How optimal life history changes with the community size-spectrum

Keith Farnsworth, U.H. Thygesen, K.H. Andersen, J.E. Beyer

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)


This paper derives optimal life histories for fishes or other animals in relation to the size spectrum of the ecological community in which they are both predators and prey. Assuming log-linear size-spectra and well known scaling laws for feeding and mortality, we first construct the energetics of the individual. From these we find, using dynamic programming, the optimal allocation of energy between growth and reproduction as well as the trade-off between offspring size and numbers. Optimal strategies were found to be strongly dependent on size spectrum slope. For steep size spectra (numbers declining rapidly with size), determinate growth was optimal and allocation to somatic growth increased rapidly with increasing slope. However, restricting reproduction to a fixed mating season changed optimal allocations to give indeterminate growth approximating a von Bertalanffy trajectory. The optimal offspring size was as small as possible given other restrictions such as newborn starvation mortality. For shallow size spectra, finite optimal maturity size required a decline in fitness for large size or age. All the results are compared with observed size spectra of fish communities to show their consistency and relevance.
Original languageEnglish
Pages (from-to)1323-1331
Number of pages9
JournalProceedings of the Royal Society of London. Series B, Biological Sciences
Volume272 (1570)
Issue number1570
Publication statusPublished - 07 Jul 2005

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Agricultural and Biological Sciences (miscellaneous)

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