##  [Nearly Neutral Theory](/nearly-neutral-theory) 

  ##  [Nearly Neutral Theory](https://natural.quantumdictionary.io/nearly-neutral-theory-0) 

  

 [![Natural & Formal Sciences Dictionary](/sites/default/files/styles/large/public/2026-01/Natural%20%26%20Formal%20Sciences.png.webp?itok=2kCDRVQv)](/topic-specific-dictionaries/natural-formal-sciences)



**Natural & Formal Sciences Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A refinement of neutral theory asserting that many mutations are not strictly neutral but have very small deleterious or beneficial effects; their fate depends on the product of selection coefficient and effective population size (Ne). It frames a continuum between neutrality and selection rather than a strict dichotomy.