Sperm competition experiment with lake char (Lake Geneva 2017/18)

Male and female wild lake char (Salvelinus umbla) were sampled from Lake Geneva in December 2017 and December 2018. Male size and colouration (all samples, N = 34) were compared to milt characteristics. For the 2017 samples, milt characteristics were also determined after sperm activation in diluted ovarian fluid or water only, and the gametes were used in sperm competition trials: Equal numbers of sperm competed for fertilization in the presence or absence of ovarian fluids. The resulting embryos were raised singly in an environment that supports symbiotic microbes (sublethal stress) or in a clean environment, and microsatellite markers were used to assign in total 1,464 embryos (from 70 experimental trials) to their fathers. Overall, the sperm of more colourful males were faster and reached higher fertilization success than the sperm of pale males. These differences were enhanced by the presence of ovarian fluids. The primary sex ratio did not differ among families and was about 1:1. ..., See Methods in
Nusbaumer D., Garaud L., Ançay L., Wedekind C. 2021 Sex-specific stress tolerance in embryos of lake char (Salvelinus umbla). Front. Ecol. Evol. 9, 768263. (doi:10.3389/fevo.2021.768263).
Nusbaumer D., Garaud L., de Guttry C., Ançay L., Wedekind C. 2021 Sperm of more colorful males are better adapted to ovarian fluids in lake char (Salmonidae). bioRxiv. (doi: https://doi.org/10.1101/2021.10.02.462848).
Garaud L., Nusbaumer D., de Guttry C., Ançay L., Jacquet S., Lasne E., Wedekind C. 2022 Genomic compatibility excels possible good genes effects of sexual selection in lake char. bioRxiv. (doi:https://doi.org/10.1101/2022.03.03.482834).,