Wilson Robbie S, James Rob S, Bywater Candice, Seebacher Frank
School of Integrative Biology, The University of Queensland, St Lucia, QLD, 4072 Australia.
J Exp Biol. 2009 Mar;212(Pt 6):853-8. doi: 10.1242/jeb.024547.
Unreliable signals of weapon strength are considered to be problematic for signalling theory and reliable signals are predicted to be the dominant form of signalling among conspecifics in nature. Previous studies have shown that males of the Australian freshwater crayfish (Cherax dispar) routinely use unreliable signals of strength whereas females use reliable signals of weapon strength. In this study, we examined the performance benefits of increased weapon (chela) size for both males and females of C. dispar. In addition, we investigated the possibility of functional trade-offs in weapon size by assessing the relationship between chela size and maximum escape swimming performance. We found males possessed larger and stronger chelae than females and the variance in chela force was greater for males than females. By contrast, females possessed greater absolute and body length-specific escape swimming speeds than males. Swimming speed was also negatively correlated with chela size for males but not females, suggesting that a functional trade-off exists for males only. Decreases in swimming speed with increases in weapon size suggest there could be important fitness costs associated with larger chelae. Larger weaponry of males may then act as a handicap ensuring large chelae are reliable signals of quality.
武器强度的不可靠信号被认为对信号理论存在问题，而可靠信号预计是自然界中同种个体间信号传递的主要形式。先前的研究表明，澳大利亚淡水小龙虾（Cherax dispar）的雄性通常使用不可靠的力量信号，而雌性则使用可靠的武器强度信号。在本研究中，我们研究了增大武器（螯）大小对C. dispar雄性和雌性的性能益处。此外，我们通过评估螯大小与最大逃脱游泳性能之间的关系，研究了武器大小功能权衡的可能性。我们发现雄性的螯比雌性更大更强，雄性螯力的方差比雌性更大。相比之下，雌性的绝对和体长特定逃脱游泳速度比雄性更快。游泳速度对雄性而言也与螯大小呈负相关，对雌性则不然，这表明仅对雄性存在功能权衡。随着武器大小增加游泳速度降低表明，更大的螯可能存在重要的适合度成本。雄性更大的武器装备可能起到不利条件的作用，确保大螯是质量的可靠信号。
