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<p>The coexistence of sympatric species is often attributed to differences in ecological niches, to attenuate competition in the use for limited resources. In the context of seasonal and habitat variation of food availability, species may adjust their diets to avoid competition and optimize resource partitioning. This study quantifies the feeding patterns of three sympatric native killifish species (<i>Orestias agassizii</i>, <i>Orestias luteus</i>, and <i>Orestias mulleri</i>) to understand competitive interactions and how benthic macroinvertebrate availability influences their trophic niches across different habitats and seasons. Benthic macroinvertebrate availability and gut contents were analyzed from individuals captured in inshore and offshore habitats during two contrasted seasons (wet/transition in April and dry in July). We observed temporal but not spatial differences in the composition of macroinvertebrate taxa. We characterized the fish diet using four indices (richness, diversity, diet breadth, and diet overlapping). All <i>Orestias</i> species primarily fed on amphipods (<i>Hyalella</i> spp.), with <i>O. luteus</i> and <i>O. mulleri</i> showing a micro-carnivorous inclination, mainly consuming amphipods and molluscs in the offshore zones. Conversely, <i>O. agassizii</i> exhibited a versatile omnivorous pattern. Higher diet overlap was observed among <i>Orestias</i> species in the dry season (July), indicating temporal influences. The temporal variation in diet between habitats may respond to changes in diet item abundance, particularly amphipods, underscoring the influence of diet item availability shifts on these killifish’s dietary preferences. Our findings emphasize the importance of amphipods and molluscs in the diet of <i>Orestias</i>; they also provide a basis for diet seasonality as a potential explanation for the coexistence of these sympatric species.</p>

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Dietary patterns and sympatry in Lake Titicaca (Bolivia): the role of seasonality in niche overlap between native Andean killifish

  • 期刊论文

  • 发表日期：

    2025年2月13日

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  • Erick Loayza,
  • Arturo Muñoz-Saravia,
  • Julio Pinto,
  • Carla Ibañez,
  • Marc Pouilly,
  • Geert P. J. Janssens

摘要

The coexistence of sympatric species is often attributed to differences in ecological niches, to attenuate competition in the use for limited resources. In the context of seasonal and habitat variation of food availability, species may adjust their diets to avoid competition and optimize resource partitioning. This study quantifies the feeding patterns of three sympatric native killifish species (Orestias agassizii, Orestias luteus, and Orestias mulleri) to understand competitive interactions and how benthic macroinvertebrate availability influences their trophic niches across different habitats and seasons. Benthic macroinvertebrate availability and gut contents were analyzed from individuals captured in inshore and offshore habitats during two contrasted seasons (wet/transition in April and dry in July). We observed temporal but not spatial differences in the composition of macroinvertebrate taxa. We characterized the fish diet using four indices (richness, diversity, diet breadth, and diet overlapping). All Orestias species primarily fed on amphipods (Hyalella spp.), with O. luteus and O. mulleri showing a micro-carnivorous inclination, mainly consuming amphipods and molluscs in the offshore zones. Conversely, O. agassizii exhibited a versatile omnivorous pattern. Higher diet overlap was observed among Orestias species in the dry season (July), indicating temporal influences. The temporal variation in diet between habitats may respond to changes in diet item abundance, particularly amphipods, underscoring the influence of diet item availability shifts on these killifish’s dietary preferences. Our findings emphasize the importance of amphipods and molluscs in the diet of Orestias; they also provide a basis for diet seasonality as a potential explanation for the coexistence of these sympatric species.