What type of natural selection occurs when intermediate variants are favored and extreme phenotypes are acted against?

Stabilizing selection occurs when individuals with intermediate phenotypes are favored over those with extreme phenotypes, leading to a decrease in variation and maintaining the status quo for a particular character. This type of natural selection promotes traits that are average or moderate, effectively reducing the likelihood of extreme traits being passed on to future generations.

For example, in a population of birds, if birds with very small or very large beaks are less successful in obtaining food compared to those with moderate-sized beaks, the moderate-sized beaks will be more likely to survive and reproduce. This can result in a stabilization of that trait over generations, as the extremes are selected against.

This concept is key in understanding how certain traits become more common in a population due to environmental pressures favoring average or typical characteristics over extremes. It highlights the importance of balance in traits that confer reproductive success in a stable environment.