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Sperm of more colorful males are better adapted to ovarian fluids in lake char (Salmonidae)
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  • David Nusbaumer,
  • Laura Garaud,
  • Christian de Guttry,
  • Laurie Ançay,
  • Claus Wedekind
David Nusbaumer
University of Lausanne
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Laura Garaud
University of Lausanne
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Christian de Guttry
University of Lausanne
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Laurie Ançay
University of Lausanne
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Claus Wedekind
University of Lausanne

Corresponding Author:claus.wedekind@unil.ch

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Abstract

Fish often spawn eggs with ovarian fluids that have been hypothesized to support sperm of some males over others (cryptic female choice). Alternatively, sperm reactions to ovarian fluids could reveal male strategies. We used wild-caught lake char (Salvelinus umbla) to experimentally test whether sperm react differently to the presence of ovarian fluid, depending on male breeding coloration, male inbreeding coefficients (based of 4,150 SNPs), or the kinship coefficients between males and females. Male coloration was positively linked to body size and current health (based on lymphocytosis and thrombocytosis) but was a poor predictor of inbreeding or kinship coefficients. We found that sperm of more colorful males were faster in diluted ovarian fluids than in water only, while sperm of paler males were faster in water than in ovarian fluids. We then let equal numbers of sperm compete for fertilizations in the presence or absence of ovarian fluids and genetically assigned 1,464 embryos (from 70 experimental trials) to their fathers. The presence of ovarian fluids significantly increased the success of the more colorful competitors. Sperm of less inbred competitors were more successful when tested in water only than in diluted ovarian fluids. The kinship coefficients had no significant effects on sperm traits or fertilization success in the presence of ovarian fluids, although parallel stress tests on embryos had revealed that females would profit more from mating with least related males rather than most colored ones. We conclude that sperm of more colorful males are best adapted to ovarian fluids, and that the observed reaction norms suggest male strategies rather than cryptic female choice.
24 Apr 2023Submitted to Molecular Ecology
26 Apr 2023Submission Checks Completed
26 Apr 2023Assigned to Editor
26 Apr 2023Review(s) Completed, Editorial Evaluation Pending
02 May 2023Reviewer(s) Assigned
30 Jun 2023Editorial Decision: Revise Minor
11 Jul 20231st Revision Received
12 Jul 2023Submission Checks Completed
12 Jul 2023Assigned to Editor
12 Jul 2023Review(s) Completed, Editorial Evaluation Pending
07 Aug 2023Editorial Decision: Accept