Natural hybridization in JapaneseCalamagrostis

Taxonomic relationships betweenCalamagrostis langsdorffii andC. sachalinensis were investigated in connection with the discovery that a considerable number of plants intermediate between these species occur in the high mountains of central Honshu. The studies were mainly carried out on the basis of cytological voucher specimens for which a chromosome number was known. Their morphological features, leaf flavonoids and pollen grains were subjected to examination. Hybridization, polyploidy and gametophytic apomixis are related to the organization of this complex, and plants referable to the “intermediates” are apomictic octoploids superimposed on the ancestral and sexual tetraploid taxa. The internal structure of this complex is discussed together with its probable course of evolution, and a diagram showing the outline of the structure is presented. The variability of morphological features and flavonoid patterns of the plants concerned is examined, and the delimitation ofC. langsdorffii andC. sachalinensis is made clearer.     

Calamagrostis hakonensis (Poaceae): Distribution and differentiation of cytotypes

Chromosome counts were made for a total of 540 collections ofCalamagrostis hakonensis from 66 localities ranging from Kyushu to Hokkaido. Distribution and habitat preferences of the cytotypes involved are described. Sympatric occurrence of tetraploids (=semidiploids, 2n=28) and higher polyploids, as well as that of septaploids and plants at hexaploid and/or octoploid levels, was confirmed in several localities, and mixtures of hexaploids and octoploids within a population were frequently observed. Plants at hexaploid and octoploid levels were the most abundant and widespread. An examination of pollen of the voucher specimens showed that tetraploids (amphimictic) had good pollen, while higher polyploids (apomictic) were generally devoid of pollen and very rarely produced moderately good pollen, the grains of higher polyploids being larger than those of tetraploids. Distributions of tetraploids and higher polyploids were more precisely delineated through an examination of pollen of many herbarium specimens. In relation to the processes by which the complicated internal structure ofC. hakonensis has been established, the following subjects are discussed: infraspecific hybridization between ecotypically differentiated populations, enrichment of variability through occasional sexual reproduction expected in plants with more than 2n=42, persistence of the variants by apomictic reproduction, and probable roles of some extinct taxa.     

Phytogeographical studies ofCalamagrostis sachalinensis (Gramineae)

Chromosome numbers were determined on 223 collections ofCalamagrostis sachalinensis from 18 localities in Japan. The plants were found to be tetraploid (2n=28), hexaploid (2n=42) or octoploid (2n=56). A few collections were found to include one or two B-chromosomes. The tetraploid collections were made from central Honshu and Mt. Apoi in Hokkaido, while the hexaploids and the octoploids were detected in many localities. Pollen examination of these collections showed that the tetraploids with but one exception have good pollen and the hexaploids and the octoploids have no pollen or have bad pollen with stainability less than 10%. With the help of pollen examination of a number of herbarium specimens, the distribution of the tetraploids and that of the assemblage of the hexaploids and octoploids were delineated. Morphological studies indicated that the tetraploid, hexaploid and octoploid plants can not be separated in gross and spikelet morphology and that the tetraploids in central Honshu and those in Mt. Apoi are significantly different in leaf features. It was concluded thatC. sachalinensis represents an apo-amphimictic complex, which includes the following four races: 1) tetraploid, amphimictic, having thin leaf blades 5–10 mm broad and growing on the subalpine conifer forest belt and the conifer forest-alpine ecotone in the mountains of central Honshu; 2) tetraploid, amphimictic, having hard leaf blades 2–6 mm broad and growing on the stony, arid and exposed alpine belt on Mt. Apoi in Hokkaido; 3) hexaploid, mainly apomictic, the most variable ecologically, widely distributed; 4) octoploid, mainly apomictic, frequent in the upper montane to alpine belts, probably widely distributed.     

Stand structure and growth patterns of understorey trees in a coniferous forest,Taisetsuzan National Park,northern Japan

Stand structure was studied with special reference to growth and mortality patterns of sapling and understorey trees in a coniferousPicea jezoensis andAbies sachalinensis forest in Taisetsuzan National Park, Hokkaido, northern Japan.Picea jezoensis was dominant in the basal area, whileA. sachalinensis was abundant in large numbers in the canopy. Estimated mortalities increased significantly with diameter at breast height (DBH) for bothP. jezoensis andA. sachalinensis in the canopy, but the tendency was different between the two species.Picea jezoensis had a lower mortality rate thanA. sachalinensis, especially at small DBH classes. The spatial distribution of understorey individuals ofA. sachalinensis did not show any significant correlation with the spatial distribution of canopy gaps, but that ofP. jezoensis showed a significant correlation.Abies sachalinensis can grow higher thanP. jezoensis under suppressed conditions; whileP. jezoensis requires canopy gaps for steady height growth. This growth pattern leads to a different waiting height in the understorey (≥2 m in height and 10 cm in diameter at breast height).Abies sachalinensis waited for an improvement in light conditions at higher strata (max. 7 m), whileP. jezoensis waited at lower strata (max. 3 m). The estimated mortality of understoreyA. sachalinensis increased with size, while that of understoreyP. jezoensis decreased. Therefore,P. jezoensis gives priority to survival whileA. sachalinensis gives priority to understorey growth. The difference in the ‘waiting pattern’ between the two species in the understorey was considered a significant feature for the canopy recruitment process ofP. jezoensis andA. sachalinensis.     

Revision of the cerrado hemicryptophytic Chamaesyce of Boissier's “Pleiadeniae” (Euphorbiaceae)

The species ofChamaesyce classified by Boissier as the “Pleiadeniae” are revised in light of presently available collections. Six species are accepted and new combinations are proposed forC. nana, C. setosa, C. tamanduana, andC. viscoides. Although these herbaceous perennials of cerrado vegetation of Brazil, northern Argentina, and adjacent countries are distinctive ecologically and geographically, cladistic analysis does not support their recognition as a monophyletic group.     

Chromosome numbers and polyploidy in Castilleja (Scrophulariaceae)

Chromosome numbers are reported for 155 collections ofCastilleja representing 54 taxa. The basic haploid number of 12 was found in 34 taxa, but 10 of these also had one or more polyploid levels. The remaining 20 species were strictly polyploid in one or more levels (4X, 6X, 8X, 10X, 12X). The widespread occurrence of polyploidy, along with hybridization, is believed to be largely responsible for the complex morphological variation found within the genus. Specific examples of the role of polyploidy and hybridization in creating this variation are discussed for the following species complexes:C. affinis, C. applegatei, C. miniata, C. peckiana.     

Chromosome numbers of the genusCalamagrostis in Japan

Chromosome counts for 783 collection ofCalamagrostis in Japan are reported. These include the first record forC. tashiroi and the reports of new cytotypes inC. stricta, C. hakonensis andC. longiseta. The geographical distribution of different cytotypes ofC. langsdorffii andC. hakonensis is outlined. Counts are also reported for a number of “intermediates” which are supposed to be interspecific hybrids or hybrid derivatives. A summary of chromosome counts for JapaneseCalamagrostis so far recorded is tabulated. No diploid plants with 2n=14 chromosomes are found. The tetraploid taxa, which are plentiful and seem to have adaptively radiated in Japan, jack any sign suggestive of their recent origin from the diploids. It is suggested that plant with 2n=28 (4X in the traditional sense) may be regarded as semidiploid and having that behavior, and that speciation ofCalamagrostis in Japan has occurred principally at this chromosome level. Speciation by means of amphiploidy may have been scarce. It is also suggested that hybridization and polyploidy have greatly contributed to the formation of complicated internal structure of various species.     

Karyological study in the genusTuberaria sect.Scorpioides (Cistaceae): Taxonomic and evolutionary inferences

A polyploid complex ofTuberaria sect.Scorpioides species in S Spain has been studied. We have found the chromosome numbers n = 12 and 18, which probably originated from the extinct base number x = 6 by means of allopolyploidy. Octoploids (n = 24) seem to be the result of different crossings, and fall morphologically withinT. guttata, T. inconspicua, orT. commutata. Backcrosses between octoploids and tetraploids originate new hexaploids (n = 18), which, once stabilized, behave as amphidiploids. Most of these also fall within the traditional concept ofT. guttata, so that the enormous polymorphism of this taxon seems to be justified.     

Quantitative nuclear DNA changes inEleusine (Gramineae)

2C nuclear DNA amounts were determined in 30 collections belonging to 10 species ofEleusine. About a 2.5-fold variation in genome size is evident in the genus. The 2C DNA amount in the diploid species ranged from 2.50 pg inE. verticillata to 3.35 pg inE. intermedia. In contrast, the tetraploid species showed a range from 4.95 pg inE. africana to 6.13 pg inE. floccifolia. At intraspecific level 10 collections ofE. coracana, 6 ofE. indica, 4 ofE. africana, 2 ofE. tristachya, and 2 ofE. kigeziensis did not show any significant variation. However, 2 collections ofE. floccifolia, connected with polyploidy, displayed about 90% variation. Polyploid species showed approximately double the genome size of that of their corresponding diploids. An evolutionary increase in DNA amount is evident inE. coracana during the course of its origin and domestication fromE. africana.     

A taxonomic study of the genusCalamagrostis on Mount Yakeishidake

Populations of seven species ofCalamagrostis growing on Mt. Yakeishidake were studied from a viewpoint of taxonomy. Four of them (C. sesquifolia, C. fauriei, C. matsumurae, C. gigas) were composed of tetraploid plants with 2n=28 and high pollen fertility.C. matsumurae andC. gigas had sympatric contacts, but no sign of their hybridization could be detected. The population ofC. sachalinensis on this mountain included hexaploids (2n=42) and octoploids (2n=56), and no obvious morphological or ecological differences could be found between them. The population ofC. sachalinensis was estimated to include various ecological races which may be continuously graded. InC. langsdorffi, only octoploid plants were found. Plants with 2n=56+0?1B were found in the population ofC. hakonensis. The pollen features of the collections ofC. langsdorffii, C. sachalinesis andC. hakonensis showed that apomictic seed formation may be more or less developed in them. Populations of these species on Mt. Yakeishidake were clearly separated morphologically. It was concluded that the populations of the seven species examined each have a unity and that strains ofC. langsdorffii, C. sachalinensis andC. hakonensis found on Mt. Yakeishidake are confined to those of a derived type.     

Caloplaca sect.Xanthoriella,sect. nov.: Untersuchungen über die „Xanthoria lobulata-Gruppe“ (Lichenes,Teloschistaceae)

Reexamination ofXanthoria persica, X. polycarpoides, X. lobulata gave evidence, that the thalli of these species are devoid of a lower cortex and rhizinae. Therefore, they do not fit the definition of the genusXanthoria and are transferred toCaloplaca (under the new sectionXanthoriella) asCaloplaca persica, C. polycarpoides, andC. boulyi, respectively. — Details on development, anatomical structure, ecology and distribution are presented.

     

Genetic diversity in sexual diploid and apomictic tetraploid populations of Paspalum notatum situated in sympatry or allopatry

Paspalum notatum is a subtropical grass widely distributed in the temperate areas of America. Diploids are sexual while polyploids give rise to clonal seeds through aposporous apomixis. RAPD markers were used to analyze the genetic structure of three natural populations: i) diploids reproducing sexually (R2X); ii) sympatric apomictic tetraploids collected in the vicinity of the diploids (R4X); iii) allopatric apomictic tetraploids growing in isolation (C4X). The apomictic reproduction rate was evaluated by the use of molecular markers in progeny tests, while chromosome-counting allowed the verification of ploidy levels. Data revealed that the R4X group presented a variation considerably higher than that observed for C4X. Jaccards coefficients were used to produce a cluster diagram using the UPGMA method. All but one tetraploid genotypes grouped together and were associated to diploid genotype A21. The possibility of occasional generation of novel tetraploid clones from the interaction between tetraploid and diploid individuals is discussed.     

Demographic traits of understory trees and population dynamics of aPicea-Abies forest in Taisetsuzan National Park, northern Japan

The size structure transition matrices ofPicea jezoensis, Picea glehnii andAbies sachalinensis of a sub-boreal forest in Hokkaido, northern Japan were constructed based on the demography of each species (Picea jezoensis andPicea glehnii were dealt with together asPicea) during a 4-year period. Two types of matrices, density-independent and density-dependent population dynamics models, were investigated for evaluating the ‘waiting pattern’ betweenPicea spp. andA. sachalinensis. For the density-dependent model, it was assumed that the demographic traits of understory trees, the recruitment rate, the understory mortality rate and the transition probability from the understory to canopy stages, were regulated by the one-sided competitive effect of canopy trees. The observed size structure ofPicea was almost consistent with the stationary size structure obtained in both the density-independent and the density-dependent models, whereas the observed size structure ofA. sachalinensis was not realized in the two models. The effects of both the transition probability from the understory to canopy stages and the recruitment rate on the dynamics of canopy trees were investigated. ForPicea, two parameters—recruitment rate (e _i ) and transition probability from the understory to canopy stages-exponentially affected the dynamics of canopy trees. In contrast, forAbies sachalinensis, the two parameters affected linearly the dynamics of canopy trees. In conclusion, the population dynamics ofPicea andA. sachalinensis was determined by the parameters of the recruitment rate and the transition probability from the understory to canopy stages, relating to waiting patterns of understory trees for future gap formation. InPicea, the demographic parameters of understory trees intensively regulated the dynamics of canopy trees if compared withA. sachalinensis, suggesting that the performance of understory trees plays a key role in the population dynamics ofPicea. This reflects the growth pattern of understory trees in the regeneration of the two species.     

Morphological and chromosomal variation in Fallopia section Reynoutria (Polygonaceae) in Korea

We have examined morphological and chromosomal variation inFallopia sect.Reynoutria in Korea to clarify their taxonomic identities and to determine whether their morphological variability is associated with ploidy levels. Principal components analysis (PCA) of individuals from 21 populations, using major distinguishing characters, revealed the presence of four major entiries of sect.Reynoutria in Korea; these includeF. sachalinensis, F. japonica var.japonica, F. forbesii, and the Nonsan population consisting of presumed hybrids. Based on morphology, it is hypothesized that the Nonsan population was probably derived from multiple hybridization events involving the three named taxa. The results also indicate thatF. forbesii is distinct fromF. japonica var.japonica. Polyploidy is more prevalent in sect.Reynoutria than has been previously recognized.Fallopia sachalinensis in Korea occurs as dodecaploids with 2n=132; our count is the first dodecaploid count for the species, and represents the highest chromosome number known in the genus.Fallopia japonica var.japonica occurs as tetraploids (2n=44), hexaploids (2n=66), and octoploids (2n=88), whileF. forbesii occurs as hexaploids (2n=66) and octoploids (2n=88); our counts appear to be the first reported chromosome numbers forF. forbesii. Morphological analysis indicates that there is no apparent correlation between the ploidy levels in these taxa and the morphological characters that we have considered in this study except that the tetraploids ofF. japonica var.japonica tend to have somewhat thicker leaves.     

Numerical analysis of sexual dimorphism inSaguinus dentition

Among New World monkeys, more or less sexual dimorphism exists in the dentition, especially in the Cebidae. On the other hand, the Callitrichidae includingSaguinus are said to be characterized by a broad lack of sexual dimorphism with the exception of the reproductive organs. In the present article, sexual dimorphism in the dentition of someSaguinus species was reconfirmed using univariate and multivariate analytical methods. The results of the analysis were as follows: (1) there is no sexual dimorphism in the canine tooth size, except for the upper canine ofS. geoffroyi and lower canine ofS. mystax; (2) the overall tooth size difference between males and females is slight or none inS. geoffroyi, S. leucopus, andS. fuscicollis, relatively small inS. oedipus andS. mystax, and rather larger inS. midas; (3) an overall difference in shape factor between both sexes exists in all species ofSaguinus to a greater or lesser extent; (4) although only slight sexual dimorphism is recognized in the canine tooth itself, sexual dimorphism does exist in some adjacent teeth of the canine in a few species; and (5) there are some interspecific differences in the magnitude of the sexual dimorphism of theSaguinus dentition and these differences are more evident in species inhabiting the peripheral regions of the distribution areas of this genus. Taking all the evidence obtained into account, the sexual dimorphism in theSaguinus dentition must be re-investigated in comparison with other genera of the Callitrichidae.     

Two chemical races inSalix sachalinensis Fr. Schmidt (Salicaceae)

High-performance liquid chromatography (HPLC) profiles based on chemical constituents of the leaves of 145 individuals ofSalix sachalinensis were classified into two different patterns: one composed of flavonoids (myricetin and dihydromyricetin), and the other composed of phenylpropanoid derivatives. This led to the conclusion that two chemical races exist inS. sachalinensis with different biosynthetic abilities to produce secondary metabolites.     

Detection of species within the Xerocomus subtomentosus complex in Europe using rDNA–ITS sequences

Identification of species within the boletoid genus Xerocomus has relied heavily upon the macromorphological features of the basidiomes. However, the phenotypic plasticity of these features has resulted in considerable confusion over the delimitation of taxa. In this study, we examined collections attributed to the X. subtomentosus complex in Europe using morphological and rDNA–ITS sequence data. In total, 45 European collections from a wide range of geographical areas and ecological conditions were included in the study. In spite of detecting considerable genetic variation, even within individual basidiomes of X. subtomentosus, molecular data, spore size, flesh colour, and the colour of the basal mycelium allow for the recognition of four distinct taxa: two correspond to X. subtomentosus (13 collections) and X. ferrugineus (20); one X. chrysonemus sp. nov. (10), to date only found in the UK, is described as new; and the existence of another taxon (two; Italy and UK) is noted but left undescribed owing to lack of material. Eight collections from North America were also included in the study, from which two taxa with a close affinity to X. ferrugineus were recognised.     

Unique disialosyl gangliosides from salmon kidney: Characterization of V3αFuc, IV3βGalNAc, II3(αNeuAc)2-Gg4Cer and its analogue with 4-O-acetyl-N-acetylneuraminic acid

Four unidentified acidic glycolipids (X3-X6) were isolated from the kidney of the Pacific salmon on an anion exchange column and by high performance liquid chromatography using a silica bead (Iatrobeads) column. Based on methylation analysis, chemical and enzymatic degradation, proton nuclear magnetic resonance spectroscopy and mass spectrometry, the glycon structure of X5 and X6 was identified as a unique disialosyl fucosyl-N-acetylgalactosaminyl ganglio-N-tetraose: Fucα3GalNAcβ3Galβ3GalNAcβ4[NeuAcα8NeuAcα3] Galβ4Glcβ1Cer. NMR showed that X3 and X4 were analogues of X5 and X6 and contained O-acetyl groups on C4 of the outer N-acetylneuraminic acid, first disialosyl gangliosides containing 4-O-acetyl-N-acetylneuraminic acid. The ceramides of X3 and X5 contained predominantly C24: 1, and X4 and X6 contained saturated fatty acids (C14: 0, C16: 0 and C18: 0), whereas the long chain base was exclusively sphingenine. The concentrations of X3 and X4 were 0.13 and 0.16 nmol/g of kidney respectively and those of X5 and X6, were 0.07 nmol/g each.     

Molecular population genetics of the<Emphasis Type="Italic">β-esterase</Emphasis> gene cluster of<Emphasis Type="Italic">Drosophila melanogaster</Emphasis>

We have investigated nucleotide polymorphism at theβ-esterase gene cluster including theEst-6 gene andψEst-6 putative pseudogene in four samples ofDrosophila melanogaster derived from natural populations of southern Africa (Zimbabwe), Europe (Spain), North America (USA: California), and South America (Venezuela). A complex haplotype structure is revealed in bothEst-6 andψEst-6. Total nucleotide diversity is twice inψEst-6 as inEst-6; diversity is higher in the African sample than in the non-African ones. Strong linkage disequilibrium occurs within theβ-esterase gene cluster in non-African samples, but not in the African one. Intragenic gene conversion events are detected withinEst-6 and, to a much greater extent, withinyEst-6; intergenic gene conversion events are rare. Tests of neutrality with recombination are significant for theβ-esterase gene cluster in the non-African samples but not significant in the African one. We suggest that the demographic history (bottleneck and admixture of genetically differentiated populations) is the major factor shaping the pattern of nucleotide polymorphism in theb-esterase gene cluster. However there are some ’footprints’ of directional and balancing selection shaping specific distribution of nucleotide polymorphism within the cluster. Intergenic epistatic selection betweenEst-6 andψEst-6 may play an important role in the evolution of theβ-esterase gene cluster preserving the putative pseudogene from degenerative destruction and reflecting possible functional interaction between the functional gene and the putative pseudogene.Est-6 andyEst-6 may represent an indivisible intergenic complex (‘intergene’) in which each single component (Est-6 orψEst-6) cannot separately carry out the full functional role.