管涔山青扦(Picea wilsoni)天然林年龄结构及其动态的研究

地种群年龄的研究表明,虽经人为频繁干扰,管涔肝扦天然林仍表现出异龄林结构特征,立木年龄范围超过一个级期,根据年龄结构特征值可分为相对龄林、相对异龄林和异龄林３种类型林下新一代种群的数量和结构受林冠郁闭度和结构的影响。具垂直郁闭型林冠的异龄林,林下更新数量充足,幼苗幼树年龄结构合理;而服闭型林冠,不利于一代种群的发生和发展,青扦种群年龄结构受种群发生和自疏两个过程的控制,林下种群的发生以小规模林冠空     

MORPHOLOGICAL AND ALLOZYMIC VARIATION IN POPULATIONS OF MYTILUS GALLOPROVINCIALISFROM THE AEGEAN SEA

Eight populations of Mytilus galloprovincialis from differentcoasts of the Northern and Central Aegean Sea have been investigatedat the morphological and allozymic level. A significant degreeof variation was found within and among the populations. Theaverage degree of heterozygosity ranges from 0.085 to 0.14 andit is lower than those reported for other populations of thesame species. No correlation was found between the degree ofheterozygosity and the morphological variability among the populationsexamined. (Received 14 May 1992; accepted 1 October 1992)     

管涔山青扦(Picea wilsoni)天然林年龄结构及其动态的研究

对种群年龄结构的研究表明,虽经人为频繁干扰,管涔山青扦天然林仍表现出异龄林结构特征,立木年龄范围超过一个龄级期,根据年龄结构特征值可分为相对同龄林、相对异龄林和异龄林３种类型。林下新一代种群的数量和结构受林冠郁闭度和结构的影响。具垂直郁闭型林冠的异龄林,林下更新数量充足,幼苗幼树年龄结构合理;而水平郁闭型林冠,不利于新一代种群的发生和发展。青扦种群年龄结构受种群发生和自疏两个过程的控制,林下种群的发生以小规模林冠空隙干扰下的连续更新为主。青扦华北落叶松混交林,在其共同适生范围内是某种干扰格局控制下的稳定群落     

VOCAL DIALECTS AND THE STRUCTURE OF GEOGRAPHIC VARIATION IN MORPHOLOGICAL AND ALLOZYMIC CHARACTERS IN THE RUFOUS-COLLARED SPARROW,ZONOTRICHIA CAPENSIS

The geographical patterns of variation shown at 20 allozyme and non-enzymatic protein-coding loci, in 8 external, and in 12 skeletal morphological characters in the rufous-collared sparrow, Zonotrichia capensis, were analyzed in order to test the local (genetic) adaptation hypothesis regarding the origin and maintenance of vocal dialects in birds. Approximately 20 males were collected from each of four sites within each of six different dialect zones. There was significant variability in both external and skeletal morphology among all 24 sites and among dialect groups. Average Wright's corrected fixation coefficient (F_ST) was 0.118, indicating significant genetic differentiation among all sites, regardless of dialect. Hierarchical F statistics indicated that only 50% of among site variability was due to a dialect effect. Puna dialect sites were highly differentiated from all other sites with respect to both morphology (external and skeletal measures) and allozyme frequencies. Heterogeneity at the PGM-1 locus among puna scrub sites was the major cause of the high average F_ST across all sites, and within the puna scrub dialect. Average genetic differentiation among non-puna sites (F_ST = 0.018) was similar to differentiation among sites within each of the five non-puna dialect groups (mean F_ST = 0.0132 ± 0.0069). Hierarchical F statistics indicated that none of the among-site differentiation in this subset of samples was due to a dialect effect. These observations are not consistent with the local adaptation hypothesis. All significant genetic heterogeneity occurred among sites in mountainous habitats, and we suggest that topography and patchiness of habitat may have been major factors involved in population differentiation, rather than vocal dialects.     

MICROGEOGRAPHIC PATTERNS OF GENETIC AND MORPHOLOGICAL VARIATION IN SAVANNAH SPARROWS (PASSERCULUS SANDWICHENSIS)

Surveys of genetic population structure are often limited to large geographic scales because geographically close populations are indistinguishable. Genetic uniformity across adjacent demes can be interpreted as evidence for cohesion (panmixia) or recent divergence. However, poor genetic resolution at microgeographic scales can also arise from the use of overly conservative (slowly evolving) markers. This study examines the ability of hypervariable, minisatellite loci to discriminate among geographically close populations of Savannah sparrows (Passerculus sandwichensis) and to track morphological differentiation at a microgeographic scale (interregional distance < 55 km). Savannah sparrows breeding at five island and two mainland sites in the Bay of Fundy, New Brunswick, Canada, show concordant patterns of variation in external morphology (seven characters) and multilocus DNA fingerprinting profiles (S_xy): island sparrows are phenotypically larger and genetically more similar to each other than they are to mainland sparrows. This pattern of variation is consistent with both adaptive (natural selection) and nonadaptive (genetic drift) mechanisms of population divergence. Based on minisatellite diversity, the effective size of both island and mainland populations is 37, an estimate substantially lower than census population sizes. These data are discordant with observations of sparrow vagility and abundance and suggest a closer examination of microgeographic patterns in avian systems.     

IMPLICATIONS OF MORPHOLOGICAL AND ANATOMICAL VARIATION IN ABIES BALSAMEA AND A. LASIOCARPA (PINACEAE) FROM WESTERN CANADA

Abies balsamea and A. lasiocarpa are closely related North American balsam firs that are generally thought to hybridize and intergrade where their ranges overlap in west-central Alberta. To test this hypothesis, a series of collections was made from ten populations along an east-west transect between western Saskatchewan and central British Columbia. Each tree was scored for various vegetative and cone characters. The resulting data were analyzed by Principal Components Analysis and Canonical Variates Analysis. Analyses based on vegetative data produced somewhat different results from analyses based on cone data, indicating that vegetative and sexual features of the trees respond to different selection pressures at the ecologically diverse sample sites. The combined results of analyses of vegetative and sexual data indicate that the ten populations do not represent elements of two morphologically distinct taxa. Instead, the results apparently reflect population differentation within a single, regionally variable complex in response to local selection pressures following east-west gene flow. It is recommended that the separate species designations, A. balsamea and A. lasiocarpa, be retained since: 1) present day elements of the complex are evidently derived from separate refugia isolated by the Rocky Mountains during past glacial periods, and 2) gradual morphological differences exist between populations on each side of the Rocky Mountain crest.     

GENETIC, MORPHOLOGICAL, AND TOXICOLOGICAL VARIATION AMONG GLOBALLY DISTRIBUTED STRAINS OF NODULARIA (CYANOBACTERIA)

Morphological, toxicological, and genetic variation was examined among 19 strains of Nodularia. The strains examined could be morphologically discriminated into four groups corresponding to N. spumigena Mertens, N. sphaerocarpa Bornet et Flahault, and two strains that did not clearly correspond to currently accepted Nodularia species. Genetic variation was examined using nucleotide sequencing of the phycocyanin intergenic spacer region (cpcBA-IGS) and RAPD-PCR. The PCR-RFLP of the cpcBA-IGS differentiated four genotypes corresponding to the four morphological groups. However, nucleotide sequencing of 598 bp of the 690-bp fragment showed that one of the three strains corresponding to N. sphaerocarpa (PCC 7804) was genetically divergent from the other two, suggesting that it constitutes a distinct species. Nucleotide variation within the morphospecies groups was limited (<1%), and all 14 Australian strains of N. spumigena possessed identical cpcBA-IGS sequences. The RAPD-PCR differentiated the same groups as the cpcBA sequencing and discriminated each of the seven different Australian populations of N. spumigena. Strains from within a bloom appeared genetically identical; however, strains isolated from different blooms could be separated into either a western or a southeastern Australian cluster, with one strain from western Australia showing considerable genetic divergence. The pattern of variation suggests that individual blooms of N. spumigena are clonal but also that Australian N. spumigena populations are genetically distinct from each other. Examination of genetic distance within and between blooms and within and between morphological groups showed clear genetic dicontinuities that, in combination with the cpcBA-IGS data, suggest that Nodularia contains genetically distinct morphospecies rather than a continuous cline of genetic variation. Furthermore, these morphospecies are genetically variable, exhibiting hierarchical patterns of genetic variation on regional and global scales. Production of the hepatotoxin nodularin was not restricted to one genetic lineage but was distributed across three of the five genotypic groups. A strain of N. spumigena from a nontoxic Australian population was found to fall within the range of genetic variation for other toxic Australian strains and appears to be a unique nontoxic strain that might have arisen by loss of toxin production capacity.     

羊草遗传多样性的研究

本文运用光镜和电镜技术,对不同土壤条件下７个羊草种群营养体形态结构进行了观察,在此基础上,运用ＲＡＰＤ技术,对７个羊草种群的遗传多样性进行了研究,分析了遗传多样性与环境因子的相关关系。结果表明：１）７个羊草种群根的结构与盐碱土型羊草结构相似;茎的结构与黑钙土型羊草结构相似;叶的结构呈现黑钙土型羊草结构和盐碱土型羊草结构之间的过渡类型。２）羊草种群的遗传多态性非常高,５３个引物在７个羊草种群中共检测到３６５条扩增片段,多态带３０３条,多态率达到８３．０１％。特有带１２１条,占３３．２１％。３）７个羊草种群之间的遗传距离变异范围为０．２３４９－０．６１６６,聚类分析表明这７个种群可分子为３组。４）多态位点百分数与土壤有机质、全氮含量呈现比较大的负相关;特有带百分数与土壤镁离子、钙离子呈现较大的负相关;遗传距离值与土壤的电导率、水溶性钠离子呈现较大的正相关。     

MORPHOLOGICAL AND GENETIC VARIATION IN ECOLOGICALLY CENTRAL AND MARGINAL POPULATIONS OF RUMEX ACETOSELLA L. (POLYGONACEAE)

Six ecologically central (old field) and marginal (strip mine) populations of the hexaploid Rumex acetosella were collected, grown under uniform conditions, and examined for genetic and morphological variation. Extensive electrophoretic variation was found in alcohol dehydrogenase and phosphoglucose isomerase, while other enzymes surveyed showed little or no variation. Hedrick's genotypic measure of identity revealed mean values of 0.506 for central populations, 0.836 for marginal populations, and 0.633 for comparisons of central with marginal populations. Alcohol dehydrogenase phenotypes had significantly fewer electromorphs per individual in marginal populations. Clones of individuals from both environments were subjected to different watering regimes. No significant differences in root/shoot ratio, leaf number, total leaf area, or relative growth rate were found between strip mine and old-field individuals within each watering treatment, although significant differences were found between watering treatments. There are small, but significant amounts of isozyme differentiation between central and marginal populations, while there was no such differentation for morphological characters.     

GEOGRAPHICAL AND GENETIC STRUCTURE OF LIFE-HISTORY VARIATION IN MILKWEED BUGS (HEMIPTERA: LYGAEIDAE: ONCOPELTUS)

Life-history variation was investigated using crosses within and among the laboratory-bred descendants of six geographic samples of the large milkweed bug, Oncopeltus fasciatus. These samples spanned the species' range, from permanent (year-round) populations on tropical islands to seasonal middle-latitude populations found in temperate North America. The seasonal populations must be refounded each year by colonists from more southern populations. Marked differences in life-history traits (particularly in age at first reproduction, clutch size, and rate of egg production) were observed among the six population samples, with tropical-island and west-coast populations being the most distinct. In the eastern and central United States, there was a marked north-south difference in life history. Crossing experiments demonstrated a genetic basis for these differences. F₁ and F₂ hybrids from crosses between continental populations tended to have intermediate phenotypes. The similarity of the seasonal middle-latitude populations' life histories and the consistency of the distribution of life-history characteristics among populations (across years) may indicate that the north-south difference in life history is due to selection on these traits during the annual northward movement or that migrants represent a distinct genetic form of this species.     

GENETIC AND MORPHOLOGICAL VARIATION IN THE LAND WINKLE POMATIAS ELEGANS (MULLER) (CAENOGASTROPODA: POMATIASIDAE)

Population genetics and shell morphology have been studiedin 11 populations of the poorly colonizing land caenogastropodPomatias elegans. The total area of suitable habitats in northwestEurope is shrinking and many isolated populations are becomingvulnerable to extinction. In this study we tested whether theconcept of management units (i.e. groups of population withsignificantly different allele frequencies due to demographicindependence) is applicable to the conservation of P. elegans.F_st values indicated strong genetic differentiation and thuslittle genetic exchange between populations. Allozyme differentiationcould be explained with an isolation by distance model, whereasmorphological differentiation could not. A morphological differenceexists between sexes but not sufficient to discriminate malesand females. A Mantel test showed no significant relationshipbetween morphological distance (size corrected or not) and geneticdistance. Since allele frequencies differed even among populationsin areas where P. elegans is not threathened, we conclude thatin the case of P. elegans, defining management units with allozymesmay not be an appropriate way to select the most suitable populationsfor conservation. (Received 3 April 2000; accepted 25 August 2000)     

CHLOROPLAST-DNA AND ALLOZYMIC VARIATION IN DIPLOID AND AUTOTETRAPLOID HEUCHERA GROSSULARIIFOLIA (SAXIFRAGACEAE)

Diploid and autotetraploid populations of Heuchera grossulariifolia occur throughout mountainous regions of the Pacific Northwest. Controlled greenhouse crosses indicated that the two cytotypes are largely reproductively isolated. Fourteen diploid and 11 tetraploid populations were analyzed electrophoretically. Individual tetraploid plants expressed up to four alleles per isozyme locus, and tetraploid populations had significantly higher levels of heterozygosity than diploids. Mean observed heterozygosity was 0.159 for tetraploid populations and 0.058 for diploid populations. The patterns of allelic distribution between cytotypes suggested multiple origins of autotetraploids. This hypothesis was supported by restriction-site analysis of chloroplast-DNA (cpDNA) variation which indicated that there had been at least three independent origins of tetraploids. Electrophoretic data, in conjunction with a cpDNA-based phylogeny and geographic distribution of populations, suggest that autopolyploid populations evolved several times as migration of diploids occurred down river systems. This study further supports the contention that autopolyploidy can be a common and successful speciation process in some groups of plants.     

MORPHOLOGICAL AND GENETIC VARIATION IN THE ANTARCTIC LIMPET NACELLA CONCINNA (STREBEL, 1908)

Samples of the Antarctic limpet, Nacella concinna (Strebel,1908), were collected from four sites in the South Orkney Islandsand from Stromness in South Georgia during 1988. At three SouthOrkney sites, both littoral and sub-littoral samples of limpetswere taken. Shell dimensions were measured and littoral andsub-littoral limpets were shown to have significantly differentshell shapes. Foot and digestive gland tissues were subjectedto electrophoresis and five polymorphic loci {Es-1, lcd-1, lcd-2,Gpi, Got-1 and Pgm-1) and two monomorphic loci (Es-2 and Got-2)were scored. Genetic identities between littoral and sub-littoralforms and also between sites were calculated. At the loci scored,the littoral and sub-littoral forms were virtually identicaland this suggests that the shell shape differences between theforms are the result of environmentally induced phenotypic plasticity.However, significant genetic differences and some morphologicaldifferences were apparent between the sample of limpets fromSouth Georgia and all other sites. Genetic identity values suggestedthat the South Georgia and South Orkney N. concinna are geographicallyseparated populations of a single species rather than distinctsub-species. (Received 21 November 1990; accepted 17 April 1991)     

MORPHOLOGICAL AND GENETIC VARIATION IN THE POPULATIONS OF SARGASSUM HEMIPHYLLUM (PHAEOPHYCEAE) IN THE NORTHWESTERN PACIFIC1

Difficulty in species identification of Sargassum (Sargassaceae, Fucales) is partly attributed to the high polymorphism among its individuals and populations. This study aimed at assessing morphological and genetic variations in two varieties, var. hemiphyllum J. Agardh and var. chinense J. Agardh, of Sargassum hemiphyllum (Turner) C. Agardh, a widely distributed species in the northwestern Pacific. We investigated 26 measurable, five numerical, and 33 categorical morphological parameters associated with different branching levels of specimens from each of six localities within its distribution range using cluster analysis (CA) and principal coordinate analysis (PCoA). Leaf size of the primary and secondary branching levels and the vesicle size of the secondary branches of the specimens examined were determined to be the most important morphological parameters that were significantly different among populations. Change in leaf and vesicle length of individuals among the six populations followed a latitudinal gradient, with smaller leaves and vesicles associated with northern populations and larger ones in the southern populations. The possible influence of the gradual change in sea surface temperatures (SSTs) along this gradient in the northwestern Pacific on leaf and vesicle morphologies of this species was suggested. PCR‐RFLP analysis of the RUBISCO spacer in the chloroplast genome revealed two distinct and highly homogenous clades, a China clade and a Japan‐Korea clade, which corresponded to var. chinense and var. hemiphyllum, respectively. The formation of refugia along the “Paleo‐coast” in the East China Sea during glacial periods is suggested to have led to the vicariance of ancestral populations of S. hemiphyllum and thus to have promoted genetic differentiation. The massive freshwater outflow of the Yellow and Yangtze rivers may continue to act as a barrier, prolonging the allopatric distribution of the two varieties.     

甘南地区紫果云杉、岷江冷杉生命表

本文以径级(胸径间隔)为基础,编制甘南地区紫果云杉、岷江冷杉生命表。 一、研究方法 本项研究于1986和1987年,在甘肃省南部云、冷杉林主要分布地带的白龙江林区和洮河林区进行。选择原始状态下的紫果云杉(Picea purpurea Mast.)、岷江冷杉(Abies faxoniana Rehd.et Wils)林,海拔3000米至3600米之间,位于白龙江中上游;同时选取择伐后的云杉(Picae asperata Mast.)、岷江冷杉林     

POLLEN BRUSH OF PAPILIONOIDEAE (LEGUMINOSAE): MORPHOLOGICAL VARIATION AND SYSTEMATIC UTILITY

The pollen brush commonly is referred to as a “bearded” or “pubescent” style in taxonomic literature and traditionally is taken to be an aggregation of trichomes on the distal end of the style, and occasionally including the stigma. We present data that support the taxonomic utility of the pollen brush but define it more specifically as a dense aggregation of erect trichomes emanating from the style (not stigma or ovary) and functioning in secondary pollen presentation. We recommend avoiding such vague terminology as bearded or pubescent styles as these refer not only to the pollen brush but also to ciliate and penicillate stigmas and ciliate styles. The latter three conditions have some taxonomic use, and since their occurrence is not necessarily correlated with the presence of a pollen brush, they should be distinguished from it. We estimate that the pollen brush has arisen independently in the following eight taxa: 1) Crotalaria and Bolusia (Crotalaraieae), 2) subtribe Coluteinae (Galegeae), 3) Tephrosia subgenus Barbistyla (Millettieae), 4) Adenodolichos (Phaseoleae subtribe Cajaninae), 5) Clitoria (Phaseoleae subtribe Clitoriinae), 6) the subtribe Phaseolinae (Phaseoleae), 7) the Robinia group (Robinieae), and 8) the tribe Vicieae. Its hypothesized homology within each of these groups is supported by a cooccurrence with other taxonomic characters, both morphological and molecular.     

MORPHOLOGICAL AND ALLOZYMIC EVIDENCE FOR SABATIA FORMOSA (GENTIANACEAE) IN THE SECTION CAMPESTRIA

An investigation of eleven populations of Sabatia, utilizing twelve morphological traits and fifteen allozymic loci, revealed the presence of three species in the section Campestria. Currently, the section has two recognized species, S. campestris Nutt. and S. arenicola Greenm. A stepwise discriminant analysis of the morphological data indicated the presence of the third previously described species, S. formosa Buckl. Eight of the loci were either monomorphic or there were no allozyme frequency differences among the three species. An analysis of the allozyme frequencies of the seven polymorphic loci substantiated the presence of S. formosa. Ecological and phenological phenomena further separate the three species. A distribution map of the populations analyzed, populations observed, and populations represented in herbarium specimens indicates that the ranges of the three species are separate although sympatry does occur. Thus, the morphological form described and designated S. formosa by Buckley in 1862 is a separate species.