Characterization of genomic biodiversity through comprehensive species sampling has the potential to change our understanding of evolution. To study evolution across a major vertebrate class, dissect the genomics of complex traits, and resolve a centuries-old debate on the avian species tree, we formed large-scale comparative genomic research for birds covering a wide range of avian evolutionary diversity. We propose to use full genome data as golden standard for building the tree of life and demonstrate a well resolved avian family tree with phylogenomic approach. The new avian phylogenic tree has dramatically changed our view of the evolutionary process of many avian life-history traits. Whole genome comparison for all bird species with other vertebrate species revealed several distinct macroevolution patterns of avian genome. The small genome size of bird was a consequence of massive loss of repeat elements and thousands of functional genes in bird ancestral stage. Different with other animal lineages that develop evolutionary innovation by obtaining new genetic materials, the bird genomes have extremely low new gene born rate. Instead, the bird genomes obtain millions of elements that specifically only conserved in bird lineages. These avian specific highly conserved elements are dominated by non-coding regions and have significantly high level of enhancer potential. Through functional experiments, we demonstrate regulatory roles of ASHCEs in the punctuated evolution of dinosaur-avian transition, and further highlight the importance of regulatory rewiring during macroevolutionary changes.
Guojie Zhang is full Professor at Department of Biology in University of Copenhagen, Denmark. The major research interests in his group are on biodiversity genomics and genome evolution. Zhang tackles the biodiversity and evolutionary questions with large-scale comparative genomics and has revealed the molecular mechanisms underlying speciation and adaptation for a broad spectrum of animal taxa. His group is also trying to establish ants as model systems for eco-evo-devo study of social behavior.
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