TABLE 1

Expected genotypic values as a function of the ordered offspring genotypes (i.e., ordered by the parent-of-origin of alleles, with the first allele indicating the paternally inherited copy and the second the maternally inherited copy) and the unordered maternal genotypes when variation in offspring traits is caused by maternal and direct effects

Offspring genotype
LLSLLSSSEmbedded Image
Maternal genotype
    LL+am + ao (p3)+am + do − io (p2q)+am + do + io (0)+am − ao (0)+am + aop + doq − ioq
    LS, SLdm + ao (p2q)dm+ do − io (pq2)dm+ do + io (p2q)dm − ao (pq2)+ dm + Embedded Imagedo Embedded Image(ao + i)(pq)
    SS−am + ao (0)−am + do − io (0)−am+ do + io (pq2)−am − ao (q3)−am − aoq +dop + iop
Embedded Imageamp + dmq + aoamp + dmq +do − io−amq + dmp +do + io−amq + dmp − ao
  • The average phenotypes of individuals (offspring) with each of the four ordered genotypes (Embedded Image) are given at the bottom of the table. Also shown in the right-hand column is the average phenotype of the offspring of mothers (Embedded Image) with each of the three unordered maternal genotypes. The frequencies of the maternal–offspring genotype combinations are given in parentheses, where p and q are the frequencies of the L and S alleles, respectively. Note that four maternal–offspring combinations (boldface) cannot occur (i.e., have zero frequency) under Mendelian inheritance and, therefore, do not contribute to the means. am, the additive maternal-effect genotypic value; dm, the dominance maternal-effect genotypic value; ao, do, and io, the additive, dominance, and imprinting direct-effect genotypic values.