Presumptive environmental effects on body shape of Aplochiton zebra (Pisces, Galaxiidae) in northern Patagonian lakes

Abstract

The family Galaxiidae exhibits a marked tendency toward morphological variation, particularly in characteristics related to feeding and caudal propulsion. The body shape of Aplochiton zebra from six Andean water bodies was examined and related to diet and to environmental characteristics such as transparency and predation risk. Although adults and larger juveniles showed no inter-lake dependence in their morphology, smaller juveniles (SL < 40 mm) did show differences in eye diameter and dorsal fin length. Aplochiton zebra juveniles from Lake Puelo, where transparency showed the minimum value, have the largest eyes; those from Lake Futalaufquen with high transparency values have the smallest eyes. No clear relationship to predation risk was established. In Futalaufquen, Puelo and Rivadavia lakes the relationship between the principal components for morphology and for diet indicates, at least in part, that variation in body shape – and particularly traits related to swimming ability – could be related to diet.