POLYMORPHISM REGENERATION FOR A NEUTRALIZED SELFISH B-CHROMOSOME

Long-run evolution of B chromosomes is mainly made up by an evolutiona ry arms race between these selfish genetic elements and the standard g enome. The suppression of B drive is one of the dearest expressions of genome defense against B chromosomes. After drive neutralization, the B is condemned to extinction unless a new variant showing drive can e merge and replace it. This paper reports the first empirical evidence for the substitution of a neutralized B variant by a new selfish B var iant. Such a polymorphism regeneration has recently taken place in a n atural population of the grasshopper Eyprepocnemis plorans.