The reproductive modes of vertebrates are mainly divided into oviparous and viviparous. How to evolve from oviparous to viviparous is a very important biological basic problem.
On June 38+03, the news from Kunming Institute of Zoology, Chinese Academy of Sciences, with the cooperation of Chinese and foreign researchers, successfully revealed the evolutionary genetic mechanism of oviparous and viviparous reproduction patterns of reptiles. Viviparous reproduction mode can optimize the embryo development environment and protect the embryo from external adverse effects, so it can greatly improve the survival rate and fitness of offspring.
The viviparous species in scaly reptiles account for about 20%, including lizards, snakes, earthworm lizards, etc., and their independent origin may reach 98 ~ 129 times, which is more than 2/3 of the viviparous origin of the whole vertebrate. However, viviparous evolution is accompanied by eggshell degeneration, embryo attachment, placental development, prolonged detention time of fertilized eggs, immune tolerance and other issues, and the study of genetic mechanism is still blank.
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