Meeting Abstract

81.5  Wednesday, Jan. 6  Matching between dietary preferences and digestive capacity in passerine birds KOHL, K.D.*; BRZEK, P.; CAVIEDES-VIDAL, E.; KARASOV, W.H.; University of Wisconsin, Madison; University of Wisconsin, Madison; Universidad Nacional de San Luis-CONICET, Argentina; University of Wisconsin, Madison kkohl78@gmail.com

It has been argued that evolutionary shifts in diet preferences are paired with changes in digestive physiology. For example, the adaptive modulation hypothesis states that enzyme activities should match the relative levels of substrate present in an animal’s diet so as not to waste biosynthetic energy or cell membrane space with unneeded enzymes. Indeed, a previous study in birds (Martinez del Rio 1990) found interspecific variation in enzyme activities that matched species’ feeding guilds (frugivore, omnivore, nectivore, etc.). To enhance the findings of this study, we measured the activities of pancreatic, intestinal, and hepatic enzymes in six avian species where diet patterns have been extensively studied (estimated % starch and % protein). After using phylogenetic independent contrasts to analyze all data, we found that proteases (aminopeptidase-N, trypsin, chymotrypsin, alanine-aminotransferase) did not correlate with dietary protein. However, carbohydrases (amylase, maltase, sucrase) all correlated positively with % starch. This is especially interesting as short term modulation of carbohydrases by their specific substrates has for the most part not been exhibited in studies on passerine birds. Therefore, it could be that these results support the idea of evolutionary matching between activity of digestive enzymes and the prevalence of their specific substrate in an animal’s diet. Natural selection may favor a constitutive level of enzymes that reflect average intake of dietary substrates, especially those mainly supplying energy, such as carbohydrates. Supported by NSF IOS 0615678 to WHK.