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Tradeoffs are a fundamental aspect of biodiversity as they prevent a few species from monopolizing the planet. Well-known ecological concepts, such as the niche, only make sense in the context of this more fundamental idea of tradeoff. The resulting biodiversity will have a positive Gaian effect, that is, it will tend to make an ecological community more stable than if it was composed of a smaller number of species. Biodiversity does not evolve to help stabilize the system (except in the limited sense that taxon poor systems may be more prone to extinction), it is an inevitable by-product of tradeoffs and other processes such as geographical isolation. One potentially important way to think about the Gaian effect of biodiversity is the idea of the ‘portfolio effect’ from economics, although other ideas, such as Grime's ‘transient species’ are also important.

This chapter assesses the consequences of individual nutrition for populations and the assemblages of species that comprise ecological communities. However, the ecological consequences of nutrition are not restricted to the effects of diet on individual organisms but include as well the direct and indirect interactions occurring among individuals within populations and between species. Understanding the complex network of interactions that produce food webs and structure ecosystem dynamics requires the understanding of the participants' differing nutritional requirements, priorities, and regulatory capacities. Geometric Framework analyses have shown that these features differ between species and across trophic levels. Nutritional space is one part of the fundamental niche of an organism, and there is a need to integrate nutrition with the biophysical ecology of organisms. Evolutionary processes also need to be taken into account, and agent-based models offer promise toward development of a new understanding of the evolutionary ecology of nutrition.

This chapter focuses on local ecological communities, and on whether local communities are structured, organized systems; that is, systems whose organization has important effects on the identity and abundance of the local biota. In analyzing the idea that communities are indeed structured systems, it considers the claim that communities control their own membership and the claim that they have biologically important collective properties. If these ideas are vindicated, we do need more than species information. We need information about organization and variation in that organization from community to community. In the chapter's “units-and-differences” framework, it asks whether local ecological communities are themselves units, and, if so, what are the relevant similarities and differences among them.

This chapter focuses on the assumption that ecological communities are wholes and on explaining its importance to a community. This assumption posits that communities are closed networks of interacting populations. According to it, ecological interactions among populations and among individual organisms arrange themselves into “groups of species that at least weakly interact with one another and not others at a time and through time” or what Odenbaugh refers to as “Hutchinsonian Communities.” It is important to discuss this assumption because there is a possibility that the boundaries of “ecological communities” are not fixed by robust discontinuities in ecological interactions. This chapter focuses on addressing the question “What is the relationship between diversity and stability?”.

This chapter discusses how ecology and ecological communities affect both the life-history and evolution of the parasite and the host. Ecological communities consist of populations of different species. Community ecology is an active area of ecological research that makes inquiries such as: what processes might be responsible for the coexistence, or mutual exclusion of species, and how can the number of species and the diversity of a community be explained? The chapter goes into the ecological communities of parasites, or parasite ecology, which have equivalent properties to those of hosts. The difference, however, is that only hosts represent a suitable environment for a parasite. The chapter looks at the characteristics of parasite communities, such as the ‘compound parasite community’, which is the community of all parasites in a given ecosystem.

The difficulty we have distinguishing the legitimate use of nature from the abuse of it is illustrated by conflicting claims that it is wrong or immoral to use riparian corridors in ways that kill mussels in rivers. We can resolve such disputes only by constructing an overall normative standard for evaluating human changes to nature, preferably by taking into account all relevant normative factors. The chapter critiques the popular notion of sustainability, explaining its vagueness and incompleteness and arguing that our embrace of it illustrates our failure to engage meaningfully this foundational norm-creating task. This failure appears also when environmental activists unthinkingly equate all human change to a landscape with land abuse and when speaking of restoration, which is best understood not as goal-directed but simply as an impulse to undo certain human-caused landscape changes. Adding complexity and confusion is the reality of nature’s dynamism and the much-discussed changes in the understandings of ecologists over the past half century and more. The chapter questions whether a true paradigm shift occurred in ecology, or whether the changes are more due to simple shifts in temporal perspectives and in whether depictions of ecological communities should or should not include ecological disturbances.

Lotka and Volterra were among the first to attempt to mathematize the dynamics of interacting populations. While their work had a profound influence on ecology, leading to many of the results that were covered in the preceding chapters, their approach is difficult to generalize to the case of many interacting species. When the number of species in a community is sufficiently large, there is little hope of obtaining analytical results by carefully studying the system of dynamical equations describing their interactions. Here, we introduce an approach based on the theory of random matrices that exploits the very large number of species to derive cogent mathematical results. We review basic concepts in random matrix theory by illustrating their applications to the study of multispecies systems. We introduce tools that can be used to yield new insights into community ecology and conclude with a list of open problems.

This chapter highlights two conceptual roadblocks to systematic comparisons of competing ecological communities and crime models. First, key indicators in several communities and crime models are plagued by semantic ambiguity. In essence, different researchers connect the same indicators to different constructs. Second, researchers rarely engage in systematic, multimethod ecological construct validation to clarify which indicators clearly belong to which constructs. Multimethod patterns of convergent and discriminant validation are rarely examined. Of course, such examinations are particularly challenging when examining spatially aggregated indicators. The establishment of discriminant validity, a key part of the construct validation process, is needed but challenging to accomplish with data aggregated by geographic proximity. The solution is to first adopt a unified perspective on the construct validation process, which opens up the range of empirical relationships relevant to establishing construct validity. The second is to carry out the unified construct validation activities using a Boudon/Coleman boat metamodel aligned with methodological individualism.

This chapter considers the evolution of restraint in simple ecosystems. It specifically presents both simulation and experimental data on the evolution of restraint. It argues that spatial structure may play an important role in setting the stage for egalitarian major transitions. It concentrates on the evolution of restraint in nontransitive ecological communities. This chapter reveals that spatial structure can favor the evolution of restraint. It also illustrates that restraint evolves in structured ecosystems with cyclic networks of interaction.

This chapter discusses the relationship between complexity and stability in ecological communities and how it has been a major area of speculation and research in ecology since the 1930s. Most mathematical models of communities have shown that stability declines as complexity increases, but so far, modelers have not included the material environment in their calculations. Here, an otherwise conventional community ecology model is described that includes feedback between the biota and their climate. This “geophysiological” model is stable in that it resists perturbation. The more complex the community included in the model, the greater its stability in terms of resistance to perturbation and rate of response to perturbation. This is a realistic way to model the natural world because organisms cannot avoid feedback to and from their material environment.

This chapter describes the major geomorphic regions and ecological communities in Lake Pontchartrain. Three major geomorphic regions are: the Marginal Deltaic Basin, which includes Lakes Pontchartrain and Maurepas; the Mississippi River Deltaic Plain, which includes the Lake Borgne area and its surrounding wetlands; and the Pleistocene Terraces, which include the forested habitats that abut the northern side of the lakes and contribute to the Pontchartrain drainage basin. The Marginal Deltaic Basin is further subdivided into eight distinct areas based upon habitat characteristics, plant communities, and faunal assemblages. Within these geomorphic regions and their subdivisions, several major ecological communities may be recognized, based on general living conditions, habitat characteristics, and living organisms present.

Natural disturbances such as fire and grazing create a mosaic of patches during the dry season. We found that fire, in particular, changed avian abundance. Although richness of species did not change with either disturbance, there was a turnover of species with some species coming in to replace those whose populations were reduced by fire. Thus, there was an overall increase in diversity as a result of these natural disturbances. In contrast, major habitat modifications by humans due to agriculture have been found to significantly reduce both richness and abundance by as much as 50 percent. In essence, large disturbances to habitat such as agricultural modifications are detrimental to the conservation of savanna avifauna whereas moderate disturbances such as burning enhance the overall diversity.

Host ecological characteristics, such as body size, longevity, or social living, affect parasitism. Host populations can be regulated in size by their parasites; they can even drive host populations to extinction, usually after hosts have been weakened by other factors. Parasites, therefore, threaten endangered populations and species. Parasites also affect host ecological communities and food webs via effects on competitive ability or with apparent competition. In diverse host communities, infectious diseases become ‘diluted’. Parasite ecological communities seem to have a variable and transient structure; no universal explanation for the observed patterns exists. Host migration can transfer parasites to new areas or leave parasites behind. Disease emergence from an animal reservoir (zoonoses) is especially important. Many human diseases have such an origin, and these have repeatedly caused major epidemics. Climate change will also affect parasitism; however, the direction of change is rather complex and depends on the particular systems.

This chapter reviews the study of cooperative behavior between species, with emphasis on examples of cooperative hunting found in a wide range of species. Seen in this context, the idea of cooperative hunting between humans and wolves that evolved into present relationships with dogs does not seem unusual or surprising. The chapter then critiques the proposal that competition between species is more important than cooperation in structuring ecological communities, discussing how this notion leads to a suite of ideas philosophically separating humans from the rest of the natural world. In many ways Western science is unintentionally complicit in such thinking. The chapter concludes by discussing complex cooperation, including long-term relationships between members of different species.

This chapter describes how the industrial plantation created a living rhythm to the tune of a global market that dictated the lives of workers and shaped the land. The plantation community is an ecological community of plants, animals, and humans sustained by soils, rains, and technology. Carved from a tropical environment of indigenous species and human communities, Hawaiʻi's plantations were artificial creations planted on the landscape and managed from the top through minutely sequenced decisions and actions. The managers and owners were temperate-climate and continental people, either born or educated in Western nations. The workers were from different ecological zones and cultures of Asia, the Pacific, Europe, and North America.