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  • 1
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Ecology, Evolution, and Systematics 30 (1999), S. 133-165 
    ISSN: 0066-4162
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: Abstract Declines and losses of amphibian populations are a global problem with complex local causes. These may include ultraviolet radiation, predation, habitat modification, environmental acidity and toxicants, diseases, changes in climate or weather patterns, and interactions among these factors. Understanding the extent of the problem and its nature requires an understanding of how local factors affect the dynamics of local populations. Hypotheses about population behavior must be tested against appropriate null hypotheses. We generated null hypotheses for the behavior of amphibian populations using a model, and we used them to test hypotheses about the behavior of 85 time series taken from the literature. Our results suggest that most amphibian populations should decrease more often than they increase, due to highly variable recruitment and less variable adult mortality. During the period covered by our data (1951-1997), more amphibian populations decreased than our model predicted. However, there was no indication that the proportion of populations decreasing changed over time. In addition, our review of the literature suggests that many if not most amphibians exist in metapopulations. Understanding the dynamics of amphibian populations will require an integration of studies on and within local populations and at the metapopulation level.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Melbourne, Australia : Blackwell Science Pty
    Austral ecology 30 (2005), S. 0 
    ISSN: 1442-9993
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract  Antipredator mechanisms employed by animals are obviously beneficial if they increase survival, but their use may be costly and decrease fitness. Fitness costs of antipredator mechanisms may, in turn, be defrayed by behavioural compensation. We used lizards as a model to measure behavioural fitness costs of the antipredator mechanism, autotomy, as they commonly lose their tails when attacked by predators. In addition, we examined whether male skinks, Carlia jarnoldae (Scincidae), behaviourally compensate for tail loss by comparing the behaviour of tailed and tailless males in experimental enclosures, either alone, with a conspecific male or female, or with a predator. Tailless males experience several costs of autotomy including reduced energy stores, and loss of autotomy as a defence. We identified an additional cost of tail loss: reduced mating success. However, this species did not behaviourally compensate these costs. Instead, characteristics of the ecology of C. jarnoldae may minimize the costs of autotomy. This species experiences an extended breeding season, which means that they experience reduced mating success for only 20% of this breeding season. Additionally, the presence of inguinal fat stores which supply energy in addition to stores in the tail reduce energetic costs.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Oecologia 68 (1986), S. 199-204 
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four sibships of Hyla chrysoscelis larvae were used to examine the effects of parentage on mass at day 23 of growth and on vulnerability to predation. The H. chrysoscelis larvae were raised alone, in competition with Rana clamitans larvae, and in competition with siblings. Vulnerability to predation by adult Notophthalmus viridescens dorsalis was evaluated for Hyla that had been raised in competition with siblings. Sibships differed in body mass and vulnerability to predation. Competition with Rana or with siblings resulted in a major reduction in body mass. There were no interactions between the effects of parentage and level of competition on body mass. Vulnerability to predation by newts appeared to be determined partially by body mass and partially by parental influences on factors other than body mass. If the differences observed between factors determining body mass and vulnerability to predation reflect negative genetic correlations among these determinants, tradeoffs between selection for increased competitive ability and reduced vulnerability to predators may partially account for the existence of genetic variation for growth rate in larval Hyla.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 412 (2001), S. 499-500 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The decline and disappearance of relatively undisturbed populations of amphibians in several high-altitude regions since the 1970s suggests that they may have suffered a global decline, perhaps with a common cause or causes. Houlahan et al. examined means of trends for 936 amphibian populations ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 447.2007, 7144, E3-, (2 S.) 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Arising from: J. A. Pounds et al. Nature 439, 161–167 (2006); Pounds et al. reply Is global warming contributing to amphibian declines and extinctions by promoting outbreaks of the chytrid fungus Batrachochytrium ...
    Type of Medium: Electronic Resource
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