Trade‐Off between Interspecific Competitive Ability and Growth Rate in Bacteria

Abstract

In an attempt to clarify the significance of interspecific competition in evolutionary ecology, the growth characteristics of bacterial populations were investigated. Bacteria from aquatic microcosms were subjected to serial transfer at 12—h and 3—d intervals in both single— and two—species culture. Selection in single—species populations under serial transfer at 3—d intervals favored an increased growth rate.In mixed culture, serial transfer at 3—d intervals led to coexistence of the two species, and resulted in the r values of both species undergoing slight reductions or remaining unchanged in comparison to the parental strain; serial transfer at 12—h intervals led to extinction of the species with lower r. These results can be viewed as evidence for a trade—off between interspecific competitive ability and growth rate. This interpretation was examined by computer simulation.