Abstract
Species diversity is important for a range of ecosystem processes and properties, including the resistance to single and multiple stressors. It has been suggested that genetic diversity may play a similar role, but empirical evidence is still relatively scarce. Here, we report the results of a microcosm experiment where four strains of the marine diatom Skeletonema marinoi were grown in monoculture and in mixture under a factorial combination of temperature and salinity stress. The strains differed in their susceptibility to the two stressors and no strain was able to survive both stressors simultaneously. Strong competition between the genotypes resulted in the dominance of one strain under both control and salinity stress conditions. The overall productivity of the mixture, however, was not related to the dominance of this strain, but was instead dependent on the treatment; under control conditions we observed a positive effect of genetic richness, whereas a negative effect was observed in the stress treatments. This suggests that interactions among the strains can be both positive and negative, depending on the abiotic environment. Our results provide additional evidence that the biodiversity-ecosystem functioning relationship is also relevant at the level of genetic diversity.
Highlights
Genetic Diversity and Ecosystem Functioning The loss of species and its consequences for ecosystem functioning has received considerable attention in the last two decades [1,2]
It has been argued that differences at the genetic level can influence ecosystem processes [9] and that genetic diversity may play a role similar to that of species diversity in ecosystems with one or few numerically abundant key species [10]
A growing body of research suggests that, like species diversity, genetic diversity influences a range of ecosystem processes and properties [10,11,12,13,14,15,16,17,18,19]
Summary
Genetic Diversity and Ecosystem Functioning The loss of species and its consequences for ecosystem functioning has received considerable attention in the last two decades [1,2]. The underlying mechanisms by which genetic diversity may alter ecosystem processes are analogous to those proposed for species diversity. In both cases, the effects of diversity can be partitioned into ‘selection’ and ‘complementarity’ effects [20] where a selection effect occurs if the community includes a genotype with a specific trait that becomes dominant over time. Selection effects can result in higher or lower functioning than expected based on the average performance of the genotypes in monoculture, which is called non-transgressive over-yielding. Complementarity effects can result in a diverse assemblage performing better than its best performing member, which is called transgressive over-yielding [21]
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