ASSESSING POPULATION-SPECIFIC AND ENVIRONMENTAL INFLUENCES ON BLUEGILL LIFE HISTORIES: A COMMON GARDEN APPROACH

Abstract

Investigations into vertebrate life histories have demonstrated trade-offs between growth and reproduction that can result in individual and population-specific variation in life-history strategies. Mechanisms to explain variation among populations, however, often remain unidentified. We examined the relative strength of genetic (population source) and environmental (population social structure) factors on variation in growth and timing of maturation for juvenile male bluegill in a common garden experiment. We placed juvenile male bluegill collected from two different wild source populations, one with parental males that are large (>190 mm total length) and one with parental males that are stunted (<155 mm total length), in a common environment and varied the social structure by controlling the presence or absence of large, mature, male bluegill collected from a third population. Juvenile male bluegill from both populations allocated significantly more energy to reproduction in the absence of large males than in their presence. Within ponds, differences in growth and maturation rates between juvenile males from the two source populations were small but significant. These results indicate both genetic and environmental components to growth and maturation in bluegill but emphasize the importance of social interactions in shaping individual life-history strategies.