Genetic Conflict and Imprinting


‘Imprinting’ is a mechanism causing differential expression of the parental alleles of certain genes during embryonic and postnatal development in mammals and during seed development in angiosperm plants. Imprinting evolves due to the reduced genetic relatedness of paternal, relative to maternal, alleles at loci influencing maternal investment in the offspring of polygamous females.

Keywords: kin selection; parent–offspring conflict; placenta; endosperm; X‐chromosome inactivation

Figure 1.

Influence of polyandry on parental allele relatedness. Note that relatedness of maternal alleles is ‘neutral’ with respect to number of mates, whereas polyandry (different fathers) abolishes relatedness between paternal allelic components of embryo genotype.

Figure 2.

Schematic of a transcriptional ‘arms race’ between maternal and paternal alleles at a locus that influences parental investment (PI). Incremental increases in expression of one parental allele are tracked by incremental decreases in expression of the other parental allele.

Figure 3.

(a) Active ‘selfish’ Xp. Embryos of genotype XmXp (female) and XmY (male) compete for maternal resources. Thickness of vertical arrows represents relative amount of maternal resources demanded or transferred. In the absence of preferential paternal X‐inactivation, ‘selfish’ Xp‐linked alleles (e.g. X‐linked placental growth factors) will cause dosage imbalances between male and female embryos that may be translated into relatively increased PI in female embryos to the detriment of male sibs. (b) Inactivated Xp. On the assumption that the Y‐chromosome does not contain loci encoding significant effects on PI, imprinted Xp inactivation equalizes gene dosage and PI between male and female embryos.



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Web Links


MRC Mammalian Genetics Unit. Genetic and physical imprinting maps of the mouse

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Moore, Tom(Dec 2008) Genetic Conflict and Imprinting. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0005978.pub2]