Darrin Hulsey C
Center for Population Biology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
Proc Biol Sci. 2006 Mar 22;273(1587):669-75. doi: 10.1098/rspb.2005.3375.
The pharyngeal jaw of cichlids may represent a key innovation that facilitated their unparalleled trophic divergence. In cichlids, 'fusion' of the lower pharyngeal jaw (LPJ) results from suturing between the two lower ceratobranchials. To examine, what novel abilities a more extensively fused pharyngeal jaw may confer, the function of LPJ suturing was examined in Heroine cichlids. Greater LPJ suturing, pharyngeal jaw splitting under compression and the forces used to crush molluscs in the wild suggest increased LPJ fusion in the trophically polymorphic Herichthys minckleyi operates to strengthen the pharyngeal jaw. Among Heroine cichlid species, the presence of an external LPJ suture and feeding specialization on molluscs was evolutionarily quite variable, but greater LPJ fusion estimated from the amount of external suturing was highly correlated with molluscivory. Throughout cichlid diversification, increased pharyngeal jaw fusion via suturing has likely helped to reinforce the LPJ during pharyngeal processing thereby facilitating the ability of cichlids to exploit durable prey.
丽鱼科鱼类的咽颌可能代表了一项关键创新，这一创新促进了它们无与伦比的食性分化。在丽鱼科鱼类中，下咽颌（LPJ）的“融合”是由两个下鳃骨之间的缝合造成的。为了研究更广泛融合的咽颌可能赋予哪些新能力，我们在英雄丽鱼中研究了LPJ缝合的功能。更大程度的LPJ缝合、受压时咽颌的分裂以及在野外碾碎软体动物所使用的力量表明，食性多态的米氏赫氏丽鱼中LPJ融合程度的增加起到了强化咽颌的作用。在英雄丽鱼物种中，外部LPJ缝线的存在以及对软体动物的食性特化在进化上差异很大，但根据外部缝合量估计的更大程度的LPJ融合与食软体动物的习性高度相关。在整个丽鱼科鱼类的多样化过程中，通过缝合增加咽颌融合可能有助于在咽部处理过程中强化LPJ，从而促进丽鱼科鱼类捕食耐嚼猎物的能力。
