The biodiversity hierarchy: a historical overview of biodiversity research from genes to ecosystems.
Agrawal, Anurag*,1, Johnson, Marc2, 1 Cornell Univeristy, Ithaca, NY2 University of Toronto, Toronto, Ontario
ABSTRACT- Research on the ecological consequences of biodiversity has long been a fundamental focus in ecology. Early research and debate centered on the relationship between species diversity and community stability. Although empirical data and observation suggested that diversity promotes stability, mathematical theory predicted that the reverse was true, at least for randomly assembled communities. In the last decade, these theoretical predictions have been subject to intense experimentation, which supports the early hypothesis that diversity and stability are positively related, and that biodiversity has important consequences for multitrophic interactions and the functioning of ecosystems. Traditionally, biodiversity research has focused on the ecological consequences of diversity at the species and functional group levels, where species are largely treated as homogeneous sets of identical individuals. Such an approach ignores the genetic diversity inherent to nearly all populations of species, as well as the potential importance that rapid evolution may have for community patterns and processes. This gap is now being filled by a flurry of recent studies that investigate the ecological consequences of genetic diversity and evolutionary processes within communities. These studies find that genetic diversity in plants increases the stability of populations subject to biotic and abiotic disturbance, and may promote the stability of entire plant communities. Greater genetic diversity in plant populations also increases the diversity of consumers and alters ecosystem processes relating to litter decomposition. The population dynamical consequences of evolutionary change have been studied in microcosms, where it has been found that selection on genetic variation can shape predator-prey dynamics and adaptive radiations. We suggest that biodiversity research must accelerate its efforts to understand the ecological consequences of genetic diversity and the interrelationship between species diversity, genetic diversity, and evolution.
Key words: evolutionary ecology, genetic diversity, community genetics
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