Recessive Z-linked lethals and the retention of haplotype diversity in a captive butterfly population

摘要

a Timeline of the Bicyclus anynana Leiden/Liverpool lab population, showing the samples genotyped in this study, their relationship to each other and the order in which they were analysed (1–5). b Design of daughter–father backcross, highlighting the identify (by descent) of Z chromosome segments (denoted by ƶi, where i refers to the identity of the paternal Z in generation P). The position of the recombination breakpoints, indicated by change in colour, is arbitrary, as is which of the daughters to backcross (recombination does not occur in female Lepidoptera). ZF and ZM refer to whether the Z copy came from the father (F) or mother (M). This design is expected to generate F2 brothers that differ with respect to which portion of the Z is either homozygous (hom) or heterozygous (het). Autosomes (not shown) are expected to experience the same degree of inbreeding, regardless of sex (probability of identity by descent ~0.25, averaged across all offspring, assuming zero coancestry between P-generation parents). To assess the fertility of F2 males, they were mated to unrelated outbred females. The F2 generation is referred to as BF1 (backcross F1).