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[dinosaur] Bird evolution genetic mechanism (free pdf) + avian brains

Ben Creisler

New papers:

Free pdf:

Ryohei Seki, Cai Li, Qi Fang, Shinichi Hayashi, Shiro Egawa, Jiang Hu, Luohao Xu, Hailin Pan, Mao Kondo, Tomohiko Sato, Haruka Matsubara, Namiko Kamiyama, Keiichi Kitajima, Daisuke Saito, Yang Liu, M. Thomas P. Gilbert, Qi Zhou, Xing Xu, Toshihiko Shiroishi, Naoki Irie, Koji Tamura & Guojie Zhang (2017)
Functional roles of Aves class-specific cis-regulatory elements on macroevolution of bird-specific features.
Nature Communications 8, Article number: 14229 (2017)

Unlike microevolutionary processes, little is known about the genetic basis of macroevolutionary processes. One of these magnificent examples is the transition from non-avian dinosaurs to birds that has created numerous evolutionary innovations such as self-powered flight and its associated wings with flight feathers. By analysing 48 bird genomes, we identified millions of avian-specific highly conserved elements (ASHCEs) that predominantly (>99%) reside in non-coding regions. Many ASHCEs show differential histone modifications that may participate in regulation of limb development. Comparative embryonic gene _expression_ analyses across tetrapod species suggest ASHCE-associated genes have unique roles in developing avian limbs. In particular, we demonstrate how the ASHCE driven avian-specific _expression_ of gene Sim1 driven by ASHCE may be associated with the evolution and development of flight feathers. Together, these findings demonstrate regulatory roles of ASHCEs in the creation of avian-specific traits, and further highlight the importance of cis-regulatory rewiring during macroevolutionary changes.


How dinosaurs may have evolved into birds



 Also (not free):

Tadashi Nomura and Ei-Ichi Izawa (2017)
Avian brains: Insights from development, behaviors and evolution
Development, Growth & Differentiation (advance online publication)
DOI: 10.1111/dgd.12362

Birds are an extensively specialized animal group with unique anatomical, physiological and ecological characteristics. Sophisticated social behaviors and remarkable cognitive abilities are present in several avian lineages, driven by their enlarged brains and intricate neural networks. These unique traits could be a result of adaptive evolution under the wide range of environmental constraints; however, the intrinsic mechanisms of avian brain development and evolution remain unclear. Here, we introduce recent findings regarding developmental aspects of avian brain organization and neuronal networks for specific avian behaviors, which provide an insight into the link between the evolution of brain development and complex cognitive functions.