Red Queen communities.
Clay, Keith 1, Reinhart, Kurt*,1, Rudgers, Jennifer*,1, Tintjer, Tammy*,1, Koslow, Jennifer*,1, Flory, S. Luke*,1, 1 Indiana University, Bloomington, Indiana, USA
ABSTRACT- We extend the Red Queen Hypothesis from pathogen selection for genetic diversity and sexual recombination in hosts to species diversity at the community level. The Red Queen Hypothesis assumes that pathogens become specialized on common host genotypes and reduce their fitness, thereby favoring genetic mechanisms generating rarity. Here we develop the idea that pathogens favor diversity in communities by an analogous mechanism of density- and/or frequency-dependent selection against common species. Empirical evidence from a variety of studies suggests that host-specific pathogens are more likely to attack and reduce population sizes of common species relative to rarer members of the community. Dependency of pathogen impact on relative species abundance counteracts competitive exclusion and prevents domination by one or more abundant species, maintaining species diversity in communities. Field and laboratory studies suggest a link between species diversity and improved functioning of ecosystems. Thus, we postulate an indirect relationship between pathogens and ecosystem function.
Key words: pathogens, diversity, communities, ecosystems
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