TRADE-OFFS OF ECOLOGICAL SPECIALIZATION - AN INTRASPECIFIC COMPARISONOF PUMPKINSEED SUNFISH PHENOTYPES

Most empirical studies of specialists and generalists have focused on comparisons among different species. Interspecific comparisons have re cently been criticized because phenotypic trade-offs can evolve after ecological specialization. As a result, it has been suggested that int raspecific variation is the appropriate level to demonstrate functiona l trade-offs. We demonstrate functional trade-offs for two components of fitness in pumpkinseed sunfish (Leponzis gibbosus) from a single tr ophically polymorphic population: condition factor and growth rate. Co ndition factor was estimated using somatic lipid content, while growth rate was determined from scale measurements. Fish with extreme benthi c and limnetic morphologies are on average superior to fish with inter mediate morphologies, especially in the pelagic habitat. Our study is a particularly stringent test of functional trade-offs at the intraspe cific level because the morphological variation is very subtle in this population.