The Development of Adaptive Embryo Behavior

许多物种的胚胎以对生存至关重要的方式评估并对环境做出反应。胚胎生命的许多特征和挑战在动物中都是普遍存在的，但青蛙卵特别容易研究。卵囊等结构保护和限制了内部的胚胎，从而实现了成本和利益的权衡。一旦孵化，动物就进入了一个新的环境，既有新的危险，也有新的资源。何时孵化是胚胎根据环境线索做出的一个重要决定。孵化也是胚胎必须完成的一项物理壮举。随着胚胎的发育，评估信号、退出卵子以及在卵子外生存的能力都会发生变化。因此，在相同的条件下，胚胎可以做什么以及它们应该做什么来生存也会发生变化。这个项目将研究发育如何以及为什么会改变行为，使用红眼树蛙的胚胎，这些胚胎提前孵化了40%，以躲避卵子的威胁。它将评估成熟的重要性，与能力匹配的决策的适应性变化，胚胎学习，以及胚胎如何使用两种信息：氧气可获得性的简单线索和可以指示捕食者攻击的复杂振动。它将提高我们对胚胎生命、行为发育以及动物如何使用不同类型的信息做出决定的理解，包括广泛重要但知之甚少的振动信息。胚胎的适应行为是可获得和吸引人的，因此是科学教育和推广的理想选择。该项目将为研究生和本科生提供跨学科的生物工程培训，以及为美国学生和拉丁美洲实习生提供新热带研究和跨文化体验。PIS将与媒体、博物馆和动物园合作，广泛传播结果。他们将为教师提供研究经验，并为多层次的教育工作者开发在线多媒体资源。该项目开发的新方法和工具将促进其他关于胚胎行为和动物对振动提示的反应的研究。这个项目是对红眼树蛙环境线索孵化的发展和调控的综合研究，对红眼树蛙孵化时机的多个选择性权衡是已知的。胚胎使用至少两种感官模式的线索来决定孵化。较老的胚胎更容易孵化，但即使是30%--早熟胚胎有时会在提示的几秒钟内孵化。本项目将评估：i)孵化的速度和成功如何在效应器发育过程中发生变化，重点是孵化腺体；ii)传感器的发展如何改变对线索和线索性质的敏感性，解决内耳和侧线机械接收与更一致的、早期发展的氧气感应的发育变化；iii)对简单的低氧线索和复杂的振动以及潜在的触觉、物理干扰线索的反应的孵化决策规则如何通过发育变化的权衡、阶段特定选择的历史和胚胎的早期经验来形成。该团队将使用(A)组织学和显微镜来表征形态变化，(B)呼吸测量来评估新陈代谢变化，(C)前庭-眼睛反射的测量来评估耳朵功能，以及(D)宏观摄像技术来分析胚胎行为和孵化性能。他们将评估在受控缺氧、振动回放和捕食者攻击下孵化的个体发育变化，并开发新的回放方法来分离物理干扰线索的运动和触觉成分。机械感觉刺激和低氧是跨越类群孵化的常见线索。此外，振动信号和提示在许多其他环境中提供信息，在生命后期，氧气的可获得性塑造了许多水生动物的行为。红眼树蛙胚胎的结果将促进我们对行为发育和动物信息更广泛使用的理解。数据集将存放在Dryad中。包括图像和视频在内的宣传材料将发布在Warkentin的实验室网站上，或者贡献给生命百科全书或全国生物学教师协会的网页。

Embryos of many species assess and respond to their environment in ways that matter for survival. Many features and challenges of embryonic life are broadly shared across animals, but frog eggs are particularly tractable to study. Structures such as egg capsules protect and constrain the embryo inside, creating a trade-off of costs and benefits. Upon hatching, animals enter a new environment, with both new dangers and resources. When to hatch is an essential decision embryos make, based on environmental cues. Hatching is also a physical feat that embryos must perform. The ability to assess cues, to exit the egg, and to survive outside the egg all change as embryos develop. Thus, under the same conditions, what embryos can do and what they should do to survive also changes. This project will examine how and why development changes behavior, using embryos of red-eyed treefrogs that hatch up to 40% prematurely to escape threats to the egg. It will assess the importance of maturation, adaptive changes in decisions matched to abilities, embryonic learning, and how embryos use two kinds of information; simple cues of oxygen availability and complex vibrations that can indicate predator attack. It will improve our understanding of embryo lives, behavioral development, and how animals use different kinds of information to make decisions, including broadly important but poorly understood vibrational information. The adaptive behavior of embryos is accessible and appealing, and thus ideal for scientific education and outreach. This project will offer interdisciplinary biology-engineering training for graduate and undergraduate students, as well as Neotropical research and cross-cultural experiences for US students and Latin American interns. The PIs will work with the media, museums, and zoos to disseminate results broadly. They will offer research experiences for teachers and develop online multimedia resources for educators at multiple levels. New methods and tools developed by this project will facilitate other research on embryo behavior and animal responses to vibrational cues. This project is an integrative study of the development and regulation of environmentally cued hatching in red-eyed treefrogs, for which multiple selective trade-offs shaping hatching timing are known. Embryos use cues in at least two sensory modalities for their hatching decision. Older embryos hatch more readily, but even 30%-premature embryos sometimes hatch within seconds of a cue. This project will assess: I) how the speed and success of hatching change across effector development, focusing on hatching glands; II) how sensor development changes sensitivity to cues and cue properties, addressing developmental changes in mechanoreception by the inner ear and lateral line vs. more consistent, early developed, oxygen sensing; and III) how hatching decision rules for responses to simple hypoxia cues and complex vibrational, and potentially tactile, physical disturbance cues are shaped by developmentally changing trade-offs, a history of stage-specific selection, and the earlier experiences of embryos. The team will use (a) histology and microscopy to characterize morphological changes, (b) respirometry to assess metabolic changes, (c) measures of vestibulo-ocular reflexes to assess otic function, and (d) macro-videography to analyze embryo behavior and hatching performance. They will assess ontogenetic changes in hatching under controlled hypoxia, vibration playback, and predator attacks, and develop new playback methods for separating motion and tactile components of physical disturbance cues. Mechanosensory stimuli and hypoxia are common cues for hatching across taxa. Moreover, vibrational signals and cues inform behavior in many other contexts, later in life, and oxygen availability shapes the behavior of many aquatic animals. Results from red-eyed treefrog embryos will advance our understanding of behavioral development and animal information use more broadly. Datasets will be deposited in DRYAD. Outreach materials, including images and video, will be posted on Warkentin's lab website or contributed to the Encyclopedia of Life or National Association of Biology Teachers web resource page.