Simms, E.L., D.L. Taylor, J. Povich, R.P. Shefferson, M. Urbina, and Y.
Tauszick. 2006. An empirical test of partner choice mechanisms in a legume-
rhizobium interaction. Proceedings of the Royal Society of London Series B,
Biological Sciences 273:77-81


Abstract Mutualisms can be viewed as biological markets in which individuals
exchange goods and services with partners of different species. However, markets
often require mechanisms to prevent exploitation, especially when conflicting
interests arise from horizontal transmission and/or competition among potential
mutualists. One such mechanism is partner choice, in which one partner
preferentially directs benefits to cooperative individuals of the other species. Recent
evolutionary theory models partner choice but has rarely been tested empirically.
Bacteria that inhabit legume root nodules, called rhizobia, can convert atmospheric
dinitrogen (N2) to a plant-available form in exchange for photosynthates. Biological
market theory is well suited to legume-rhizobium symbioses. Individual plants
exchange resources with multiple rhizobia and microbial co-operation might be
maintained by plant mechanisms to preferentially allocate resources to nodules
harbouring co-operative rhizobial strains. A greenhouse experiment suggests that
Lupinus arboreus Sims (yellow bush lupine; Fabaceae) shrubs, when nodulated by
mixed populations of naturally co-occuring bacterial isolates, can direct resources to
more cooperative symbionts.

Article copyright notice: © 2006 by The Royal Society

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Copyright 2009 Richard P. Shefferson.  All rights reserved.
Simms et al. 2006