Seasonal Variation in Cuckoldry Rates in the Socially Monogamous Cichlid Fish Variabilichromis moorii
Summary
Section titled “Summary”This note summarizes a longitudinal field study of brood parentage in Variabilichromis moorii, a socially monogamous cichlid from Lake Tanganyika. Across five field trips over three years, the authors found substantial extra-pair paternity in every season, but cuckoldry pressure was stronger during rainy-season spawning than during dry-season spawning. The paper argues that mating patterns can shift materially over time even within the same population.
Key Findings
Section titled “Key Findings”- Extra-pair paternity was common across all sampled seasons rather than being a rare exception.
- Brood-tending males retained a larger share of paternity in dry seasons than in rainy seasons.
- Rainy-season broods had more sires per brood, indicating heavier cuckolder pressure.
- The authors attribute the difference to seasonal environmental conditions, with water turbidity discussed as one plausible mechanism.
- Positive size-assortative pairing remained relatively stable, which suggests that the main seasonal shift was in cuckoldry pressure rather than in mate-choice structure.
Clinical Relevance
Section titled “Clinical Relevance”This is not human research, but it is useful for thinking clearly about how environmental context can modulate rivalry and reproductive outcomes. It cautions against treating cuckoldry as a fixed property of a species or a relationship system. Conditions matter, and background ecology can alter how much outside-male intrusion actually occurs.
Interpretation
Section titled “Interpretation”The paper is valuable because it moves beyond one-time snapshots. It shows that paternity loss is dynamic and that social monogamy tells us much less than many readers assume. For this site, the broader lesson is that exclusivity signals and actual reproductive outcomes can diverge, and that any evolutionary story about jealousy or mate guarding needs to account for fluctuating background conditions rather than static assumptions.
Related Topics
Section titled “Related Topics”- Inclusive Fitness Benefits and Socially Paired Males Under Cuckoldry
- Sperm Morphology and Sperm Velocity in Passerine Birds
Sources
Section titled “Sources”- Zimmermann, H., Bose, A. P. H., Eisner, H., Henshaw, J. M., Ziegelbecker, A., Richter, F., Bračun, S., Katongo, C., Fritzsche, K., & Sefc, K. M. (2023). Seasonal variation in cuckoldry rates in the socially monogamous cichlid fish Variabilichromis moorii. Hydrobiologia, 850, 2371-2383. https://doi.org/10.1007/s10750-022-05042-0