Diversity and membership of species in a biological community result from the interplay between evolutionary and ecological processes. Plant ecologists often rely on family-level phylogenies to address various issues of community assembly because phylogenies resolved at the species or genus level are generally not available. Here, we present an updated time-calibrated family-level phylogeny that includes all families of extant seed plants (i.e., angiosperms and gymnosperms) in the world, and use the phylogeny to show patterns of genus and species richness and life forms of all seed plant families in the world across the phylogeny. In addition, we use the phylogeny to examine whether life forms (woody vs. herbaceous) of seed plant families in the world are non-randomly distributed across the phylogeny. Our study shows that life forms exhibit significant phylogenetic signal across the phylogeny of seed plants.

The phylogeny of Asian Schefflera was inferred from sequences of the nuclear ribosomal internal transcribed spacer region, and six plastid regions (the ndhF gene, the trnL-trnF region, the rps16 intron, the atpB-rbcL intergenic spacer, the rpl16 intron, and the psbA-trnH intergenic spacer). Phylogenetic analyses of the combined plastid and internal transcribed spacer data with parsimony and Bayesian methods strongly support the monophyly of Asian Schefflera. The genus is supported to be closely related to Heteropanax and Tetrapanax with the small tropical continental Asian genus Heteropanax as its sister. Within Asian Schefflera, four distinct subclades were identified: (i) the widely distributed Asian Heptapleurum group with no styles in the gynoecium; (ii) the main Agalma group with racemose or spicate inflorescence units with a few umbellate taxa; (iii) the Schefflera hypoleuca group; and (iv) the Schefflera heptaphylla group. In a broader phylogenetic framework of Araliaceae, Asian Schefflera is hypothesized to have originated in continental Asia at 57.41 Mya (95% high posterior density interval of 40.33–76.06 Mya) in the early Tertiary and radiated into the now SE Asia, eastern Himalaya, and E Asia at 46.11 Mya (95% high posterior density interval of 33.02–60.69 Mya). Its subsequent diversification in Asia may have been driven largely by the collision of the Indian plate with the Asian plate in the middle Eocene and the collision of the Australian margin with the Eurasian margin in the early Miocene.

Cystoathyrium chinense Ching, the sole representative of Cystoathyrium, is a critically endangered species endemic to China with no more than 40 extant individuals. Until now, its systematic position and relationships among leptosporangiate ferns remained unknown. The present study assessed the phylogenetic relationships ofCystoathyrium chinense with potential relatives densely sampled using three chloroplast DNA markers (matK, rbcL, and trnG-R intergenic spacer). Our results support the inclusion of Cystoathyrium in Cystopteris. A hybrid origin hypothesis of Cystoathyrium chinense is neither supported nor rejected by the present study. According to our ancestral area reconstruction analysis, the disjunct distribution of Cystoathyrium and its closely related North American taxa may be attributed to the long-distance dispersal by way of Beringia. Consequently, a new combination (Cystopteris chinensis comb. nov.) is made, and the description is supplemented based on our new observations in the field.

The genetic variation and structure of Sladenia celastrifolia Kurz, a species of conservation concern, were investigated. Analyses of two chloroplast DNA loci (trnS-trnGand atpB-rbcL intergenic regions) were carried out for 24 populations of S. celastrifolia and five haplotypes were identified. High levels of genetic differentiation (G_ST = 1, F_ST = 1) were detected, which may be a result of limited gene flow caused by geographic isolation. Analysis of molecular variance suggests that the existence of marked phylogeographical structure within the haplotype distribution is probably due to geographic barriers among populations. The haplotype network and mismatch distribution analyses did not detect any signals for recent population expansions in S. celastrifolia. Thus, it can be inferred that the species likely persistedin situ during climatic oscillations. Considering its genetic diversity and uniqueness, conservation strategies are further discussed for this species.

The significant role of segregation distortion as a driving force of evolution has increasingly gained recognition worldwide. Segregation distortion of parental alleles is commonly reported in hybrid progeny between crops and wild relative species, which possibly influences the evolution potential of the hybrid progeny. Whether transgene introgression into wild and weedy populations through repeated hybridization causes changes of segregation distortion of parental alleles in hybrid progeny is an important question to be addressed to understand the long-term evolution potential of the populations that have received transgenes. To study the influence of a transgene on allelic segregation, we examined gene and genotype frequencies in transgenic and non-transgenic populations of F₃ and F₄ lineages derived from hybrids between transgenic insect-resistant rice (Bt/CpTI) and weedy rice, involving randomly selected 25 simple sequence repeat markers with polymorphisms between the two parents. We found that the transgenes can significantly alter the segregation distortion pattern in hybrid progeny, particularly the direction of segregation deviated to different parents. In transgenic F₃ and F₄ populations, there are approximately 64% and 77% simple sequence repeat loci, respectively, with alleles deviated significantly to the insect-resistant cultivated rice parent; whereas, in non-transgenic F₃ and F₄ populations, approximately 68% and 58% loci, respectively, deviated significantly to the weedy rice parent. Transgenes with strong selection advantages may have evolutionary impacts on hybrid progeny by changing their pattern of allelic segregation distortion after introgression from transgenic crops to wild relatives through hybridization.

Malus toringoides Hughes and its close relatives, M. maerkangensis M. H. Cheng et al., M. setok Vassilcz., and M. xiaojinensis M. H. Cheng & N. G. Jiang were supposed to derive from hybridizations. However, molecular data are still inadequate to corroborate the hybrid origin hypotheses. In this study, we sequenced a single-copy nuclear gene SbeI and three chloroplast fragments and carried out phylogenetic analyses to investigate the evolutionary origins of the above four putative hybrid taxa. The hybrid nature of M. toringoides is confirmed by the detection of two distinct types of SbeI sequences from it. The chloroplast and SbeI gene phylogenies show that the maternal progenitor of M. toringoides is closely related to M. sikkimensis N. P. Balakr. and M. spectabilis Borkh., and the paternal progenitor is most likely M. transitoria C. K. Schneid. The hypothesis that M. kansuensis (Batalin) C. K. Schneid. is one of the parents of M. toringoides is not supported. Malus maerkangensis and M. xiaojinensis might have originated through hybridization between M. toringoides and M. kansuensis, whereas M. setok is genetically closely related to M. toringoides. The three close relatives of M. toringoides were designated as three novel species by some researchers, however, as they were all apomictic with limited distribution areas and they originated from hybridization and polyploidization, we recommend that their species status should be re-evaluated.

Species of Podophyllum, Dysosma, Sinopodophyllum, and Diphylleia, genera from Podophylloideae of Berberidaceae, have long been used in traditional herbal medicine in East Asia and/or North America. Accurate identification of the species of these four genera is crucial to their medicinal uses. In this study, we tested the utility of nine barcodes (matK, rbcL, atpH-atpI, rpl32-trnL^UAG, rps18-clpp, trnL-trnF, trnL-ndhJ, trnS-trnfM, and internal transcribed spacer (ITS)) to discriminate different species of Podophylloideae. Thirty-six individuals representing 12 species of Podophylloideae were collected from different locations in China, Japan, and North America. We assessed the feasibility of amplification and sequencing of all markers, examined the levels of the barcoding gap based on DNA sequence divergence between ranges of intra- and interspecific variation using pairwise distances, and further evaluated successful identifications using each barcode by similarity-based and tree-based methods. Results showed that nine barcodes, except rps18-clpp, have a high level of primer universality and sequencing success. As a single barcode, ITS has the most variable sites, greater intra- and interspecific divergences, and the highest species discrimination rate (83%), followed by matKwhich has moderate variation and also high species discrimination rates. However, these species can also be discriminated by ITS alone, except Dysosma versipellis (Hance) M. Cheng ex T. S. Ying and D. pleiantha (Hance) Woodson. The combination of ITS + matK did not improve species resolution over ITS alone. Thus, we propose that ITS may be used as a sole region for identification of most species in Podophylloideae. The failure of ITS to distinguish D. versipellis and D. pleiantha is likely attributed to incomplete lineage sorting due to recent divergence of the two species.

Natural hybridization was assumed to play an essential role for the diversification of Primula; however, only one study of hybridization in the region of the Himalayas has been undertaken. In the present study, we examined another natural hybrid zone where morphologically putative hybrids as well as P. beesiana Forrest, P. bulleyana Forrest, and P. poissonii Franch. co-occurred. We used molecular data to confirm the parental species of putative hybrids and the unidirectional hybridization pattern between P. beesiana and P. bulleyana. Moreover, with reference to synthetic F₁s, most hybrids examined are possibly advanced generations, although the possibility of F₁ hybrids currently examined could not be completely excluded. In addition, pollinator observations on experimental arrays of transplanted parental species showed interspecific pollen flows during visitations of shared pollinators, indicating an incomplete pre-zygotic barrier between P. beesiana and P. bulleyana. Seed productions from both flower morphs of putative hybrids were significantly lower than parental species, suggesting lower reproductive success in these hybrids. Combined with the evidence of recent habitat disturbance in the study area, we might witness the early process of hybridization between P. beesianaand P. bulleyana.

Fossil fruits including nuts and associated husk valves of a new species of Carya (Juglandaceae) are described from the latest Miocene to earliest Pliocene in northeastern Tennessee, eastern United States. The husk valves are elliptic, 1.2–4.5 mm thick, with a convex exterior face and a concave interior face; the nuts are globose to ovoid in shape, smooth and longitudinally ribbed on exterior surface, with a short protruding apex and a slightly 4-angled base; inner ribs, lacunae and primary septa are well-developed, while secondary septa are absent or weakly developed. The combination of these carpological characteristics clearly shows a close resemblance to the genus Carya in Juglandaceae. Detailed comparisons of carpological morphology and anatomy indicate that the present fossil taxon is different from both living and most other fossil species of the genus, and therefore warrants the designation of a new fossil species, Carya tennesseensis Huang et al., sp. nov. Carya tennesseensis displays a carpological similarity to C. ventricosa from the late Oligocene to early Pliocene in Europe, suggesting a potential species exchange of the genus between Europe and southeastern North America during the late Neogene. The new fossil species represents one of the few fruit fossil species of Carya from its modern distribution range in southeastern North America. It provides crucial information for better understanding the rapid diversification of the genus from the late Miocene to early Pliocene, and the origin and establishment of today's Carya biodiversity in this region.

Both papillae and mammillae are important structural characteristics for Pottiaceae classification, but these characters are diverse and their nomenclature is confused, hindering the classification of Pottiaceae. So, we selected representative species that cover all types of papillae and mammillae of Chinese Pottiaceae and observed and compared differences between them using light and scanning electronic microscopy. We corrected the chaotic descriptions of papillae of representative species, and have provided a uniform set of terms (“simple”, “forked”, “branched”, and “pedicellate”) to describe the shapes of papillae. In addition, we described how to quickly and accurately use papillae and mammillae to classify representative species in Chinese Pottiaceae.

In order to investigate the embryological characteristics of Delavaya toxocarpa Franch. and provide a basis for further understanding the phylogeny within Sapindaceae s.l., we studied the sporogenesis and gametogenesis of D. toxocarpa using the conventional paraffin section method. The results were as follows: anthers are tetrasporangium; tapetum is typically secretory type; cytokinesis in the microsporecyte meiosis is of the simultaneous type and microspore tetrads are tetrahedral; mature pollen contains two cells; the ovary is bilocular with two ovules per locule; placentation is axial; the ovule is amphitropous, bitegmic, and crassinucellate; the chalazal megaspore in a linear tetrad becomes functional; and the development of megaspore is of the polygonum type. Most similarities shared by the species observed suggest that the species and genera of Sapindaceae s.l. have phylogenetic consistency. The distinctive trait, lacking hypostase, indicatesDelavaya (and Handeliodendron) might be more primitive than other genera in Sapindaceae. Moreover, some characters, such as opposite palmate compound leaf, apical thyrse, rounded seed without wing, 2 hemitropous ovules per locule, and lacking aril, indicate the close relationship between Delavaya, Aceraceae, and Hippocastanaceae. The preliminary data about the embryological and morphological characteristics in Delavaya might justify the basic systematic position of this genus in the family Sapindaceae s.s.