Table of Contents

17 September 2013, Volume 51 Issue 5
Cover illustration: Photos display main developmental stages of the life history of Adiantum capillus-veneris. The center photo is a chimera with sporophyte and gametophyte. For detailed information, please see LI et al., pp. 499–510 in this issue.
    Research Articles
  • Xia LI, Yu-Han FANG, Ji YANG, Shu-Nong BAI, Guang-Yuan RAO
    J Syst Evol. 2013, 51(5): 499-510.
    Adiantum capillus-veneris L., commonly regarded as a good experimental plant for the study of fern development, is investigated, and its life cycle under laboratory conditions is described. In our study, the life cycle of A. capillus-veneris was completed in 100 days. Features of spore germination, antheridium and archegonium ontogeny and development, and embryogenesis are investigated. Exosporic gametophytes of A. capillus-veneris came from spores, and ended with the cordate prothallia. Antheridia and archegonia were generally situated toward the posterior end and the notch of the prothallia, respectively. Sporophyte was also studied with emphasis on leaf morphology and the vascular system. There were vascular bundles of dictyostele without secondary vascular tissues. Sporogenesis was scrutinized from sporangial initial of a single surface cell to the annulus shedding spores explosively. Our findings provide insight into the life cycle of the leptosporangiate ferns under experimental conditions, and make it possible for A. capillus-veneris to be an underlying model plant for the study of evolutionary and developmental biology.
  • Zhi-Yong PEI, Guang-Li MU, Jin PAN, Da-Ming ZHANG
    J Syst Evol. 2013, 51(5): 511-521.
    As the most abundant protein on Earth, ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the key enzyme in carbon fixation of photosynthesis in all green plants. It is hexadecimal polymer, consisting of two kinds of subunits, large and small ones, which are encoded by different genomes. The large subunit (LSU) is encoded by the chloroplast genome; the small one by the nuclear genome. The function of RuBisCO relies on the two subunits, and only when they are combined to be hexadecimal, can it carry out its whole function. However, how the LSU and small subunits evolved, and if they coevolved, has remained mysterious. In this study, based on data in 21 species, phylogenies were analyzed on two subunits, respectively, and a mirror tree was reconstructed to reveal phylogenetic similarity. Furthermore, a comparative analysis method, using the codon usage bias and correlation calculation for RuBisCO subunits, was carried out. The relative synonymous codon usage (RSCU) values of LSU and small subunits were calculated. Finally, a novel parameter, RSCU distances-based correlation (RDC), for evaluating molecular coevolution was proposed based on Pearson's correlation coefficient between RSCU value matrices of two subunits. The results show that the topological similarity of the mirror tree gave positive evidence of coevolution between subunits. Similarly, the RDC was high, at 0.558, revealing that the RuBisCO subunits coevolved to an extent. The results confirmed that coevolution happened between the two subunits of RuBisCO, although they were encoded by different genomes. This study added new evidence that functional constraint plays an important role in the evolution of the two subunits.

  • Leandro FREITAS, Mariana ANDRICH
    J Syst Evol. 2013, 51(5): 522-535.
    Tribe Condamineeae appears to be well supported in recent phylogenetic studies. However, the species of Bathysa were divided into two clades, leading to restoration of Schizocalyx. We studied the reproductive biology of one species from each clade, which occur sympatrically in the montane Brazilian Atlantic forest. Flowering overlap was short (from December to March in B. australis and from February to June in S. cuspidatus). The flowers of both species are protogynous and homostylous and last for about 3 days. The unit of pollination in B. australis is the inflorescence. Its flowers have a greenish hypocrateriform corolla (tube about 5 mm long) and were mainly pollinated by bees and wasps in search of nectar. Schizocalyx cuspidatus has white flowers with an infundibuliform corolla (tube about 8 mm long), and its main pollinators were stingless bees in search of pollen. The pollination systems of the two species did not correspond to their pollination syndromes. Morphological differences between Bathysa and Schizocalyx were reflected in their pollination systems, with greater phenotypic specialization in S. cuspidatus, the flowers of which offer pollen as the main resource, an unusual feature within Rubiaceae. Schizocalyx cuspidatus showed higher reproductive capacity by having more inflorescences per plant, more ovules per flower, and twice the proportion of flowering individuals. However, the reproductive efficiency (fruit set, seed/ovule ratio) did not differ between the species, despite the higher frequency of visits by pollinators to S. cuspidatus. Self-compatibility in B. australis and self-incompatibility in S. cuspidatus seem to explain these results.
  • Yi-Ying LIAO, Xiao-Li YUE, You-Hao GUO, Wahiti Robert GITURU, Qing-Feng WANG, Jin-Ming CHEN
    J Syst Evol. 2013, 51(5): 536-544.
    Nymphoides peltata is a distylous aquatic plant. In order to explore the relative importance of clonal growth and sexual reproduction within populations and also to reveal the origin of the commonly occurring one style morph populations in China, we studied the clonal diversity and population genetic structure of this species. By using seven single sequence repeat primer pairs, a total of 192 multilocus genotypes (MLGs) were identified among the 472 samples from the 21 populations analyzed; each population had two or more MLGs. The number of MLGs was lower for the one style morph populations than distylous populations. Analysis of molecular variance showed that a smaller proportion of genetic variation resided among populations (36.8%). A neighbor-joining tree indicated that there was no significant geographical structure of the genetic variation among populations of N. peltata. The Bottleneck tests indicated that there had been significant bottlenecks in most of the studied populations. The successful sexual recruitment from seeds may have contributed to the high clonal diversity in distylous populations of N. peltatain China. Demographic stochasticity or bottleneck should account for the one style morph population with several MLGs. And also the bottleneck effects or demographic changes caused by human activities occurring randomly in populations should account for the finding of no significant geographical structure of the genetic variation among the investigated populations of N. peltata.

  • Yue-Long GUO, Andrew PAIS, Alan S. WEAKLEY, Qiu-Yun (Jenny) XIANG
    J Syst Evol. 2013, 51(5): 545-563.
    Philadelphus (Hydrangeaceae) comprises 60 or fewer species distributed disjunctly in eastern Asia, eastern and western North America to Central America, and southeastern Europe and western Asia. The genus is highly valued in horticulture, but poorly understood regarding taxonomy, species relationships, and biogeographic history. The present study was the first phylogenetic and biogeographic analysis of Philadelphus using both nuclear and chloroplast DNA markers to evaluate classification schemes and to elucidate the biogeographic origin. Our results suggest that Philadelphus is a paraphyletic group with the monotypic genusCarpenteria nested within. Three major lineages were identified in the Philadelphus–Carpenteria clade, each strongly supported by the molecular data. Biogeographic analysis using the Bayes-DIVA method (implemented in the newly developed RASP) and divergence time dating with BEAST resolved the origin and early diversification of Philadelphus s.l. (including Carpenteria) in western North America (including Mexico) in the Eocene. The lineage diversified and subsequently spread into Asia and other areas in the late Tertiary or Neogene to obtain a worldwide distribution. The study adds an additional example of an “out of western North America” migration in the phylogeographic history of the northern hemisphere.
  • Xue-Mei Zhang, Xing-Jin He
    J Syst Evol. 2013, 51(5): 564-577.
    Geological and climatic changes in the Quaternary of the Qinghai–Tibet Plateau (Q-T Plateau) strongly affect the migration route and distribution pattern of the plants in this region. The Angelica nitida Wolff endemic to the Q-T Plateau was used as a model to examine the response to Quaternary climatic oscillations. Three chloroplast DNA fragments (trnD–trnT, trnQ–rps16, rpl32–trnL) were sequenced and 20 haplotypes were identified. The 20 haplotypes clustered into four major clades, which were associated with geographical distribution, and the populations from the edge of the Q-T Plateau contained 19 haplotypes. Based on the average substitution rate, the divergence time in A. nitida was estimated at 1.1 million years ago (Mya), 0.80 Mya, and 0.70 Mya, corresponding to the recently continuous uplift of the Q-T Plateau and the interglacial in the Quaternary. A significant phylogeographic structure was presented (NST > GST, P < 0.01). Our results also suggested that multiple refugia for A. nitida were located on the edge of the Q-T Plateau in the Quaternary. The restricted gene flow and past fragmentation were likely the major processes that shaped the present-day spatial distribution of haplotypes in this species. These results suggested that past fragmentation mainly resulted from the maximum glaciation advance on the Q-T Plateau. The uplift of Loess Plateau, Huya fault of Minshan Mountain could also play important roles responsible for the present phylogeographical pattern of A. nitida.

    J Syst Evol. 2013, 51(5): 578-589.
    Nuclear ribosomal ITS and four cpDNA intergenic spacer sequences were used to assess how the patterns of molecular differentiation are related to taxonomic boundaries and geographic distribution in polymorphic and taxonomically complex Orostachys subsection Orostachys (Crassulaceae). Two major cpDNA lineages were identified in a set of Orostachys populations, lineage A, comprising 13 closely related haplotypes found in 11 populations of monocarpic O. malacophylla var.malacophylla, O. maximowiczii, and O. gorovoii and lineage B that included 9 out of 10 divergent haplotypes found in five populations of O. paradoxa, distinct in perennial stoloniferous habit. Our data suggest that the current concepts of O. malacophylla var. malacophylla, O. maximowiczii, and O. gorovoii are incompatible with the differentiation at the cpDNA level. Neither of these taxa could be allied to a particular haplotype or haplotype clade. The pattern of relationships between 7 ITS ribotypes found in 17 populations supported neither the morphology-based taxonomic subdivision in the subsection Orostachys nor grouping according to geographical origin of the populations or lineages recovered with cpDNA data. A high level of similarity of ITS rDNA sequences between the subsection members suggests their relatively recent and rapid divergence from a common ancestor.
  • You-Hua CHEN
    J Syst Evol. 2013, 51(5): 590-600.
    Adaptive radiation predicted that diversification rate of species and/or the divergence of trait evolution are declined from ancient to contemporary time due to reduced novel niches, namely the “early burst” model. It is still controversial whether the early burst model is ubiquitous over various taxa for species diversification and/or phenotypic evolution. The applicability of the model on plants has little been tested yet in current literature. To address this question, in the present study, a subclade-level phylogenetic comparative analysis of range size evolution and diversification rates of 6885 endemic woody seed plant species in China (i.e., species only found in China) was performed. My study showed that phylogenetic signals of range sizes depend on the phylogenetic scope and the sampling of subclades. Early burst model was not supported for the range size evolution for endemic woody plants of China, while the simple Brownian motion model of adaptive radiation had the best fit. Diversification of species over the subclades of the phylogeny showed that young clades have higher diversification rates than old clades, being contradictory to the “early burst” prediction of adaptive radiation. However, a whole-phylogeny diversification analysis suggests that the BOTHVAR model where speciation rate is decreasing while extinction rate is increasing is the best one to describe the time-dependent trend of diversification of endemic woody plants of China. Moreover, the evolution of range sizes of woody plants is found to be largely independent to diversification rates of species, deprecating the positive range sizes-diversification hypothesis. At last, a strong positive relationship between phylogenetic mean and variance of range sizes was observed. In conclusion, the “early burst” model predicted by adaptive radiation might be applied to the diversification rates, but not the range size evolution of endemic woody plants of China. Further studies are required by sampling more taxa and building a high-quality phylogeny to test and verify the patterns found in the present study.
  • Qing-Wen MA, Sergey Vasilyevich VIKULIN, Cheng-Sen LI, Yu-Fei WANG
    J Syst Evol. 2013, 51(5): 601-608.
    Branches and leafy shoots of fossil Glyptostrobus Endlicher (Cupressaceae s.l.), preserved as compressions of leaf cuticle with stomata and a single scale of a seed cone, have been found for the first time in the Jijuntun Formations of the Eocene in Fushun, Liaoning Province, NE China. These fossil remains are identified asGlyptostrobus by comparing them with Sequoia, Metasequoia, and Taxodium, which are commonly in association and have similar morphological features. The fossil remains are assigned to Glyptostrobus based on characters of leaf morphotypes, phyllotaxis, leaf apex, leaf base, epidermal cell morphology, orientation of stomata, and a single flabellate ovuliferous scale of a seed cone. All of the characteristics of the fossil remains are in agreement with those of the diagnosis of G. europaeus(Brongn.) Ung. These newly described Glyptostrobus specimens from China represent linear, linear-subulate, and scale-like leaves. The species G. europaeus is common for Eurasia where it has a wide geographic and stratigraphic range, but the cuticle characteristics of the species are rarely reported. In China, fossil remains of G. europaeus have been found in the provinces of Heilongjiang, Jilin, Liaoning, Xinjiang, Yunnan, and Hong Kong.
  • Zhong-Yang LI, Zhao-Rong HE, Xian-Chun ZHANG
    J Syst Evol. 2013, 51(5): 609-638.
    This paper deals with species of the genus Cyclosorus subgenus Cyclosoriopsis (Thelypteridaceae) from China, which is characterized by goniopteroid venation and unicellular glands on sporangial stalks. Morphological study of specimens and living plants reveals that venation and glands/glandular hairs on laminae are the most important diagnostic characters for species identification. Twenty-two species are recognized, including seven species endemic to China. Fifty species names are newly reduced to synonyms. A key to species from China, description, and distribution map of each species are provided. Three species are treated as dubious species, and 22 species are treated as putative hybrids.
  • Corrigendum
  • J Syst Evol. 2013, 51(5): 639-639.

    Leak‐Garcia, J, Holt, JS, Kim, S‐C, Mu, L, Mejías, JA, Ellstrand, NC. 2013. More than multiple introductions: Multiple taxa contribute to the genesis of the invasive California's wild artichoke thistle. Journal of Systematics and Evolution 51: 295307. 10.1111/j.1759‐6831.2012.00222.x

    The authors would like to draw readers' attention to the fact that the affiliations for authors of the abovementioned paper should read as follows:

    Seung‐Chul KIM: Department of Biological Sciences, Sungkyunkwan University, 2066 Seobu‐ro, Suwon, 440‐746, Korea

    José A. MEJÍAS: Departmento de Biología Vegetal y Ecología, Universidad de Sevilla, 41080 Seville, Spain.

    The affiliations of the other authors and the assignment of the corresponding author remain unchanged.

    The authors apologize for this error.