Figure 5.

Univalent drive in worms and grasshoppers. (a) Univalent X chromosomes preferentially segregate to the polar body in Caenorhabditis elegans. These univalents lag in meiosis I and are captured by the septin tube during contractile ring activity. (b) Univalent B chromosomes in Myrmeleotettix maculatus are preferentially segregated to the egg. The side of the spindle facing the egg pole is longer than the side facing the polar body pole. Univalent B chromosomes are not aligned at the metaphase plate and can be randomly found anywhere along the spindle. The B chromosome is more likely to reside on the side of the spindle facing the egg pole due to this spatial asymmetry and is therefore more likely to be incorporated into the egg.