BRC-BIO: Pick your poison: The physiological cost of alkaloid sequestration in dendrobatid poison frogs

生物体通常具有适应其所处环境的生理功能。然而，由于人类活动和气候变化，许多栖息地正在迅速变化。这些变化可能会影响物种在以前足够的环境中持续生存的能力。Dendrobatidae家族的毒蛙很有魅力，因为它们鲜艳的颜色和独特的能力将生物碱防御从它们的自然食物--螨类和蚂蚁--中隔离出来。青蛙使用这些生物碱作为一种化学防御手段来抵御捕食者和微生物，但人们对开发这些防御手段的生理成本知之甚少。更具体地说，生物碱的封存如何影响个体生存所需的能量？反过来，这又如何影响青蛙与环境的互动，比如它们需要花费多少时间寻找食物或寻找配偶？青蛙是变温的，这意味着环境温度的变化将直接影响它们的体温。随着温度的升高，代谢率也会提高，这将需要青蛙获得更多的能量(例如，吃更多的食物)或利用不同的热微生境。因此，气候变化导致的气温上升有可能增加青蛙生物碱封存的成本。目前的项目旨在建立一个职业学习体系，根植于本科生和社区成员的参与。本科生将接受学习生理学和化学生态学的尖端技术培训。青蛙的魅力还将允许开展外展活动，让社区了解生态生理学和保护。两栖动物特别容易受到气候变化的影响，因为它们的生理，特别是呼吸和新陈代谢的其他方面，取决于特定的温度和湿度条件。Dendrobatidae家族中的新热带毒蛙也有特殊的生理功能，使它们能够隔离食物中的生物碱，用作化学防御。这个BRC-BIO项目的目标是量化树蛙对生物碱的固定如何影响与生态相关的生理过程，如新陈代谢。为了实现这一目标，将在斯克兰顿大学建立一个由10种树形动物组成的繁殖群体，用于检验三个基本假设：(1)生物碱的固定会产生生理成本，从而导致代谢率和能量消耗增加；(2)代谢率的变化会因蛙类的不同而有所不同，因为生物碱的固定在家族内经历了多次进化；以及(3)代谢率将随着生物碱的固定数量而成比例增加。这些假说将通过为青蛙提供对照或添加生物碱的饲料，并通过测量和比较二氧化碳产生和氧气消耗的速率来量化每只青蛙的代谢率来验证。Dendrobatis天然含有20多种不同类型的生物碱，因此将测量各种生物碱及其对生理的影响。这个BRC-BIO项目产生的数据，与青蛙繁殖群体的发展相结合，将继续支持其他问题，重点是学生主导的独立项目、本科课程中的新生理学实验，以及与社区和K-12学校的联系。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Organisms typically have physiologies adapted to the environments that they inhabit. However, many habitats are rapidly changing due to human activities and climate change. These changes can impact species’ ability to persist in previously adequate environments. Poison frogs in the family Dendrobatidae are charismatic because of their bright colors and unique ability to sequester alkaloid defenses from their natural diet of mites and ants. The frogs use these alkaloids as a chemical defense against predators and microbes, yet little is known about the physiological costs associated with developing these defenses. More specifically, how does alkaloid sequestration influence the energy requirements for individuals to survive? And in turn, how does this impact how frogs interact with their environment such as how much time they need to spend foraging for food or finding a mate? Frogs are poikilothermic, which means changes to environmental temperature will directly impact their body temperature. As temperature increases, so does metabolic rate, which will require frogs to acquire more energy (for example, eat more food) or utilize different thermal microhabitats. Therefore, increases in temperature due to climate change have the potential to increase the cost of alkaloid sequestration for frogs. The current project aims to establish a career study system, rooted in involving undergraduate students and community members. Undergraduate students will be trained in cutting edge techniques for studying physiology and chemical ecology. The charismatic nature of the frogs will also allow for outreach events, engaging the community to learn about ecophysiology and conservation. Amphibians are especially susceptible to climate change as their physiologies, specifically respiration and other aspects of metabolism, are dependent on specific temperature and moisture conditions. Neotropical poison frogs in the family Dendrobatidae also have specialized physiologies that allow them to sequester dietary alkaloids to be used as chemical defenses. The goal of this BRC-BIO project is to quantify how alkaloid sequestration by dendrobatid frogs impacts ecologically relevant physiological processes, such as metabolism. To accomplish this goal, a breeding colony of 10 species of dendrobatids will be established at The University of Scranton, which will be used to test three primary hypotheses: (1) sequestration of alkaloids has a physiological cost that will result in increased metabolic rate and energy expenditure; (2) changes in metabolic rate will vary by frog lineage, as alkaloid sequestration has evolved multiple times within the family; and (3) metabolic rate will increase proportionally with the quantity of alkaloid sequestered. These hypotheses will be tested by providing frogs with a control or alkaloid-supplemented diet and quantifying individual frog’s metabolic rate by measuring and comparing rates of carbon dioxide production and oxygen consumption. Dendrobatids naturally possess more than 20 different types of alkaloids, and therefore a diversity of alkaloids and their effects on physiology will be measured. The data generated by this BRC-BIO project, in conjunction with the development of a frog breeding colony, will continue to support additional questions with an emphasis on student-led independent projects, novel physiology experiments in undergraduate courses, and outreach with the community and K-12 schools.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.