Revista Chilena de Historia Natural 79 (3): 287-294, 2006
RESEARCH ARTICLE
On the relationship between sugar digestion and diet preference in two Chilean avian species
belonging to the Muscicapoidea superfamily
It has been hypothesized that species belonging to the Sturnidae-Muscicapidae lineage,
despite having generalist diets comprising fruits with sugars of diverse kinds, do not express intestinal sucrase. In order to increase the
taxonomical range of species for which sucrase intestinal activity has been investigated, we analyzed the relationship between
enzymatic activity (sugar digestion) and feeding preference for native fruits containing sucrose, in two South American members of the
superfamily Muscicapoidea, the Austral thrush (Turdus falcklandii) and the Chilean mockingbird (Mimus
thenca). We hypothesized that these birds would lack intestinal sucrase activity and that in preference tests they would reject
sucrose solutions. Both thrushes and mockingbirds lacked significant intestinal sucrase activity. Considering the phylogenetic
constraint hypothesis for sucrose digestion in the Muscicapoidea superfamily, our results support the notion that lack of sucrase
activity is a shared derived-character only for the Cinclidae-Sturnidae-Turdinae lineage, and suggests that the selective pressure that
these birds can exert on the plants whose seeds they disperse and whose flowers they visit are consistent across world hemispheres.
Food preference by thrushes was significantly biased toward glucose and fructose, showing scant to nil consumption of sucrose, thus
corroborating a positive relationship between digestion capabilities and food preference for different sugar types.
Key words:
intestinal hydrolases,
Mimus thenca, physiological constraint, sucrase activity, sugar preferences, Turdus
falcklandii
