material and paleoenvironmental reconstructions,e.g.,fluorescence microscopy and paleoclimatic models,have been essential for interpreting Cenozoic floras on the Tibetan Region.However,despite significant progress investigating Cenozoic floras of the Tibetan Region,fossil records across this large region remain sparse,and for a better understanding of regional ecosystem dynamics and management more paleobotanical discoveries and multidisciplinary studies are required.

横断山南段上新世的植被多样性与分布格局

横断山南段复杂的地形地貌和多样的气候环境造就了高度丰富的植被多样性。这种植被多样性的演化与形成是植物学、生态学等领域共同关注的科学问题,而植物化石是回答这一科学问题的重要媒介。本文基于横断山南段的9个上新世化石植物群,根据其植物组成和优势成分,分析其所代表的植被类型,总结了该地区上新世的植被多样性与空间分布,并结合古环境研究资料,探讨该地区植被多样性的兴起,植被分布格局的形成,及其与环境变迁之间的关联。结果显示,横断山南段在上新世时期已经具有了多种植被类型,包括亚热带常绿阔叶林、亚热带落叶阔叶林、硬叶常绿阔叶林、针阔叶混交林、灌丛草地等,体现了丰富的植被多样性;植被类型从南面的偏热性植被向北面的偏温性植被逐渐转变,反映了当时随纬度变化的海拔梯度,植被类型与分布呈现出与现在高度相似的格局。同时,小范围内也具有适应于不同气候的植被类型,反映了当地较大的海拔落差,可能与高大山体的存在有着密切关联。我们推测,横断山南段现在丰富的植被多样性和随纬度变化的植被面貌最晚在上新世就已基本形成,但形成时间是否更早则需要更多、更老化石植物群的发现与研究。

滇东南普阳盆地含煤地层孢粉组合特征及其年代

云南地处青藏高原东南缘,生物多样性丰富,季风气候特征明显。新生代剧烈的构造活动形成了众多山间盆地,其间保存了大量精美的植物化石,是探讨新生代以来植被、植物多样性和地球环境演变的理想地区。但是长期以来,由于地层年代学证据的缺乏,这些新生代沉积盆地的地质年代还存在很大争议。本研究通过对滇东南地区富宁县普阳盆地的含煤地层开展深入的孢粉学研究,探讨盆地含煤地层年代及其古气候演化过程。剖面下部煤层孢粉组合以杉粉属(Taxodiaceaepollenites)为主,指示以杉科为主的湿润沼泽森林,冬春季相对湿润;剖面上部孢粉组合指示以常绿栎类为主的亚热带常绿-落叶阔叶混交林,生长山核桃粉属(Caryapollenites)、冬青粉属(Ilexpollenites)、胡桃粉属(Juglanspollenites)、枫香粉属(Liquidambarpollenites)等亚热带常见树种,气候温暖湿润,季节分明。结合新发现的哺乳动物化石证据和周边地区不同地质时代的孢粉组合,普阳盆地含煤地层的沉积时代应为晚始新世;同时,孢粉组合也表明滇东南地区植被现代化面貌至少在晚始新世就已经开始出现。