Amorphous mineral incrustations in the moss Homalothecium sericeum

Abstract

Internal mineral deposits in stem and seta were found in living, healthy-looking specimens of the moss Homalothecium sericeum from a Spanish locality. The deposits consisted of an amorphous crust of smooth texture. After examination with EDS probes coupled to a transmission and a scanning electron microscope, and X-ray diffraction analysis, the minerals were identified as mainly opal, carbonates, and Fe and Al hydroxides, although it is irregular throughout a given mineralized region of the moss. These mineral crusts are considered to be the product of biomineralization of ions taken from the substratum. A comparison is established between these deposits and the mineral crystals found in a previous study of Hookeria lucens.     

Identification and characterization of nuclear microsatellite loci in the aquatic moss Platyhypnidium riparioides (Brachytheciaceae)

Eight microsatellite loci from the aquatic moss Platyhypnidium riparioides were identified using the method of microsatellite‐enriched libraries. Polymorphism was assessed in a sample of four populations of 20 individuals each from four streams of the Meuse hydrographic basin in southern Belgium. The markers amplified three to seven alleles per locus. Comparison of observed and expected heterozygosities as well as F‐statistics (F_ST = 0.62) reveals a significant genetic differentiation among populations. These markers will be useful for further investigation of population genetic structure and diversity at different nested spatial scales.     

Chromosome evolution in the Brachytheciaceae

Abstract

Twenty-eight moss species have been investigated cytologically. Mitotic karyograms have been presented for most of these species and these show a remarkable similarity in the n = 11 karyotype. Nine of the eleven chromosomes have terminal or sub-terminal centromeres. Lightly staining heterochromatic bands frequently occur along the axis of the chromosomes and very often these are the sites of chromosome bending; it has been suggested that these may be areas of neocentric activity. The karyotypes investigated show a reduction series of chromosome number which is paralleled by an increase in the number of long metacentrics; since the number of major chromosome arms is maintained in most of the species it has been suggested that Robertsonian fusion has been an important mechanism in the evolution of the Bracytheciaceae, and probably in all Diplolepidous mosses. Polyploidy has also played an important role in speciation. Finally it has been proposed that n = 11 is the primary basic number in the Diplolepideae.     

A revision of the moss genus Trachyphyllum Gepp (Thuidiaceae)

Trachyphyllum is transferred from the Entodontaceae to the Thuidiaceae on the basis of correlated gametophytic and sporophytic characters. The genus is considered to consist of two subgenera: subg.Trachyphyllum forT. inflexum (with numerous new synonyms),T. gastrodes, T. dusenii andT. borgenii; and subg.Carinatum, subg. nov., forT. carinatum,T. jeyporense andT. touwianum, n. sp. All the species are keyed, described and illustrated.     

Phylogeny, biogeography, and evolution of sex expression in the southern hemisphere genus Leptinella (Compositae, Anthemideae)

Leptinella is exceptional in the Anthemideae (Compositae) in its evolution of dimorphic sex expression. A molecular phylogeny including 40 of its 42 described taxa based on nucleotide sequences from two plastid regions (psbA-trnH and trnC-petN spacers) and one nuclear marker (nrDNA ITS) is presented. Phylogenetic reconstruction was hampered by inadequate phylogenetic signal indicating recent radiation of species during the last 5Ma and high level of reticulate evolution presumably caused by hybridisation and polyploidisation. Nevertheless, Leptinella is nested within a paraphyletic genus Cotula that also engulfs the South American genus Soliva. Within Leptinella, the highly polyploid and sexually polymorphic subgenus Leptinella is monophyletic, while subgenus Oligoleima as well as subgenus Radiata are polyphyletic. We found a basal split between a lineage of Australian and New Guinean taxa and one of largely New Zealand taxa. At least five long-distance dispersal events have to be assumed in order to explain the distribution pattern in Leptinella. Among those, one is from New Zealand to Australia, while the others are dispersals to South America and to several subantarctic islands. The phylogeny presented here indicates that the ancestral sex expression in Leptinella is monoecy and that dioecy and paradioecy are derived conditions. High ploidy is especially common in the dioica-group, where dioecy is also common. However, the occurrence of a dioecious sex expression in tetraploid representatives of this group and of polyploidy in other clades that only exhibit monoecious or paradioecious conditions indicate that there is no consistent correlation between these two characters.     

八种青藓科植物蒴齿及孢子的超微形态研究

利用扫描电镜观察了八种青藓科植物孢子及蒴齿的形态,青藓科植物的孢子纹饰多以芽孢状和瘤状突起为主,孢子的大小、外壁纹饰的差异显示了不同种之间的遗传分化及系统演化。青藓属外齿层腹面中部分为四种类型:光滑无疣、颗粒状疣、短刺状小疣、棒状和芽孢状疣,外齿层中上部的特征属与属之间存在差异,该研究可为分类鉴定提供一定的依据。     

Balance between inbreeding and outcrossing in a nannandrous species,the moss Homalothecium lutescens

Epiphytic dwarf males on the females present a possible solution to the problem of short fertilization distances in mosses. However, leptokurtic spore dispersal makes dwarf males likely to be closely related to their host shoot, with an accompanying risk of inbreeding. The capacity of a female to harbour a high number of different dwarf males suggests that there may be mechanisms in place that counteract inbreeding, such as polyandry and post-fertilization selection. We have genotyped sporophytes, female host shoots and dwarf males in four populations of the moss Homalothecium lutescens. We found no evidence of selective sporophyte abortion based on level of heterozygosity. The occurrence of entirely homozygous sporophytes together with significantly positive inbreeding coefficients in three of the populations (mean F_IS between 0.48 and 0.64) suggest frequent mother–son mating events. However, 23% of all sampled sporophytes had a higher level of heterozygosity compared with the mean expected heterozygosity at the population level. Polyandry was frequent, on average 59% of the sporophytes on a female shoot were sired by distinct fathers. In conclusion, sporadic fertilizations by dwarf males originating from nonhost female shoots appear to counteract strong inbreeding.     

The adaptive background of nannandry: dwarf male distribution and fertilization in the moss Homalothecium lutescens

Dwarf males (nannandry) occur in many unrelated, mostly aquatic, groups of organisms. Among land plants they are unique to bryophytes. In this study our aim was to explain variation in frequency of dwarf males and fertilization within populations in the moss Homalothecium lutescens. We compared parameters related to dwarf male presence and sporophyte production in 90 colonies from three localities. Dwarf male density was positively associated with colony moisture at two of the localities, suggesting increased spore germination and dwarf male survival with moist conditions. At one of these localities, dwarf male density was also positively associated with the presence of perichaetia (female sexual branches). Dwarf male density and fertilization frequency were positively associated in two of the localities. Furthermore, in one population, fertilization was also positively associated with canopy cover, which could be attributed to improved nutrient status as a result of throughfall, increased sperm‐dispersal efficiency because of larger water drops, or more favourable moisture conditions as a result of shading. Nannandry thus appears to strongly reduce the problem of short fertilization distances in bryophytes, but the presence of water is still critical because the dwarf males are dependent on a certain level of humidity for recruitment and/or development. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 74–84.     

Genome evolution in the genus Sorghum (Poaceae)

BACKGROUND AND AIMS: The roles of variation in DNA content in plant evolution and adaptation remain a major biological enigma. Chromosome number and 2C DNA content were determined for 21 of the 25 species of the genus Sorghum and analysed from a phylogenetic perspective. METHODS: DNA content was determined by flow cytometry. A Sorghum phylogeny was constructed based on combined nuclear ITS and chloroplast ndhF DNA sequences. KEY RESULTS: Chromosome counts (2n = 10, 20, 30, 40) were, with few exceptions, concordant with published numbers. New chromosome numbers were obtained for S. amplum (2n = 30) and S. leiocladum (2n = 10). 2C DNA content varies 8.1-fold (1.27-10.30 pg) among the 21 Sorghum species. 2C DNA content varies 3.6-fold from 1.27 pg to 4.60 pg among the 2n = 10 species and 5.8-fold (1.52-8.79 pg) among the 2n = 20 species. The x = 5 genome size varies over an 8.8-fold range from 0.26 pg to 2.30 pg. The mean 2C DNA content of perennial species (6.20 pg) is significantly greater than the mean (2.92 pg) of the annuals. Among the 21 species studied, the mean x = 5 genome size of annuals (1.15 pg) and of perennials (1.29 pg) is not significantly different. Statistical analysis of Australian species showed: (a) mean 2C DNA content of annual (2.89 pg) and perennial (7.73 pg) species is significantly different; (b) mean x = 5 genome size of perennials (1.66 pg) is significantly greater than that of the annuals (1.09 pg); (c) the mean maximum latitude at which perennial species grow (-25.4 degrees) is significantly greater than the mean maximum latitude (-17.6) at which annual species grow. CONCLUSIONS: The DNA sequence phylogeny splits Sorghum into two lineages, one comprising the 2n = 10 species with large genomes and their polyploid relatives, and the other with the 2n = 20, 40 species with relatively small genomes. An apparent phylogenetic reduction in genome size has occurred in the 2n = 10 lineage. Genome size evolution in the genus Sorghum apparently did not involve a 'one way ticket to genomic obesity' as has been proposed for the grasses.     

Karyotype evolution in the genus Boronia (Rutaceae)

New chromosome counts are reported for Boronia clavata 2 n  = 14, B. heterophylla 'Near White' 2 n  = 15, B.  'Carousel' 2 n  = 16, B. deanei 2 n  = 22, B. chartacea 2 n  = 32, B. keysii 2 n  = 32, B. pilosa 2 n  = 44, B. anethifolia 2 n  = 36 and B. citriodora 2 n  = 108. Studies in 20 genotypes of 18 species and one interspecific hybrid revealed that they are highly complex in terms of chromosome number, ploidy level, chromosomal length, karyotype constitution and asymmetry. Karyotype analysis indicated that Boronia taxa with high chromosome numbers are primitive and those with lower numbers are derived. The basic chromosome number for this genus is suggested to be x = 18. Analysis of chromosome number, variations of total chromosome length (TCL) and average chromosome length (ACL), Nombre Fondamental (NF) and karyotype asymmetry suggest that dysploid reduction is the major mechanism in Boronia karyotype evolution. Chromosomal rearrangements might also have been involved. Origin, chromosome number changes and spread of Boronia are discussed in relation to the species divergence and the geological and climatic changes of the Australian continent.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 142 , 309–320.     

Chromosome evolution in the genus Mikania (Compositae)

Karyotypic analysis of ten species of the genus Mikania was carried out using Feulgen staining. Species belonging to the following sections were analyzed: Section Thyrsigerae containing M. additicia (2n = 34), M. hemisphaerica, M. lanuginosa, and M. punctata (2n = 36), and Mikania sericea (2n = 42), which adds a new basic chromosome number (x = 21) to the genus and to the tribe Eupatorieae; Section Corymbosae with M. hastato-cordata (2n = 34) and M. involucrata and M. microptera with 2n = 36 chromosomes; Section Spicato-Racemosae with M. sessilifolia, with 2n = 108 chromosomes. One unidentified species with 2n = 34 chromosomes was also analyzed. All the species studied show one large pair of chromosomes with a secondary constriction in the middle region of the long arm. The morphology of this chromosome suggests that it can be considered as a cytological marker for the genus. Because of the distinctive inflorescence types found in the genus Mikania and the high frequency of species with x = 18, a correlation between morphological and chromosomal evolution is discussed. The present study suggests that the basic original chromosome number for the genus is x = 18, from which the others (x = 17, 19, 20, 21) have been derived by aneuploidy to form the observed aneuploid series.     

Origin of pisatin demethylase (PDA) in the genus Fusarium

Host specificity of plant pathogens can be dictated by genes that enable pathogens to circumvent host defenses. Upon recognition of a pathogen, plants initiate defense responses that can include the production of antimicrobial compounds such as phytoalexins. The pea pathogen Nectria haematococca mating population VI (MPVI) is a filamentous ascomycete that contains a cluster of genes known as the pea pathogenicity (PEP) cluster in which the pisatin demethylase (PDA) gene resides. The PDA gene product is responsible for the detoxification of the phytoalexin pisatin, which is produced by the pea plant (Pisum sativum L.). This detoxification activity allows the pathogen to evade the phytoalexin defense mechanism. It has been proposed that the evolution of PDA and the PEP cluster reflects horizontal gene transfer (HGT). Previous observations consistent with this hypothesis include the location of the PEP cluster and PDA gene on a dispensable portion of the genome (a supernumerary chromosome), a phylogenetically discontinuous distribution of the cluster among closely related species, and a bias in G + C content and codon usage compared to other regions of the genome. In this study we compared the phylogenetic history of PDA, beta-tubulin, and translation elongation factor 1-alpha in three closely related fungi (Nectria haematococca, Fusarium oxysporum, and Neocosmospora species) to formally evaluate hypotheses regarding the origin and evolution of PDA. Our results, coupled with previous work, robustly demonstrate discordance between the gene genealogy of PDA and the organismal phylogeny of these species, and illustrate how HGT of pathogenicity genes can contribute to the expansion of host specificity in plant-pathogenic fungi.     

A revision of Schimperella (Brachytheciaceae)

Schimperella is a small African genus related toRhynchostegium. It is characterized by noncomplanate plants with erect capsules and reduced endostomes. Two species are recognized:S. katalensis andS. rhynchostegioides. A proposed synonym ofS. rhynchostegioides, Rhynchostegium nervosum, is best placed inIsothecium, asIsothecium nervosum.     

Acrobat ants go global - Origin, evolution and systematics of the genus Crematogaster (Hymenoptera: Formicidae)

This study unravels the evolution and biogeographic history of the globally distributed ant genus Crematogaster on the basis of a molecular phylogeny, reconstructed from five nuclear protein-coding genes and a total of 3384bp of sequence data. A particular emphasis is placed on the evolutionary history of these ants in the Malagasy region. Bayesian and likelihood analyses performed on a dataset of 124 Crematogaster ingroup taxa lend strong support for three deeply diverging phylogenetic lineages within the genus: the Orthocrema clade, the Global Crematogaster clade and the Australo-Asian Crematogaster clade. The 15 previous subgenera within Crematogaster are mostly not monophyletic. Divergence dating analyses and ancestral range reconstructions suggest that Crematogaster evolved in South-East Asia in the mid-Eocene (40-45ma). The three major lineages also originated in this region in the late Oligocene/early Miocene (～24-30ma). A first dispersal out of S-E Asia by an Orthocrema lineage is supported for 22-30ma to the Afrotropical region. Successive dispersal events out of S-E Asia began in the early, and continued throughout the late Miocene. The global distribution of Crematogaster was achieved by subsequent colonizations of all major biogeographic regions by the Orthocrema and the Global Crematogaster clade. Molecular dating estimates and ancestral range evolution are discussed in the light of palaeogeographic changes in the S-E Asian region and an evolving ocean circulation system throughout the Eocene, Oligocene and Miocene. Eight dispersal events to/from Madagascar by Crematogaster are supported, with most events occurring in the late Miocene to Pliocene (5.0-9.5ma). These results suggest that Crematogaster ants possess exceptional dispersal and colonization abilities, and emphasize the need for detailed investigations of traits that have contributed to the global evolutionary success of these ants.     

中国青藓科新资料

通过对模式标本、国外借阅标本及采自新疆维吾尔自治区的青藓科植物的研究,报道青藓科中国新记录1种:糙柄青藓[Brachythecium trachypodium(Funck ex Brid.)Schimp.],重新确定了曾有文献记载但缺少图文描述的高山青藓[Brachythecium collinum(Schleich.ex Müll.Hal.)Schimp.]和直枝同蒴藓[Homalothecium philip-peanum(Spruce)Schimp.]在中国的分布,并提供了详细的形态描述及图版。为中国青藓科植物提供新资料。     

Notes on the Chinese Brachytheciaceae (II)

From 1896 to 1898, Carolo Mueller published thirteen Chinese species in the genus Brachythecium based on Jos. Giraldi’s collections from Shaanxi Province made during 1890～1896. They are B . campylothallum , B . amnicolum , B . homocladum , B . pinnirameum , B . permolle , B . glauco-viride, B . garovaglioides, B . viridefactum, B . glauculum, B . perminusculum, B . dicranoides , B . micrangium and B . thraustum . In this paper, holotypes of nine species, isotypes of three species, and one specimen which was examined by Mueller himself and referred to as B . thraustum by him, were studied. As a result, B . permolle and B . glauco-viride are reduced to B . rivulare as synonyms, B . wichurae is reduced to B . garovaglioides, B . micrangium is transferred to the genus Okamuraea as an independent species, i. e. O. micrangia (C. Muell. ) Wanget Hu, and the remaining 9 species are still recognized as species in the genus Brachythecium.     

中国青藓科研究资料(III)

研究了青藓科的7种1变种（Brachythecium planiusculum,Eurhynchium coarctum,E.serricuspis,Rhynchostegium leptomitophyllum,R.longirameum,R.pallenticaule,R.subspeciosum和R.subspeciosum var.filiforme）的模式标本。提出了3个新组合（E urhynchium longirameum,E.filiforme,Bryhnia serricuspis）,     

Biogeographical contingency and the evolution of tropical anchovies (genus Cetengraulis) from temperate anchovies (genus Engraulis)

Aim Similar regimes of selection in different geographical settings can deterministically produce similar adaptive morphologies. We tested the hypothesis that the evolutionary trajectories of fish in upwelling zones can be altered by biogeographic contingencies in the biological and physical environment. Location Eastern Pacific and western Atlantic oceans. Methods We estimated phylogenetic relationships among eastern Pacific temperate anchovies (genus Engraulis) and tropical anchovies (genus Cetengraulis) with neighbour‐joining and Bayesian tree analysis of a 521‐bp segment of mitochondrial DNA cytochrome b. Available sequences for five additional engraulid taxa were included to establish polarity of the tree. Bayesian estimates (BEAST) of time to most recent common ancestor (TMRCA) for the nodes in the phylogeny were calibrated with divergence between Cetengraulis edentulus and Cetengraulis mysticetus precipitated by the rise of the Panama Isthmus 2.8–3.2 Ma. Results Neighbour‐joining and Bayesian trees indicate that South American Engraulis anchoita (Argentina) and Engraulis ringens (Chile) together are basal sister taxa to the California anchovy (Engraulis mordax) and Old World anchovies (Engraulis japonicas, Engraulis australis, Engraulis capensis and Engraulis encrasicolus). The two tropical species of Cetengraulis are sister‐taxa to Californian E. mordax, even though their phenotypes and ecologies differ markedly. A relaxed molecular clock indicates a TMRCA between Californian E. mordax and Cetengraulis at about 4.2 Ma (3.0–6.3 Ma 95% highest probability density). Main conclusions The TMRCA between the California anchovy, E. mordax, and tropical Cetengraulis coincides with the formation of the Gulf of California, which provided opportunities for allopatric isolation during climate oscillations. Mid‐Pliocene warming (3.1–2.9 Ma) may have trapped ancestors of Cetengraulis in the Gulf of California, where they evolved digestive tract morphologies to exploit inshore tropical habitats with low plankton productivities. While populations of several other temperate fishes have become isolated in the Gulf of California, few of these derived species show strong adaptive shifts from temperate sister taxa or range expansions into the tropical provinces of the western Atlantic and eastern Pacific.