Theoretical Study of Diadrmous Migration Evolution in Fish Species.

鱼类逆水洄游演化的理论研究。

• 批准号: 08640794
• 负责人: NISHIMURA Kinya
• 金额: $ 1.34万
• 依托单位: HOKKAIDO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08640794/
• 关键词: life history; diadrmous migration; osmoticregulation; freshwater; seawater; 適応度

Of roughly thirty thousand fish species, about 130 species are diadrmous that migrate between freshwater and the ocean in their life history. Diadromous fishes include two distinctly different groups ; (i) such as salmon (Salmonidae) and lamprey (Petromyzonidae) , which are born in freshwater, migrate to the ocean, and return to freshwater to spawn (anadrmous migration) ; and (ii) such as some eels (Anguillidae) and mullets (Mugilidae) , which are born in the ocean, migrate to freshwater, and return to the ocean to spawn (catadrmous migration). The existence of these contrasting directions of migration has long been perplexing. The most serous physiological barrier of diadrmous migration is maintenance of homeostasis, when fish migrate between different types of mediums. Ionic and osmotic regulation is essential, and it is well scheduled in the course of evolutionary process.I represented growth (dB/dt) and survival (dL/dt) as functions with respective to habitat type (river or sea) and body size (B). Further dL/dt was assumed as function with proportion of energy allocated (u (t)) to ionic and osmotic regulation. How fish choose energy allocating to ionic and osmotic retaliation, and how it choose habitat so as to maximize B (T) L (T) were analyzed by the Pontryagin's maximum principle, where T is a terminal time considered. Optimal habitat choice schedule exhibits optimal sea-run schedule in anadrmous species.The most interesting result acquired by the mathematical model is that individual born from large egg goes down sea earlier than that born from small egg. Several experiments and observations exhibit the same pattern. Thus it should be concluded that the result acquired by the mathematical model is heuristically robust.

在大约三万种鱼类中，大约有 130 种是淡水鱼类，在其生活史中在淡水和海洋之间洄游。产鱼鱼类包括两个截然不同的类群： (i)如鲑鱼(Salmonidae)和七鳃鳗(Petromyzonidae)，它们出生在淡水中，洄游到海洋，然后返回淡水产卵(溯河洄游)； (ii) 例如一些鳗鱼（Anguillidae）和鲻鱼（Mugilidae），它们出生在海洋中，洄游到淡水中，然后返回海洋产卵（下海洄游）。这些截然不同的移民方向的存在长期以来一直令人困惑。当鱼在不同类型的介质之间洄游时，反水洄游最严重的生理障碍是维持体内平衡。离子和渗透调节是必不可少的，并且在进化过程中得到很好的安排。我将生长（dB/dt）和生存（dL/dt）表示为与栖息地类型（河流或海洋）和体型（B）相关的函数。进一步假定 dL/dt 是分配给离子和渗透压调节的能量比例 (u (t)) 的函数。利用庞特里亚金极大值原理分析了鱼类如何选择能量分配给离子和渗透报复，以及如何选择栖息地以使B(T)L(T)最大化，其中T是考虑的终止时间。最佳栖息地选择时间表表现出产卵物种的最佳海上运行时间表。数学模型得到的最有趣的结果是，大卵出生的个体比小卵出生的个体更早下海。一些实验和观察显示出相同的模式。因此可以得出结论，数学模型获得的结果是启发式稳健的。