An expanded predator-prey community model, its application to dinosaur coummunities, and selection for giant body size in sauropods

兽脚亚目动物捕食大型蜥脚类动物的照片主导了公众对恐龙生态系统的看法，但现代捕食者-猎物大小动力学能否证实这一观点仍存在争议。虽然众所周知，相对能量需求（每单位体重）随着体重的增加而减少，但很少有文献记载体型越大的捕食者的猎物尺寸相应减少。相反，猎物的相对大小似乎要么随着捕食者体型的增加而增加，要么保持不变。群落食物网通常以三角形的方式构建，体型越来越大的捕食者以体型比自己小的所有猎物为食。然而，大型陆生哺乳动物捕食者的数据表明情况并非如此。我们将扩展目前陆生脊椎动物捕食者-猎物大小关系的模型，基于有关时间-能量预算、密度和相遇率以及猎物脆弱性（由敏捷性和运动决定）的生理模型，研究超过或低于捕食者不再接受的猎物大小阈值。这个阈值将用于扩展捕食者-猎物群落模型，超越通常的“三角形”方法。模型将通过生理和社区数据集进行验证。研究结果将用于重建基于生理假设（如敏捷性和新陈代谢）的捕食者-猎物关系的恐龙生态系统。重建还将包括猎物生产力的场景和追踪蜥脚类动物对捕食者的个体发生易感性的场景，测试它们的快速生长速度和成年巨人的影响。

Pictures of theropods preying on large sauropods dominate the public conception of the dinosaur ecosystem, but modern predator-prey size dynamics that would corroborate this view remain under debate. Although it is well known that relative energy requirements (per unit body mass) decrease with increasing body mass, a corresponding decrease in the prey size of predators of increasing size is rarely documented. Instead, relative prey size appears to either increase with predator body size or remain constant. Community foodwebs are usually constructed in a triangular way, with predators of increasing body mass feeding on the whole range of prey below their own body size. However, data for large mammalian terrestrial predators indicate otherwise. We will expand current models of predator-prey size relationships for terrestrial vertebrates, basing a physiological model on first principles concerning time-energy budgets, densities and encounter rates, and prey vulnerability as determined by agility and locomotion, to investigate a size threshold above and below which prey is no longer acceptable for a predator. This threshold will be used to expand a predator-prey community model beyond the usual ‘triangular’ approach. Models will be validated by physiological and community datasets. The results will be used for a reconstruction of dinosaur ecosystems in terms of predator-prey relationships that are based on physiological assumptions (such as to agility and metabolism). The reconstructions will also include scenarios of prey productivity and scenarios that trace the ontogenetic susceptibility of sauropods to predators, testing the effect of their fast growth rates and adult gigantism.