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  • 1
    Electronic Resource
    Electronic Resource
    Phospholipid composition ofDipylidium caninum (1978)
    Springer
    Cellular and molecular life sciences 34 (1978), S. 1457-1458 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The phospholipid composition ofDipylidium caninum has been studied. Chloroform-methanol-soluble fraction amounted to 2.4% and phospholipids to 0.5% of the wet weight of the parasite. Phosphatidyl choline and phosphatidyl ethanolamine represented the bulk of the phospholipids, whereas phosphatidyl serine, phosphatidyl inositol, lysolecithin and lysophosphatidyl ethanolamine were present in minor amounts. Sulfatides were also identified in this parasite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01932350
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  • 2
    Electronic Resource
    Electronic Resource
    On the phospholipids of adultAncylostoma caninum (1977)
    Springer
    Cellular and molecular life sciences 33 (1977), S. 1585-1585 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The phospholipid composition ofAncylostoma caninum has been examined. Phospholipids amounted to 0.9% of the wet weight of the parasite. Ethanolamine and choline containing lipids comprised about 76% of the total phospholipids. Lysolecithin, sphingomyelin, phosphatidyl inositol and phosphatidyl serine were present in minor amounts. Cerebrosides and sulfatides were also identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01934011
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  • 3
    Electronic Resource
    Electronic Resource
    Inheritance of phenotypic plasticity in soft chess,Bromus mollis L. (Gramineae) (1978)
    Springer
    Cellular and molecular life sciences 34 (1978), S. 835-836 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Phenotypic plasticity, measured by the phenotypic variation of a genotype living under diverse environments, was shown to be under genetic control in annual grass,Bromus mollis. Genetic polymorphism and phenotypic plasticity appear to be alternative strategies of adaptation in plant populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01939649
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  • 4
    Electronic Resource
    Electronic Resource
    Population regulation in Bromus rubens and B. mollis: Life cycle components and competition (1979)
    Springer
    Oecologia 39 (1979), S. 337-357 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A series of Bromus rubens and B. mollis populations were sampled in the coastal range and northern part of the Central Valley of California in order to study their population ecology in demographic terms. Quantitative estimates were obtained on plants collected directly in nature, and their progenies in controlled environments with randomized block design in the greenhouse. Two parameters of population growth — the intrinsic rate of increase, r, and the carrying capacity, K-were estimated by using the logistic model (r=ln R and K=equilibrium population size). It was found that B. mollis is a relatively K-type species, while B. rubens is a relatively r-type species. The effects of density on competition between individuals in pure and mixed populations of B. mollis and B. rubens were studied. In both species, increasing density induced greater mortality and a striking plastic reduction in the size and reproductive potential of the individuals. Further, B. rubens showed a relatively greater mortality and less plastic response to densities than B. mollis in both pure and mixed stands. Two different types of plasticity were considered: one in response to changing density (d-plasticity); and the other in response to changing enironmental conditions (e-plasticity). High plasticity in one of them need not imply that the other one is high too. B. rubens showed higher e-plasticity, but lower d-plasticity than B. mollis. The relationships between r, K and competitive ability were discussed. Two types of K-strategy were distinguished: one involving greater nonreproductive effort with longer life span, or lowered mortality (Type-I) and the other with density-induced adjustments in body size along with survival in higher numbers (Type-II). Different populations of these two Bromus species showed different values of r and K (Type-II) and different competitive abilities. It was found that higher r was usually accompanied by lower K (Type-II), while higher K (Type-II) was accompanied by lower competitive ability, which in turn is correlated with higher d-plasticity. In general, coexistence was predicted on the basis of estimates derived from the interspecific competition experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00345444
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  • 5
    Electronic Resource
    Electronic Resource
    The effect of rodent seed predation on four species of California annual grasses (1978)
    Springer
    Oecologia 33 (1978), S. 101-113 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of seed predation by Microtus californicus and Mus musculus on plant numbers of four species of California annual grasses was investigated for one year period on a grassland near Davis, California. In winter, mice utilized dead star thistle plants for cover when grasses in open areas were short, but moved into open areas when grass grew tall in spring. Using exclosures and plots sown with known quantities of seed, it was estimated that a mouse population (approximate density 120/acre) consumed 75% of Avena fatua seed, 44% of Hordeum leporinum seed, and 37% of Bromus diandrus seed. Mice showed a strong preference for Avena seed. Plant numbers of Avena and Hordeum were reduced by 62% and 30%, respectively. Hordeum, Lolium, and to a lesser extent, Bromus responded to a competitive release from Avena by increases in plant size and reproductive output. In addition, seed predation markedly increased seed to adult plant survivorship of Avena, Hordeum, and Bromus. Vertebrate seed predation is discussed as a potentially important factor in the yearly patterns of plant population regulation in California annual grasslands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376999
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  • 6
    Electronic Resource
    Electronic Resource
    Biosystematics and agronomic potential of some weedy and cultivated amaranths (1978)
    Springer
    Theoretical and applied genetics 52 (1978), S. 177-185 
    Details
    ISSN: 1432-2242
    Keywords: Amaranths ; Biosystematics ; Agronomic Potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Three weedy amaranths (Amarantkus hybridus, A. retroflexus and A. powellii) from nine California sites, three domesticated species (A. caudatus, A. hypochondriacus and A. cruentus) from the USDA plant inventory as well as other sources and a naturally-occurring crop-weed hybrid were studied for numerical taxonomy using morphological and allozyme variation data. The crop and weedy species groups were easily separated and the hybrid populations were found to be intermediate. Surprisingly, very little intraspecific variation was present. Crop, weed and hybrid amaranths were also compared for their yielding ability, harvest index, seed efficiency of grain production and protein, popping quality and other agronomic traits. Although field plot yields were similar among the three groups of species (700 Kg/ha seed without fertilizer treatment and water, ranging to 3000 Kg/ha with fertilizer applications of 170 Kg N/ha, and abundant water), the harvest index of the weedy group was much higher (25–40%) than the domesticated species (10–15%). The allocation of biomass to seed production is positively correlated with seed yield in the domesticated but not in the weedy types, whereas the percentages of biomass as stem material and as seeds are negatively correlated. Several weedy and crop characteristics together should provide the basis of new improved cultivars through genetic recombination and selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00282575
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  • 7
    Electronic Resource
    Electronic Resource
    Reproductive system and pattern of genetic variation in two Limnanthes species (1979)
    Springer
    Theoretical and applied genetics 54 (1979), S. 181-190 
    Details
    ISSN: 1432-2242
    Keywords: Evolution of inbreeding ; Electrophoretic variation ; Phenotypic plasticity ; Variation patterns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Several populations of two species of the genus Limnanthes, (L. alba, an outbreeder and L. floccosa, an inbreeder) were examined with respect to variability of fifteen quantitative characters, allozyme variation at 11 loci, and response to different pollination conditions and moisture stress. Nearly equal amounts of phenotypic variability were found in the two species. L. alba had higher within-family variability than L. floccosa, but this result was highly heterogeneous among characters. A study of between- and within-population variance estimates did not reject the null hypothesis that L. alba and L. floccosa are similar with regard to the partitioning and amount of variability for quantitative characters. However, allozyme variation at 11 loci in a large number of populations showed L. alba to be highly polymorphic in contrast to the virtual monomorphism within L. floccosa populations. The average number of alleles per locus in L. alba and L. floccosa was 1.97 and 1.02, respectively, and on an average, L. alba and L. floccosa populations had 63% and 3% loci with polymorphism, respectively. Three groups of allozyme allelic combinations emerged which correlated well with the taxonomic delineation of allogamous L. alba, three semi-autogamous L. floccosa forms and two autogamous L. floccosa forms. All taxa showed a significant reduction in the seed output per plant due to moisture stress. L. alba suffered a further loss of fecundity under the paucity of pollinators, L. floccosa ssp. floccosa showed no significant effect from this factor, whereas L. floccosa ssp. grandiflora exhibited a curvilinear response which peaked at ‘partial pollination’ and decreased to a lower level at ‘full pollination.’ The geographic distribution of the two species with regard to the temperature and rainfall distribution did not suggest L. floccosa to be living in drier marginal areas. Patterns of variation in flowering time showed L. alba to be less variable than L. floccosa. Overall, there seemed to be little direct support for the thesis that inbreeding species originated from outcrossing taxa in marginal environments as a direct adaptation to a shortened growing season of xeric environments and to the lack of pollinators. Alternative hypotheses suggest that autogamy in L. floccosa might have evolved as a reproductive isolating barrier acting through either cleistogamy or divergence in flowering times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00263049
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  • 8
    Electronic Resource
    Electronic Resource
    Population biology of avena. VI. The role of genetic polymorphisms in the outcome of interspecific competition (1978)
    Springer
    Genetica 48 (1978), S. 151-159 
    Details
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Three different series of population samples of two Avena species cooccurring in California were grown for an analysis of the role of genetic variation in interspecies competition: I, samples from mixed fatua-barbata sites in nature, grown in mixed stands; II, samples from pure sites and grown in pure stands, and III, the same sites as in II but grown in mixed stands. Four macroenvironments and four densities were used giving a total of sixteen entries for each genetic/competitive unit in order to measure both mean and variance of survival and reproductive rates as fitness characters. Sites used in each series included low versus high levels of genetic polymorphism within each species. In general, high polymorphism favored A. fatua in competition with monomorphic A. barbata, and high polymorphism in A. barbata allowed it to compete better with monomorphic A. fatua observation fits well into the pattern of reduced polymorphism in natural mixed stands. Mean performance of polymorphic mixed stands was not consistently higher than the monomorphic combinations or pure stands but the greater relative stability over environments seemed to favor polymorphisms in one or both of the competitors. A relatively less regular pattern of density or competitive response in series III was interpreted as evidence for the lack of coadaptedness between samples drawn from pure sites. Several limitations characteristic of such controlled studies were briefly discussed; however, the tentative conclusions from laboratory studies provided several promising clues for more critical field studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00127512
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  • 9
    Electronic Resource
    Electronic Resource
    Genetic variation in the outcrossing rates in barley (1979)
    Springer
    Genetica 50 (1979), S. 41-49 
    Details
    ISSN: 1573-6857
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00122677
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  • 10
    Electronic Resource
    Electronic Resource
    Fitness and yield components associated with genetic changes at the aleurone color loci in barley (1977)
    Springer
    Euphytica 26 (1977), S. 797-804 
    Details
    ISSN: 1573-5060
    Keywords: Hordeum vulgare ; barley ; aleurone color ; fitness ; yield ; isolines ; population dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotypic frequency data at two loci governing blue vs. white aleurone color in barley showed that composite cross (CC) populations grown at Davis varied in the changes in allelic frequencies as well as heterozygosity levels. The blue class increased steadily over 20 generations in CC V and CC XXI along with an excess of heterozygotes over expected under high selfing rates, fluctuated without a directional shift in CC XIV, and declined in CC XVI. Utilizing the xenia feature of this character, nearly 100 Bl/bl Bl2/bl2 individuals were randomly drawn from the CC XVI and CC XXI populations and used in a paired-plot study of some yield components for comparing the blue and white isogenic classes within lines in the varied genetic backgrounds of different lines. For seed number blue vs. white isogenic class differences were significant only in one out of four populations (CC XXI-F8) whereas differences among the lines were significant in CC XVI-F12, CC XXI-F3 and CC XXI-F8. Thus, specific locus effects were relatively much smaller than the genetic background component although overall the genotypic frequency changes at the aleurone color loci were found to be consistent with the relative average seed output per plant in the three genotypic classes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00021709
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