摘要:

SummaryAfter a brief resumé of the principal alternatives the author concludes that the only reasonable hypothesis for the fully autogenous development of the eukaryotes is that involving a cyanophyte‐like photosynthetic ancestor: the “Uralga.” A structurally explicit scenario for the internal events necessary to produce general eukarotic organisation within that framework is outlined. Central to the model is the progressive differentiation of membrane systems, leading to enclosure of specialised, double‐membraned metabolic compartments by engulfment during the stage in which endo‐ and exocytotic properties were attained. Some minor differences between this model and that of Cavalier‐Smith (1975) are discussed.The paper concludes with some comments about hypotheses involving endosymbiosis, including the virtues of a compromise hypothesis in which mitochondria arose autogenously, but chloroplasts arose by endosymbiosis.

ISSN:0040-0262    

DOI:10.2307/1220521

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThe assumption is made that photosynthesis evolved in prokaryotes and was acquired by symbiosis in all eukaryotes. By studies of comparative mitosis and genetic systems of “lower” eukaryotes (e.g., nucleate algae, protozoa, flagellated fungi and so forth) consistent phylogenies of these organisms may be constructed. It follows logically from these considerations that the traditional concept of “plant” and “animal” kingdoms are obsolete. An internally consistent modification of Whittakers five kingdoms (Monera, Protist, Fungi, Animal and Plant) is represented and defended on the basis of information from ultrastructure, comparative biochemistry and life cycles, molecular biology and other modern work. Higher taxa (Kingdoms, Phyla, Classes) for major groups based on the recognition of the prokaryotic‐eukaryotic dichotomy is offered for critical evaluation.

ISSN:0040-0262    

DOI:10.2307/1220522

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1976.tb00436.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryVariation inCannabisis evaluated in the context of the confusing systematic history of this genus. Aside from some experimentally produced polyploids, allCannabisis diploid (n= 10), and there appear to be no barriers to successful hybridization within the genus. The present pattern of variation is due in large part to the influence of man. Two widespread classes of plant are discernible: a group of generally northern plants of relatively limited intoxicant potential, influenced particularly by selection for fibre and oil agronomic qualities, and a group of generally southern plants of considerable intoxicant potential, influenced particularly by selection for inebriant qualities. These two groups are treated respectively as subsp.sativaandindica, of C.sativa, the only species of the genusCannabis.Within each subspecies two parallel phases are recognizable. The “wild” (weedy, naturalized or indigenous) phase is more or less distinguishable from the domesticated (cultivated or spontaneous) phase by means of an adaptive syndrome of fruit characteristics. The resulting four discernible groups are recognized as varieties.

ISSN:0040-0262    

DOI:10.2307/1220524

出版商:Wiley    

年代:2019

数据来源: WILEY

ISSN:0040-0262    

DOI:10.1002/j.1996-8175.1976.tb00440.x

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryPhenetic analyses are valuable at all taxonomic ranks. A review of work at higher ranks is presented, and certain difficulties are discussed: these are just as serious for traditional studies, though often glossed over. Difficulties include determination of homologies, incompleteness of data and shortage of constant characters. It is also necessary to employ similarity coefficients and cluster methods that are not too sensitive, respectively, to effects of gross size and numbers of OTU's. The number of OTU's required to represent a homogeneous cluster is apt to be underestimated: even with a simplified model of phenetic variation this number should be at least 10 and preferably 25 or more. Some newer developments in numerical analysis of phytogeny are briefly reviewed.

ISSN:0040-0262    

DOI:10.2307/1220526

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryData of Heiser et al. (1965) on species, hybrids, autoploids, and alloploids inSolanumwere re‐examined using additional methods of numerical analysis. The phenogram produced after the removal of hybrids from the data matrix indicated that distortion of taxa observed in the phenogram of the previous study was due to the influence of hybrids. Hybrids, with one exception, were found to fall in an intermediate position relative to their parents in the graph obtained from principal components analysis. The ability to display intermediate groups makes principal components analysis better suited than cluster analysis for revealing hybrids from phenetic data.

ISSN:0040-0262    

DOI:10.2307/1220527

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryThis study presents 126 original reports of chromosome numbers for 101 taxa of North AmericanAstragalus; 46 are the first records for species. Chromosome numbers are now known from at least one count for slightly more than 40 % of the North American species; on a world wide basis about 80% of the species are still unknown from a single count. This study supports earlier work demonstrating the basic division between Old World species, including their close New World relatives (x = 8, euploidy common), and strictly New World lineages (x = 11, 12, 13, 14, 15, euploidy rare). Two euploids of New World relationship,A. layneaeGreene andA. pictiformisBarneby, are added to the long knownA. grayiParry ex Wats.; all are 2n = 44. The number 2n = 30 is reported for the first time in New World species, being recorded forA. guatemalensisHemsl.,A. radicansHornm.,A. ervoidesH.&A.,A. parvusHemsl., andA. diphacusWats. All are Mexican species; some are considered primitive, others advanced. The chromosome number 2n = 22 is also reported for primitive species. It is proposed, therefore, that the New World species originated from a tetraploid of 2n = 32 or a hypotetraploid, evolutionary radiation in some lineages concommitant with descending aneuploidy, in other lineages with little or no change in number.

ISSN:0040-0262    

DOI:10.2307/1220528

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryMecodiumas a subdivision of the genusHymenophyllumhas a different type than when it is ranked as a genus. As a legitimate generic name, it must be typified byM. diversilabiumCopel., a fact overlooked since the original publication, and many combinations have been made in a later homonym. If considered to apply to the original genus, these combinations are later pseudo‐isonyms. It is argued that later pseudo‐isonyms have no actual existence in nomenclature and do not necessitate the making of new combinations.

ISSN:0040-0262    

DOI:10.2307/1220529

出版商:Wiley    

年代:2019

数据来源: WILEY

摘要:

SummaryHerbarium labels were photographed using single frames of 8 mm movie film. Up to 3200 labels can be captured on a 15 m roll of film. Total costs for capturing 60,000 labels was only $ 735 (1.2c/label) (US$). This should be an inexpensive method to transmit label data and decrease specimen borrowing for distribution mapping purposes.

ISSN:0040-0262    

DOI:10.2307/1220530

出版商:Wiley    

年代:2019

数据来源: WILEY