Ontogeny of Digestion in Altricial Birds

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In this study the PIs will investigate the ontogeny of digestion in passerine (perching) birds, which are altricial; that is, newborns hatch without plumage, eyes closed, and little ability to move and feed indepedndently. There has been little attention on the developmental changes in digestive physiology in birds, except for poultry which hatch in a much more advanced (precocial) state. Developmental changes in digestion will likely differ in many respects between altricial perching birds and precocial chickens. Similar developmental studies on mammals and poultry have advanced knowledge of fundamental digestive physiology and its applications in medicine and animal production. In the first aim the PI's ask "in altricial nestlings, how do digestive features, such as enzyme and absorption levels, change during normal growth and development?" In the second aim the PIs ask "how flexible is the gut of altricial nestlings?" Many passerine species are fed insects (high in protein and fat and nearly starch-free) during the first few days of life, but as adults consume mainly seeds (high in carbohydrate). Presumably their digestive biochemistry changes with the diet change, and Project II asks whether the developmental changes are fixed according to a genetic program or whether they are partly influenced by the diet the nestling eats. The PI's will study two common bird species, the house sparrow and the zebra finch. In each species, they will feed nestlings either different synthetic diets or at different rates, and they will test the nestlings' digestive function at several time points in their development, through adulthood. The PI's will modify and apply some molecular techniques to altricial passerines for the first time. In addition to increasing valuable knowledge about physiology of wild birds, the methods developed and applied in the projects increase the scientific capacity to study avian digestive physiology at a more molecular level. A graduate student, a postdoctoral scholar, and undergraduates and high school students, some from underrepresented groups, will be trained in integrative biology, emphasizing concepts and methods spanning from the whole-animal to the molecular. Mentors of pre-graduate students will participate in the new Wisconsin Program for Scientific Teaching, whose aim is to improve the instructional abilities of young scientists.