Muscle fibre number varies with haemoglobin phenotype in Atlantic cod as predicted by the optimal fibre number hypothesis

Ian A. Johnston, Marguerite Abercromby, Oivind Andersen

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Atlantic cod (Gadus morhua L.) with the HbI-(2/2) haemoglobin phenotype have a higher blood oxygen affinity at low temperatures and a lower routine metabolic rate than individuals with the HbI-(1/1) phenotype. In the present study, muscle structure was found to be related to haemoglobin phenotype in a coastal population of Atlantic cod from the Saltenfjord region of Northern Norway. The maximum number of fast muscle fibres ( FNmax) was reached at approximately 39 cm fork length and was 15% greater in the HbI-(1/1) than in the HbI-(2/2) phenotypes whereas the average fibre diameter for fish of the same fork length was significantly lower. Theoretically, the higher oxygen affinity of the HbI-(2/2) phenotype in the cold water of northern latitudes could have resulted in a relaxation of diffusional constraints at the level of individual muscle fibres, permitting the observed increase in fibre diameter. The results support the optimal fibre number hypothesis which envisages a trade-off between diffusional constraints and the energy cost of maintaining ionic homeostasis with fewer larger diameter muscle fibres in the HbI-(2/2) phenotype contributing to a lower routine metabolic rate.

Original languageEnglish
Pages (from-to)590-592
Number of pages3
JournalBiology Letters
Volume2
Issue number4
DOIs
Publication statusPublished - 22 Dec 2006

Keywords

  • muscle fibre recruitment
  • biogeographic patterning
  • biodiversity
  • HAEMOGLOBIN POLYMORPHISM
  • GADUS-MORHUA
  • POPULATIONS
  • FISHES
  • COASTAL
  • GROWTH
  • SALMON

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