Ploidy level,genetic diversity,and differentiation in two closely related mosses,Scorpidium cossonii and S. revolvens (Calliergonaceae)

As ploidy level and mating system can affect genetic diversity and differentiation, we conducted population genetic analyses of two closely related mosses, Scorpidium cossonii (Schimp.) Hedenäs, and S. revolvens (Sw. ex Anonymo) Rubers which differ in ploidy level and sexual system. We collected 315 specimens in total from five populations of S. cossonii and four populations of S. revolvens in the Swiss Alps. Ploidy level, genetic diversity within populations, and genetic differentiation between populations and species were estimated using nine microsatellite markers. In each S. cossonii sample, each locus bore only one allele, while in S. revolvens, seven out of the nine loci were fixed or nearly fixed for two alleles per locus per individual. These findings are consistent with a gametophytic haploid S. cossonii and allodiploid S. revolvens. The haploid and dioicous S. cossonii was genetically more diverse than the (allo)diploid and monoicous S. revolvens. Differences in genetic diversity between the two species may be explained by different mating systems, different population sizes, and different population histories. Genetic differentiation among populations of S. cossonii was higher than among those of S. revolvens. The low genetic differentiation among populations of the monoicous species was not unexpected, since monoicous species frequently produce sporophytes, long-distance spore dispersal is more likely and leads to low differentiation.     

Variation in habitat factors and species composition of Scorpidium scorpioides communities in NW-Europe

To assess the natural range in habitat parameters of the once common rich-fen bryophyte Scorpidium scorpioides, water chemistry and vegetation were studied in different regions characteristic of its NW-European distribution area: the Netherlands, Ireland, Denmark and Fennoscandia. Scorpidium scorpioides was found in an environment with circumneutral pH. The variation in solute content and composition was large and nutrient (N and P) concentrations ranged from zero to values indicative of more eutrophic conditions. Six different vegetation types with S. scorpioides were distinguished, resembling Caricion davallianae, Caricion curto-nigrae and Hydrocotylo-Baldellion communities. Type of substrate and solute levels were strongly correlated with the first ordination axis (DCA) and nutrient status and geographic position with the second axis. Habitat and vegetation characteristics in Dutch rich-fens with S. scorpioides indicated that mineral status was higher than in Fennoscandia and Ireland; solute-poor habitats with S. scorpioides have disappeared from the Netherlands. Trophic status was higher in the Netherlands than in Fennoscandia, but in some cases lower than in Ireland. Acidification and eutrophication may have played a role in the decrease of the species in the Netherlands. However, the wide ecological ranges suggest that the decrease of S. scorpioides is not a physiological effect of unsuitable environmental conditions per se.     

Relationships among New World species of Hibiscus section furcaria (Malvaceae)

Seventeen species ofHibiscus sectionFurcaria are native to the New World, of which 12 (one diploid, nine tetraploids, one octoploid and one decaploid) have been studied cytotaxonomically. New chromosome counts (2n=4x=72) are reported forH. cucurbitaceus, H. flagelliformis, H. kitaibelifolius, andH. laxiflorus. Seventeen types of tetraploid interspecific hybrids (seven new to this study) all showed complete meiotic chromosome homology (genome formulaGGPP) and normal floral development. That all hybrids were nevertheless almost completely sterile suggests a cytoplasmic component to the genetic differentiation of the species. The diversification of the tetraploid species in habits, habitats and geographical ranges is considerable, despite their similar genome constitutions. A key to 17 native and four introduced African species is presented.Hibiscus cerradoensis sp. nov. is described.     

Phylogeny of the Calliergonaceae (Bryophyta) based on molecular and morphological data

Phylogeny of the Calliergonaceae is reconstructed based on nuclear and chloroplast sequence data, and morphology. Depending on treatment of insertions and deletions, the total number of informative characters was 194 or 163. The study yielded good support for two major clades, one with Hamatocaulis, Scorpidium, and possibly Hygrohypnum ochraceum (Wils.) Loeske, and one with Calliergon, Loeskypnum, Straminergon, and Warnstorfia. Inclusion of H. ochraceum in the ingroup increased tree length, markedly decreased consistency and retention indices, and decreased support for the structure of the Hamatocaulis-Scorpidium clade, and its position within the family is challenged. When H. ochraceum was excluded, good support is found for the genera Hamatocaulis and Scorpidium. Within the other major subclade the monophyly of a clade with Loeskypnum, Straminergon, and Warnstorfia, of a portion of Calliergon, and of Warnstorfia fluitans plus W. pseudostraminea are well supported.     

Reproductive strategies in two arctic Pedicularis species (Scrophulariaceae)

A study of a number of reproductive traits in two sympatric species of Pedicularis in northern Swedish Lapland, the subarctic-alpine P lapponica and the artic P hursuta , revealed that the life-history strategies of the two species differ profoundly High fruit set and low seed abortion rate, as m P hursuta , is common in arctic plants in late-thawing habitats and represents a case of extreme adversity selection rather than an indication of a ruderal life-history strategy Pedicularis lapponica , on the other hand, is a typical K-strategist (or stress-tolerator) requiring a longer period of growth for optimal reproduction Occuring at both low and high altitudes in the area, P lapponica tends to increase in self-compatibility with altitude, which is interpreted as an adaptation to lower pollinator visitation frequency in arctic environments The variation in length of the protruding part of the style in P lapponica is shown to be correlated with exposure to light Predispersal seed predation is severe m P lapponica at low altitudes, where the capsules are attacked by fly and moth larvae At high altitudes, a minor proportion of the capsules of P lapponica experience predation and only from flies, while P hursuta is completely unpredated     

Relationships among species inCarex sect.Phyllostachys (Cyperaceae) based on allozyme divergence

Allozyme variation was examined inCarex sect.Phyllostachys (Cyperaceae) to provide insight into phylogenetic relationships hypothesized in an earlier study and to determine the degree of genetic differentiation within and between taxa. Genetic identity values are concordant with the morphological differences found between species. The lowest values are found between species with the greatest morphological dissimilarity. Conversely, the highest values are associated with species pairs distinguished by relatively few morphological differences. Conspecific populations possess high genetic identities, although interpopulation differentiation has characterized the evolutionary history of some species. Geographic patterning is also evident within species, with geographically proximate populations often having the highest identity values. Phylogenetic trees produced using different cladistic methods were poorly supported and varied in their depiction of relationships among species. One cladogram produced using presence/absence allelic data is more or less congruent with a topology recovered from an earlier analysis utilizing molecular and morphological data. The wide- and narrow-scaled clades are maintained as are the sister species pairsC. backii/C. saximontana, C. basiantha/C. superata, andC. jamesii/C. juniperorum. Contrary to the finding of our previous study, however,C. willdenowii is aligned withC. jamesii/C. juniperorum.     

Relationships among several species of the subfamily Gymnelinae (Zoarcidae) inferred from mitochondrial DNA sequence analysis

Nucleotide sequences of the mtDNA COI and cytochrome b genes were determined in Magadanichthys skopetsi, a member of the new monotypic genus Magadanichthys, endemic to the northern coast of the Sea of Okhotsk. Comparison of this species with other representatives of the subfamily Gymnelinae (family Zoarcidae) revealed high genetic similarity of M. skopetsi to Hadropareia middendorffii and considerable differences between these species and Gymnelopsis ochotensis.     

The resilience and functional role of moss in boreal and arctic ecosystems

CONTENTS: Summary 49 I. Mosses in the northern, high-latitude region 50 II. The role of moss in ecological resilience 51 III. Response of moss to disturbance 54 IV. Future research needs 60 V. Conclusions 62 Acknowledgements 62 References 62 SUMMARY: Mosses in northern ecosystems are ubiquitous components of plant communities, and strongly influence nutrient, carbon and water cycling. We use literature review, synthesis and model simulations to explore the role of mosses in ecological stability and resilience. Moss community responses to disturbance showed all possible responses (increases, decreases, no change) within most disturbance categories. Simulations from two process-based models suggest that northern ecosystems would need to experience extreme perturbation before mosses were eliminated. But simulations with two other models suggest that loss of moss will reduce soil carbon accumulation primarily by influencing decomposition rates and soil nitrogen availability. It seems clear that mosses need to be incorporated into models as one or more plant functional types, but more empirical work is needed to determine how to best aggregate species. We highlight several issues that have not been adequately explored in moss communities, such as functional redundancy and singularity, relationships between response and effect traits, and parameter vs conceptual uncertainty in models. Mosses play an important role in several ecosystem processes that play out over centuries - permafrost formation and thaw, peat accumulation, development of microtopography - and there is a need for studies that increase our understanding of slow, long-term dynamical processes.     

Relationships between five species ofLolium (Poaceae)

Morphological analysis and electrophoresis of seed proteins of fiveLolium species disclosed that they form two distinct groups corresponding to those recognized from compatibility data.Lolium temulentum andL. remotum of the self-pollinated group were shown to be distinct but closely related species. Morphological intergradation and high similarities between protein profiles ofL. perenne, L. multiflorum andL. rigidum (cross-pollinated species) suggest little genetic differentiation between these taxa. This implies that treatment at the infraspecific level might better accomodate the data.     

Relationships between seven species ofVulpia (Poaceae)

Seven species ofVulpia were subjected to morphological and protein studies using principal component and cluster analysis and theJaccard's Similarity Coefficient. Studies showed all species were uniform and distinct from each other. Species of sect.Loretia were very dissimilar from those of sect.Monachne and sect.Vulpia. The latter section comprises taxa of high mutual affinity.     

Relationships among the tiphiid wasp subfamilies (Hymenoptera)

Abstract. The phylogenetic relationships among the subfamilies of Tiphiidae are discussed, with detailed analysis of characters, and presentation of a phylogenetic tree. The tribe Diammini Turner is elevated to subfamily status. A key to the subfamilies is included, and a brief synopsis of each subfamily is given.     

Allozyme variability within and among populations of the epiphytic moss Leucodon (Leucodontaceae: Musci)

Enzyme electrophoresis was used to estimate genetic variability within and among populations of five species of the genus Leucodon (L. atrovirens, L. luteus, L. nipponicus, L. sapporensis, and L. temperatus). All of these perennial, dioecious plants are epiphytic on tree trunks and produce numerous spores that are released in winter. Gene diversity within populations (H_S) was low (0.070) in L. nipponicus, which grows in disturbed habitats, and high (0.169–0.202) in the other four species, which inhabit stable environments. Gene diversity between populations relative to total diversity (G_ST) was low in L. temperatus (0.042) and L. luteus (0.043), suggesting that extensive gene flow occurs among populations. G_ST was moderate in L. sapporensis (0.104) and L. atrovirens (0.114); these values are still less than those previously reported for terrestrial mosses. Since epiphytes could disperse their spores effectively by the wind, low genetic divergence among populations may be related to the epiphytic habit of the species. On the other hand, high G_ST value (0.208) was found in L. nipponicus. It is probably explained by the genetic differentiation of populations by genetic drift, for the species forms geographically and ecologically isolated populations with small number of individuals. We also observed incongruity between morphological and genetic similarity among species.     

Herbivore impact on moss depth, soil temperature and arctic plant growth

We provide evidence for a mechanism by which herbivores may influence plant abundance in arctic ecosystems. These systems are commonly dominated by mosses, the thickness of which influences the amount of heat reaching the soil surface. Herbivores can reduce the thickness of the moss layer by means of trampling and consumption. Exclusion of grazing by barnacle geese and reindeer over a period of 7?years at Ny-Ålesund, Spitsbergen, caused an increase in the thickness of the moss layer, and a reduction in soil temperature of 0.9?°C. Soil temperature was negatively correlated with moss-layer thickness across sites, with highest soil temperatures where moss layers were shallow. We found that moss growth did not respond to experimental manipulation of soil temperature, but the grass Poa arctica (arctic meadow-grass) and the dicot Cardamine nymanii (polar cress) suffered a 50% reduction in biomass when growing in chilled soils.     

地黄属种间亲缘关系研究

对地黄属6个物种进行了形态解剖学观察、染色体计数、核核糖体内转录间隔区(ITS)序列分析.结果表明,茎的高度、幼叶形态、花萼和花冠形态及颜色、种子千粒重和大小、外种皮网壁厚度、外种皮内侧网纹直径等均是该属内分类的可靠依据.高地黄与裂叶地黄在外部形态及解剖结构的各个方面均极为近似,地黄与茄叶地黄间也存在较大的相似性.茄叶地黄、高地黄、湖北地黄、天目地黄的染色体数目,分别为n=28、14、14、14,确认地黄和茄叶地黄为属内四倍体物种,其余种均为二倍体.ITS测序分析显示,地黄属为单系起源,天目地黄与湖北地黄、高地黄与裂叶地黄、地黄与茄叶地黄构成属内3个分支,与形态学及细胞学研究结果一致.研究认为,天目地黄与湖北地黄有较近的亲缘关系;高地黄和裂叶地黄应为同一物种;地黄与茄叶地黄是属内进化水平最高的类群.     

利用RAPD分子标记评价仲彬草属的种间关系

利用随机扩增多态性DNA(RAPD)技术分析了14种仲彬草属Kengyilia植物的种间关系。对34个OPRON公司十聚体随机引物进行多态性筛选,20个(58．8％)能产生多态性。14个引物产生的112个DNA片断,用于计算种间Jaccard遗传相似性系数分析,在NTSYS程序中利用UPGMA构建系统发育树状图。分析结果表明：(1)14个Kengyilia物种存在较大的遗传多样性;(2)青藏高原的物种与新疆的物种 的RAPD变异极大;(3)形态相似、地理分布一致的物种有一定的亲缘关系,聚类在一起;(4)RAPD结果与形态学和细胞学等分析结果一致。RAPD分析方法将为Kengyilia系统分类提供DNA水平上丰富的资料。     

Relationships within the melanogaster species subgroup of the genus Drosophila (Sophophora)

The polytene chromosomes of two new species of Drosophila, D. sechellia and D. orena, both members of the melanogaster species subgroup, are described. The chromosomes of D. sechellia, a species endemic to certain islands in the Seychelles, are homosequential with those of D. simulans and D. mauritiana. The chromosomes of D. orena, a species from the mountains of west Africa, are very similar to those of D. erecta. We discuss the interrelationships of the eight known species of the melanogaster species subgroup, based upon an analysis of their chromosome banding patterns.     

Relationships within the Melanogaster subgroup species of the genus Drosophila (Sophophora)

Five members of the melanogaster species subgroup of the subgenus Sophophora have been studied cytologically, their mitotic chromosomes analysed after Giemsa, C-banding and quinacrine staining. In all five species (D. yakuba, D. teissieri, D. erecta, D. orena and D. mauritiana) n=4 and all of the species except D. orena have a typical melanogaster like mitotic karyotype though there are clear differences between species in the distribution of both C⁺ and Q⁺ material. D. orena has large metacentric X and Y chromosomes due to the accumulation of intensively fluorescing material on these elements with respect to their homologues in melanogaster. This extra heterochromatin of D. orena correlates with a very high proportion of satellite DNA in its nuclear genome (S. Barnes, unpublished). The polytene chromosomes of these species were studied after quinacrine staining and Q⁺ material found to be restricted to the polytene fourth chromosomes, with the exception of D. orena which possesses considerable Q⁺ material in its chromocentre. These findings are discussed in the light of other studies of karyotype evolution in the genus Drosophila.     

DNA/DNA hybridization studies of carnivorous marsupials. III. Relationships among species ofDidelphis (Didelphidae)

We report three sets of DNA hybridization experiments conducted to determine relationships among species ofDidelphis (D. albiventris, D. marsupialis, D. virginiana). The 1989 and 1991 sets had fewer replicates per cell than the 1990 series (3.4 and 5.4 vs 9), but in 1991 we distinguished two populations ofD. marsupialis and utilized several individuals for each heterologous comparison. BothPhilander opossum andLutreolina crassicaudata were used as outgroups in 1989, but onlyLutreolina was included in subsequent sets. For each set, we calculated all four standard indices of thermal stability (T _mode,T _m,T ₅₀ H, and NPH) and constructed trees by least-squares (FITCH) and neighbor-joining methods, both before and after correction for asymmetric reciprocal cell values. Subsets of the 1989 data lacking eitherPhilander orLutreolina were analyzed similarly. To explore measurement imprecision, the corrected and uncorrected matrices for each of the four indices were bootstrapped 100 times for the 1989 set and subsets and 1000 times for the 1990 and 1991 sets. Again, for the 1990 and 1991 data, an additional 100 bootstrapped distances were fitted to user trees representing the three possible pairings ofDidelphis spp. to determine the significance of the FITCH branch lengths. The successive experimental sets generated increasingly consistent evidence for pairingD. marsupialis withD. albiventris. The 1989 experiments involved just 85 comparisons, and only T _mode's pairedD. marsupialis withD. albiventris (at bootstrap percentages of 70% or above), but did so whetherPhilander orLutreolina or both were included as the outgroup(s). FITCH and neighbor-joining trees had identical topologies for T _mode's but sometimes differed for the other measures. In contrast, all but one of the corresponding FITCH and neighborjoining trees matched for the 1990 and 1991 data, and three of the four distance measures (T _mode, T _m, and T ₅₀ H) unitedD. marsupialis withD. albiventris at bootstrap percentages averaging 81%; NPH gave a different result for 1990, associatingD. marsupialis withD. virginiana. Further, all but 2 of the 16 matrices for 1990 and 1991 gave mean bootstrapped branch lengths for a consensus pairing that were positive and at least one standard deviation from zero, despite the very short internodes recovered. These results illustrate that the potential of DNA hybridization for resolving very close relationships depends on both the index and the experimental design employed. We conclude that of the three species,D. albiventris andD. marsupialis shared a more recent common ancestor and estimate thatDidelphis spp. have diverged at about 0.39% in nucleotide sequence per myr.Deceased.