The main finding from my PhD work is that species have evolved several distinct developmental mechanisms to expand their brain or brain parts but that each kind of change may be constrained by the species' reproductive mode. For instance, some altricial species such as parrots and songbirds expand their telencephalon by delaying telencephalic neurogenesis. In contrast, some precocial species such as ducks and geese expand their telencephalon before telencephalic neurogenesis begins. Yet some other precocial birds (i.e. chickens, bobwhite quail) expand their overall brain mainly because of species differences in cell cycle rates during early stages of embryonic development. The functional consequences of these different developmental strategies remain to be studied.
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