SGER: Predation in evolution: paleobiological consequences of cidaroid predation on crinoids

进化中的捕食：西达类捕食对海百合的古生物学后果。来自澳大利亚蜥蜴岛和新西兰渐新世的证据T。 K. Baumiller 捕食被普遍认为是自然选择的重要因素，对化石记录中捕食者与猎物相互作用的研究使我们能够评估其进化影响。 大量工作致力于探索捕食在海百合生态和进化中的作用。 例如，有人认为，在过去约 100 年内，有柄海百合向深水迁移（Bottjer & Jablonski 1988）是捕食压力增加的结果，特别是来自碎壳鱼类的捕食压力（Meyer & Macurda 1977；Meyer 1985；Oji 1996）。 相比之下，有人认为，如今在浅水中繁衍生息的无柄海百合的成功是由于它们应对捕食压力的能力（Meyer & Macurda 1977）。海百合和海百合在应对捕食压力方面的差异通常归因于后者的身体部位脱落和再生能力以及运动能力。然而，最近发现，当今有柄海百合的优势群体异海百合也能够快速爬行（Baumiller & Messing 2007），这一特征通常与无柄海百合有关。研究还表明，这些异百里香科海胆会受到西达类海胆的捕食（Baumiller 等人，2008 年）。 响应于与 cidaroid 的相互作用，isocrinids 脱落茎的锚定端并爬离全神贯注于脱落茎部分的 cidaroid。 这是“蜥蜴”的尾巴吗？逃逸策略不仅将一系列行为特征（茎脱落和爬行）与捕食联系起来，而且表明在评估海百合的生态和进化历史时需要考虑底栖捕食者，例如西达类。这项研究的主要目标是确认西达类对海百合的捕食直接代理的稳健性（咬痕和骨折模式）。 这将涉及研究活体西达类动物如何用牙齿和肠道处理海百合物质。 这将在澳大利亚蜥蜴岛研究站（LIRS）进行实验。 此外，LIRS 还将探索其他潜在捕食者（例如鱼类和甲壳类动物）对海百合材料的加工，以了解这些不同的捕食者是否在海百合猎物的骨骼上留下独特的特征。 该研究的实验部分随后将探索化石记录，寻找这种捕食者与猎物相互作用的历史证据。 具体来说，我们将研究 Kokoamu 砂岩（渐新世；新西兰南岛）的有柄海百合，以寻找西达类损害的证据。 之所以选择 Kokoamu 砂岩，是因为它含有丰富的海百合柱状结构以及西达类动物 Histocidaris 的遗骸，该类群最近在其肠道中发现了海百合元素。 如果成功，这项研究的结果将成为追求更大目标的基础：（1）通过检查海百合茎的遗迹来探索整个地质时期这种相互作用的历史，这些海百合茎来自已知与海百合共生的地区，（2）分析海百合的形态，以了解与茎脱落和爬行相关的特征，以及（3）在这些“逃避性”的背景下检查海百合的多样性趋势。特征和互动频率。

Predation in evolution: paleobiological consequences of cidaroid predation on crinoids.Evidence from Lizard Island, Australia and the Oligocene of New ZealandT. K. BaumillerPredation is generally recognized as an important agent of natural selection and the study of predator-prey interactions in the fossil record allows us to evaluate its evolutionary impact. A large body of work has been devoted to exploring the role of predation in crinoid ecology and evolution. For example, it has been argued that the displacement of stalked crinoids to deep water over the past ~100my (Bottjer & Jablonski 1988) was the result of increased predation pressure, especially from shell-crushing fish (Meyer & Macurda 1977; Meyer 1985; Oji 1996). In contrast, it has been suggested that the success of the stalkless comatulid crinoids that today thrive in shallow water is due to their ability to deal with predation pressure (Meyer & Macurda 1977). The differences in handling predation pressure by stalked crinoids and comatulids have generally been attributed to the ability to shed and regenerate body parts and locomotory abilities of the latter. However, recently it has been discovered that today?s dominant group of stalked crinoids, the isocrinids, are also capable of rapid crawling (Baumiller & Messing 2007), a trait generally associated with stalkless comatulid crinoids. It also has been shown that these isocrinids are subject to predation by cidaroid sea urchins (Baumiller et al. 2008). In response to the interaction with a cidaroid, isocrinids shed the anchored end of the stalk and crawl away from the cidaroid which is preoccupied with the shed stalk portion. This ?lizard?s tail? strategy of escape not only links a set of behavioral traits (stalk shedding and crawling) to predation, but suggests that benthic predators, such as cidaroids, need to be considered in assessing the ecological and evolutionary history of crinoids. The major goal of this study is to confirm the robustness of a direct proxy for cidaroid predation on crinoids (bite marks and fracture patterns). This will involve studying how living cidaroids process crinoid material with their teeth and in their gut. This will be done experimentally at the Lizard Island Research Station (LIRS), Australia. Also at LIRS, the processing of crinoid material by other potential predators, such as fish and crustaceans, will be explored to see whether these different predators leave unique signatures on the skeletons of their crinoid prey. The experimental portion of the study will be followed by exploring the fossil record for historical evidence of this predator-prey interaction. Specifically, stalked crinoids of the Kokoamu Sandstone (Oligocene; South Island, New Zealand) will be studied for evidence of cidaroid damage. The Kokoamu Sandstone was chosen because it contains abundant crinoid columnals as well as remains of the cidaroid, Histocidaris, the very taxon which in the Recent was found with crinoid elements in its gut. If successful, the results of this study will serve as the basis for pursuing larger goals: (1) to explore the history of this interaction through geologic time by examining remains of crinoid stalks from localities where they are known to co-occur with cidaroid echinoids, (2) analyze the morphology of crinoids for traits associated with stalk shedding and crawling, and (3) examine diversity trends of crinoids in the context of these ?escapability? traits and the frequency of interaction.