Revista Chilena de Historia Natural 80 (4): 431-437, 2007
RESEARCH ARTICLE
Trophic niche overlap between two Chilean endemic species of Trichomycterus
(Teleostei: Siluriformes)
Trichomycterus areolatus and Trichomycterus chiltoni are
endemic siluriform fishes of Chile. They are the only Chilean species of this genus that live in sympatry and coexist in the Biobío basin.
High trophic niche overlap between both species was found. Horn’s index varied from 0.668 to 0.885 among seasons, without
significant differences, and Schoener’s index varied from 0.639 to 0.912. Also the discriminant analysis showed no significant
differences in prey item between the two species. Trophic composition of T. chiltoni and T. areolatus
consisted mainly in chironomid larvae and other aquatic invertebrates. At all seasons T. chiltoni
showed the greatest prey richness. Principal component analysis (PCA) showed a high similarity between diets of T.
areolatus and T. chiltoni. These diet scores were significantly related with body size in T. chiltoni
whereas T. areolatus showed a significant relationship with seasons. This may indicate a generalist strategy in
T. areolatus by varying its diet in function of available prey items in each season, whereas T. chiltoni
would be specialized in relation to individual size and intraspecific habitat partitioning.
Key words:
diet, sympatry,
Trichomycterus areolatus, Trichomycterus chiltoni
