Selection (Adaptation in Microbial Populations)

Through selection, better-adapted variants within a population produce more offspring over their lifetime than poorly-adapted competitors. Selection pressures are often imposed by "habitat filters" or environmental conditions, such as:

• Availability of metabolic resources


• pH levels


• Adhesion sites

Microbes that do not use the available resources effectively are driven out of the gut microbiota and cannot find a suitable niche. Conversely, microbes that arrive at a site and make particularly effective use of those resources may experience positive selection, allowing them to outgrow other populations.

Selection pressures can also be exerted through interactions with other microbes, host cells, and [bacter…