Niche shifts in sunfishes: experimental evidence and significance.

Three species of sunfishes segregate ecologically when stocked together in small ponds. When each species is stocked separately in replicate ponds, it exhibits competitive release through increases in growth rate and average food size. Niche shifts are indicated by convergence of these species to the same food habits in the absence of competitors. These shifts are due to phenotypic (behavioral) plasticity. The significance of niche flexibility is related to seasonal patterns in resource availability.