Absence of crossing-over in female butterflies (Heliconius).

Absence of recombination between linked markers in female Heliconius is suggested by coupling backcross broods in H. erato, by a repulsion F2 in H. melpomene, and by other crosses with this species. No recombinants have been found in the offspring of doubly heterozygous females in either species. This supports the contention that the absence of chiasmata at oogenesis in these butterflies prevents genetic crossing-over. Chiasmata are absent in all the female Lepidoptera examined by Suomalainen and others, but Ephestia seems to show the absence of chiasmata but the presence of genetic recombination in the female, and therefore would repay further study.