Adaptive Peaks and Alternative Foraging Tactics in Brook Charr: Evidence of Short-Term Divergent Selection for Sitting-and-Waiting and Actively Searching

Some recently emerged brook charr (Salvelinus fontinalis) inhabiting still-water pools along the sides of streams are sedentary and eat crustaceans from the lower portion of the water column. Others are more active and eat insects from the upper portion of the water column. We provide evidence that...

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Bibliographic Details
Published in:Behavioral ecology and sociobiology 1999-04, Vol.45 (5), p.386-395
Main Authors: McLaughlin, Robert L., Ferguson, Moira M., David L. G. Noakes
Format: Article
Language:English
Subjects:
Agnatha and pisces
Animal ethology
Animal morphology
Biological and medical sciences
Creeks
Ecological competition
Fish
Foraging
Freshwater
Fundamental and applied biological sciences. Psychology
Marine fishes
Natural resources
Proportions
Psychology. Psychoanalysis. Psychiatry
RNA
Salvelinus fontinalis
Trout
Vertebrata
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Summary:Some recently emerged brook charr (Salvelinus fontinalis) inhabiting still-water pools along the sides of streams are sedentary and eat crustaceans from the lower portion of the water column. Others are more active and eat insects from the upper portion of the water column. We provide evidence that this divergent foraging behavior reflects short-term divergent selection brought about by intraspecific competition in the presence of alternative food sources. Rates of encounters and interactions between individuals were density dependent, and encounter and interaction events were closely timed with prey capture attempts. In addition, aggressive fish made more foraging attempts per minute than nonaggressive fish. Aggressive fish were also either inactive or very active, while nonaggressive fish exhibited intermediate levels of activity. Growth rate potential, an important component of fitness during the early life stages of brook charr, was assessed using tissue concentrations of RNA and found to be highest for sedentary fish and for active fish making frequent foraging attempts, and lower for fish exhibiting intermediate levels of activity. Our findings support contentions that individual behavior plays an important role during initial steps in the evolution of resource polymorphisms.
ISSN:0340-5443
1432-0762
DOI:10.1007/s002650050575