Massote Clara, Palaoro Alexandre V, Arnott Gareth, Jennings Domhnall, Peixoto Paulo Enrique Cardoso
Departamento de Ecologia, Conservação e Manejo da Vida Silvestre, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Departamento de Zoologia, Universidade Federal do Paraná, Curitiba, Paraná, Brazil.
J Anim Ecol. 2025 Jul;94(7):1335-1345. doi: 10.1111/1365-2656.70058. Epub 2025 May 26.
In animal contests, the decision to flee or to remain in a contest is crucial to the individual's fitness because a wrong decision can dramatically change the costs individuals accrue over their lifetime. Empirical evaluations of the rules that individuals adopt to remain on a contest often provide support for two major possibilities: self-assessment strategies, in which each individual remain in the contest until reaching its own cost threshold, and a mutual-assessment strategy, in which individuals assess the rival's capacity to sustain or to impose costs during the contest and decide to flee when they consider that the rival is stronger. However, it is unclear what drives the evolution of different assessment strategies among species. A factor that may be key to understanding such variation is contest cost. If contests provide a fast and/or large cost accrual, mutual assessment strategies may be favoured because they avoid contests in which individuals always reach their own cost threshold. On the other hand, in species in which cost accrual during the contest is slow and/or small, self-assessment may prevail. Here, we performed a meta-analysis using information on the way individuals engage in contests in different species. Our goal is to test the hypothesis that contests involving high-cost accrual, such as contests in species in which rivals use weapons, can favour the evolution of mutual assessment strategies, while contests with lower costs, such as contests without physical contact, should favour the evolution of self-assessment strategies. We obtained 80 effect sizes spanning 36 species. Contrary to our hypothesis, we found that species with high-cost contests consistently adopted self-assessment strategies, while species with low-cost contests did not present a consistent assessment strategy. We suggest that high-cost contests may evolve in species in which individuals experiencing defeat or opting to flee from a contest have a significant decrease in their reproductive success. Consequently, individuals would be compelled to engage in contests regardless of their opponent. In low-cost contests, however, we suggest that any potential selective pressure for a specific assessment strategy is relaxed, which could explain the diversity of assessment strategies observed in this category.
在动物竞争中，决定逃离还是继续竞争对个体的适应性至关重要，因为错误的决定会极大地改变个体一生中所积累的代价。对个体用于继续参与竞争的规则进行实证评估，往往支持两种主要可能性：自我评估策略，即每个个体在竞争中一直坚持到达到自己的代价阈值；以及相互评估策略，即个体在竞争中评估对手承受或施加代价的能力，并在认为对手更强时决定逃离。然而，尚不清楚是什么驱动了不同物种间不同评估策略的进化。一个可能是理解这种差异的关键因素是竞争代价。如果竞争会快速和/或大量地积累代价，相互评估策略可能会受到青睐，因为它们能避免个体总是达到自己代价阈值的竞争。另一方面，在竞争中代价积累缓慢和/或较小的物种中，自我评估可能占主导。在此，我们利用不同物种中个体参与竞争方式的信息进行了一项荟萃分析。我们的目标是检验这样一个假设，即涉及高代价积累的竞争，比如对手使用武器的物种中的竞争，会有利于相互评估策略的进化，而代价较低的竞争，比如无身体接触的竞争，应该有利于自我评估策略的进化。我们获得了涵盖36个物种的80个效应量。与我们的假设相反，我们发现高代价竞争的物种一直采用自我评估策略，而低代价竞争的物种没有呈现出一致的评估策略。我们认为，高代价竞争可能在那些经历失败或选择逃离竞争的个体繁殖成功率会大幅下降的物种中进化。因此，个体无论对手如何都将被迫参与竞争。然而，在低代价竞争中，我们认为针对特定评估策略的任何潜在选择压力都有所放松，这可以解释在这类竞争中观察到的评估策略的多样性。
