Figure 1.

Deficiency mapping approach to detect alleles involved in hybrid inviability. A significant dearth of df/san individuals compared to their Bal/san sisters indicates that the deficiency uncovers a lethal or semilethal allele involved in hybrid inviability. D. melanogaster balancer chromosomes are shown as striped bars; deficiency chromosomes are shown as a line connecting two bars. D. santomea chromosomes are shown in light gray. Sex chromosomes are shown as shorter bars than autosomes, and Y is shown as shorter than the X. Bal, balancer chromosome; df, deficiencies; mel, D. melanogaster; san, D. santomea.