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#selfing

3 public questions tagged with this topic.

Plant Breeding 2

Selfing reduces heterozygosity by:

Selfing systematically reduces heterozygosity because segregation from heterozygous parent yields one quarter AA, one half Aa, one quarter aa. Only half offspring remain heterozygous, halving H each generation. Formal relationship Ht equals H zero times one half to power t, where t number selfing generations, independent of allele frequencies for loci not under selection. After first selfing heterozygosity 50 percent, after second 25 percent, after six cycles about 1.6 percent. Inbreeding coefficient F rises reciprocally approaching 0.99 after six generations. This principle underpins extracti

Ref: Hartl & Clark Principles Population Genetics selfing reduction; Falconer Introduction Quantitative Genetics; NCBI Bookshelf Heterozygosity equation.

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Plant Breeding 1

Reduced vigor due to repeated selfing is known as:

Inbreeding depression emerges as phenotypic deterioration in vigor, height, fecundity and stress tolerance following repeated selfing of naturally outcrossing species. Underlying genetic architecture includes dominance hypothesis: many loci carry partially recessive deleterious mutations in genes governing chlorophyll biosynthesis, auxin transport, root elongation and defense signaling. Increased homozygosity makes these recessives expressed, reducing enzyme activity and hormone levels. Pseudo-overdominance where two linked loci in repulsion mimic overdominance also contributes. Quantitative s

Ref: Charlesworth & Willis Annu Rev Ecol Inbreeding depression; Falconer Quantitative Genetics; Singh BD Inbreeding depression cause.

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Plant Breeding 1

Repeated selfing leads to:

Repeated self-fertilization progressively eliminates heterozygosity because each heterozygous locus segregates 1 AA:2 Aa:1 aa, only half progeny retain heterozygosity. Mathematically heterozygosity after t generations Ht equals H0 multiplied by one-half raised to power t, so after seven generations approximately 0.8 percent remains. Continuous inbreeding drives allele fixation toward homozygous states, exposing recessive homozygotes for selection. In breeding this rapid homozygosization underlies development of pure lines, recombinant inbred lines for QTL mapping and near-isogenic lines via re

Ref: Allard Principles Plant Breeding homozygosity; Hartl & Clark Population Genetics selfing equation; Falconer Quantitative Genetics.

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