Discuss the Nature of Communities Under the Following Headings: a)Organismic Versus Individualistic Distribution B) Stochastic Versus Equilibrium Schools

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INTRODUCTION

At the beginning of the 20th century there was much debate about the nature of communities. The driving question was whether the community was a self-organized system of co-occurring species or simply a haphazard collection of populations with minimal functional integration (Verhoef, 2010). Krebs (1972) described a community as an assemblage of populations of living organisms in a prescribed area or habitat. However, according to Wright (1984), the working definitions of community can be divided into two basic categories: organismic or individualistic. The organismic approach contends that communities have discrete boundaries and that the sum of the species in an area behaves as organism with both structure and function. In contrast, the individualistic concept regards communities as collections of species requiring similar environmental conditions (Wright, 1984).

A)Organismic versus individualistic distribution

Solomon (2005) stated that the nature of communities is discussed based on two traditional views which are Clements’s organismic model and Gleason’s individualistic model. The organismic model views community as a superorganism that goes through certain stages of development (succession) toward adulthood (climax). In this view, biological interactions are primarily responsible for species composition, and organisms are highly interdependent. In contrast, according to individualistic model, abiotic environmental factors are the primary determinants of species composition in a community, and organisms are largely interdependent on each other.

According to organismic concept it is expected that an entire community or biome will respond as a unit and to relocate as climatic conditions change. Pleistocene biome migration in response to multiple glaciations, the accordian effect, is a classic example of this model (Wright, 1984). In contrast, Wright (1984) further explained that the individualist expects each species experiencing...
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