Age-dependent winner–loser effects in a mangrove rivulus fish, Kryptolebias marmoratus

• Published in: Animal cognition 2023-09, Vol.26 (5), p.1477-1488
• Main Authors: Li, Cheng-Yu, Pan, Chun-Ying, Hsu, Yuying
• Format: Article
• Language: English
• Subjects: Androgens; Animal cognition; Behavioral Sciences; Biomedical and Life Sciences; Body size; Decay rate; Developmental stages; Fighting; Fish; Growth rate; Influence; Kryptolebias marmoratus; Life Sciences; Original Paper; Psychology Research; Zoology
• ISSN: 1435-9448; 1435-9456
• DOI: 10.1007/s10071-023-01797-8

The outcomes of recent fights can provide individuals information about their relative fighting ability and affect their contest decisions (winner–loser effects). Most studies investigate the presence/absence of the effects in populations/species, but here we examine how they vary between individuals of a species in response to age-dependent growth rate. Many animals’ fighting ability is highly dependent on body size, so rapid growth makes information from previous fights unreliable. Furthermore, fast-growing individuals are often at earlier developmental stages and are relatively smaller and weaker than most other individuals but are growing larger and stronger quickly. We therefore predicted winner-loser effects to be less detectable in individuals with high than low growth rates and to decay more quickly. Fast-growing individuals should also display stronger winner than loser effects, because a victory when small indicates a strength which will grow, whereas a loss might soon become irrelevant. We tested these predictions using naïve individuals of a mangrove killifish, Kryptolebias marmoratus , in different growth stages. Measures of contest intensity revealed winner/loser effects only for slow-growth individuals. Both fast- and slow-growth fish with a winning experience won more of the subsequent non-escalated contests than those with a losing experience; in fast-growth individuals this effect disappeared in 3 days, but in slow-growth fish it did not. Fast-growth individuals also displayed winner effects but not loser effects. The fish therefore responded to their contest experiences in a way which reflected value of the information from these experiences to them, consistent with our predictions.