Abstract
The original distribution area of the Patagonian 'pejerrey' Odontesthes hatcheri has been subjected to the introduction of a related species; the Bonaerensean 'pejerrey' Odontesthes bonariensis. This species currently coexists with O. hatcheri in lakes and reservoirs, and can interbreed and produce fertile hybrid offspring. The purposes of this study were; a) the extensive sampling of Patagonian and Andean-Cuyan populations of pejerrey, b) the species identification according to taxonomic key, c) validation of taxonomic results on the basis of mitochondrial DNA composition, and d) applying morphometric analysis to explore the effects of hybridization and environmental conditions on body shape. Cytochrome b sequence analysis showed a high degree of genetic divergence between species and low intraspecific variation in O. hatcheri. Geometric Morphometric Analyses detected shape differences in agreement with diagnostic characteristics of each species. Putative hybrids exhibiting intermediate diagnostic characteristics were identified by Geometric Morphometric Analysis. Significant regressions between body shape and total phosphorus and altitude were found, suggesting a dependence on trophic web structure. This multi-level approach suggests the introgression of O. bonariensis into several O. hatcheri populations throughout Patagonia. Managers should take this into account when considering further exotic introductions into regions where non-native fishes have not yet become established.
Highlights
The Patagonian pejerrey, Odontesthes hatcheri (Eigenmann, 1909) is a native freshwater species from the Andean Region of southern South America (Dyer, 2000; López et al, 2008), encompassing a vast latitudinal range, from 27oS to 54oS
The closer the hatcheries participating in stocking programs (Estación de Piscicultura de Embalse and Estación de Piscicultura Río Limay) were to the sampling site, the higher the percentage of misclassified individuals
The aim of this study is to review the taxonomic status of native populations of O. hatcheri after the introduction of O. bonariensis
Summary
The Patagonian pejerrey, Odontesthes hatcheri (Eigenmann, 1909) is a native freshwater species from the Andean Region of southern South America (Dyer, 2000; López et al, 2008), encompassing a vast latitudinal range, from 27oS to 54oS. This species is commonly found in rivers, lakes, and reservoirs of both Atlantic and Pacific Patagonian drainages (Aigo et al, 2008). Odontesthes populations in Andean region carried out by three hatcheries (Estación Hidrobiológica de Chascomús 35o36’S, 58o01’W, Estación de Piscicultura de Embalse 32o13’S, 64o29’W, and Estación de Piscicultura Río Limay 38o59’S, 68o14’W) since 1930 (Dyer, 2006; Crichigno et al, 2013). The closer the hatcheries participating in stocking programs (Estación de Piscicultura de Embalse and Estación de Piscicultura Río Limay) were to the sampling site, the higher the percentage of misclassified individuals
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