Department of Biology, University of Maryland, 4094 Campus Dr, College Park, MD, 20742, USA.
Department of Life Science, National Taiwan Normal University, No. 88, Section 4, Tingchou Rd, Taipei, 11677, Taiwan.
Anim Cogn. 2023 Sep;26(5):1477-1488. doi: 10.1007/s10071-023-01797-8. Epub 2023 Jun 9.
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.
近期战斗的结果可以为个体提供有关其相对战斗能力的信息，并影响他们的竞争决策（胜负效应）。大多数研究都在调查这些效应在种群/物种中的存在/缺失情况，但在这里，我们研究了它们如何因个体的年龄相关增长率而在物种个体之间变化。许多动物的战斗能力高度依赖于体型，因此以前战斗的信息是不可靠的。此外，快速生长的个体通常处于较早的发育阶段，与大多数其他个体相比，体型较小且较弱，但它们生长迅速，体型和力量迅速增大。因此，我们预测高增长率个体的胜负效应不太明显，且衰减速度更快。快速生长的个体也应该表现出更强的胜利者效应，因为在体型较小时获胜表明力量会增长，而失败可能很快变得无关紧要。我们使用不同生长阶段的红树林食蚊鱼（Kryptolebias marmoratus）的天真个体来测试这些预测。比赛强度的衡量标准仅揭示了生长缓慢个体的胜负效应。具有获胜经验的快速和慢速生长的鱼类比具有失败经验的鱼类赢得了更多随后的非升级比赛；在快速生长的个体中，这种效应在 3 天内消失，但在慢速生长的鱼类中则没有。快速生长的个体也表现出胜利者效应，但没有失败者效应。因此，这些鱼类以一种反映他们从这些经验中获得的信息价值的方式对竞争经验做出了反应，这与我们的预测一致。
