Modeling biodiversity response to disturbance and change: History, challenges, and successes

Background/Question/Methods

The question of how biodiversity ‘responds’ to disturbance and change requires an understanding of what factors are responsible for maintaining the levels of biodiversity observed. The question is of immense importance, because rapid loss of many specific habitat types, as well as possible large scale changes such as climate change, ocean acidification, and pollution, to name a few. Biodiversity may be important not only as a value is its own right, but as important to efficient ecosystem functioning. Methods to preserve biodiversity, such as instating of nature reserves, require knowledge from both empirical and theoretical ecologists.  Ecological modeling is already playing a role in understanding the numerous patterns of biodiversity that exist in nature as well as the factors that affect survival of individual species. This modeling forms a basis for prediction of the effects of the environmental changes that are expected to occur through increased human impacts on the earth. The objective of this talk is to give a brief but broad overview of theoretical attempts to understand the mechanisms underlying the biodiversity observed in nature, which will provide the context for the following talks in this session.

Results/Conclusions

The response of theoretical ecologists to supply an understanding to biodiversity has been enormous. From the ecological point of view, numerous features of natural ecosystems exist that appear to be plausible mechanisms for allowing coexistence.  For one thing, competitive abilities may be evened out by various tradeoffs in the relative advantages and disadvantages of species.  For another, predators may affect a superior competitor more than an inferior one.  Environmental disturbances may make it difficult for a superior competitor to monopolize space or resources.  Spatial extent combined with disturbances may allow some inferior competitors to specialize in acquiring newly available resources before the superior competitor arrives.  Mutualisms may also improve the competitive abilities of weaker competitors. However, merely pointing out plausible ecological mechanisms for maintaining the coexistence of many competing species is not a guarantee that these mechanisms would actually work over long time scales.  Fortunately, theoretical ecologists have provided some of the rigorous conditions that must be met for such ecological mechanisms to be effective in maintaining biodiversity.  Some of the history and current status of understanding will be summarized.