Biography:

Dr. Li was born at Ruili, a small beautiful town on the border between China and Burma, and grew up at Tonghai, a town near Kunming. After finishing his high school there, he went to the Shangdong University and got his BS degree. Then jointly supervised by Prof. Ya-Ping Zhang (Kunming Institute of Zoology, Chinese Academy of Sciences) and Prof. Yun-Xin Fu (University of Texas at Houston), he got my PhD degree in Zoology/Genetics in 2002. His major work during this period is related to population genetics, and they have found that the endangerment of the most of species may not be due to reduced genetic diversity. Then he went to the University of Munich and worked with Prof. Wolfgang Stephan. They provide evidence for the recent action of positive selection in the fruit fly Drosophila melanogaster. After another one-year stay at the University of Cologne with Prof. Thomas Wiehe, he went to Shanghai and set up the Laboratory of Evolutionary Genomics at the CAS-MPG Partner Institute for Computational Biology, Chinese Academy of Sciences in September, 2007. The long-standing interest of his group is to study the molecular mechanism of evolution and speciation. Currently, they are focusing on developing reliable methods to detect recent positive Darwinian selection and artificial selection. By applying these methods to the study of adaptive evolution of human, Drosophila, HIV and several domesticated species, they are expecting to reveal the molecular mechanism of adaptation as well as functional genes underlying economic traits.

Abstract:

Adaptive evolution in Drosophila and humans

It has been a long-standing interest in evolutionary biology to search for the traces of recent positive Darwinian selection in organisms. We describe a new statistical method to detect footprints of selection in the genome of the fruit fly Drosophila melanogaster and apply it to a large set of DNA polymorphism data from the X chromosome. We find that numerous selective events occurred in the past 60,000 years, while the fruit fly expanded its ancestral range in Africa and subsequently colonized temperate zones in the rest of the world after the last ice age. The findings are important as they indicate where in the genome the genes are located that have been involved in the adaptation of D. melanogaster to environmental changes in the recent past. Moreover, we applied another novel test to a microsatellite dataset from the Han-Chinese population (1247 markers). We detected a signature of recent positive selection on eight markers (p < 0.001) in humans. The majority of the putative selection events (5/8) are likely to be caused by beneficial substitutions in transcriptional regulatory elements. Interestingly, there is an enrichment of candidate sites in regions which are adjacent to brain-related genes (p = 0.0016). This makes the regions around these markers especially interesting to search for brain-specific regulatory elements that experienced selective sweep during a time-frame which would coincide with human migration out of Africa about 100ky ago.