02493nab a2200349 a 4500003000900000005001700009008004100026041000800067100002400075700002100099700002400120700002100144700002200165700002200187700002300209245019300232264000900425300001700434500004100451520141300492650001401905650001401919650001001933650002001943650001801963650002401981650001102005773006802016035001702084001000702101040003502108AR-ReUNN20260702003057.0260630s2006    ag |||||||||||||||||eng  0 aeng1 aMacchi, Patricio J.1 aWalde, Sandra J.1 aRuzzante, Daniel e.1 aIverson, Sara J.1 aLogan, Matthew S.1 aCussac, Victor e.1 aAlonso, Marcelo F.10aLong term diet differences between morphs in trophically polymorphic Percichthys trucha - Pisces : Percichthyidae - populations from the southern Andes [PDF] / Matthew S. Logan ...[et al.] 1c2006  a18 páginas  aDisponible en caja 14 no 4 de INICNE  aDivergent natural selection is often believed to be the driving force behind phenotypic differentiation in characters related to resource acquisition, leading to trophic polymorphism in fishes. Here we use variation in the fatty acid composition of adipose and muscle tissues to look at differences in resource use by two recently described sympatric morphs ofPercichthys trucha , a common freshwater fish of the Andean and Patagonian regions of South America. Because dietary fatty acids are often stored in carnivorous animals with little modification after consumption, they can be used to infer information about dietary habits of individuals. We found that the two morphs differed in the overall composition of fatty acids in both adipose and muscle tissue, but that there were some differences in how the morphs differed in lakes from the northern vs southern part of the range. Furthermore, we found that certain fatty acids were correlated with diet as determined by gut content analysis. Consumption of anisopteran larvae was highly correlated with 14:0 in adipose and muscle tissue; and higher levels of longer chain unsaturated fatty acids (i.e. 20 and 22 carbons) were correlated with the presence of fish and also amphipods in the diets. Taken together, the results suggest that there are marked differences in the foraging ecology of the two morphs of P. trucha inhabiting southern Andean lakes 4aArgentina 4aPatagonia 4aDiets 4aFreshwater Fish 4aInland Waters 4aPeces de Agua Dulce 4aDietas0 tBiological Journal of the Linnean Societygv. 69 (2000)w234706  a(INICN)36136234707  aAR-ReUNNbspacAR-ReUNNeaacr2