“Ménage à trois”: the presence/absence of thyme shapes the mutualistic interaction between the host plant Medicago truncatula (Fabaceae) and its symbiotic bacterium Sinorhizobium meliloti
Article first published online: 18 JUN 2012
© 2011 The Authors. MicrobiologyOpen published by Blackwell Publishing Ltd.
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Ecology and Evolution
Volume 2, Issue 7, pages 1676–1681, July 2012
How to Cite
Ehlers, B. K., Grøndahl, E., Ronfort, J. and Bataillon, T. (2012), “Ménage à trois”: the presence/absence of thyme shapes the mutualistic interaction between the host plant Medicago truncatula (Fabaceae) and its symbiotic bacterium Sinorhizobium meliloti. Ecology and Evolution, 2: 1676–1681. doi: 10.1002/ece3.270
- Issue published online: 6 JUL 2012
- Article first published online: 18 JUN 2012
- Received: 18 January 2012; Revised: 29 March 2012; Accepted: 31 March 2012
- genetic correlation;
- legume–rhizobium symbiosis
The long-term maintenance of specialized mutualisms remains an evolutionary puzzle. Recent focus has been on factors governing the stability of these mutualisms, including sanctions by the host, partner choice, and coevolutionary constraint, that is, the genetic correlation (rG) between fitness of both partners. So far these studies have been typically carried out in a single environment. Here, we ask if the genetic correlation between fitness of the host plant Medicago truncatula (Fabaceae) and its bacterial symbiont Sinorhizobium meliloti is affected by the presence/absence of a monoterpene (carvacrol) leached into the soil by Thymus vulgaris—a common plant of the Mediterranean vegetation, often co-occuring with Medicago. We show that the presence of carvacrol in the soil dramatically affects fitness of the rhizobial partner and increases the magnitude of rG between plant and rhizobia fitness (rG= 0.02 ± 0.05 vs. rG= 0.57 ± 0.02). This finding emphasizes the importance of heterogeneity in the biotic environment for understanding the evolution of species interactions.