Morphological and swim performance variation among reproductive tactics of bluegill sunfish (Lepomis macrochirus)

摘要

Ecomorphology examines the relationship between morphology and ecological characteristics often in relation to foraging, predation, and habitat use. However, ecomorphology may also be linked to reproductive behaviour ("tactic"), but few studies have examined this relationship. We examined bluegill sunfish (Lepomis macrochirus Rafinesque, 1819), a species in which some males become "parentals" while others adopt a parasitic "cuckolder" tactic. Parentals build nests, court females, and care for the young. Cuckolders instead act as "sneakers", darting into nests while females are releasing eggs, and then transition to "satellites", mimicking female appearance. We predicted that reproductive tactic would be associated with morphological variation and swimming performance. We collected bluegill parentals, sneakers, satellites, females, and juveniles to compare morphology, burst swim, and swim endurance. We found significant morphological variation among the groups, with only satellites and females having similar body shapes. Interestingly, satellites did not overlap in shape with sneakers, despite representing a single ontogenetic life history, providing evidence for a relationship between reproductive tactic and morphology. We also found that swim performance varied among the groups, with sneakers having the fastest burst swim and longest swim endurance. Our results indicate that reproductive tactic is an important factor in the ecomorphology of fish.