Abstract
Divergent natural selection affecting specific trait combinations that lead to greater efficiency in resource exploitation is believed to be a major mechanism leading to trophic polymorphism and adaptive radiation. We present evidence of trophic polymorphism involving two benthic morphs within Percichthys trucha, a fish endemic to temperate South America. In a series of lakes located in the southern Andes, we found two morphs of P. trucha that could be distinguished on the basis of gill raker length and five other morphological measures, most of which are likely associated with the use of food resources. The differences were consistent across all lakes examined, and were correlated with habitat use and diet. Individuals with longer gill rakers were more abundant in the littoral zone (littoral morph) while the short gill-raker morph was more abundant at 10 m depth and deeper (deep benthic morph). Both morphs fed primarily on benthic invertebrates, but the littoral morph fed more on larval Anisoptera than did the deep benthic morph. Phenotypic correlations among traits were high for the littoral morph, but low and non-significant for the deep-benthic morph. We suggest that gill raker length may influence the relative efficiency of suction feeding for the two morphs. This is the first evidence of trophic polmorphism in fishes from temperate South America.
| Original language | English |
|---|---|
| Pages (from-to) | 191-214 |
| Number of pages | 24 |
| Journal | Biological Journal of the Linnean Society |
| Volume | 65 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - Oct 1998 |
Bibliographical note
Funding Information:We thank Miguel Battini, Amalia Denegri, and Pablo Vigliano for logistical support while conducting much of this work. We also thank Oscar Jeijo, Claudio ‘Bulon’ Knaup, and Valeria Ojeda for much appreciated assistance in the field, David Hamilton for statistical advice, and Marcos Zentilli and Jose Cembrano for assisting with information on the geology of the region. We thank Tom Miyake for help with some of the figures and E. B. Taylor for a stimulating discussion. This work would not have been possible without the cooperation of the ‘Dirección Técnica de Parques Nacionales’ and we especially thank Claudio Chehébar and Pablo Martinez for permission to collect native fish within the Parque Nacional Nahuel Huapi and Parque Nacional Lanín. SJW was supported by an Organization of American States fellowship while conducting the fieldwork. Funds for the research were provided by an NSERC (Canada) grant to SJW, and by Universidad Nacional del Comahue and ANPCYT (Argentina) grants to VEC. We especially thank Beren Robinson and a team of two anonymous referees for comments that greatly enhanced the quality of this paper. Violeta Ruzzante and Pascal and Sacha Walde Ruzzante contributed immeasurably (not standardized by size) to our enjoyment of the field work.
ASJC Scopus Subject Areas
- Ecology, Evolution, Behavior and Systematics