Table of Contents

06 March 2014, Volume 52 Issue 2

Cover illustration: Impatiens L. Top left, flower of I. campanulata. Bottom left, flower of I. hians. Bottom right, flower of I. burtonii. Top right, visual comparison of intron lengths related to intron position in def1 and def2. The genes are displayed as bars with exon lengths and number of corresponding amino acids given in brackets. Introns rise as bubbles above the insertion position. Intron lengths are given. Locks mark introns that exhibit similar or equal substitution rates at terminal branches. Photographs by Steven B. JANSSENS. See VOLKMAR et al., pp. 134–148 in this issue. [Detail] ...

  

Research Articles
• Mechanisms underlying flower color variation in Asian species of Meconopsis: A preliminary phylogenetic analysis based on chloroplast DNA and anthocyanin biosynthesis genes

  Chao ZHAO, Xiao-Quan WANG, Fu-Sheng YANG

  J Syst Evol. 2014, 52(2): 125-133.
  https://doi.org/10.1111/jse.12071

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  The Qinghai–Tibet Plateau (QTP) harbors the highest species diversity of alpine plants in the world, with a spectacular diversity of flower colors. Among these QTP plants, the genus Meconopsis comprises more than 50 species, for which flower color is a key diagnostic character. However, the mechanisms underlying flower color variation have rarely been investigated. In the present study, we used three chloroplast (cp) DNA fragments and two anthocyanin biosynthesis genes (F3H andF3′H) for phylogenetic reconstruction of Meconopsis. We revealed the presence of three well-supported clades and/or subclades in the cpDNA and nuclear gene trees; further, flower color transition occurred in each lineage. The results of selection tests and preliminary expression analyses of the anthocyanin biosynthesis genes indicate that the pigment pathway leading to cyanidin is active in blue and red flowers of Meconopsis; further, a blue–red color shift is not attributable to an on/off switching of the anthocyanin biosynthetic pathway (ABP) branches. Together with the results of previous flower pigment analyses, our findings suggest that blue–red flower color transitions in Meconopsis are attributable to modification of cyanidin. Our molecular dating results indicate that the lineage diversification inMeconopsis is closely related to the QTP uplift; thus, it is likely that environmental changes arising from the QTP uplift have played important roles in driving the diversification of flavonoids, through which species of Meconopsis have adapted physiologically to diverse habitats.
• Intron evolution in a phylogenetic perspective: Divergent trends in the two copies of the duplicated def gene in Impatiens L. (Balsaminaceae)

  Ute VOLKMAR, Erik F. SMETS, Henning LENZ, Steven B. JANSSENS

  J Syst Evol. 2014, 52(2): 134-148.
  https://doi.org/10.1111/jse.12070

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  The history of MADS box genes is well-known in angiosperms. While duplication events and gene losses occur frequently, gene structure and intron positions are very conserved. We investigated all six introns in a duplicated MADS box gene (deficiens, def) in selected Impatiens taxa, thereby assessing intron features. For the first time, our study provides a comparison of molecular changes in all introns of a gene from a phylogenetic perspective. Interestingly, a uniform pattern of molecular evolution in the introns of each copy was not observed, but intron length increases, decreases, and size retention can be found in each copy. A tendency to accumulate long autapomorphic indels is also present, thus, a longer intron length does not reflect a higher number of parsimony-informative characters. Substitution rates vary between introns of each gene copy. While four of the six introns of def1 exhibit a change in their substitution rate, five of the six def2 introns maintain their rates throughout the genus albeit at different levels. In MADS box genes several regulatory sequences are found residing in introns. Thus, presence of putative regulatory motifs was investigated. Most of them are not conserved in position and usually present in only one of the gene copies. In addition, the potential for phylogenetic reconstruction of introns in both def copies is shortly discussed.
• Phylogeny of Euonymus inferred from molecular and morphological data

  Yan-Nan LI, Lei XIE, Jin-Yu LI, Zhi-Xiang ZHANG

  J Syst Evol. 2014, 52(2): 149-160.
  https://doi.org/10.1111/jse.12068

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  Euonymus, a cosmopolitan genus of the family Celastraceae, has its species diversity centered in East Asia. It exhibits a complex pattern of morphological variation, making its taxonomy difficult. Monophyly of the genus remains uncertain, and the evolutionary implications of the infrageneric division and delimitation of many species are debatable. In this study, we sampled a total of 62 accessions representing 48 species/taxa covering a broad range of diversity of the genus and its allies. We first investigated the phylogeny of Euonymus using DNA sequences of multiple nuclear and plastid markers, and then used this phylogeny to discuss the circumscription and classification of the genus in combination with evolution of fruit characters, which has been used as an important criterion for the generic subdivision. The resultant data revealed the monophyly of Euonymus sensu lato with inclusion of Glyptopetalum, resolved the major lines of phylogeny of the genus, and clarified the echinate and winged capsules each as lineage-specific. Therefore, among the five sections accepted by Flora of China, only Sect. Echinococcus(with spiny fruits) and Sect. Kalonymus (with winged fruits) correspond to the molecular grouping. The globose capsule may represent an ancestral character state, and the other types of fruits, that is, the shallowly to deeply lobed capsules, may belong to a broad range of continuous variation derived from the globose.
• Towards the natural classification of tectarioid ferns: Confirming the phylogenetic relationships of Pleocnemia and Pteridrys (eupolypods I)

  Hong-Mei LIU, Li-Juan HE, Harald SCHNEIDER

  J Syst Evol. 2014, 52(2): 161-174.
  https://doi.org/10.1111/jse.12073

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  The phylogenetic relationships of the two derived fern genera Pleocnemia and Pteridrys were considered ambiguous even with molecular evidence from previous studies. In the present study we determined the phylogenetic position based on five plastid DNA regions, namely atpA, atpB, rbcL, the rps4 + rps4–trnS intergenic spacer, and the trnL-F region, and an expanded taxonomic coverage including several accessions of each of the two genera. Our results showed that the monophyletic genus Pleocnemia belonged to the Dryopteridaceae and was not related to the Tectariaceae, as it had been in the past. Pleocnemia was found to be closely related to the bolbitidoid and lastreopsioid ferns. The monophyletic genus Pteridrys was found to be sister to a clade comprising Triplophyllum and Tectarias.l. Thus, the placement of this genus into Tectariaceae was confirmed. The sinus teeth, the unique similarity shared by Pleocnemia and Pteridrys, evolved independently in the two genera. Both genera appeared to have diverged from their closest extant relatives at least since the Eocene, whereas the crown group ages indicated radiation events in the Late Miocene for both genera.
• Phylogeography of the widespread plant Ailanthus altissima (Simaroubaceae) in China indicated by three chloroplast DNA regions

  Yi-Ying LIAO, You-Hao GUO, Jin-Ming CHEN, Qing-Feng WANG

  J Syst Evol. 2014, 52(2): 175-185.
  https://doi.org/10.1111/jse.12065

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  Ailanthus altissima (Mill.) Swingle, a temperate tree species, has a wide distribution in China. To infer its refugia and patterns of migration during past climatic changes in China, genetic variations among different populations were studied. Gene sequences of three chloroplast DNA spacer regions, psbA-trnH, trnL-trnF, andtrnD-trnT, were obtained from 440 individuals of 44 populations. The distribution of haplotype and the relationships among them were investigated by haplotype network. In addition, the genetic diversity of the sampled regions was inferred, and the biogeographic history was also reconstructed. Twelve haplotypes were identified, among which, five were unique. The phylogenetic analysis and geographical distribution of haplotypes indicate that multiple glacial refugia existed in mainland China during the Quaternary oscillations. Due to the combined effects of contiguous range expansion and allopatric fragmentation, significant genetic structure was not found in this study. Based on biogeographic and demographic analysis, three main dispersal routes were identified for the major haplotypes, whereas others were more likely localized demographic expansion.
• Contribution of temporal floral closure to reproductive success of the spring-flowering Tulipa iliensis

  Aysajan ABDUSALAM, Dun-Yan TAN

  J Syst Evol. 2014, 52(2): 186-194.
  https://doi.org/10.1111/jse.12036

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  Temporal flower closure is a non-morphological floral character of adaptive significance for growth of some species in extreme environments, and it has important implications for plant reproductive success. Flowers of Tulipa species responded to changes in temperature and closed temporarily at low temperatures, but they reopened when temperatures increased. In this study, we determined the effects of temporal flower closure of Tulipa iliensis Regel. on mating pattern, flower microenvironmental temperature, and sexual organ functions during exposure to low temperatures, rainfall, and wind. First, flowers of T. iliensis were incompletely herkogamous with stamens longer than the pistil. Floral closure resulted in the contact of dehisced anthers with the stigma and auto-pollen deposition on the stigma, thus facilitating automatic self-pollination. Second, floral closure maintained the temperature inside the flower, providing a stable microenvironment that promoted pollen germination and avoided a decline in stigma receptivity. Third, flower closure of T. iliensis before rainstorms avoided flushing of pollen from anthers and helped maintain both pollen viability and stigma receptivity during exposure to rain. Finally, flower closure maintained pollen clumping in the anthers during exposure to wind, thereby enhancing pollination efficiency by pollinators and/or automatic selfing. Therefore, temporal flower closure of T. iliensis is an important floral strategy in facilitating automatic selfing, extending the functional period of male and female organs, and it thus ensures reproductive success in the unpredictable early spring environment.
• Comparative floral development in the tribe Mentheae (Nepetoideae: Lamiaceae) and its bearing on the evolution of floral patterns in asterids

  Somayeh NAGHILOO, Masoumeh KHODAVERDI, Zahra ESMAILLOU, Mohammad Reza DADPOUR, Paula J. RUDALL

  J Syst Evol. 2014, 52(2): 195-214.
  https://doi.org/10.1111/jse.12072

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  A comparative developmental study of flowers was carried out using epi-illumination light microscopy on four genera of Lamiaceae (Nepeta, Rosmarinus, Salvia, andZiziphora), representing all three subtribes of Mentheae. All species examined share unidirectional (adaxial to abaxial) sepal initiation, except Rosmarinus, which has the reverse unidirectional sequence, starting abaxially. Initiated but suppressed bracteoles were detected only in Rosmarinus. In Rosmarinus, Salvia, and Ziziphora, initiation of petals and stamens proceeds unidirectionally from the abaxial side. Floral initiation of Nepeta has bidirectional inception of petals and unidirectional stamen initiation from the adaxial side. Temporal overlap in organ initiation between petal and stamen whorls occurs in all taxa, though this feature is more prominent in Rosmarinus. Significant structural and developmental features that distinguish the four genera include: (1) polysymmetric calyx tube, highly tomentose corolla and deeply four-partitioned ovary in Nepeta; (2) monosymmetric two-lipped calyx and shallowly four-partitioned ovary in Ziziphora; and (3) suppression of adaxial stamens in Salvia and Rosmarinus. Adaxial stamens are absent from Rosmarinus, but reduced stamens remain as staminodia in Salvia. In a phylogenetic context, the late monosymmetry of Nepeta and very early monosymmetry of Rosmarinus could both be regarded as derived conditions compared with the early monosymmetry ofSalvia and Ziziphora.
• Systematic significance of seed morphology in the genus Veronica (Plantaginaceae), with special reference to the Egyptian taxa

  Nasr M. HASSAN, Kadry N. ABDEL KHALIK

  J Syst Evol. 2014, 52(2): 215-230.
  https://doi.org/10.1111/jse.12054

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  Seed morphology of 29 taxa including 9 subgenera belonging to the genus Veronica was compared using scanning electron microscopy to assess their diagnostic value for systematic studies. Subgenus Beccabunga is the largest in this study represented by nine taxa. Seed surface often varies from ridged reticulate or verrucose/granulate reticulate to rugose-reticulate. Seed color and size have limited taxonomic significance as their variation is uninformative. Thereagainst, seed shape and seed coat ornamentation present informative characters that can be used efficiently in distinguishing the studied taxa. Our seed features support the DNA sequence data in showing close relationships between V. biloba and V. campylopoda, and between V. fruticans and V. fruticulosa. The present study indicates thatV. anagallis-aquatica, V. anagalloides, V. comosa, and V. catenata have more or less the same seed features; consequently, these four former species are most likely representing a single species as reported by earlier studies. Furthermore, V. polita and V. persica are very similar in terms of seed characteristics. Our results justify placement of V. peregina within subgenus Beccabunga and support the monophyly of the subgenus Veronica.
• Species diversity and distribution of Ruppia in China: Potential roles of long-distance dispersal and environmental factors

  Shuo YU, Miao-Miao SHI, Xiao-Yong CHEN

  J Syst Evol. 2014, 52(2): 231-239.
  https://doi.org/10.1111/jse.12069

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  Ruppia is a cosmopolitan genus and the species identity within the genus has been often confusing due to high plasticity in morphology. We used nuclear ribosomal DNA internal transcribed spacer and seven chloroplast DNA fragments combined with morphological traits to distinguish Ruppia species along the coastline of China, and to infer the potential mechanisms shaping their distribution patterns. Molecular and morphological data distinguished three congruent clades corresponding with three species: R. cirrhosa (Petagna) Grande, R. maritima L., and R. megacarpa Mason. The geographical ranges of R. cirrhosa and R. maritimacoincided closely with coastal current breaks by the Taiwan Strait; R. cirrhosa was found in 17 locations mainly in the north, whereas R. maritima was common in the south, most likely to be the result of differentiated adaptation to optimal temperatures of growth and/or seed germination. Ruppia megacarpa, usually considered as an endemic species of Australia and New Zealand, was first reported in China at two bird stopover sites, Qingdao and Yancheng. The transoceanic dispersal by migratory birds may contribute to the presence and distribution of R. megacarpa in China.