Pakaraimaea dipterocarpacea is ectomycorrhizal, indicating an ancient Gondwanaland origin for the ectomycorrhizal habit in Dipterocarpaceae

The consistent association of Paleotropical Dipterocarpaceae with ectomycorrhizal (ECM) fungi suggests that ECM status is an ancestral character in the family. Despite its distinctive morphology, Pakaraimaea dipterocarpacea, a Neotropical Dipterocarpaceae endemic to the Guayana Region, is phylogenetically related to the Paleotropical Dipterocarpaceae. The confirmation of P. dipterocarpacea ECM status would indicate that Paleotropical Dipterocarpaceae and P. dipterocarpacea probably had a common ECM ancestor. Mycorrhizal colonization of P. dipterocarpacea was assessed, and ECMs were recorded using histological and molecular methods. P. dipterocarpacea was highly colonized by typical ECMs, and several ECM fungal taxa belonging to Clavulinaceae, Sebacinaceae, Cortinariaceae and Amanitaceae were identified. This paper provides the first documented evidence of ECM in a neotropical genus of Dipterocarpaceae and indicates that ECMs possibly evolved in Gondwana in ancestors of Dipterocarpaceae before the separation of South America from Africa by the Atlantic, c. 135 million years ago. The observation of Sebacinaceae and Clavulinaceae suggests that broad host range fungi are important components of P. dipterocarpacea ECM communities.     

Three New Species of Lagenophryid Peritrichs (Ciliophora) Ectocommensal on Freshwater Decapod Crustaceans from Madagascar1

One species of Lagenophrys and two species of Operculigera are described for the first time. Lagenophrys machaerigera n. sp. was discovered on the freshwater crab Gecarcinautes goudoti and varies between two extreme forms in the structure of its lorica aperture. Operculigera carcini n. sp. was also found on G. goudoti and exhibits several characteristics that set it apart from other members of its genus. Some of these characteristics also suggest a phylogenetic link between O. carcini and the genus Lagenophrys. Operculigera madagascarensis n. sp. was discovered on the parastacid crayfish Astacoides granulimanus. The occurrence of O. madagascarensis on a Madagascan parastacid and other species of Operculigera on Chilean parastacids suggests that parastacids are the oldest hosts of the genus Operculigera. Continental drift is the most likely mechanism by which species of Operculigera and parastacids could have been dispersed to distant parts of the southern hemisphere. The absence of Operculigera on Australian parastacids may be due to its replacement by the genus Setonophrys on those hosts.     

Australasian bryogeography: fact, fallacy and fantasy

It is claimed that possible mechanisms leading to the present patterns of distribution of Australasian bryophytes cannot be rigorously deduced from the patterns themselves, and that the distribution data are all imperfect and rapidly changing. Possible causes of the major disjunctions are discussed. There are serious deficiencies in discussions of endemism.     

青藏高原白垩纪双壳类生物地理

青藏高原白垩纪沉积见于６条东西向延伸的条带内。双壳类主要发育于这些条带的Ｂｅｒｒｉａｓｉａｎ,Ａｐｔｉａｎ－Ａｌｂｉａｎ,Ｃｅｎｏｍａｎｉａｎ－Ｔｕｒｏｎｉａｎ,Ｃｏｎｉａｃｉａｎ－Ｓａｎｔｏｎｉａｎ和Ｃａｍｐａｎｉａｎ－Ｍａａｓｔｒｉｃｈｔｉａｎ５个时期的地层。雅鲁藏布江缝合线为白垩纪双壳类地理分布的主要控制界线。早白垩世期间,雅鲁藏布江缝合带以南的喜马拉雅地区的双壳类Ｐｅｔｒｏｃｅｒａｍｕｓ,     

The role of flavonoids in the establishment of plant roots endosymbioses with arbuscular mycorrhiza fungi,rhizobia and Frankia bacteria

Flavonoids are a group of secondary metabolites derived from the phenylpropanoid pathway. They are ubiquitous in the plant kingdom and have many diverse functions including key roles at different levels of root endosymbioses. While there is a lot of information on the role of particular flavonoids in the Rhizobium-legume symbiosis, yet their exact role during the establishment of arbuscular mycorrhiza and actinorhizal symbioses still remains unclear. Within the context of the latest data suggesting a common symbiotic signaling pathway for both plant-fungal and plant bacterial endosymbioses between legumes and actinorhiza-forming fagales, this mini-review highlights some of the recent studies on the three major types of root endosymbioses. Implication of the molecular knowledge of endosymbioses signaling and genetic manipulation of flavonoid biosynthetic pathway on the development of strategies for the transfer and optimization of nodulation are also discussed.     

Preliminary studies of micropropagation of Hopea odorata,a dipterocarp tree

Plantlet development from in vitro cultures of Hopea odorato Roxb. is described. Embryos excised from seeds and cultured on Gamborg's B5 or modified Murashige and Skoog (MS) medium with benzyladenine (BA, 2.2–22.2 M) produced axillary shoots at cotyledonary and/or stem nodes. Shoot production was greatest in germinated embryos on modified MS medium with 8.9 M BA. Excised axillary shoots formed few buds when cultured on medium with BA and limited root development occurred on Woody Plant Medium with naphthaleneacetic acid. Nodal explants from aseptically grown plantlets sprouted axillary shoots in modified MS medium with BA.Abbreviations BA 6-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - GA₃ gibberellic acid - IBA indolebutyric acid - NAA naphthaleneacetic acid - PVPP polyvinylpolypyrrolidone     

A palaeogeographic link between Australia and eastern North America: a New England connection?

Abstract. This research tests the hypothesis that Australia and eastern North America met in rotational collision during the Palaeozoic with the corollary that the New England fold belt of Australia, rather than the Reguibat promontory of Africa, collided with the Alleghanian orogen in the central Appalachians. Identical Lancefieldian-stage, zone 1 (Early Ordovician) graptolites of the Anisograptid family are found in identical environments in Newfoundland, Norway, and the Lachlan fold belt of Australia. Palaeozoic granites are consistent with a tectonic model in which the Lachlan fold belt caused mechanical deformation of the Canadian Appalachians. The Lachlan and New England fold belts of Australia and the Alleghanian orogen of North America are tectonically consistent with the east coast hypothesis. Major deformations and magmatic episodes are coeval from Silurian to Permian. The tectonic, palaeontologic, lithologic, and geometric evidence for this position is more abundant and precise than the stratigraphic evidence for a west coast location of Australia relative to North America.     

Phytogeographic relationships between neotropical and African-Madagascan pteridophytes

The purpose of this study is to determine the floristic affinities of pteridophytes between the neotropics and Africa-Madagascar and examine how these affinities might have arisen. We present an annotated list that contains two kinds of affinities: 1) species in common between both regions (excluding pantropical species) and 2) species pairs (or clusters of species paris) where one of the species (or infrageneric group) occurs in the Neotropics and the other in Africa and/or Madagascar. There are 114 examples on the list, of which 27 are same-species and 87 are species pairs or closely related taxa at some infrageneric level. About 13% of the African pteridoflora and 14% of the Madagascan pteridoflora show affinities with the Neotropics. To determine how these similarities might have originated, we assess three hypotheses: 1) the boreotropics hypothesis, 2) continental drift, and 3) long-distance dispersal. The boreotropics hypothesis is difficult to assess without further phylogenetic information on the groups to which the species belong. Continental drift seems to best explain one example in the geologically old family Schizaeaceae (species inAnemia subgen.Coptophyllum sect.Tomentosae). Nearly all the other examples seem best explained by long-distance dispersal because they belong to families that first appeared during the Paleocene, more than 30 million yearsafter drift had effectively separated South America and Africa. Most of the dispersal events appear to have taken place from the neotropics to Africa-Madagascar, but recent African extinctions may have obscured directionality. Species with green spores or gemmiferous gametophytes were slightly overrepresented on the list compared to pteridophytes as a whole.     

Quantifying the effects of the break up of Pangaea on global terrestrial diversification with neutral theory

The historic richness of most taxonomic groups increases substantially over geological time. Explanations for this fall broadly into two categories: bias in the fossil record and elevated net rates of diversification in recent periods. For example, the break up of Pangaea and isolation between continents might have increased net diversification rates. In this study, we investigate the effect on terrestrial diversification rates of the increased isolation between land masses brought about by continental drift. We use ecological neutral theory as a means to study geologically complex scenarios tractably. Our models show the effects of simulated geological events that affect all species equally, without the added complexity of further ecological processes. We find that continental drift leads to an increase in diversity only where isolation between continents leads to additional speciation through vicariance, and where higher taxa with very low global diversity are considered. We conclude that continental drift by itself is not sufficient to account for the increase in terrestrial species richness observed in the fossil record.     

Ecological studies on ectomycorrhizal fungi: an introduction

Abstract

The characteristics of mycorrhizal associations in general and of different kinds of mycorrhizas are briefly indicated. The morphology, functional relationships, distribution, host specifity, succession and decline of ectomycorrhizas are concisely treated. Methods, advantages and limitations of four main approaches to ectomycorrhizal research are discussed. At the end an example of an attempt to an integrated approach is given.     

Ungulate saliva inhibits a grass–endophyte mutualism

Fungal endophytes modify plant–herbivore interactions by producing toxic alkaloids that deter herbivory. However, studies have neglected the direct effects herbivores may have on endophytes. Antifungal properties and signalling effectors in herbivore saliva suggest that evolutionary pressures may select for animals that mitigate the effects of endophyte-produced alkaloids. Here, we tested whether saliva of moose (Alces alces) and European reindeer (Rangifer tarandus) reduced hyphal elongation and production of ergot alkaloids by the foliar endophyte Epichloë festucae associated with the globally distributed red fescue Festuca rubra. Both moose and reindeer saliva reduced the growth of isolated endophyte hyphae when compared with a treatment of distilled water. Induction of the highly toxic alkaloid ergovaline was also inhibited in plants from the core of F. rubra''s distribution when treated with moose saliva following simulated grazing. In genotypes from the southern limit of the species'' distribution, ergovaline was constitutively expressed, as predicted where growth is environmentally limited. Our results now present the first evidence, to our knowledge, that ungulate saliva can combat plant defences produced by a grass–endophyte mutualism.     

One hundred years of continental drift: the early Italian reaction to Wegener’s ‘visionary’ theory

One hundred years ago in 1915 ‘Die Entstehung der Kontinente und Ozeane’ by Alfred Wegener was published, destined to become one of the most controversial geological opus in the first half of the twentieth century. Wegener is the first to combine the most diverse geological (sensu lato) evidences in a single great synthesis. Nonetheless, apart from few upholders, the initial reaction to the drift hypothesis was fierce opposition, and the strongest criticism came from geophysics, the same discipline that, paradoxically, starting from the 1950s led to the Plate Tectonics revolution and, ultimately, to a complete re-evaluation of Wegener’s hypothesis. In the present paper we discuss the initial reaction of Italian scientists to the original continental drift theory, with particular focus on the period between the two world wars. Italian geologists like Fossa-Mancini and Gortani were almost favourable to the new theory, while authors such as Vardabasso and Sacco were neutral or even hostile to the new hypothesis, so iconoclastic for the widely accepted fixist vision of the time. In any case, all these scientists agreed that the new theory had great potential for reopening an enthusiastic debate on issues that were given as established paradigms – the genuine way for progress in science.     

中国龙脑香科植物纪要

广义的龙脑香科是泛热带分布。中国有 5属 12种 ,其中 1种为引种栽培 ,产云南、广西、海南及西藏。本科分布北界在印度的喜马偕尔邦 ,在该地粗壮娑罗双Shorearobusta约达北纬 31°。《中国植物志》所报道见于我国的纤细龙脑香Dipterocarpusgracilis确实未见于我国。我国自然生长的东京龙脑香Dipterocarpusretusus依据毛被的多少可分为 2个变种 ,它们可能同时出现在同一林中。由于毛被多少不是区分种的可靠特征 ,因此将河内坡垒Hopeahongayanensis及多毛坡垒H mollissima两者都归并到狭叶坡垒H chinensis。鉴于雄蕊数目的不确定性 ,海南所产的Hopeaexalata与越南所产的H reticulata就视为同一种 ,而采用后者作为种名。版纳青梅Vaticaxishuangbannaensis与广西青梅V guangxiensis两者以叶脉数目来区分是不可靠的 ,也应视为同种而采用后者作为种名。经野外实地考察 ,望天树Parashoreachinensis仍应恢复其原来的学名。     

In vitro propagation of Dipterocarpus alatus and Dipterocarpus intricatus

Seedlings were grown in vitro from embryos of Dipterocarpus alatus and D. intricatus. The problem of explant browning could be overcome by growing embryos initially on a filter paper bridge in liquid medium with activated charcoal. The best basal medium was Woody Plant Medium without the ammonium nitrate. Cytokinin appeared to stimulate seedling growth, 5×10^-5 M 2-isopentenyladenine and 10^-4 M 6-benzyladenine (BA) being the optimum concentrations for D. alatus and D. intricatus respectively. Cotyledonary nodes, excised from the seedlings, were induced to form axillary shoots and in the case of D. intricatus these could be multiplied rapidly. D. intricatus shoots elongated by reducing the BA level from 10^-5 M to 5×10^-7 M. Roots developed when shoots were dipped in 10^-3 M indolebutyric acid for two minutes and subsequently grown in liquid medium supported by a filter paper bridge.Abbreviations AC activated charcoal - BA 6-benzyladenine - 2iP 2-isopentenyladenine - IBA indolebutyric acid - MS Murashige & Skoog medium - PVP polyvinylpyrrolidone - PVPP polyvinylpolypyrrolidone - WPM Woody Plant Medium - 1/2 WPM Woody Plant Medium with half-strength macro salts - WPM (-NH₄NO₃) Woody Plant Medium without ammonium nitrate