A model for quantifying genetic recombination in chromosome polymorphisms due to supernumerary heterochromatic segments.

Heterochromatic supernumerary segments can modify chiasma distribution in the affected bivalents. A model is developed for quantifying the genetic recombination in populations polymorphic for such segments. This paper describes this model for a monochiasmate bivalent, and its application in different populations of the grasshopper Chorthippus parallelus. The observations suggest that these polymorphic systems have evolutionary implications.