‘Superbull’ males: what role do they play and what drives their appearance within the Doryteuthis gahi Patagonian Shelf population?

Jessica B. Jones* (Corresponding Author), Graham J. Pierce, Paul Brickle, Zhanna N. Shcherbich, Alexander I. Arkhipkin

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Citation (Scopus)
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Abstract

Cephalopod populations exhibit high variability in life history characteristics such as longevity and size-at-age. Here, we aim to understand how characteristics of a newly-described ‘super-bull’ male morph in Doryteuthis gahi populations (Patagonian shelf) arise and whether there is a selective advantage. At the population level it is speculated that super-bulls provide temporal and spatial connectivity, but individual benefit is less obvious. Age structure and reproductive potential of males was investigated to determine whether super-bulls could provide connectivity. Environmental variables affecting size-at-age were explored to ascertain whether morphological differences were primarily phenotypically driven. Super-bulls from the autumn spawning cohort were significantly older than the residual population, with added longevity potentially leading to spawning with the following cohort. A reduction in relative testis weight was apparent in super-bulls, but spermatophore production remained high. Generalised additive mixed models (GAMMs) indicated temperature, location and hatch year had significant effects on size-at-age. Weak correlations between warm El Niño southern oscillation (ENSO) phases and super-bull abundance were found. Results suggest super-bulls provide temporal connectivity and arise through phenotypic plasticity, likely providing connectivity as a side effect of body shape and size rather than a genetically selected advantage.
Original languageEnglish
Pages (from-to)1805-1817
Number of pages13
JournalMarine and Freshwater Research
Volume70
Issue number12
Early online date12 Apr 2019
DOIs
Publication statusPublished - 31 Dec 2019

Keywords

  • cephalopods
  • ecology
  • marine
  • population dynamics
  • reproductive biology
  • otoliths
  • population structure
  • plasticity
  • southwest Atlantic
  • reproduction
  • statolith

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