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  • 1
    Electronic Resource
    Electronic Resource
    DNA hybridization, cladistics, and the phylogeny of phalangerid marsupials (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 298-311 
    Details
    ISSN: 1432-1432
    Keywords: DNA/DNA hybridization ; Cladistics ; Phylogeny ; Phalangeridae ; Marsupials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Single-copy DNA/DNA hybridization experiments and numerical cladistic analyses of anatomical characters were used to investigate relationships among nine phalangerid (Marsupialia) species from four different genera. Both rate-dependent and rate-independent analyses of molecular data indicate that species ofTrichosurus form one clade and thatStrigocuscus, Phalanger, andSpilocuscus form a second. Within the latter group,Spilocuscus is excluded from aStrigocuscus-Phalanger calde, which, in turn, is not fully resolved on a jackknife strict consensus tree. Minimum-length Dollo, Wagner, and Camin-Sokal parsimony trees based on 35 anatomical characters, in contrast, suggest placement ofStrigocuscus withTrichosurus rather than withSpilocuscus andPhalanger. However, there are two derived characters that support the alternative arrange ofStrigocuscus withSpilocuscus andPhalanger and one character that further unitesStrigocuscus andPhalanger. Thus, DNA hybridization results are not inconsistent with the distribution of derived character states among anatomical characters, only with minimum-length trees based on character data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02100000
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  • 2
    Electronic Resource
    Electronic Resource
    Molecular clocks and the incompleteness of the fossil record (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 531-538 
    Details
    ISSN: 1432-1432
    Keywords: Molecular clocks ; Marsupials ; Fossils ; Relative-rate test
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular clocks can be evaluated by comparing absolute rates of evolution and by performing relative-rate tests. Typically, calculations of absolute rates are based on earliest observed occurrences in the fossil record. Relative-rate tests, on the other hand, merely require an unambiguous outgroup. A major disadvantage of relative-rate tests is their insensitivity to concomitant and equal rate changes in all lineages. Apparent differences in absolute rates, in turn, may be artifacts that are attributable to an incomplete fossil record. Recently developed methods in quantitative biostratigraphy recognize the incompleteness of the fossil record and allow us to place confidence intervals on the endpoints of taxon ranges. These methods are applicable to taxa whose fossil records are of markedly different quality. When we extend these methods and integrate molecular and paleontologic data, we can test the null hypothesis that seemingly disparate rates of molecular evolution are in fact equal under the simplifying assumption that fossils are randomly and independently distributed over their temporal ranges and that fossils can be accurately placed in a phylogenetic context. We can also estimate the range of ticking rates, if any, that are compatible with known fossil data. Ultimately, more accurate rate estimates for widely divergent taxa should allow for more meaningful comparisons of evolutionary rates. DNA hybridization data for monotremes and marsupials suggest a 17-fold difference for 14 different rate calculations with a mean value of approximately 1% divergence per million years. Variation among marsupials is sevenfold. However, when we apply appropriate statistical tests and make additional allowances for fossils of uncertain taxonomic assignment, etc., all 14 rates are compatible with a molecular clock ticking at approximately 0.4% divergence per million years. In addition, this analysis brings relative- and absolute-rate tests into accord.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175810
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  • 3
    Electronic Resource
    Electronic Resource
    DNA/DNA hybridization studies of the carnivorous marsupials. I: The intergeneric relationships of bandicoots (Marsupialia: Perameloidea) (1990)
    Springer
    Journal of molecular evolution 30 (1990), S. 434-448 
    Details
    ISSN: 1432-1432
    Keywords: DNA/DNA hybridization ; Phylogeny ; Perameloidea ; Marsupials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A complete suite of comparisons among six bandicoot species and one outgroup marsupial was generated using the hydroxyapatite chromatography method of DNA/DNA hybridization; heterologous comparisons were also made with three other bandicoot taxa. Matrices of ΔTm's, Δmodes, and ΔT50Hs were generated and corrected for nonreciprocity, homoplasy, and, in the case of ΔTm's, normalized percent hybridization; these matrices were analyzed using the FITCH algorithm in Felsenstein's PHYLIP (version 3.1). Uncorrected and nonreciprocity-corrected matrices were also jackknifed and analyzed with FITCH to test for consistency. Finally, sample scores for ΔTm, Δmode, and ΔT50H matrices were bootstrapped and then subjected to phylogenetic analysis. These manipulations were carried out, in part, to address criticisms of the statistics used to summarize DNA/DNA hybridization (especially T50H) and the method itself. However, with the exception of an unresolved trichotomy among the twoEchymipera species andPeroryctes longicauda, all trees showed the same branchpoints. Except in the case of the tree generated from reciprocal-corrected ΔTm data, nodes were stable under jackknifing; and, again excepting the above-mentioned trichotomy, all nodes were supported by 95% or more of the bootstrapped trees. These results suggest that, despite arguments to the contrary, all three summary statistics can be valid for DNA/DNA hybridization data. Of taxonomic interest is the placement ofEchymipera spp. andPeroryctes longicauda together and separate from the more distantPeroryctes raffrayanus; the genusPeroryctes is thus at least paraphyletic. The trees further groupedEchymipera-plus-Peroryctes as the sister group ofIsoodon-plus-Perameles. Limited hybridizations withMacrotis lagotis suggest that its current position as representative of an entirely distinct family of perameloids is correct.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02101115
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  • 4
    Electronic Resource
    Electronic Resource
    Calculation of sequence divergence from the thermal stability of DNA heteroduplexes (1992)
    Springer
    Journal of molecular evolution 34 (1992), S. 379-382 
    Details
    ISSN: 1432-1432
    Keywords: DNA/DNA hybridization ; ΔTm ; Hydroxyapatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Measurements are reported of the thermal stability of DNA heteroduplexes between clones of the eta-globin pseudogene from a variety of primates. The known sequences of this 7.1-kb region differ from each over a range from 1.6% for human versus chimp to nearly 12% for human versus spider monkey. Thermal stability was determined by standard hydroxyapatite thermal elution, and the results show a precisely linear decrease in thermal stability with divergence. The slope of the regression line is 1.18% sequence divergence per degree centigrade reduction in thermal stability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162994
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  • 5
    Electronic Resource
    Electronic Resource
    Secondary Structure and Patterns of Evolution Among Mammalian Mitochondrial 12S rRNA Molecules (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 357-373 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Mitochondrial 12S rRNA — Secondary structure — Evolutionary rates — Nucleotide substitution patterns — Mammalia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Forty-nine complete 12S ribosomal RNA (rRNA) gene sequences from a diverse assortment of mammals (one monotreme, 11 marsupials, 37 placentals), including 11 new sequences, were employed to establish a ``core'' secondary structure model for mammalian 12S rRNA. Base-pairing interactions were assessed according to the criteria of potential base-pairing as well as evidence for base-pairing in the form of compensatory mutations. In cases where compensatory evidence was not available among mammalian sequences, we evaluated evidence among other vertebrate 12S rRNAs. Our results suggest a core model for secondary structure in mammalian 12S rRNAs with deletions as well as additions to the Gutell (1994: Nucleic Acids Res. 22) models for Bos and Homo. In all, we recognize 40 stems, 34 of which are supported by at least some compensatory evidence within Mammalia. We also investigated the occurrence and conservation in mammalian 12S rRNAs of nucleotide positions that are known to participate in the decoding site in E. coli. Twenty-four nucleotide positions known to participate in the decoding site in E. coli also occur among mammalian 12S rRNAs and 17 are invariant for the same base as in E. coli. Patterns of nucleotide substitution were assessed based on our secondary structure model. Transitions in loops become saturated by approximately 10–20 million years. Transitions in stems, in turn, show partial saturation at 20 million years but divergence continues to increase beyond 100 million years. Transversions accumulate linearly beyond 100 million years in both stems and loops although the rate of accumulation of transversions is three- to fourfold higher in loops. Presumably, this difference results from constraints to maintain pairing in stems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006095
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  • 6
    Electronic Resource
    Electronic Resource
    Secondary structure and patterns of evolution among mammalian mitochondrial 12S rRNA molecules (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 357-373 
    Details
    ISSN: 1432-1432
    Keywords: Mitochondrial 12S rRNA ; Secondary structure ; Evolutionary rates ; Nucleotide substitution patterns ; Mammalia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty-nine complete 12S ribosomal RNA (rRNA) gene sequences from a diverse assortment of mammals (one monotreme, 11 marsupials, 37 placentals), including 11 new sequences, were employed to establish a “core” secondary structure model for mammalian 12S rRNA. Base-pairing interactions were assessed according to the criteria of potential base-pairing as well as evidence for base-pairing in the form of compensatory mutations. In cases where compensatory evidence was not available among mammalian sequences, we evaluated evidence among other vertebrate 12S rRNAs. Our results suggest a core model for secondary structure in mammalian 12S rRNAs with deletions as well as additions to the Gutell (1994:Nucleic Acids Res. 22) models forBos andHomo. In all, we recognize 40 stems, 34 of which are supported by at least some compensatory evidence within Mammalia. We also investigated the occurrence and conservation in mammalian 12S rRNAs of nucleotide positions that are known to participate in the decoding site inE. coli. Twenty-four nucleotide positions known to participate in the decoding site inE. coli also occur among mammalian 12S rRNAs and 17 are invariant for the same base as inE. coli. Patterns of nucleotide substitution were assessed based on our secondary structure model. Transitions in loops become saturated by approximately 10–20 million years. Transitions in stems, in turn, show partial saturation at 20 million years but divergence continues to increase beyond 100 million years. Transversions accumulate lin early beyond 100 million years in both stems and loops although the rate of accumulation of transversions is three- to fourfold higher in loops. Presumably, this difference results from constraints to maintain pairing in stems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02339010
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  • 7
    Electronic Resource
    Electronic Resource
    Mesozoic origin for West Indian insectivores (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 429 (2004), S. 649-651 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The highly endangered solenodons, endemic to Cuba (Solenodon cubanus) and Hispaniola (S. paradoxus), comprise the only two surviving species of West Indian insectivores. Combined gene sequences (13.9 kilobases) from S. paradoxus established that solenodons diverged from other eulipotyphlan ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature02597
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  • 8
    Electronic Resource
    Electronic Resource
    Parallel adaptive radiations in two major clades of placental mammals (2001)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 409 (2001), S. 610-614 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Higher level relationships among placental mammals, as well as the historical biogeography and morphological diversification of this group, remain unclear. Here we analyse independent molecular data sets, having aligned lengths of DNA of 5,708 and 2,947 base pairs, respectively, for all orders ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35054544
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  • 9
    Electronic Resource
    Electronic Resource
    Molecular evidence regarding the origin of echolocation and flight in bats (2000)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 403 (2000), S. 188-192 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Bats (order Chiroptera) are one of the few orders of mammals that echolocate and the only group with the capacity for powered flight. The order is subdivided into Microchiroptera and Megachiroptera, with an array of characteristics defining each group, including complex laryngeal echolocation ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/35003188
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular Clocks and the Timing of the Placental and Marsupial Radiations in Relation to the Cretaceous–Tertiary Boundary (1997)
    Springer
    Journal of mammalian evolution 4 (1997), S. 285-302 
    Details
    ISSN: 1573-7055
    Keywords: Eutheria ; Metatheria ; 12S rRNA ; molecular clock
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Paleostratigraphic estimates of divergence time for nine independent cladogenic events within Mammalia, ranging from 14 to 130 million years, were regressed against Tamura–Nei-corrected 12S rRNA transversions. Relative rate-adjusted distances were also regressed against paleostratigraphic divergence times. The resulting equations were used to estimate interordinal divergence times within Eutheria and Metatheria for a data set that includes representatives of all orders in each infraclass. Without the adjustment for rate variation, divergence times range from 34 to 156 million years for placental orders, versus 32 to 86 million years for marsupial orders. With rate adjustments, the range of divergence estimates decreases to 53 to 133 million years for placentals versus 40 to 79 million years for marsupials. The effect of rate adjustments is most noticeable for carnivores and perissodactyls, where rates are slow, and proboscideans, where rates are fast. In agreement with studies based on nuclear genes, both unadjusted and rate-adjusted estimates of sequence divergence indicate that the majority of placental orders originated before the terminal Cretaceous extinction. Exceptions include the perissodactyl–carnivore split and cladogenesis among paenungulate orders. Most marsupial orders, in turn, may have originated in the early Tertiary although didelphimorphs, at least, appear to have split from other lineages in the late Cretaceous. Marsupial divergence times based on 12S rRNA data are in good agreement with estimates based on single-copy DNA hybridization and disagree with the suggestion of Hershkovitz (1992) that Dromiciops separated from other marsupials in the Jurassic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1027378615412
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