EAPSI: The role of freshwater-marine migratory behaviors on dispersal in Pacific Oceanic Islands fishes

许多鱼类只生活在海洋或淡水环境中，但在30,000种鳍状鱼类中，约有250种是双栖的，即在淡水和咸水之间洄游，通常是为了繁殖，例如鲑鱼和鳗鱼。这种行为很重要，因为海洋岛屿上的许多小溪都受到变化的影响。风暴、干旱、火山活动和污染往往会使小岛上的小溪流在一段时间内变得不适合居住，并可能导致当地一种完全淡水物种的灭绝。随着时间的推移，无法在邻近的溪流中定居可能导致一个物种的灭绝。虽然二生境限制了它们在特定生命阶段的扩散机会，但许多二生境物种的地理分布跨越多个海洋。为了解决这些问题，本研究旨在了解迁徙模式的变化如何影响鱼类种群间的基因流动。为了确定迁移行为，将使用耳石微化学技术，并与国立台湾大学该技术的知名专家肖仁杰博士合作。然后，可以将种群之间的遗传信息水平与不同的迁移策略进行比较。种类将从台湾周围的多条溪流收集（除了关岛和帕劳）。耳石微化学是一种识别鱼类生命过程中所处环境中的化合物的技术，它将被用于将鱼类分类为双栖、海洋和淡水。为了了解这些不同的生活史模式对传播的重要性，遗传标记将用于推断岛屿海洋鱼类的基因流动和种群结构。将比较DNA序列的变化，以了解河流和岛屿之间的运动模式。这个项目将有助于弥合生命史中变异的生态重要性与基因流的进化意义之间的鸿沟。​

Many fishes are limited to marine or freshwater environments, but about 250 of 30,000 ray-finned fishes are diadromous, or migrate between fresh and saltwater, usually for reproduction purposes, e.g., Salmon and eel. This behavior is important because many small streams on oceanic islands are subject to variation. Storms, droughts, volcanic activity and pollution can often make small insular streams become uninhabitable for periods of time and can lead to local extinction of a completely freshwater species. Over time, the inability to colonize neighboring streams can lead to a species' extinction. While diadromy limits opportunities for dispersal ability to a specific life stage, many diadromous species have geographic distributions which span multiple oceans. To address these issues, this research aims to understand how variations in migration pattern affect the flow of genes across fish populations. To determine migratory behvior, otolith microchemistry techniques will be used, in collaboration with Dr. Jen-Chieh Shiao, a prominent expert in this technique at the National Taiwan University. Levels of genetic information moving between populations can then be compared to varying migration strategies. Species will be collected from multiple streams around Taiwan (in addition to Guam and Palau). Otolith microchemistry, a technique that identifies chemical compounds in a fish's environment over the course of their life, will be used to classify fishes as diadromous, marine, or freshwater. To understand the importance of these different life-history patterns on dispersal, genetic markers will be used to infer gene flow and population structure of insular oceanic fishes. Variation in DNA sequences will be compared to understand patterns of movement between streams and islands. This project will help bridge the lingering gap between the ecological importance of variation in life history and evolutionary significance of gene flow. This NSF EAPSI award is funded in collaboration with National Science Council of Taiwan.