Baliga Vikram B, Mehta Rita S
Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California Santa Cruz, Santa Cruz, CA 95060, USA
Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California Santa Cruz, Santa Cruz, CA 95060, USA.
J Exp Biol. 2014 Oct 15;217(Pt 20):3597-606. doi: 10.1242/jeb.107680. Epub 2014 Sep 4.
In fishes, cleaning is a mutualistic behavior wherein a species will remove and consume ectoparasites from other organisms. More than two-thirds of cleaner fishes display this behavior predominately as juveniles and discontinue cleaning as adults; such species are here referred to as 'facultative cleaners'. Whether allometric changes in morphological traits coincide with ontogenetic shifts away from cleaning is unknown. We tested the hypothesis that transitions away from cleaning are associated with scaling patterns in the feeding apparatus of facultative cleaners, and then compared such patterns with those exhibited by non-cleaner congeners. We measured functional traits related to feeding, such as vertical gape distance, premaxillary protrusion distance and maxillary kinematic transmission coefficient (KT) in each ontogenetic series of 11 Thalassoma wrasses (Labridae). As these fishes predominately capture prey via biting, we modeled bite force using MandibLever (v3.3) to create an ontogenetic trajectory of bite force for each species. Our results indicate that cleaner fishes in Thalassoma, as juveniles, possess jaws with low mobility that exhibit weaker bite forces. Additionally, there was remarkable consistency in the range of body lengths over which we observed significant differences between facultative cleaners and non-cleaners in bite force, vertical gape distance and premaxillary protrusion distance. Through ontogeny, facultative cleaner fishes exhibit positive allometry for a number of functionally important feeding traits, which possibly obviates the need to continue cleaning.
在鱼类中，清洁是一种互利行为，即一个物种会从其他生物体上清除并消耗体外寄生虫。超过三分之二的清洁鱼在幼年时主要表现出这种行为，成年后则停止清洁；这类物种在此被称为“兼性清洁鱼”。形态特征的异速生长变化是否与个体发育过程中远离清洁行为的转变相一致尚不清楚。我们检验了这样一个假设：远离清洁行为的转变与兼性清洁鱼摄食器官的缩放模式有关，然后将这些模式与非清洁同属鱼类所表现出的模式进行比较。我们测量了11种海猪鱼（隆头鱼科）每个个体发育阶段与摄食相关的功能特征，如垂直口裂距离、前上颌骨突出距离和上颌运动传递系数（KT）。由于这些鱼主要通过咬来捕获猎物，我们使用MandibLever（v3.3）对咬合力进行建模，以创建每个物种咬合力的个体发育轨迹。我们的结果表明，幼年时，海猪鱼属的清洁鱼颌骨活动度低，咬合力较弱。此外，在兼性清洁鱼和非清洁鱼的咬合力、垂直口裂距离和前上颌骨突出距离存在显著差异的体长范围内，具有显著的一致性。在个体发育过程中，兼性清洁鱼在一些功能上重要的摄食特征上表现出正异速生长，这可能消除了继续清洁的必要性。
