Table of Contents

01 January 2021, Volume 59 Issue 1

Cover illustration: The population genetic structure and admixture history of Tibeto-Burman-speaking Tujia people are largely unknown due to a lack of sampling. Investigation on the fi ne-scale genetic structure in 505 unrelated individuals from 63 indigenous central Chinese populations by He et al. (pp. 1–20 in this issue) not only discovered the strong genetic similarities between Tujia and surrounding Han Chinese, suggesting massive population movements and genetic admixture under language borrowing, but also illuminated that all central Chinese populations could be modelled as a two-way admixture deriving primary ancestry from a northern ancestral population closely related to the ancient DevilsCave and present-day Tibetans and a southern ancestral population closely related to the present-day Tai-Kadai and Austronesian-speaking groups.
Photograph by Peng Deng. Designed by Chuan-Chao Wang and Guang-Lin He. [Detail] ...

  

Research Articles
• 

  Fine‐scale genetic structure of Tujia and central Han Chinese revealing massive genetic admixture under language borrowing

  Guang-Lin He, Ying-Xiang Li, Meng-Ge Wang, Xing Zou, Hui-Yuan Yeh, Xiao-Min Yang, Zheng Wang, Ren-Kuan Tang, Su-Min Zhu, Jian-Xin Guo, Ting Luo, Jing Zhao, Jin Sun, Zi- Yang Xia, Hao-Liang Fan, Rong Hu, Lan-Hai Wei, Gang Chen, Yi- Ping Hou, and Chuan-Chao Wang

  J Syst Evol. 2021, 59(1): 1-20.
  https://doi.org/10.1111/jse.12670

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  Archaeological, genetic, and linguistic evidence has supported the idea that northern China is the original center of modern Sino‐Tibetan‐speaking populations. However, the demographic history of subsequent southward migration and genetic admixture of Han Chinese with surrounding indigenous populations remain uncharacterized, and the language shifts and assimilations accompanied by movement of people, or just an adaptation of cultural ideas among populations in central China is still unclear, especially for Tibeto‐Burman‐speaking Tujia and central Han Chinese populations. To resolve this, we genotyped over 60K genome‐wide markers in 505 unrelated individuals from 63 indigenous populations. Our results showed both studied Han and Tujia were at the intermediate position in the modern East Asian North–South genetic cline and there was a correlation between the genetic composition and the latitude. We observed the strong genetic assimilation between Tujia people and central Han Chinese, which suggested massive population movements and genetic admixture under language borrowing. Tujia and central Han Chinese could be modeled as a two‐way admixture deriving primary ancestry from a northern ancestral population closely related to the ancient DevilsCave and present‐day Tibetans and a southern ancestral population closely related to the present‐day Tai‐Kadai and Austronesian‐speaking groups. The ancestral northern population we suspect to be related to the Neolithic millet farming groups in the Yellow River Basin or central China. We showed that the newly genotyped populations in Hubei Province had a higher proportion of DevilsCave or modern Tungusic/Mongolic‐related northern ancestries, while the Hunan populations harbored a higher proportion of Austronesian/Tai‐Kadai‐related southern ancestries.

  We genotyped over 600K genome‐wide markers in 505 unrelated individuals from 63 indigenous populations. Our results showed that both studied Han and Tujia were at the intermediate position in the modern East Asian North–South genetic cline and there was a correlation between the genetic composition and the latitude. We observed the strong genetic assimilation between Tujia people and central Han Chinese, which suggested massive population movements and genetic admixture under language borrowing. Tujia and central Han Chinese could be modeled as a two‐way admixture deriving primary ancestry from a northern ancestral population closely related to the ancient DevilsCave and present‐day Tibetans and a southern ancestral population closely related to the present‐day Tai‐Kadai and Austronesian‐speaking groups. The ancestral northern population we suspect to be related to the Neolithic millet farming groups in the Yellow River Basin or central China. We showed that newly genotyped populations in Hubei Province had a higher proportion of DevilsCave or modern Tungusic/Mongolic‐related northern ancestries, while the Hunan populations harbored a higher proportion of Austronesian/Tai‐Kadai‐related southern ancestries.
Issue Information
• Issue Information

  J Syst Evol. 2021, 59(1): 1-4.
  https://doi.org/10.1111/jse.12605

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Research Articles
• Evolution of reproductive traits in the mahagony family (Meliaceae)

  Rebeca Laino Gama , Alexandra Nora Muellner-Riehl , Diego Demarco , and José Rubens Pirani

  J Syst Evol. 2021, 59(1): 21-43.
  https://doi.org/10.1111/jse.12572

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  Meliaceae are a mostly pantropical family in the Sapindales, bearing flowers typically provided with a staminal tube, formed by filaments that are fused partially or totally. Nevertheless, several genera of subfamily Cedreloideae have free stamens, which may be adnate to an androgynophore in some taxa. The fact that the family exhibits a wide diversity of floral and fruit features, as well as of sexual systems and pollination syndromes, presents interesting questions on the evolutionary processes that might have taken place during its history. In this study, we analyzed the distribution of 20 reproductive morphological traits of Meliaceae, upon an available molecular phylogenetic framework, using 31 terminals from the family's two main clades (Cedreloideae and Melioideae), plus six Simaroubaceae taxa as outgroup. We aimed to identify and/or confirm synapomorphies for clades within the family and to develop hypotheses on floral evolution and sexual systems in the group. Our reconstruction suggests that the ancestor of Meliaceae was possibly provided with united stamens and unisexual flowers in dioecious individuals, with a subsequent change to free stamens and monoecy in the ancestor of Cedreloideae. Most characters studied show some degree of homoplasy, but some are unique synapomorphies of clades, such as the haplostemonous androecium. An androgynophore defines the Cedrela‐Toona clade. The comparative approach of our study and the evolutionary hypotheses generated herein reveal several aspects demanding further structural investigation, and possible evolutionary pathways of the reproductive structures along with the lineages' diversification, mostly related to the specialization of sexual systems, floral biology, and dispersal strategies.
• Restriction‐site associated DNA sequencing data reveal a radiation of willow species (Salix L., Salicaceae) in the Hengduan Mountains and adjacent areas

  Li He, Natascha Dorothea Wagner, and Elvira Hörandl

  J Syst Evol. 2021, 59(1): 44-57.
  https://doi.org/10.1111/jse.12593

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  The Hengduan Mountains (HDM) in China are an important hotspot of plant diversity and endemism, and are considered to be a secondary diversification center for the woody plant genus Salix L. (Salicaceae). Here we aimed to reconstruct the spatiotemporal evolution of the Salix Chamaetia‐Vetrix clade in the HDM and to test for the occurrence of a local radiation. We inferred phylogenetic relationships based on more than 34 000 restriction‐site associated DNA loci from 27 species. Phylogenetic analyses recovered a well‐resolved tree topology with two major clades, the Eurasian clade and the HDM clade, with a divergence time of ca. 23.9 Ma. Species in the HDM clade originated in the northern part of the range and adjacent areas, and then dispersed into the southern HDM, westwards to the Himalayas and eastwards to the Qinling Mountains. Niche modelling analyses reveal that range contractions occurred in the northern areas during the last glacial maximum, while southward expansions resulted in range overlaps. Reconstructions of character evolution related to plant height, inflorescence, and flower morphology suggest that adaptations to altitudinal distribution contributed to the diversification of the HDM willows. Our data support the occurrence of a radiation in the HDM within the Salix Chamaetia‐Vetrix clade. Dispersal within the mountain system, and to adjacent regions, in addition to survival in glacial refugia shaped the biogeographical history of the clade, while adaptations of the HDM willows along an altitudinal gradient could be important ecological factors explaining the high species diversity of Salix in this area.
• Using RAD seq for reconstructing phylogenies of highly diverged taxa: A test using the tribe Scandiceae (Apiaceae)

  Marcin Piwczyński, Paulina Trzeciak, Madalina-Oana Popa, Maciej Pabijan, José María Corral, Krzysztof Spalik, and Andrzej Grzywacz

  J Syst Evol. 2021, 59(1): 58-72.
  https://doi.org/10.1111/jse.12580

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  The angiosperm Apiaceae tribe Scandiceae includes four major clades—subtribes Daucinae, Ferulinae, Torilidinae, and Scandicinae—that originated ca. 20 Mya. Although all four subtribes are highly supported in molecular analyses, and morphological data indicate a sister relationship between Daucinae and Torilidinae, their branching order has not been resolved using standard Sanger multilocus data. Therefore, in this study, we test the utility of genomic RAD seq data in resolving deep phylogenetic relationships (up to 20 Mya) in Apiaceae subfamily Apioideae, with special emphasis on tribe Scandiceae using 12 representative species. We used two bioinformatic pipelines, pyRAD and RADIS (based on STACKS), to assemble RAD seq data and we tested the influence of various combinations of parameters on the robustness of the inferred tree topologies. Although different data processing approaches produced alignments with various amounts of missing data, they converged to two well‐supported topologies, irrespective of the phylogenetic method applied. Highly supported trees showed Scandicinae as sister to all other clades and indicated that Daucinae and Torilidinae are sister groups, thus confirming the relationship inferred from morphology. We conclude that the RAD seq method can be successfully used to resolve deep relationships formed 20 Mya within Apiaceae. We provide recommendations for parameter settings in RADIS and pyRAD for the analysis of taxa that have accumulated considerable genomic divergence.
• Phylogeny and biogeography of the hollies (Ilex L., Aquifoliaceae)

  Xin Yao, Yu Song, Jun-Bo Yang, Yun-Hong Tan, and Richard T. Corlett

  J Syst Evol. 2021, 59(1): 73-82.
  https://doi.org/10.1111/jse.12567

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  The holly genus, Ilex L., in the monogeneric Aquifoliaceae, is the largest woody dioecious genus (>664 spp.), with a near‐cosmopolitan distribution in mesic environments. We constructed a phylogeny based on two nuclear genes, representing 177 species spread across the geographical range, and dated using macrofossil records. The five main clades had a common ancestor in the early Eocene, much earlier than previously suggested. Ilex originated in subtropical Asia and extant clades colonized South America by 30 Ma, North America by 23 Ma, Australia by 8 Ma, Europe by 6 Ma, and Africa by 4 Ma. South and North America were colonized multiple times. Ilex also reached Hawaii (10 Ma) and other oceanic islands. Macrofossil and pollen records show the genus has tracked mesic climates through time and space, and had a wider distribution before late Miocene global cooling. Our phylogeny provides a framework for studies in comparative ecology and evolution.
• Genome structure and apomixis in Phoenicaulis (Brassicaceae; Boechereae)

  Terezie Mandáková, Kaylynn Ashby, Bo J. Price, Michael D. Windham, John G. Carman, and Martin A. Lysak

  J Syst Evol. 2021, 59(1): 83-92.
  https://doi.org/10.1111/jse.12555

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  Apomixis in crucifer (Brassicaceae) species is rare, reported in just four genera (Boechera, Draba, Erysimum, and Parrya), and one intergeneric hybrid (Raphanobrassica). It is well studied only in Boechera, where it is widespread among 100+ recognized species. However, its occurrence in related genera of the tribe Boechereae has not been documented previously. Here we analyzed genome evolution, mode of reproduction, and fertility of the monospecific Boechereae genus Phoenicaulis (P. cheiranthoides), endemic to the northwestern United States. We discovered that the species encompasses diploid (2n = 2x = 14), triploid (2n = 3x = 21), and tetraploid (2n = 4x = 28) populations. Comparative chromosome painting analyses revealed that the three karyotypes are essentially structurally identical, differing only in the presence of a largely heterochromatic chromosome (Het) in the triploid and tetraploid cytotypes. The genome structure of Phoenicaulis appeared identical to that of Boechera species previously analyzed, suggesting genomic stasis despite the morphological and molecular divergence of the two genera. This genome colinearity extended to the presence and structure of the Het chromosomes, which are closely associated with apomictic reproduction in Boechera. Interestingly, all three cytotypes of Phoenicaulis proved to be apomictic, regardless of the presence or absence of a Het chromosome, and sexual populations have yet to be identified.
• Origin and diversification of Indian Ceropegieae (Apocynaceae) and its possible relation to the Indian monsoon

  Siddharthan Surveswaran, Sharad S. Kambale, Mansa Srivastav, Sachin A. Punekar, Shrirang R. Yadav, and K. Praveen Karanth

  J Syst Evol. 2021, 59(1): 93-112.
  https://doi.org/10.1111/jse.12578

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  The Indian subcontinent has experienced a major shift in climatic regime from a wet tropical regime to increased seasonal rainfall, since the late Miocene. This shift has been attributed to the intensification of monsoons, which led to opening up of dry habitats in humid forests and formation of deciduous forests. We explored the role of this climatic shift in the origin and diversification of dry‐adapted plant genera Ceropegia and Brachystelma (Ceropegiae, Asclepiadoideae, Apocynaceae). We sampled Ceropegia and Brachystelma from across India and used five markers (two nuclear and three plastid regions) to reconstruct a global phylogeny of this group. Indian members of the tribe Ceropegiae were derived from Africa through at least four independent dispersal events. All dispersal events occurred in late Miocene after establishment of a monsoon climate. One of these early dispersing lineages underwent rapid radiation in peninsular India, giving rise to around 50 species. Thus, both dispersal and diversification events coincided with the intensification of monsoons and concomitant aridification. The role of environment in the evolution of floral characteristics and root type in the Indian radiation is also discussed. This is one of the first reports on a dry‐adapted endemic radiation of plants in India.
• Evidence of widespread hybridization among couch grasses (Elymus, Poaceae)

  Romana Urfusová, Václav Mahelka, František Krahulec, and Tomáš Urfus

  J Syst Evol. 2021, 59(1): 113-124.
  https://doi.org/10.1111/jse.12563

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  Hybridization, polyploidization, and crop‐to‐wild gene transfer within the agriculturally important tribe Triticeae are well explored experimentally, but the true consequences of both phenomena under natural conditions remain understudied. The present paper reports on an investigation of three species of couch grasses (Elymus hispidus, E. repens, and E. caninus) examining the ploidy levels and absolute genome sizes (1081 plants from 302 natural populations in Central Europe, verified by chromosome counts) and their morphological delimitation. In the present study, the hexaploid level prevailed in E. hispidus and E. repens whereas E. caninus was exclusively tetraploid. Introgressive hybridization between hexaploid species, unidirectionally shifted towards E. hispidus, was indicated by a continual pattern of genome size values. We did not find any evidence for heteroploid hybridization involving tetraploid E. caninus; however, we detected minority cytotypes among both E. caninus plants (hexaploid) and E. repens–E. hispidus hybrids (heptaploid and nonaploid) suggesting the formation of unreduced gametes. Morphometric results (367 plants, redundancy analysis, principal component analysis, and correlation analysis) mirrored the continual homoploid pattern of absolute genome size (including the unidirectional shift), and a significant correlation between absolute genome size and morphology was confirmed. Moreover, morphometric analyses detected additional characteristics for the delimitation of the Elymus taxa under study. Considering the crossability of E. hispidus with Triticum aestivum (bread wheat), the revealed extent of introgressive hybridization has implications for assessing the potential risk of gene flow between crops and troublesome weeds.
• Exploring the reticulate evolution in the Asplenium pekinense complex and the A. varians complex (Aspleniaceae)

  Si-Qi Liang, Ronald L. L. Viane, Xian-Chun Zhang, and Ran Wei

  J Syst Evol. 2021, 59(1): 125-140.
  https://doi.org/10.1111/jse.12530

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  The Asplenium pekinense complex mainly comprises one diploid, A. sarelii Hook. (rare), one autotetraploid, A. pekinense Hance (best known and very common), and shares two allotetraploids, A. anogrammoides Christ (common but often misidentified) and A. altajense (Komarov) Grubov (rare and endemic) with the A. varians complex. The latter is further constituted by two diploids, A. tenuicaule Hayata (widespread) and A. semivarians Viane & Reichstein (rare), as well as other three tetraploids, A. kansuense Ching (barely known), A. varians Wallich ex Hooker & Greville (well‐known, relatively common, and morphologically variable), and A. kukkonenii Viane & Reichstein (rare and often misidentified). These two species complexes are notorious for their taxonomic difficulty based on general morphology, which is mainly caused by their history of reticulate evolution. Here, we collected most species within the two complexes, and obtained ploidy information by spore size measurement and flow cytometry investigation. Phylogenetic analyses using DNA markers representing maternally inherited chloroplast and biparentally inherited nuclear genomes helped to reconstruct the reticulate evolution history. The present results support previous hypotheses that A. sarelii is the ancestor of both A. pekinense and A. anogrammoides, as well as that A. tenuicaule is the common progenitor of A. anogrammoides, A. varians, and A. kukkonenii. We also unraveled the autotetraploid origin of A. kansuense from A. tenuicaule for the first time, and found that A. altajense shares essentially identical genomes with A. anogrammoides.
• Species richness and phylogenetic diversity of different growth forms of angiosperms across a biodiversity hotspot in the horn of Africa

  Ya-Dong Zhou, Biyansa Hirpo Boru, Sheng-Wei Wang, and Qing-Feng Wang

  J Syst Evol. 2021, 59(1): 141-150.
  https://doi.org/10.1111/jse.12559

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  Woody and herbaceous plants are differentially influenced by the environment, with non‐random association with the evolutionary history of these taxa and their traits. In general, woody plants may have climate‐dominated niches, whereas herbaceous plants may have edaphic and microhabitat‐dominated niches. Here, we explored and mapped how the patterns of species richness, phylogenetic diversity, and structures of total, woody, and herbaceous plants vary across the geographical regions and with respect to 12 environmental variables across Ethiopia and Eritrea, in the horn of Africa. Our result showed that both richness and phylogenetic diversity had almost the same tendency in total woody and herbaceous plants, in which they showed positive relationships with annual precipitation, precipitation annual range of climate, all the three variables of topography, and total nitrogen and total extractable phosphorus of soil, and negative relations with mean annual temperature. Compared with the total and herbaceous plants, the environmental variables explained greater variance both in the standardized effect size phylogenetic diversity and net relatedness index for woody plants. Our results highlight that, on the large spatial scales, the environmental filtering process has played a greater role in structuring species into local communities for woody plants than for herbaceous plants.
• Geoclimatic factors influence the population genetic connectivity of Incarvillea arguta (Bignoniaceae) in the Himalaya–Hengduan Mountains biodiversity hotspot

  Santosh Kumar Rana, Dong Luo, Hum Kala Rana, Alexander Robert O’Neill, and Hang Sun

  J Syst Evol. 2021, 59(1): 151-168.
  https://doi.org/10.1111/jse.12521

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  Geoclimatic factors related to the uplift of the Himalaya and the Quaternary climatic oscillations influence the population genetic connectivity in the Himalaya–Hengduan Mountains (HHM) biodiversity hotspot. Therefore, to explore the relative roles played by these two factors, we examined the population dynamics and dispersal corridors of Incarvillea arguta (Royle) Royle incorporating ensemble species distribution modelling (SDM). Thirty‐seven populations were genotyped using plastid chloroplast DNA and low copy nuclear gene (ncpGS) sequences. Phylogeographic analysis was carried out to reveal the genetic structure and lineage differentiation. Ensemble SDMs were carried out for distributional change in the last glacial maximum, present, and future. Finally, the least cost path method was used to trace out possible dispersal corridors. The haplotypes were divided into four clades with strong geographical structure. The late Miocene origin of I. arguta in the western Himalaya ca. 7.92 Ma indicates lineage diversification related to the uplift of the HHM. The variability in habitat connectivity revealed by SDM is due to change in suitability since the Pleistocene. A putative dispersal corridor was detected along the drainage systems and river valleys, with strong support in the eastern Hengduan Mountains group. Our results support the signature of geoclimatic influence on population genetic connectivity of I. arguta in the HHM. We proposed that the major drainage systems might have assisted the rapid dispersal of isolated riverine plant species I. arguta in the HHM. The population genetic connectivity, using the fine‐tuned ensemble SDMs, enables scientists and policymakers to develop conservation strategies for the species gene pool in the HHM biodiversity hotspots.
• Evolution and diversity of axon guidance Robo receptor family genes

  Yi-Qin Xu, Xin Li, Yang Zhong, and Yu-Fang Zheng

  J Syst Evol. 2021, 59(1): 169-182.
  https://doi.org/10.1111/jse.12587

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  The diversity of axon guidance (AG) receptors reflects gains in complexity of the animal nervous system during evolution. Members of the Roundabout (Robo) family of receptors interact with Slit proteins and play important roles in many developmental processes, including AG and neural crest cell migration. There are four members of the Robo gene family. However, the evolutionary history of Robo family genes remain obscure. We analyzed the distribution of Robo family members in metazoan species ranging in complexity from hydras to humans. We undertook a phylogenetic analysis in metazoans, synteny analysis, and ancestral chromosome mapping in vertebrates, and detected selection pressure and functional divergence among four mammalian Robo paralogs. Based on our analysis, we proposed that the ancestral Robo gene could have undergone a tandem duplication in the vertebrate ancestor; then one round of whole genome duplication events occurred before the divergence of ancestral lamprey and gnathostome, generating four paralogs in early vertebrates. Robo4 paralog underwent segmental loss in the following evolutionary process. Our results showed that Robo3 paralog is under more powerful purifying selection pressure compared with other three paralogs, which could correlate with its unique expression pattern and function. Furthermore, we found four sites under positive selection pressure on the Ig1‐2 domains of Robo4 that might interfere with its binding to Slits ligand. Diverge analysis at the amino acid level showed that Robo4 paralog have relatively greater functional diversifications than other Robo paralogs. This coincides with the fact that Robo4 predominantly functions in vascular endothelial cells but not the nervous system.
• Floral development in the androdioecious tree Tapiscia sinensis: Implications for the evolution to androdioecy

  Gui-Liang Xin, Guo-Lun Jia, Xiao-Long Ren, Yue-Yue Wang, Peng Zhao, and Wen-Zhe Liu

  J Syst Evol. 2021, 59(1): 183-197.
  https://doi.org/10.1111/jse.12517

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  The evolutionary pathway between hermaphroditism and dioecy (females and males in a single population) draws widespread interests, and androdioecy (bisexuals and males in a single population) is rarely achieved as an intermediate state between the two breeding systems. Flower bud differentiations in the pistils of hermaphrodites and the pistillodes of males in androdioecious Tapiscia sinensis Oliv. are investigated by routine paraffin section technology, light microscopy, and scanning electron microscopy. A phylogenetic approach is used to analyze the origin of androdioecy. In T. sinensis, hermaphroditic flowers (HF) and male flowers (MF) experienced a similar development pattern in early flower bud differentiation, including the initiation of tepals and stamens. However, the carpel differentiation of MF and HF proceed in different patterns. In HF, the central zone bulges out and produces a ring meristem on which two to three carpel primordia emerge, which eventually developed into a normal pistil with a stigma, a style, and an ovary. However, in most MF, vestigial pistils are stem‐like (type I), and very few have an empty ovary (type II) or a sterile ovule (type III). Moreover, the evolution of sexual systems within the Huerteales indicates that hermaphroditism is the primitive character of T. sinensis. Tapiscia sinensis shows different degrees of reduction between male flowers and bisexual ones in the evolution to dioecy. Functional androdioecy originated from a hermaphroditic ancestor in T. sinensis and, as an intermediate sexual system, involves evolution from hermaphrodites to dioecy.
• Mummified fossil of Keteleeria from the Late Pleistocene of Maoming Basin, South China, and its phytogeographical and paleoecological implications

  Lu-Liang Huang, Jian-Hua Jin, and Alexei A. Oskolski

  J Syst Evol. 2021, 59(1): 198-215.
  https://doi.org/10.1111/jse.12540

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  Keteleeria is a small genus of Pinaceae now mainly restricted to eastern Asia. Although this genus has been documented with a wide distribution in the geologic record of Europe, North America, and Asia, its history in low‐latitude areas (including South China) has remained obscure. In this paper, a fossil wood of Keteleeria sp. is described from the Late Pleistocene (29–27 ka BP) of the Maoming Basin, South China. This wood is the most ancient megafossil evidence of Keteleeria within the modern distribution area of this genus. The fossil records of Keteleeria suggests that this thermophyllous genus migrated into South China by the Middle Pleistocene escaping from glacial cooling and became widespread over this region in the Late Pleistocene beginning from the interglacial stage preceding the Last Glacial Maximum. The analysis of growth rings in the fossil wood and its comparison with those of modern Keteleeria davidiana (Bertrand) Beissner indicates that in the Late Pleistocene of Maoming Basin (29–27 ka BP) there was a humid climate with less pronounced seasonality of precipitation than that seen in the subtropical monsoonal climate of modern northeastern Vietnam. Apparently, the Maoming Basin was influenced by interglacial regime with summer–monsoon circulation. The previously proposed method to distinguish between evergreen and deciduous conifers based on growth ring anatomy, is not reliable because of the wide variance and ambiguity in its results.
• First fossil record of an East Asian endemic genus Sladenia (Sladeniaceae) from its modern range: Implications for floristic evolution and conservation biology

  Lin-Bo Jia, Steven R. Manchester, Jian Huang, Tao Su, Li Xue, Shi-Tao Zhang, Yong-Jiang Huang, and Zhe-Kun Zhou

  J Syst Evol. 2021, 59(1): 216-226.
  https://doi.org/10.1111/jse.12518

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  Fossil records of endemic plants play an important role in recognizing the floristic history of East Asia and thereby facilitate the conservation of plant diversity in the region. However, the fossil record of many extant East Asian endemic genera remains poorly documented thus far. Here, we report an infructescence fossil of an East Asian endemic genus, Sladenia (Sladeniaceae), from the early Miocene of southeastern Yunnan, China. The fossil is characterized by: (i) dichasial cymes; and (ii) flask‐shaped ovary with dense subparallel ribs on the surface extending from the base to the distal end of the united style. It represents the first fossil record of Sladenia in Asia, showing that the genus was established in the region at least by the early Miocene. Given that a much older fossil record of Sladeniaceae has been reported from Africa and the sister group of Sladenia is distributed only in Africa, Sladenia is not likely of East Asian origin. The present endemic status of Sladenia was possibly achieved by regional extirpation in Africa and taking refuge in East Asia. This case thus supports the “Museum” rather than “Cradle” hypothesis for the genesis of high plant species in the flora of East Asia. A comparison of the present fossil with extant Sladenia infructescence shows morphological stasis from the early Miocene to present. Such evolutionary tardiness might have resulted in the reduced fitness of the genus, which further caused its current endangered situation.
Reviewers List
• List of Reviewers

  J Syst Evol. 2021, 59(1): 227-228.
  https://doi.org/10.1111/jse.12601

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  The Journal of Systematics and Evolution would like to acknowledge and thank the following reviewers for their contributions in the period January 1–December 31 in 2020:

  Andrés‐Sánchez, Santigo

  Antunes Carvalho, Fernanda

  Appelhans, Marc

  Bachelier, Julien

  Bai, Wei‐Ning

  Baldwin, Bruce

  Banasiak, Lukasz

  Bao, Ying

  Bard, Nicholas

  Benítez Benítez, Carmen

  Berry, Paul

  Bonifacio de Leon, Mauricio

  Bontrager, Megan

  Boufford, David

  Brandrud, Marie Kristine

  Bruederle, Leo

  Camara, Paulo

  Cameron, Kenneth

  Cannon, Chuck

  Carta, Angelino

  Catherine, Lafarge

  Chen, Chun‐Yan

  Chen, Hua

  Chen, Lei

  Chen, Zhi‐Duan

  Clark, Lynn

  Compton, James

  Conran, John

  Corlett, Richard

  Costa, Suzana

  Crane, Peter

  Crawford, Daniel

  Crespo, Manuel B.

  Crowl, A

  Davis, Aaron

  Davis, Jerrold

  De Franceschi, Dario

  de Sousa, Philipe

  Del Rio, Cédric

  Deng, Min

  Denk, Thomas

  Dickinson, Timothy A.

  Dou, Quan‐Wen

  Du, Fang

  Dupuis, Julian R.

  Duvall, Melvin

  Ebersbach, Jana

  Eder, Johanna

  Edera, Alejandro

  Elliott, Tammy L.

  Eriksson, Torsten

  Escudero, Marcial

  Evans, Timothy M.

  Favre, Adrien

  Figlar, Dick

  Fior, Simone

  Fitzpatrick, Matt

  Ford, Bruce

  Foster, Charles

  Freire, Susana

  Freudenstein, John

  Friis, Else

  Fritsch, Peter

  Gao, Lian‐Ming

  Ge, Xue‐Jun

  Geltman, Dmitry

  Gensel, Patricia

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