Evol Ecol Res 5: 439-457 (2003)     Full PDF if your library subscribes.

Optimal energy allocation to ovaries after spawning

David B. Bunnell and Elizabeth A. Marschall*

Aquatic Ecology Laboratory, Department of Evolution, Ecology and Organismal Biology, The Ohio State University, 1314 Kinnear Road, Columbus, OH 43212, USA

Address correspondence to either author.
e-mail: bunnell.6@osu.edu; marschall.2@osu.edu


For iteroparous organisms in which fecundity is positively related to body size, a trade-off exists between allocation of energy to gonads, thus ensuring some reproductive output, and allocation to somatic growth, thus increasing potential fecundity in the future. This trade-off can influence several life-history patterns, including when, for organisms that grow after maturity, allocation to gonads begins following the previous reproductive event. White crappie Pomoxis annularis, a spring-spawning freshwater fish, began allocating energy to ovaries in autumn at the expense of continued somatic growth and higher potential fecundity. Within five populations, the amount of early allocation varied between years. We combined dynamic programming with an individual-based model to determine how summer and spring feeding conditions interact to influence when allocation to reproduction should begin. Model results indicated that autumn allocation to ovaries was in response to future spring feeding conditions rather than recent summer feeding conditions. At least a 10% probability of poor spring feeding conditions resulted in ovary investment patterns that matched field observations. The model was unable to explain the inter-annual variation in autumn energy observed in the field. Early allocation of energy to ovaries is probably an evolutionary adaptation to the possibility of poor spring feeding conditions.

Keywords: dynamic programming, optimal energy allocation, Pomoxis annularis, reproduction, timing, uncertainty.

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        © 2003 David B. Bunnell and Elizabeth A. Marschall. All EER articles are copyrighted by their authors. All authors endorse, permit and license Evolutionary Ecology Ltd. to grant its subscribing institutions/libraries the copying privileges specified below without additional consideration or payment to them or to Evolutionary Ecology, Ltd. These endorsements, in writing, are on file in the office of Evolutionary Ecology, Ltd. Consult authors for permission to use any portion of their work in derivative works, compilations or to distribute their work in any commercial manner.

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