Abstract: The gut microbiota inhabits a highly complex intestinal environment that is strongly influenced by the host and community composition. Furthermore, the gut microbiota evolves in response to changes in the environment, acquiring characteristics that are more conducive to their survival within the host gut. Nevertheless, the mechanism of microbial evolution in the host gut remains poorly understood. In recent years, the continuous development of sequencing technology has enabled the acquisition of more accurate data on the adaptive evolution of microorganisms in the host gut, resulting in the emergence of high-quality research results. In this context, this paper presents a comprehensive analysis of the selective pressure that microorganisms experience in the intestinal environment, the factors influencing this pressure, and the mechanisms underlying the adaptive evolution of the gut microbiota. The objective is to provide theoretical guidance for the use of microbial therapies to maintain and restore human health.

Key words: adaptive evolution; gut microbes; evolutionary mechanism; selective pressure; host-microbe interaction