| origins of cheating and loss of symbiosis in wild bradyrhizobium. | rhizobial bacteria nodulate legume roots and fix nitrogen in exchange for photosynthates. these symbionts are infectiously acquired from the environment and in such cases selection models predict evolutionary spread of uncooperative mutants. uncooperative rhizobia - including nonfixing and non-nodulating strains - appear common in agriculture, yet their population biology and origins remain unknown in natural soils. here, a phylogenetically broad sample of 62 wild-collected rhizobial isolates wa ... | 2010 | 20345811 |