LIFE SCIENCE

The mystery of the world’s first ancient tiger gene has been solved


Jilin Tonghua Da’an Cave Ancient Tiger Fossil Research Group provided pictures

On July 27, the ancient DNA team led by Lai Xulong, a professor at China University of Geosciences (Wuhan), collaborated with Jilin University and the University of Copenhagen in Denmark to complete the research results of “Paleogene genome research found an extinct and deeply differentiated tiger branch in northern China”, which was published in the Proceedings of the Royal Society B: Biological Sciences. This is also the world’s first ancient tiger genome research results.

In 2003, the archaeology team of Jilin University excavated a large number of paleontological fossils in a cave in Da’an Town, Tonghua City, Jilin Province, and provided some of the spotted hyena fossils to the ancient DNA research team of China University of Geosciences (Wuhan) for collaborative research. Through the analysis and identification of the remaining DNA in the fossils, the researchers accidentally found that one of the broken mandibles (specimen number: CADG482) was not a spotted hyena, but belonged to a tiger (hereinafter referred to as “Daan Tiger”), which was more than 43,500 years old.

In terms of biological classification, tigers belong to the cat family, leopard genus, tiger species, and are the “stars” of big cats, and their evolutionary history and living conditions have been widely concerned by society and academia. Current tigers mainly include six geographical subspecies: Siberian tiger (Siberian tiger), South China tiger, Indochinese tiger, Bengal tiger (Indian tiger), Malay tiger and Sumatran tiger. Studies have suggested that they all diverged from an ancestral population dating back about 110,000 years.

In order to explore the relationship between the daan tiger and the geographical subspecies of the living tiger, the researchers increased the ancient DNA extraction of the mandible fossils of the Daan tiger and the construction of the second-generation sequencing library, and assembled the nearly complete mitochondrial genome and part of the nuclear genome information of the Daan tiger from 24 sequencing libraries. Based on the comparative analysis of the genetic components of Daan tiger and all living tigers and the construction of phylogenetic trees, it is found that Daan tiger is different from any living tiger, belonging to the previously unknown and now extinct genetic branch, and the genetic branch it represents and the ancestor of the living tiger have diverged from each other about 260,000 years ago. Unlike the ancestors of the living tiger, which subsequently radiated and differentiated in various places to form different geographical subspecies, the genetic branch represented by the Daan tiger subsequently embarked on the road to extinction.

The study of living tigers can only reveal the evolutionary history of their immediate ancestors. The determination and analysis of the genome of the Daan tiger shows that in the evolutionary process of the tiger, some of the genetic branches have been lost, and all modern tigers are only the descendants of one of the tribes. So far, the oldest tiger fossils were found in the Early Pleistocene, which is more than 2 million years old in Gansu, China, and other middle and late Pleistocene tiger fossils are also found in East Asia. The research group said that before obtaining ancient DNA data, the genetic information of the disappeared tiger branch has been dusted in broken and easily misread fossils, and the ancient genome research has made the extinct tiger branch reappear in the sky, providing a necessary and irreplaceable molecular basis for a systematic and comprehensive exploration of the evolutionary history of tigers. (Source: China Science Daily, Wen Caifei, Chen Huawen)

Related paper information:https://doi.org/10.1098/rspb.2022.0617



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