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

进化中的捕食：雪松捕食对海百合的古生物学影响。来自澳大利亚蜥蜴岛和新西兰渐新世的证据。捕食通常被认为是自然选择的一个重要因素，对化石记录中捕食者-猎物相互作用的研究使我们能够评估其对进化的影响。大量的工作致力于探索在海百合生态和进化中的捕食作用。例如，有人认为，在过去的100年里，被跟踪的海鲷迁移到深水区（Bottjer & Jablonski 1988）是捕食压力增加的结果，特别是来自碎壳鱼的捕食压力增加（Meyer & Macurda 1977; Meyer 1985; Oji 1996）。相比之下，有人认为，今天在浅水中茁壮成长的无茎科菊科植物的成功是由于它们应对捕食压力的能力（Meyer & Macurda 1977）。在处理捕食压力方面，有柄的海百合和普通海百合的差异通常归因于后者身体部位的脱毛和再生能力以及运动能力。然而，最近人们发现，今天？在有柄的海百合中占主导地位的是异纹海百合，它们也有快速爬行的能力（Baumiller & Messing 2007），这一特征通常与无柄的纯种海百合有关。也有研究表明，这些异辛烷类物质会被类鳄梨海胆捕食（Baumiller et al. 2008）。作为与cidaroid相互作用的响应，异碱类化合物从茎的锚定末端脱落，并从全神贯注于脱落的茎部分的cidaroid上爬开。这个蜥蜴?年代尾巴?逃避策略不仅将一系列行为特征（脱梗和爬行）与捕食联系起来，而且表明在评估海鲷的生态和进化历史时需要考虑底栖捕食者，如cidaroids。本研究的主要目的是确认cidaroid捕食海百合（咬痕和骨折模式）的直接代理的稳健性。这将包括研究活的类鳄梨如何用它们的牙齿和肠道处理类海百合物质。这将在澳大利亚的蜥蜴岛研究站（LIRS）进行实验。同样在LIRS，其他潜在的捕食者（如鱼类和甲壳类动物）对海百合材料的处理将被探索，以了解这些不同的捕食者是否会在海百合猎物的骨骼上留下独特的印记。研究的实验部分之后，将探索化石记录，以寻找这种捕食者-猎物相互作用的历史证据。具体而言，将研究Kokoamu砂岩（渐新世；新西兰南岛）的潜行海百合，以寻找cidaroid损伤的证据。之所以选择Kokoamu砂岩，是因为它含有丰富的海百合柱状体，以及cidaroid， histidaris的遗迹，最近在其肠道中发现了海百合元素。如果成功，本研究的结果将为追求更大的目标奠定基础：(1)通过对已知与cidaroid echinoids共存的地方的百合茎遗骸的研究，通过地质时间探索这种相互作用的历史；(2)分析与茎脱落和爬行相关的特征的形态学；(3)在这些“逃逸性”的背景下，研究百合的多样性趋势。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.