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Development and tests of two null theories of ecological communities: A fractal theory and a dispersal-assembly theory.

Annette Marie. Ostling University of California, Berkeley. 2004

Dissertation Abstracts International 66-07B.

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  • 題名:
    Development and tests of two null theories of ecological communities: A fractal theory and a dispersal-assembly theory.
  • 著者: Annette Marie. Ostling
  • University of California, Berkeley.
  • 主題: Biology, Ecology
  • 所屬期刊: Dissertation Abstracts International 66-07B.
  • 描述: Explaining and predicting the phenomena of ecological communities is vital to conserving biodiversity and to understanding global ecosystem processes that the human race relies on. However, ecological communities are complex systems and hence difficult to understand. In this dissertation, I demonstrate that "null theories", meaning theories based on purposely simple descriptions of a system, provide a useful starting point for gaining an understanding of ecological communities.
    In particular, I develop and test two null theories of community-level properties and their dependence on scale. The first, "fractal theory", assumes a fractal property in the spatial distribution of species equivalent to the existence of a power-law relationship species-area relationship. It is a "null theory" because this power-law does not hold in all ecosystems, and because it uses additional simplifying assumptions to predict other scaling relationships. The second theory, "dispersal-assembly theory", takes a simplified view of the dynamic processes shaping communities. It assumes that individuals of different species are equal in fitness and hence that communities are assembled primarily by stochastic events and dispersal limitation.
    I show that these two null theories enable one to: (1) uncover fundamental principles of how the factors included in each theory shape community properties, (2) create a framework into which more complex elements can be introduced to assess their potential role, and (3) derive and test quantitative predictions to glean when more complex factors matter in practice. Specifically, by studying fractal theory my colleagues and I find that the scaling behaviors of different community-level properties, such as species richness and the number of feeding links, are intimately connected through the spatial distribution of species. We also demonstrate that species differences in spatial distribution, which are ignored in the simplest version of fractal theory, have the potential to play an important role, and in fact are important in practice in a serpentine annual grassland. By studying dispersal-assembly theory, I find that dispersal alone can produce large-scale spatial synchrony if it has a fat-tailed decay with distance, and that the particular tradeoffs in species traits that can produce fitness equalization have a potentially important role in determining community structure.
  • 出版者: Thesis (Ph.D.)--University of California, Berkeley, 2004.
  • 建立日期: 2004
  • 格式: 185 p..
  • 語言: 英文
  • 識別號: ISBN054225266X
  • 資源來源: NUTN ALEPH
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