Department of Marine Biology, Texas A&M University, Galveston, TX, USA.
J Exp Biol. 2012 Dec 1;215(Pt 23):4166-74. doi: 10.1242/jeb.074385. Epub 2012 Aug 16.
Ontogenetic studies of vertebrate feeding performance can help address questions relevant to foraging ecology. Feeding morphology and performance can either limit access to food resources or open up new trophic niches in both aquatic and terrestrial systems. Loggerhead sea turtles are long-lived vertebrates with complex life histories that are marked by an ontogenetic shift from an oceanic habitat to a coastal neritic habitat, and a transition from soft oceanic prey to hard, benthic prey. Although considered durophagous and strong biters, bite performance has not been measured in loggerheads, nor has the ontogeny of bite performance been characterized. In the present study, we collected measurements of bite force in loggerhead turtles from hatchlings to adults. When subadults reach the body size at which the ontogenetic shift occurs, their crushing capability is great enough for them to consume numerous species of hard benthic prey of small sizes. As loggerheads mature and bite performance increases, larger and harder benthic prey become accessible. Loggerhead bite performance eventually surpasses the crushing capability of other durophagous carnivores, thereby potentially reducing competition for hard benthic prey. The increasing bite performance and accompanying changes in morphology of the head and jaws are likely an effective mechanism for resource partitioning and decreasing trophic competition. Simultaneous measurements of body and head size and the use of non-linear reduced major axis regression show that bite force increases with significant positive allometry relative to body size (straight carapace length, straight carapace width and mass) and head size (head width, height and length). Simple correlation showed that all recorded morphometrics were good predictors of measured bite performance, but an AICc-based weighted regression showed that body size (straight carapace width followed by straight carapace length and mass, respectively) were more likely predictors of bite force than head size morphometrics (head width and head length).
脊椎动物摄食性能的个体发育研究有助于解决觅食生态学相关问题。摄食形态和性能既可以限制对食物资源的获取，也可以在水生和陆地系统中开辟新的营养生态位。红海龟是具有复杂生活史的长寿脊椎动物，其生活史的特点是从海洋生境到沿海近岸生境的发育转变，以及从软海洋猎物到硬底栖猎物的过渡。尽管被认为是咀嚼性和强咬性的，但在红海龟中，咬合力的性能尚未测量，也没有描述咬合力的个体发育特征。在本研究中，我们收集了从孵化到成年的红海龟的咬合力测量值。当亚成体达到发生发育转变的体型大小时，它们的粉碎能力足以使它们能够消化许多小体型的硬底栖猎物。随着红海龟成熟和咬合力的增加，更大和更硬的底栖猎物变得可获取。红海龟的咬合力最终超过了其他咀嚼性肉食动物的粉碎能力，从而可能减少对硬底栖猎物的竞争。咬合力的增加和头部和下颚形态的伴随变化可能是资源分割和减少营养竞争的有效机制。同时测量身体和头部大小，并使用非线性简化主成分回归表明，咬合力相对于身体大小（直线甲壳长度、直线甲壳宽度和质量）和头部大小（头宽、头高和头长）呈显著正异速生长。简单相关表明，所有记录的形态参数都是测量咬合力的良好预测因子，但基于 AICc 的加权回归表明，身体大小（直线甲壳宽度，其次是直线甲壳长度和质量）比头部大小形态参数（头宽和头长）更有可能预测咬合力。
