Is diet-shifting facilitated by modulation of pancreatic enzymes? Test of an adaptational hypothesis in yellow-rumped warblers

Citation
Me. Ciminari et al., Is diet-shifting facilitated by modulation of pancreatic enzymes? Test of an adaptational hypothesis in yellow-rumped warblers, AUK, 118(4), 2001, pp. 1101-1107
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Animal Sciences
Journal title
AUK
ISSN journal
0004-8038 → ACNP
Volume
118
Issue
4
Year of publication
2001
Pages
1101 - 1107
Database
ISI
SICI code
0004-8038(200110)118:4<1101:IDFBMO>2.0.ZU;2-H
Abstract
Many birds exhibit seasonal switches in diet and thus alter nutrients predo minating their food intake. We tested for dietary modulation of pancreatic enzymes in Yellow-rumped Warblers (Dendroica coronata), a species for which such dietary changes are documented. Birds were fed three diets formulated from either fruit, insect, or seed. We predicted that pancreatic carbohydr ase amylase, and the proteases trypsin and chymotrypsin, would be modulated in direct correlation with relative levels of dietary carbohydrate and pro tein, respectively. In contrast to the prediction, there was no significant dietary effect on activities of amylase and chymotrypsin, and a significan t change in trypsin activity (highest on seed diet) occurred in the wrong d irection with regard to the prediction. Considering the statistical power o f our tests, we conclude that Yellow-rumped Warblers represent a case of on ly modest ability, at best, to modulate pancreatic enzymes. For some diets, especially high-starch diets that they digest relatively poorly and on whi ch they tend to lose body mass, they may lack sufficient enzyme and hence a re constrained in their dietary niche.