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<p>Morphological traits can reveal the ecological and evolutionary dynamics of species. This study examined whether external and internal traits of tetra fishes in neotropical streams were associated with their trophic niches and phylogenetic relationships. Our findings challenge the hypothesis of phylogenetic niche conservatism, revealing both convergence and divergence in morphology and resource use. Species with elongated bodies, such as <i>Bryconamericus ikaa</i> and <i>Psalidodon</i> aff. <i>paranae</i>, exhibited fewer cusps per tooth, fewer and shorter gill rakers, shorter intestines, and fewer pyloric caeca, traits linked to aquatic invertebrate assimilation. Conversely, deep-bodied species like <i>P. bifasciatus</i> and <i>P.</i> aff. <i>gymnodontus</i> had more cusps per tooth, more gill rakers, longer intestines, and more pyloric caeca, assimilating both aquatic and terrestrial invertebrates. Only <i>B. ikaa</i> showed alignment between ingestion and assimilation, reinforcing its aquatic insectivore diet. Despite plant ingestion, terrestrial plant material minimally contributed to tissue composition. Diet overlap varied, with niche shifts in generalist <i>P. bifasciatus</i> influenced more by co-occurrence than morphology. These results highlight how morphological divergence supports ecological differentiation, facilitating resource partitioning and coexistence in tetra fishes through a complex interplay of evolutionary and ecological mechanisms.</p>

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Morphological divergence and the complexity of trophic niche plasticity of tetra fishes in subtropical streams

  • 期刊论文

  • 发表日期：

    2025年10月1日

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  • Mayara Pereira Neves,
  • Pavel Kratina,
  • Clarice Bernhardt Fialho,
  • Kory M. Evans,
  • Rosilene Luciana Delariva

摘要

Morphological traits can reveal the ecological and evolutionary dynamics of species. This study examined whether external and internal traits of tetra fishes in neotropical streams were associated with their trophic niches and phylogenetic relationships. Our findings challenge the hypothesis of phylogenetic niche conservatism, revealing both convergence and divergence in morphology and resource use. Species with elongated bodies, such as Bryconamericus ikaa and Psalidodon aff. paranae, exhibited fewer cusps per tooth, fewer and shorter gill rakers, shorter intestines, and fewer pyloric caeca, traits linked to aquatic invertebrate assimilation. Conversely, deep-bodied species like P. bifasciatus and P. aff. gymnodontus had more cusps per tooth, more gill rakers, longer intestines, and more pyloric caeca, assimilating both aquatic and terrestrial invertebrates. Only B. ikaa showed alignment between ingestion and assimilation, reinforcing its aquatic insectivore diet. Despite plant ingestion, terrestrial plant material minimally contributed to tissue composition. Diet overlap varied, with niche shifts in generalist P. bifasciatus influenced more by co-occurrence than morphology. These results highlight how morphological divergence supports ecological differentiation, facilitating resource partitioning and coexistence in tetra fishes through a complex interplay of evolutionary and ecological mechanisms.