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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    International journal of primatology 21 (2000), S. 421-444 
    ISSN: 1573-8604
    Keywords: phylogenetics ; biogeography ; speciation ; Ateles ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We used the results of phylogenetic analyses of relationships among spider monkeys (Ateles) based on mitochondrial and nuclear DNA to investigate questions of their evolutionary origins and speciation mechanisms. We employed the concept of a local molecular clock to date nodes of interest (corresponding to hypothesized species and subspecies) in the various phylograms for comparison to hypothesized biogeographical events that might have affected speciation. We considered various mechanisms—Pleistocene refuge formation, riverine barriers, geological fluctuations, and ecological changes associated with these mechanisms—for their contribution to speciation in Ateles. Most speciation among the various species of Ateles occurred during the middle to late Pliocene, suggesting that Pleistocene refuge formation was not a key speciation mechanism. However, it is likely that the genetic structure of populations of Ateles was modified to some extent by refuge formation. Additionally, riverine barriers do not seem to interrupt gene flow significantly among Ateles. No river formed a barrier among species of Ateles, with the exception of the lower Amazon and possibly some of the black-water rivers draining the Guianan highlands. Large-scale geographic changes associated with the continued rise of the eastern and western cordilleras of the northern Andes and associated changes in habitat were the most important causes of speciation in Ateles. The various factors that modify genetic structure in Ateles are important to consider in order to protect endangered primate genera in the Neotropics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of primatology 21 (2000), S. 381-420 
    ISSN: 1573-8604
    Keywords: phylogenetics ; taxonomy ; systematic ; Ateles ; Cebidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Our goal was to determine phylogenetic relationships among geographically and taxonomically distinct haplotypes of spider monkeys (Ateles) based on DNA sequence variation for the mitochondrial DNA control region and cytochrome c oxidase subunit II gene. We obtained samples from most previously recognized subspecies of Ateles, ranging from Central America throughout the Amazon Basin, to determine phylogenetic relationships among racially recognized groups. Comparison of DNA sequences using both parsimony analysis and genetic distance analysis produced phylogenetic relationships that were very similar for each genetic region. We analyzed the phylograms produced, along with associated bootstrap support, confidence probabilities, and genetic distances between taxonomic groups, to identify four monophyletic species of Ateles: Ateles paniscus, composed of haplotypes from the northeastern Amazon Basin; A. belzebuth in the southern Amazon Basin; A. hybridus, located primarily along the Magdalena River valley of Colombia; and A. geoffroyi, which includes two former species: A. geoffroyi and A. fusciceps. This arrangement is contradictory to long-held taxonomies of Ateles based on pelage variation and is similar to a recent analysis based on craniodental variation. Results of this investigation suggest patterns of gene flow, evolutionary relationships, and speciation patterns that are more plausible than previous pelage-based taxonomies, which required seemingly impossible patterns of gene flow. Conservation efforts aimed at protecting Ateles, one of the Neotropics most endangered genera, will also benefit from the findings presented in this paper.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 38 (1994), S. 251-255 
    ISSN: 1040-452X
    Keywords: Bovine ; In vitro fertilization ; Buffalo Rat ; Liver cells ; Co-cultures ; Embryo culture ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Development of 8-cell bovine embryos derived from in vitro matured/in vitro fertilized (IVM/IVF) oocytes was evaluated in two simple, serum-free media (CZB and SOM) with buffalo rat liver cells co-culture (BRLC) or after conditioning compared to a commonly used, serum-supplemented complex medium TCM-199. In a 3 x 4 factorial design, 578 eight-cell embryos were randomly assigned to 12 treatment groups. The factors were: first, type of culture medium (M199/FBS, CZBg and SOM), and second, the use of BRLC (as co-culture or to condition media for 24 hr and 48 hr) and unconditioned media. Development to morula was not affected by the type of medium, but co-culture and 48 hr conditioning within media type resulted in better development when compared to the 24-hr conditioned or unconditioned groups. Blastocyst development in SOM (38.9%) was different (P 〈 0.05) than in CZBg (46.6%) and M199/FBS (48.7%) and was lowest in the unconditioned group (27.8%) followed by 24 hr conditioned (33.3%), 48 hr (56.3%), and co-culture (59.6%). No blastocyst expansion was observed with unconditioned media and 24 hr conditioned SOM. Significant differences (P 〈 0.05) were found among all treatment groups except the co-culture and 48-hr conditioned groups. Hatching occurred only with co-culture and 48-hr conditioned groups of M199/FBS and CZBg media. These data show that CZB with glucose conditioned by BRLC monolayers for 48 hr can support the development of IVM/IVF produced bovine embryos to blastocyst compared to culture in TCM-199 with serum. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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