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  • 1
    ISSN: 1439-0361
    Keywords: DNA fingerprinting ; genetic differentiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Rund 53 % der Vogelarten Madagaskars sind endemisch. Viele dieser Arten sind an Waldhabitate gebunden und durch die Verinselung der madagassischen Wälder hochgradig bedroht. In dem vorliegenden Projekt wird die Auswirkung der Verinselung auf die genetische Variabilität und die genetische Differenzierung von vier endemischen Vogelarten am Beispiel des Reservats von Ambohitantely im zentralen Hochland Madagaskars untersucht. Ambohitantely beinhaltet mehr als 500 Waldfragmente von 0,64 ha bis 1250 ha. Untersucht wurden: 1. die WaldartFoudia omissa, 2.Monticola (früherPseudocossyphus)sharpei, eine Art mit starker Bevorzugung für primäre Waldlebensräume, die aber gelegentlich auch in Sekundärvegetation auftritt, sowie 3.Terpsiphone mutata und 4.Foudia madagascariensis, beides Arten, die sowohl in Wäldern als auch in offenen Landschaften vorkommen. Die unterschiedliche Abhängigkeit dieser Arten von Waldhabitaten und der damit verbundenen Möglichkeit, offene Landschaften zwischen den Waldfragmenten zu überbrücken, führte zur Frage, ob die Verinselung die genetische Vielfalt der untersuchten Populationen beeinflußt. Für die genetischen Analysen wurden Blutproben von Tieren aus drei Gebieten mit 1250 ha, 136 ha und 28 ha gesammelt. Die Proben wurden mit Multilocus-Fingerprints genetisch charakterisiert. Zum Untersuchungszeitpunkt konnte kein Einfluß der Fragmentierung auf die genetische Populationsstruktur der vier untersuchten Arten nachgewiesen werden.
    Notes: Summary This study focuses on some genetic consequences of habitat fragmentation in populations of four endemic bird species (Monticola sharpei, Terpsiphone mutata, Foudia omissa, andFoudia madagascariensis) living in the understory of forests in the Réserve Spéciale d'Ambohitantely on the Central High Plateau of Madagascar. The four species differ in their dependency on forest habitats, which may be related to their migration abilities between isolated forest fragments. Genetic variation was analysed on the basis of multi-locus fingerprints in order to study the influence of migration and habitat size on the genetic variability of local populations. There was no evidence that forest fragmentation affects any of the four species with respect to genetic variability.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-6857
    Keywords: infinite allele model ; stepwise mutation model ; microsatellites ; genetic distance ; non-equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different genetic identity or distance measures are compared that consider allelic variation within and between populations. Particularily we analyse those suggested by Nei ( IS, DS), Rogers (DR), Reynolds, Weir and Cockerham (Dθ), Nei, Tajima and Tateno (DA), Tomiuk and Loeschcke (ITL, DTL) and Goldstein et al. ((δμ)2). The simulations focus on the influence of non-equilibrium conditions on the stability of these measures. The degree of homozygosity of an ancestral population before it splits into two sister populations is most important for the stability of the different estimates of genetic identity. If populations are not close to their equilibrium homozygosity, a considerable bias can occur and, thereby, provide very misleading estimates of the time span since divergence. The ITL-measure based on estimates of ancestral alleles is more robust than other measures of genetic identity, especially for large population sizes and high mutation rates. For the infinite allele model, the analysis shows that more precise estimates of the frequency of ancestral alleles can greatly improve the reliability of the estimate of genetic identity in the case of ITL. For the stepwise mutation model, the TL-measure combines the attributes of the DA- and (δμ)2-measures. The TL-measure is efficient for the construction of the correct tree topology of related populations as well as for the estimation of the branch length when protein or microsatellite data are analysed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Primates 30 (1989), S. 95-102 
    ISSN: 0032-8332
    Keywords: Macaques ; Hemoglobin ; Duplication hypothesis ; Evolution ; Isoelectric focusing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Blood samples were collected fromMacaca fascicularis andMacaca mulatta living in indoor breeding groups and investigated electrophoretically. Hemoglobin polymorphism was observed in both species. Isoelectric focusing was performed on urea denaturated samples to test the hypothesis of a site duplication at theα-chain locus inM. fascicularis (Barnicot et al., 1970). The results of our investigations do not support the above mentioned hypothesis. Only one locus coding theα-chain was detected, and this is under the control of two alleles. Evolutionary events at the molecular level are discussed, as well asWheatley's hypothesis (1980) that malaria was an important force behind divergence in both species. InM. fascicularis hemoglobin variants might be similarily connected with malaria resistance as in man. We suggest that this was not an important process behind speciation in macaques.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Primates 32 (1991), S. 119-123 
    ISSN: 0032-8332
    Keywords: Macaca mulatta ; Amylase ; Isoelectric focusing ; Unstable mobility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using isoelectric focusing with one ampholytic solution, double- and single-banded amylase phenotypes were found in a sample of rhesus monkeys,Macaca mulatta. When applying different ampholytic solutions, these variants were shown to change their position relative to each other. Single-banded phenotypes showed either a position corresponding to one of the bands of the double-banded phenotype or to an intermediate one. Family studies, however, suggested that the differences between the observed patterns were not caused by genetic differences. This discloses a problem with respect to the interpretation of electrophoretic data, i.e. bands with different positions produced by isoelectric focusing may not necessarily represent genetic differences.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0032-8332
    Keywords: Cercopithecoids ; Ceboids ; Hominoids ; Phylogeny ; Rate of molecular evolution ; Electrophoretic variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genetic electrophoretic variation at up to 43 protein loci was studied in four hominoid, three cercopithecoid, and three ceboid species. Phylogenetic reconstructions based on genetic distances show that the two chimpanzee species are closest to humans, while the gorilla diverged earlier than the split between humans and the chimpanzee. Within the cercopithecoids the green monkey apparently diverged earlier than the macaques, and within the ceboids, the owl monkey is only distantly related to the capuchin and squirrel monkeys. The hypothesis that rates of evolution at the level of protein electrophoretic variation are equal both among the groups, as well as within each group, could not be rejected.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Primates 30 (1989), S. 89-94 
    ISSN: 0032-8332
    Keywords: Macaques ; Amylase ; Polymorphism ; Duplication ; Population genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plasma amylase obtained from twoMacaca species,M. fascicularis andM. mulatta, was investigated by isoelectric focusing. In contrast to recent works, extensive polymorphism at the amylase loci was detected in both species. It is assumed that unequal crossing over has generated two pancreatic loci. The phylogenetic relationship between the species is recalculated. The average identity value is calculated from data obtained byNozawa et al. (1977),I=0.93. If the polymorphic amylase loci are included the genetic identity decreases by at least 2% (I=0.91), meaning that the divergence time between both species would increase by about 30%. Furthermore, the mean degree of heterozygosity also increases by about 30% to 0.10 and the effective population size is underestimated by at least the same order of magnitude.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of primatology 21 (2000), S. 853-864 
    ISSN: 1573-8604
    Keywords: allozyme variability ; genetic diversity ; sportive lemurs ; speciation ; RAPD polymorphism ; chromosome analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied the genetic differentiation of five populations of red-tailed sportive lemur Lepilemur ruficaudatus by means of allozyme variability and RAPD polymorphisms in order to test whether the Tsiribihina River separates the distribution areas of Lepilemur ruficaudatus and and L. edwardsi. Genetic data as well as the karyotype of a male individual clearly indicate that the Andramasay Forest in the north of Tsiribihina River is inhabited by Lepilemur ruficaudatus and not by L. edwardsi. We propose that the distribution of the two species are separated by the Manambolo River. However, the northernmost population of Lepilemur ruficaudatus inhabiting the Andramasay Forest is gentically differentiated from those that inhabit the dry forest in the south of Tsiribihina River.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 26 (1996), S. 89-95 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Bis November 1993 fanden weltweit 846 Freisetzungsversuche mit gentechnisch veränderten Pflanzen an 1106 Standorten statt [8]. Seither nimmt die Zahl der Versuche im Freiland kontinuierlich zu. Der Begriff „Freisetzung“ bezeichnet die Aufzucht und den Anbau von transgenen Organismen außerhalb von Labors und Gewächshäusern. Die bisherigen Versuche dienen zunächst vor allem dazu, dem Züchter Informationen über die Stabilität der „neu konstruierten“ Genome und über die Leistungsfähigkeit der transgenen Organismen unter Freilandbedingungen zu liefern. Sie sollen aber auch zusätzliche Erkenntnisse über die Biologie der jeweiligen Pflanzenarten bringen. Intensiv wird dabei der Pollenflug, die Bastardierungswahrscheinlichkeit und das Konkurrenzverhalten der Pflanzen untersucht. Doch nur wenige Überlegungen beziehen sich bisher auf das „Schicksal“ von modifizierten Genen nach ihrer Einwanderung in fremde Populationen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 24 (1994), S. 85-90 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Im April 1993 hat das Bundesgesundheitsamt zum ersten Mal Freilandversuche mit transgenen Zuckerrüben und Kartoffeln genehmigt. Nach den Feldversuchen mit Petunien am Max-Planck-Institut für Züchtungsforschung in Köln ist die Diskussion um die Freisetzung von Pflanzen, die mit Hilfe von molekulargenetischen Methoden verändert wurden, mit dieser Entscheidung wieder erheblich intensiver geworden. Unter anderem wird von Kritikern der Freisetzungsexperimente befürchtet, daß sich manipulierte genetische Substanz der Kontrolle des Menschen entzieht und die Umwelt nachhaltig verändert.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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