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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 28 (1989), S. 212-219 
    ISSN: 1432-1432
    Keywords: Primate evolution ; Tandem repeats ; Restriction fragment length polymorphisms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The clone designated hMF #1 represents a clustered DNA family, located on chromosome 1, consisting of tandem arrays displaying a monomeric length of 40 bp and a repetition frequency of approximately 7×103 copies per haploid genome. The sequence hMF #1 reveals multiple restriction fragment length polymorphisms (RFLPs) when human genomic DNA is digested with a variety of 4–6-bp recognition sequence restriction enzymes (i.e., Taq I, Eco RI, Pst I, etc.). When hamster and mouse genomic DNA was digested and analyzed, no cross-species homology could be observed. Further investigation revealed considerable hybridization in the higher primates (chimpanzee, gorilla, and orangutan) as well as some monkey species. The evolutionary relationship of this repetitive DNA sequence, found in humans, to that of other primates was explored using two hybridization methods: DNA dot blot to establish copy number and Southern DNA analysis to examine the complexity of the RFLPs. Homology to the hMF #1 sequence was found throughout the suborder Anthropoidea in 14 ape and New and Old World monkey species. However the sequence was absent in one species of the suborder Prosimii. Several discrepancies between “established” evolutionary relationships and those predicted by hMF #1 exist, which suggests that repetitive elements of this type are not reliable indicators of phylogenetic branching patterns. The phenomenon of marked diversity between sequence homologies and copy numbers of dispersed repetitive DNA of closely related species has been observed inDrosophila mice,Galago, and higher primates. We report here a similar phenomenon for a clustered repeat that may have originated at an early stage of primate evolution.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-5117
    Keywords: zooplankton ; grass carp ; lakes ; Hydrilla ; vegetation ; Ctenopharyngodon idella
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton populations were monitored monthly for a three year period in four Florida lakes. Each lake received an aquatic vegetation control program using grass carp (Ctenopharyngodon idella Val.) and herbicide, either alone or in combination. All aquatic vegetation was eliminated in the three lakes with grass carp; it was severely reduced and exhibited qualitative shifts in the lake treated with herbicide alone. Total number of recorded zooplankton species was reduced in each subsequent year as vegetation was eliminated, but mean density l−1 increased greatly. The overall trend in all lakes was toward increasing numbers of small filter-feeding herbivores, with a shift from copepod and copepod-cladoceran dominated to rotifer and small cladoceran dominated systems. It is suggested that these changes reflect primary plankton response to fluctuations in habitat, food base, and planktivore pressure resulting from gradual macrophyte alteration. Changes observed indicate apparent increases in eutrophy.
    Type of Medium: Electronic Resource
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