---

Natural Selection is Out, Molecular Drive is In

Unequal Crossing-Over

One source of genetic variety has long been attributed to the process of “crossing-over” or “recombination”. During meiosis, a pair of homologous chromosomes will break at corresponding locations and trade segments. One chromosome then, can be composed of segments derived from both parents. Unequal crossing over occurs when there is not complete alignment between two chromosomes. One chromosome will gain extra genetic material while the other will lose DNA. It is easy to imagine how this can happen in repeated segments of DNA as a break in one repeat looks identical to a break in another. This is how Dover proposes a mutant gene can spread through an array of identical genes by unequal genetic exchange:

---

NEXT PREVIOUS Back to Library Back to MacroDevelopment Home Page