Evolution of Brain Development in Birds

这项拟议的研究的主要目的是确定是什么发育机制的进化变化导致鹦鹉和鸣禽进化出不成比例的大前脑。这项工作很重要，因为不成比例的大前脑独立进化了几次(例如鹦鹉、鸣禽、灵长类、海豚和鲸鱼)，似乎以各种方式使它们的持有者变得“聪明”。然而，关于进化如何创造扩大的前脑，人们几乎一无所知。发育生物学家可以让转基因动物拥有异常大的大脑，因为它们在大脑发育的某些方面有所不同，比如降低了神经细胞死亡的水平。然而，这些突变的动物往往会以胚胎的形式死亡，永远不会变得更聪明。这项拟议中的工作的方法是询问大自然是如何操纵大脑发育来创造出前脑扩大的“更聪明”的动物的。具体地说，我们将比较长尾鹦鹉、斑马雀和鹌鹑的大脑发育，询问这些物种之间的细胞或分子机制有哪些不同。如果大自然使用相同的机制在鹦鹉和鸣禽身上产生扩大的前脑，那么这表明存在一个必须满足的约束，才能获得功能良好的扩大的前脑。对这一限制的了解反过来将为未来在实验室实验中模拟大脑进化的某些方面的尝试提供信息。这也将提高人们对人类血统中前脑大小和智力增加的进化机制的理解。拟议的工作将支持培训两名博士生和至少四名从事独立研究的本科生。国际学生协会致力于扩大各级学生的参与，并参与社区外展计划和为K-12学生提供的每月系列活动。

The principal aim of the proposed research is to determine what evolutionary changes in developmental mechanisms have caused parrots and songbirds to evolve disproportionately large forebrains. This work is important because disproportionately large forebrains evolved several times independently (e.g., parrots, songbirds, primates, dolphins and whales) and seem to make their bearer's "smart" in a variety of ways. Yet almost nothing is known about how evolution creates enlarged forebrains. Developmental biologists can make genetically modified animals that have unusually large brains because they vary in some aspect of brain development, such as having reduced levels of neuronal cell death. However, these mutant animals tend to die as embryos and never become "smarter". The approach in the proposed work is to inquire of Nature how it manipulated brain development to create "smarter" animals with enlarged forebrains. Specifically, brain development will be compared in a parakeet, a zebra finch and a quail, asking which cellular or molecular mechanisms differ between these species. If Nature used the same mechanism to produce enlarged forebrains in parrots and songbirds, then this suggests the existence of a constraint that must be satisfied in order to obtain well-functioning enlarged forebrains. Knowledge of this constraint would, in turn, inform future attempts to mimic some aspects of brain evolution in laboratory experiments. It would also improve understanding of the mechanisms that underlie the evolution of increased forebrain size and increased intelligence within the human lineage. The proposed work will support the training of two PhD students and at least four undergraduate students who do independent research. The PI is committed to broadening participation of students at all levels and is involved in community outreach programs and monthly series for K-12 students.