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.     

Sexual reproduction in the phyllodioicous bryophyte Homalothecium lutescens (Hedw.) H.Rob. in relation to habitat age,growth conditions and genetic variation

Sporophyte production and female fertility were investigated in seventeen calcareous grassland demes of the moss Homalothecium lutescens (Hedw.) H.Rob. on the Baltic island of Öland, with the aim of understanding the relationships between sexual reproduction, habitat age, genetic variation and factors related to growth conditions. The overall proportion of fertile female shoots (with perichaetia) was 35%. Fertility status at the level of individual shoots was positively associated with shoot length and density, while within deme fertility was positively associated with bush cover. There was no association between female fertility and habitat age, genetic diversity (H_S) or allelic richness. Out of 1344 investigated shoots, only two were normal-sized fertile males. Dwarf males were also extremely rare, and found almost exclusively on shoots with sporophytes. Few sporophytes were observed (in the two demes with highest fertility and bush cover). No relationship between genetic variation and the frequency of sporophytes and males was found. The lack of a relationship between sexual reproduction and genetic variation suggests that sexual reproduction may not occur in the same grassland fragments as the recruitment of new clones (from spores or vegetative fragments). The majority of the dry, open grassland habitats, where H. lutescens is typically found in the study area, appear to be suboptimal for both dwarf males and fertilization. Sexual reproduction is more likely to occur in shaded (although grazed) grassland patches, where moisture levels are likely to be higher and the moss colonies are generally more vigorous.     

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.     

Lead adsorption capacity of some moss species used for heavy metal analysis

Mosses, covering about 23,000 species of all land plants in the world, have been widely used as an indicator of heavy metal pollution in many studies. A crucial part in these researches is to regularize the adsorption capacities of different moss species obtained from different regions to objectively compare the pollution levels. In this study, we have first analyzed the lead adsorption capacities of six different moss species by means of using column filled with Amberlite XAD-2000 resin method. The adsorption capacities of the studied six mosses are found in descending order as Eurhynchium striatum, Hypnum cupressiforme, Pleurozium schreberi, Eurhynchium striatulum, Homalothecium sericeum and Thuidium tamariscinum. Then, we have regularized the Pb adsorption levels for the moss species obtained from different regions along one of the important coast highway in Turkey, namely Sarp-Samsun highway, with respect to the determined adsorption capacities.     

Mediterranean dwarf shrubs and coexisting trees present different radial-growth synchronies and responses to climate

Due to their diversity and dominance in environmentally harsh sites, Mediterranean dwarf shrubs are a valuable tool to understand the consequences of climatic variability on radial growth in woody plants. We evaluate the dendrochronological potential of three Mediterranean dwarf shrubs versus three coexisting tree species inhabiting cold- (Hormathophylla spinosa vs. Pinus sylvestris), mesic- (Ononis fruticosa vs. Abies alba), and xeric sites (Linum suffruticosum vs. Pinus halepensis). Cross-sectional wood sections of the three shrub species and cores in the case of trees were visually cross-dated and ring-widths were measured and converted into residual growth indices. We used linear mixed-effects models to assess how growth indices respond to local factors and climatic variables. The radial growth of the three dwarf shrub species was more asynchronous, i.e., ring-width series differed among conspecific individuals, than that of coexisting tree species. Growth asynchrony was higher for H. spinosa than for O. fruticosa and L. suffruticosum. Similarly, the ring-width series of O. fruticosa and L. suffruticosum was strongly correlated with that of coexisting tree species, while growth series of H. spinosa and P. sylvestris was not related at all. The growth of the three dwarf shrub species was influenced by the regional climatic conditions, but to a lesser degree than coexisting tree species. The highest responsiveness of growth to climate was observed in Mediterranean dwarf shrubs from xeric sites. However, local conditions are also major drivers of growth in Mediterranean dwarf shrubs as indicated by the stronger asynchrony in ring formation of these species as compared with coexisting trees, particularly in cold sites.     

Arbuscular mycorrhiza and water and nutrient supply differently impact seedling performance of dry woodland species with different acquisition strategies

Background: We recently demonstrated that dwarf male plants are much more common among mosses than hitherto thought. Dwarf plants, producing functional male sexual organs occur in 10–20% of the moss species worldwide.

Aims: We investigated how an inadvertent omission of dwarf males affects estimates of male sex expression rates and sex ratios.

Methods: We recorded frequencies of specimens with female-expressing plants, male-expressing normal-sized and/or dwarf plants, and sporophytes in herbarium material of five model species from Macaronesia. We analysed how frequency estimates of male occurrence and sex ratios were affected by excluding dwarf males.

Results: Occurrence of dwarf males was positively associated with sporophyte formation. When dwarf males were excluded, male mate availability was missed in 51–61% of specimens (in 74–76% of sporophyte-containing specimens). Specimen-level sex ratio was balanced in material with sporophytes in the three species exhibiting male dwarfism, but strongly female biased if dwarf males were omitted.

Conclusions: We provide the first quantitative evidence that sex-expressing dwarf males are essential for sexual reproduction and sporophyte production in mosses that form such males. Considering its abundance, male dwarfism therefore deserves more attention among plant biologists. Innovative approaches are required to further study the minute male plants.     

Nitrogen and carbon contents and δ15N and δ13C signatures in six bryophyte species: assessment of long‐term deposition changes (1980–2010) in Spanish beech forests

In this study we used recent (2010) and herbarium material (1980) of six bryophyte species to assess long‐term atmospheric deposition in natural forested areas in northern Spain. For this purpose, tissue nitrogen and carbon content, as well as δ¹³C and δ¹⁵N signatures of samples of Hypnum cupressiforme, Polytrichastrum formosum, Leucobryum juniperoideum, Rhytidiadelphus loreus, Homalothecium lutescens and Diplophyllum albicans were analysed and comparisons made between years and species. In addition, the usefulness of each of the six species was evaluated. The range of values observed was similar to that in other studies carried out in rural areas. Significantly lower values were found in 2010 for N (H. cupressiforme), δ¹⁵N (R. loreus and D. albicans), C (R. loreus) and δ¹³C (all except L. juniperoideum). Our natural areas are thus now less influenced by atmospheric pollutants than they were, most probably due to changes in some traditional local activities. Differences were observed between species for all the four parameters studied, so different species must not be analysed together. Finally, R. loreus and H. lutescens seem to be good bioindicators, sensitive even with a few samples, although further studies are needed to corroborate their usefulness.     

How do temperate bryophytes face the challenge of a changing environment? Lessons from the past and predictions for the future

Bryophytes are a group of early land plants, whose specific ecophysiological and biological features, including poikilohydry, sensitivity to moderately high temperature and high dispersal ability, make them ideal candidates for investigating the impact of climate changes. Employing a combined approach of species distribution modelling (SDM) and molecular phylogeography in the temperate moss Homalothecium sericeum, we explore the significance of the Mediterranean refugia, contrasting the southern and northern refugia hypotheses, determine the extent to which recolonization of previously glaciated areas has been facilitated by the high dispersal ability of the species and make predictions on the extent to which it will be impacted by ongoing climate change. The Mediterranean areas exhibit the highest nucleotidic diversities and host a mixture of ancestral, endemic and more recently derived haplotypes. Extra‐Mediterranean areas exhibit low genetic diversities and Euro‐Siberian populations display a significant signal of expansion that is identified to be of Euro‐Siberian origin, pointing to the northern refugia hypothesis. The SDMs predict a global net increase in range size owing to ongoing climate change, but substantial range reductions in southern areas. Presence of a significant phylogeographical signal at different spatial scales suggests, however, that dispersal limitations might constitute, as opposed to the traditional view of spore‐producing plants as efficient dispersers, a constraint for migration. This casts doubts about the ability of the species to face the massive extinctions predicted in the southern areas, threatening their status of reservoir of genetic diversity.     

Production of triploid plants from endosperm cultures of Phlox drummondii

Triploid plants of ornamental Phlox drummondii Hook. were raised from cultures of endosperm excised from immature fruits having zygotic embryo at early dicotyledonous stage. Endosperm tissue was firstly cultured with the embryo on the Murashige and Skoog’s (MS) medium supplemented with 5 μM 6-benzylaminopurine (BAP) + 10 μM α-napthaleneacetic acid (NAA) for 7 d and recultured after the embryo was removed. A friable callus appeared two weeks after removal of the embryo and it became compact callus mass in another three weeks. Upon transfer of this 5-week-old callus to the MS medium with 10 μM BAP + 2.5 μM indole-3-acetic acid (IAA), maximum percentage of green nodular shoot buds appeared from which regenerated dwarf shoots. Elongation of the dwarf shoots, however, required transfer of the individual dwarf shoots excised from the callus on the fresh medium and best results achieved on medium with low concentration of IAA (0.5 μM) in presence of 10 μM BAP. The shoots were then rooted in vitro and plants subsequently established in pots containing soil. Over 70 % of plants were triploid with a chromosome number of 2n=3x=21. Size of stem, leaves, flowers, pollen, and stomata of these triploid plants were higher and the plants were more vigorous as compared to naturally occurring diploid plants. In particular, flowers showed bright colour with enlarged central eye adding to their ornamental value.     

The geometric approach to explore the Bactrocera tau complex (Diptera: Tephritidae) in Thailand

Specimens of the genus Bactrocera were collected from several host plants in northern and western Thailand. They were morphologically recognized as Bactrocera tau and were subdivided into eleven samples according to host plant, geographic origin and time of collection. Twelve landmarks of the right wing were described in a total of 264 males and 276 females. An exploratory analysis using kernel density estimates was performed on the multivariate morphometric space. Non-parametric classification highlighted the existence of two non-overlapping clusters within both males and females. The clusters were not congruent with geography. One cluster (cluster I) contained only one plant, Momordica cochinchinensis, the other one (cluster II) contained five different plants including M. cochinchinensis. Further morphometric analyses on selected samples indicated that the influence of the plants on the shape of the wing could not explain satisfactorily the presence of two clusters. Genetic techniques identified the presence of B. tau cryptic species C in M. cochinchinensis from cluster I, and of B. tau cryptic species A in Coccinia grandis from cluster II. Our working hypothesis is that the two clusters identified by geometric morphometrics were species A and C, respectively.     

Morphological adaptation of a palatable plant to long-term grazing can shift interactions with an unpalatable plant from facilitative to competitive

Unpalatable plants can protect palatable neighbor plants from grazing pressure, but morphological evolution of a palatable species might change its interactions with unpalatable plants. We predicted that when a palatable species has locally adapted to grazing by expressing a dwarf phenotype that reduces grazer accessibility, the dwarf plants experience relatively more competitive effects than facilitative effects from large, well-defended, unpalatable species. We used a transplant experiment, in which both dwarf and large ecotypes of a palatable annual species, Persicaria longiseta, were transplanted outside and inside the canopy of an unpalatable nettle, Urtica thunbergiana, in a long-term deer grazing habitat of Nara Park, Japan. The dwarf ecotype of Persicaria has adapted to the grazing environments of the park by exhibiting inherently short shoots and small leaves, whereas the large ecotype is found in habitats with no grazing history. A previous common-garden study suggested that the phenotypic differences were genetically based and that phenotypic plasticity contributed little to the morphological difference. The large-phenotype of Persicaria experienced significantly increased morphological size, survival, and reproductive output under the Urtica canopy compared to outside the canopy, whereas these traits of the dwarf phenotype were reduced under the Urtica canopy compared to outside. These results indicate that the net effects of Urtica on Persicaria were positive for the large ecotype and negative for the dwarf ecotype. Thus, the morphological adaptation of a palatable species to avoid grazing altered its interactions with a large, well-defended neighbor.     

Homalothecium meridionale (M.Fleisch. & Warnst.) Hedenäs: a distinct species from H. sericeum (Hedw.) Schimp. (Brachytheciaceae,Bryopsida) in the Iberian Peninsula

Previous molecular studies have done much to shed some light on the taxonomy and phytogeographic position of Homalothecium sericeum and H. meridionale and the present study clarifies the taxonomy and distribution of the two species across Iberia. By conducting a revision of Homalothecium specimens available in Spanish and Portuguese herbaria, we concluded that sporophytic differences are the most appropriate characters for the delimitation of each species. Scanning electron microscope examination of the peristomes of the two taxa helped distinguish between them.

We also noted that H. meridionale is a frequently distributed taxon throughout the Iberian territory, but occurs mostly in Portuguese areas with a Mediterranean influence, becoming less frequent in the Atlantic as well as in continental parts of the Peninsula. As a result of this study, based on numerous new localities in Portugal and Spain, we provide an updated map of the distribution of H. meridionale, and an account of its ecology and habitat affinities.     

How have the alpine dwarf plants in Yakushima been miniaturized? A comparative study of two alpine dwarf species in Yakushima, Blechnum niponicum (Blechnaceae) and Lysimachia japonica (Primulaceae)

Many plant species are miniaturized in the alpine region in Yakushima, Japan. To examine how these alpine dwarf plants are different from their related lowland ones of the same species, we analyzed two phylogenetically distinct species cytologically, genetically and morphologically: one is a fern species, Blechnum niponicum, and the other is an angiosperm species, Lysimachia japonica. The analysis shows that the alpine dwarf and the lowland plants in each of these species do not differ in chromosome number or genetic constitution. The organ-level comparison between the alpine dwarf and lowland plants of B. niponicum shows that the fertile leaf size correlates closely with the sterile one. By contrast, the flower size does not correlate with the leaf size in L. japonica. At the cell level, the leaf size of the alpine dwarf plants of B. niponicum consists of a smaller number of epidermal cells than that of the lowland plants of this species. On the other hand, the smaller leaf size of the alpine dwarf plants of L. japonica depends on both the smaller number and the smaller size of the epidermal cells. We conclude that plant dwarfism in Yakushima shows variation at both the organ and cell levels.     

Female discrimination against sworded males in a poeciliid fish

Female poeciliid fish of the sister genera Xiphophorus and Priapella share a mating preference favouring a sword, despite phylogenetic evidence that the sword arose in Xiphophorus. This conclusion is based on the presence of a preference favouring a sword in three unsworded species and one sworded species. Here I investigate the response to a sword in the poeciliid fish Heterandria bimaculata by testing females with conspecific males that differ in the presence or absence of a sword. Female H. bimaculata were found to prefer unsworded males, thus sworded males were discriminated against. I also tested the strength of female response; females did not show a differential response to males based on sword length. The preference for unsworded males could indicate that when new male traits arise, biases might oppose trait evolution, even in cases in which similar male traits in related taxa are favoured. Explanations for the female preference for unsworded males are discussed.     

念珠丝瓜藓(缺齿藓科)形态特征及其在中国的新分布

通过对中国产丝瓜藓属Pohlia(缺齿藓科Mielichhoferiaceae)植物系统地分类学研究,对本属一具有假根生念珠状排列的芽胞的种——念珠丝瓜藓的形态解剖学特征和地理分布进行了修订,并讨论了念珠丝瓜藓的生境,以及与其相近种泛生丝瓜藓、明齿丝瓜藓和黄丝瓜藓等进行了比较分析。根据标本信息,确定念珠丝瓜藓在中国的分布由原来的5省区扩大到10省区,并绘制了该种在中国的分布图。     

Factors controlling in vitro hatching of Vairimorpha plodiae (Microspora) spores and their infectivity to Plodia interpunctella,Heliothis virescens, and Pieris brassicae

Factors which influence the hatching of spores and proliferation of stages of the microsporidium Vairimorpha plodiae in two susceptible insects, Plodia interpunctella and Heliothis virescens, and one nonsusceptible insect, Pieris brassicae, were investigated. Spores hatched in 0.1 and 1 m KCl solutions when subjected to a change in pH, from pH 11 to pH 8. K⁺ was essential for hatching; NaCl solutions were not effective. Ca²⁺ and Mg²⁺ inhibited hatching, and calcium and magnesium chelating agents enhanced it. All three insect species had alkaline midgut contents and smooth, fragile peritrophic membranes. Spores hatched inside the midguts of all three insect species (P. interpunctella: maximum rate, 92.5%; H. virescens, 91.5%; P. brassicae, 82%). Sporoplasms were observed in the midgut epithelial and associated tracheole cells of P. brassicae. Both H. virescens and P. brassicae became infected when injected intrahemocoelically with spores.     

Suitability of four palm species for the development of the invasive pest Brontispa longissima (Coleoptera: Chrysomelidae) in the field

The coconut hispine beetle Brontispa longissima (Gestro) supposedly originated in Indonesia and Papua New Guinea. It is a serious invasive pest of the coconut palm Cocos nucifera L. in Southeast and East Asia. In Japan, it has established itself using Satakentia liukiuensis (Hatushima) H.E. Moore as a main host on Ishigaki and Iriomote Islands where C. nucifera is rare. To assess the probability of further establishment of B. longissima in novel habitats where C. nucifera and S. liukiuensis are not available, we examined the suitability of four common palm species in Japan for oviposition and immature development of B. longissima: Chrysalidocarpus lutescens (Bory) H. Wendl., Phoenix roebelenii O'Brien, S. liukiuensis and Washingtonia filifera (Linden ex André) H. Wendl. When seedlings of the four palm species were placed in pots in an experimental field on Ishigaki Island, all four species were inhabited and infested by wild B. longissima adults. Oviposition and immature development were observed on P. roebelenii and S. liukiuensis but not on C. lutescens and W. filifera. When field‐collected adults were released into mesh bags enclosing the potted seedlings, they oviposited on all four species. The eggs developed into adults on P. roebelenii, S. liukiuensis and W. filifera. On C. lutescens, however, hatched larvae died during the first or second instar.     

Integration of Visual and Olfactory Cues in Host Plant Identification by the Asian Longhorned Beetle,Anoplophora glabripennis (Motschulsky) (Coleoptera: Cerambycidae)

Some insects use host and mate cues, including odor, color, and shape, to locate and recognize their preferred hosts and mates. Previous research has shown that the Asian longicorn beetle, Anoplophora glabripennis (Motschulsky), uses olfactory cues to locate host plants and differentiate them from non-host plants. However, whether A. glabripennis adults use visual cues or a combination of visual and olfactory cues remains unclear. In this study, we tested the host location and recognition behavior in A. glabripennis, which infests a number of hardwood species and causes considerable economic losses in North America, Europe and Asia. We determined the relative importance of visual and olfactory cues from Acer negundo in host plant location and recognition, as well as in the discrimination of non-host plants (Sabina chinensis and Pinus bungeana), by female and male A. glabripennis. Visual and olfactory cues from the host plants (A. negundo), alone and combined, attracted significantly more females and males than equivalent cues from non-host plants (S. chinensis and P. bungeana). Furthermore, the combination of visual and olfactory cues of host plants attracted more adults than either cue alone, and visual cues alone attracted significantly more adults than olfactory cues alone. This finding suggests that adult A. glabripennis has an innate preference for the visual and/or olfactory cues of its host plants (A. negundo) over those of the non-host plant and visual cues are initially more important than olfactory cues for orientation; furthermore, this finding also suggests that adults integrate visual and olfactory cues to find their host plants. Our results indicate that different modalities of host plant cues should be considered together to understand fully the communication between host plants and Asian longhorned beetles.