Abstract
Diversity generally increases ecosystem productivity over short timescales. Over longer timescales, both ecological and evolutionary responses to new environments could alter productivity and diversity–productivity relationships. In turn, diversity might affect how component species adapt to new conditions. We tested these ideas by culturing artificial microbial communities containing between 1 and 12 species in three different environments for ∼60 generations. The relationship between community yields and diversity became steeper over time in one environment. This occurred despite a general tendency for the separate yields of isolates of constituent species to be lower at the end if they had evolved in a more diverse community. Statistical comparisons of community and species yields showed that species interactions had evolved to be less negative over time, especially in more diverse communities. Diversity and evolution therefore interacted to enhance community productivity in a new environment.
Highlights
Diversity generally increases measures of ecosystem functioning; for example, biomass and productivity tend to be higher in experimental communities that contain more species (Bell et al, 2005; Hooper et al, 2005)
Greater diversity might increase evolution by increasing the strength of biotic interactions (Liow et al, 2011) or amplifying the strength of selection caused by an environmental change (Osmond and de Mazancourt, 2013; Pekkonen et al, 2013)
Changes in community productivity during the experiment could result because some species went extinct, because surviving species evolved to grow better or because species evolved greater niche differences or by other means altered their interactions (Figure 1b)
Summary
Diversity generally increases ecosystem productivity over short timescales. Over longer timescales, both ecological and evolutionary responses to new environments could alter productivity and diversity–productivity relationships. Diversity might affect how component species adapt to new conditions. We tested these ideas by culturing artificial microbial communities containing between 1 and 12 species in three different environments for B60 generations. The relationship between community yields and diversity became steeper over time in one environment. Statistical comparisons of community and species yields showed that species interactions had evolved to be less negative over time, especially in more diverse communities. The ISME Journal (2015) 9, 1235–1245; doi:10.1038/ismej.2014.215; published online 11 November 2014
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