ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Allozyme variation  (1)
  • Analytical Chemistry and Spectroscopy  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 66 (1983), S. 257-269 
    ISSN: 1432-2242
    Keywords: Allozyme variation ; Genetic distance ; Speciation ; Systematics ; Population genetic hypotheses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary An electrophoretic survey of genetic variation in 50 populations representing all ten taxa of section Inflexae of the plant genus Limnanthes is reported here with three objectives: 1) to describe genetic differentiation for testing certain phylogenetic hypotheses on the origin of species and infraspecific relationships, 2) to evaluate the concordance of electrophoretic, morphological and hybridization data within the section, and 3) to discuss models of speciation using Limnanthes as an example. Species, subspecies, and populations, designated on the basis of morphology and distribution, gave decreasing values of genetic distances that were apparently maintained across a wide ecological and geographical range. Using electrophoretic, morphological and hybrid fertility data, we concluded that L. montana, intermediate in range between the two disjunct varieties of L. gracilis, is not likely to be a relictual set of populations from what once was a continuously distributed taxon as hypothesized by earlier workers. Neither L.g. gracilis nor L.g. parishii appear to have been founded by long distance dispersal from one to the other. However, a very close genetic relationship was detected between L. gracilis and L. alba. This genetic pattern suggested that the two disjunct L. gracilis varieties were probably connected by a L. alba-like taxon and perhaps originated from that taxon. Evidence based on allozyme variation did not support the thesis that the inbreeder L. floccosa is a recent derivative from the outbreeder L. alba. Among the remaining five taxa (i.e. two varieties of L. gracilis, two varieties of L. alba, and L. montana), genetic distance and interspecific hybridization data are highly concordant, (r = -0.92, P 〈 0.001). The agreement of these two approaches with species relationships based on morphological similarity was less certain. Limnanthes species appear to exhibit greater interpopulation differentiation than many plant groups, perhaps a reflection of their distinctive island-like distribution pattern. On the other hand, an unusually high crossability is found in Limnanthes. Speciation in Limnanthes appears largely to follow a model of adaptive geographical divergence but certain other modes cannot yet be ruled out.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    X-Ray Spectrometry 8 (1979), S. 11-13 
    ISSN: 0049-8246
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: An X-ray fluorescence method for the measurement of film and coating thickness has been described for use in situations where standard foils of the same material are not available for comparison. The method is based on the measurement of combined mass absorption coefficient of the coating element at the excitation and at the fluorescent energies using thin samples of a compound in which the coating element is present and then calculating the coating thickness using the fluorescence equation. The paper describes the theoretical approach and presents the result of the measurement of certain film and coating thicknesses which support the theoretical considerations.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...