Scholarlink

<p>Geographic isolation is a key driver of adaptive divergence in freshwater fishes, yet the mechanisms through which habitat heterogeneity shapes growth strategies and life-history traits remain incompletely understood. This study combined growth allometry, condition factor analysis, and otolith microchemistry to investigate these processes across three isolated populations of <i>Megalobrama terminalis</i> in Southern China (XR: Pearl River; MY: Moyang River; WS: Wangquan River). The WS population displayed marked ecological divergence, characterized by miniaturization—reflected in a juvenile-dominated age structure and a scarcity of individuals older than 5 + years—along with negative allometric growth and a low condition factor. Otolith microchemistry revealed distinct environmental signatures in WS, indicated by elevated Sr:Ca and Ba:Ca ratios consistent with estuarine salinity gradients and temperature-mediated barium bioavailability. In contrast, negligible differences between XR and MY suggested buffering effects from hydrological connectivity. The pronounced divergence in WS underscores the role of the Qiongzhou Strait as a biogeographic barrier. Life-history strategies also differed fundamentally: WS adopted a fully resident brackish-water strategy (Type I), potentially spawning in intertidal areas, whereas XR exhibited partial migration. However, dam construction has fragmented XR habitats, promoting a shift among upstream populations toward a novel freshwater-resident strategy (Type II)—demonstrating human-mediated adaptive divergence. Migratory groups (Type III) retained the ancestral “freshwater spawning–estuarine growth” pattern linked to ontogenetic dietary shifts. These findings illustrate how habitat heterogeneity and isolation interact to drive adaptive divergence in growth allocation, physiological tolerance, and life-history plasticity, offering key insights for conserving riverine biodiversity under increasing anthropogenic pressure.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Divergent life-history traits in three geographically isolated populations of a migratory fish (Megalobrama terminalis)

  • 期刊论文

  • 发表日期：

    2026年2月18日

查看全文
  • Yaqiu Liu,
  • Jianhua Li,
  • Dongming Lin,
  • Xinhui Li,
  • Huifeng Li,
  • Yuefei Li,
  • Shuli Zhu,
  • Yiqing Song,
  • Jie Li

摘要

Geographic isolation is a key driver of adaptive divergence in freshwater fishes, yet the mechanisms through which habitat heterogeneity shapes growth strategies and life-history traits remain incompletely understood. This study combined growth allometry, condition factor analysis, and otolith microchemistry to investigate these processes across three isolated populations of Megalobrama terminalis in Southern China (XR: Pearl River; MY: Moyang River; WS: Wangquan River). The WS population displayed marked ecological divergence, characterized by miniaturization—reflected in a juvenile-dominated age structure and a scarcity of individuals older than 5 + years—along with negative allometric growth and a low condition factor. Otolith microchemistry revealed distinct environmental signatures in WS, indicated by elevated Sr:Ca and Ba:Ca ratios consistent with estuarine salinity gradients and temperature-mediated barium bioavailability. In contrast, negligible differences between XR and MY suggested buffering effects from hydrological connectivity. The pronounced divergence in WS underscores the role of the Qiongzhou Strait as a biogeographic barrier. Life-history strategies also differed fundamentally: WS adopted a fully resident brackish-water strategy (Type I), potentially spawning in intertidal areas, whereas XR exhibited partial migration. However, dam construction has fragmented XR habitats, promoting a shift among upstream populations toward a novel freshwater-resident strategy (Type II)—demonstrating human-mediated adaptive divergence. Migratory groups (Type III) retained the ancestral “freshwater spawning–estuarine growth” pattern linked to ontogenetic dietary shifts. These findings illustrate how habitat heterogeneity and isolation interact to drive adaptive divergence in growth allocation, physiological tolerance, and life-history plasticity, offering key insights for conserving riverine biodiversity under increasing anthropogenic pressure.