Predator-induced delayed maturity in bluegill sunfish (Lepomis macrochirus): variation among populations |
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Authors: | Mark C Belk |
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Institution: | (1) Department of Zoology, Brigham Young University, Provo, UT 84602, USA Fax: (801) 378-7423; e-mail: MARK_BELK@BYU.EDU, US |
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Abstract: | Previous studies suggested that differences in age at maturity among populations of bluegill sunfish (Lepomis macrochirus) were not genetically based, but rather were a phenotypic response to the presence of predators. I conducted two experiments
to determine if the presence of largemouth bass affected age at maturity in bluegill sunfish. Bluegills from three populations
were tested to see if the response to the threat of predation varied among source populations. Juvenile bluegills were maintained
in the presence of predators or in controls with no contact with predators. Refuge use and growth were monitored during the
experiments and reproductive activity was evaluated when bluegills reached age 1. Bluegills from one population exhibited
delayed maturity in the presence of predators. Individuals from the other two populations showed no significant differences
between predator and control treatments. The population that responded to the presence of predators had a history of high
predation levels over the past 30–40 years. The other populations had a history of low levels of predation. This study suggests
that presence of predators can induce phenotypic shifts in age at maturity of bluegills, but that the magnitude of response
varies among populations in a manner consistent with historical patterns of coexistence.
Received: 7 August 1996 / Accepted: 8 August 1997 |
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Keywords: | Life history Predation Phenotypic plasticity Bluegill sunfish Nonlethal effects of predators |
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