003850000a2200133000450024500830000065000240008365000160010765000150012365000150013804100130015370000230016610000220018977300400021110aSpecialization and resource trade: biological markets as a model of mutualisms14aMercado biológico14aEvolución14aMutualismo14aMicorrizas0 aInglés1 aHoeksema, Jason D.1 aSchwartz, Mark W.1 tEcology357h3q1029-1038d1998g79