Department of Biology, Graduate School of Sciences, Kobe University, 1-1 Rokkodai, Nada-ku, Kobe 657-8501, Japan.
Center for Ecological Research, Kyoto University, Hirano 2-509-3, Otsu, Shiga 520-2113, Japan.
Proc Biol Sci. 2023 Mar 29;290(1995):20230126. doi: 10.1098/rspb.2023.0126. Epub 2023 Mar 22.
The influence of resource subsidies on animal growth, survival and reproduction is well understood, but their ultimate effects on life history have been less explored. Some wild species have a partially migratory life history, wherein migration is dictated based upon threshold traits regulated in part by the seasonal availability of resources. We conducted a large-scale field manipulation experiment where we provided a terrestrial invertebrate subsidy to red-spotted masu salmon. Individuals in stream reaches that received a subsidy had, on average, a 53% increase in growth rate relative to those in control reaches. This increased growth resulted in a greater proportion of individuals reaching the threshold body size and smolting in the autumn. Consequently, 19-55% of females in subsidized reaches became migratory, whereas 0-14% became migratory in the control reaches. Our findings highlight seasonal ecosystem linkage as a key ecosystem property for maintaining migratory polymorphism in partially migratory animals.
资源补贴对动物生长、存活和繁殖的影响众所周知，但它们对生活史的最终影响却鲜少被探讨。一些野生动物具有部分洄游的生活史，其中迁徙是基于受资源季节性供应部分调节的阈值特征来决定的。我们进行了一项大规模的野外操作实验，向红大麻哈鱼提供了一种陆地无脊椎动物补贴。与对照区相比，接受补贴的溪流区个体的生长速度平均提高了 53%。这种生长的增加导致了更多的个体达到了阈值体型并在秋季变为幼鲑。因此，在受补贴的区域中，有 19-55%的雌性变为洄游性，而在对照区域中，0-14%的雌性变为洄游性。我们的研究结果强调了季节性生态系统联系作为维持部分洄游动物洄游多态性的关键生态系统特性。
