DISSERTATION RESEARCH: Experimental miniaturization of guppy offspring

本项目将研究在两种可能的原因中，即喂养困难或发展限制，哪一种是负责设定鱼的大小下限的原因。这些发现将有助于测试生活史进化理论，并为海洋渔业招募的限制提供发育和功能方面的见解。个体的大小跨越了许多数量级，但受到物理学原理的限制。随着生物体变得越来越小，它们周围的世界对它们的运动变得越来越有阻力，这被认为是限制鱼类后代的大小不小于4.5毫米。另外，出生时的大小也与达到成熟所需的时间有关。本项目将使用孔雀鱼作为模型系统来测试这些替代方案。该项目包括本科生指导和研究培训。此外，该项目将利用孔雀鱼作为当地高中课堂进化和生态学教学的模型。该项目涉及两个小型化操作：流体动力学和发展。在第一次操作中，研究人员将使用葡聚糖增加水的粘度，从而有效地使后代的大小变小，但不会发育。在第二种操作中，研究人员将从发育中的胚胎中取出蛋黄，从而使年轻人过早地分娩。因为孔雀鱼是活的，卵黄操作需要在体外培养孔雀鱼胚胎，以便进入卵黄囊。用一个拉毛细管，蛋黄将被删除，使孔雀鱼胚胎将被迫饲料外源性在约4.4毫米。饲料率将比较之间的流体动力学和发展的操作，以确定如果大小或成熟度是限制功能时，悬浮的食物项目喂养。将使用高速视频拍摄喂食试验，以测量钳口运动学并确定吸入喂食期间喂食装置运行的雷诺数。

This project will examine which of two possible causes, difficulty in feeding or constraints on development, are responsible for setting the lower limit for the size of fish. The findings will help test theories of life-history evolution, and provide developmental and functional insights into limitations on recruitment in marine fisheries. The size of individuals spans many orders of magnitude, but is constrained at the large and small extremes by principles of physics. As organisms become smaller, the world surrounding them becomes more resistive to their movements, which are thought to limit the size of fish offspring to no smaller than 4.5 mm. At this size, fish larvae experience difficulty feeding. Alternatively, size at birth is also related to the time it takes to reach maturity. This project will test these alternatives using guppies as a model system. The project incorporates undergraduate mentoring and research training. Additionally, the project will utilize the guppy as a model for the teaching of evolution and ecology within local high school classrooms. This project involves two miniaturization manipulations: hydrodynamic and developmental. In the first manipulation, the researchers will increase the viscosity of water using dextran, thereby effectively miniaturizing the offspring in size, but not development. In the second manipulation, the researchers will remove yolk from the eggs of developing embryos, thereby miniaturizing and prematurely delivering the young. Because guppies are live bearing, the yolk manipulation requires culturing guppy embryos in vitro in order to access the yolk sac. With a pulled capillary tube, yolk will be removed such that guppy embryos will be forced to feed exogenously at approximately 4.4 mm. Feeding rates will be compared between the hydrodynamic and developmental manipulations to determine if size or maturity is the limiting feature when feeding on suspended food items. Feeding trials will be filmed using high-speed video to measure jaw kinematics and determine the Reynolds number under which the feeding apparatus is operating during suction feeding.