Meeting Abstract

58.3  Tuesday, Jan. 6  The goose (Anser anser f. d.), a precocial species, enlarged its telencephalon before neurogenesis onset CHARVET, CJ*; SANDOVAL, AL; STRIEDTER, GF; Univ. of California, Irvine; Univ. of California, Irvine; Univ. of California, Irvine ccharvet@uci.edu

Many altricial and some precocial species of birds enlarged their telencephalon relative to other birds. Previous work has shown that parakeets, an altricial species, enlarged their telencephalon by delaying neurogenesis. To determine whether precocial species also enlarged their telencephalon by delaying neurogenesis, we examined brain development in geese and turkeys, two precocial species. Whereas the telencephalon occupies more than 70% of the total brain volume in geese, it occupies only 50% in turkeys. To discover how this species difference in adult brain proportions arises we examined neurogenesis onset and estimated the volume of the telencephalon, tectum and medulla from serial Nissl-stained sections of embryonic geese and turkeys. All comparisons were done in terms of Hamburger-Hamilton stage and age. We found that the telencephalon is proportionately larger in geese than in turkeys before neurogenesis onset (stage22/ED5). We also found that telencephalic neurogenesis is not delayed in geese relative to turkeys. Therefore, precocial and altricial species appear to have enlarged their telencephalons by altering different developmental parameters.