The genetics of inbreeding depression Export

@article{citeulike:5977248, abstract = {Inbreeding depression — the reduced survival and fertility of offspring of related individuals — occurs in wild animal and plant populations as well as in humans, indicating that genetic variation in fitness traits exists in natural populations. Inbreeding depression is important in the evolution of outcrossing mating systems and, because intercrossing inbred strains improves yield (heterosis), which is important in crop breeding, the genetic basis of these effects has been debated since the early twentieth century. Classical genetic studies and modern molecular evolutionary approaches now suggest that inbreeding depression and heterosis are predominantly caused by the presence of recessive deleterious mutations in populations.}, author = {Charlesworth, Deborah and Willis, John H.}, citeulike-article-id = {5977248}, citeulike-linkout-0 = {http://dx.doi.org/10.1038/nrg2664}, citeulike-linkout-1 = {http://dx.doi.org/10.1038/nrg2664}, comment = {1. Inbreeding depression is the reduced survival and fertility of offspring of related individuals. Large effects are documented in wild animal and plant populations, as well as in humans. Intercrossing inbred strains improves yield (heterosis). 2. Inbreeding depression implies that genetic variation exists in species for alleles that affect fitness. It is important for the evolutionary maintenance of outcrossing mating systems. 3. Inbreeding depression and heterosis could be caused either by the presence of (largely recessive) deleterious mutations that are present at low frequencies in populations (so that inbreeding increases the frequency of individuals expressing their effects; the 'dominance hypothesis') or by alleles with heterozygote advantage that are maintained by balancing selection at intermediate frequencies (here, homozygotes would have lower fitness; the 'overdominance hypothesis'). 4. These two hypotheses are genetically distinct but, if deleterious mutations are common, genome regions may frequently carry mutations in different genes in repulsion. Therefore, homozygotes for each chromosome type might express fitness-reducing recessive mutations, and heterozygotes (with wild-type function of both genes) would have higher fitness owing to complementation. The region would therefore show heterozygote advantage even though no overdominant gene is present. Distinguishing this 'pseudo-overdominance' from true overdominance is difficult. 5. Rather than excluding overdominance, much work has focused on assessing the extent to which genetic variation in populations can be accounted for purely by deleterious mutations. 6. The overall data suggest that inbreeding depression is predominantly caused by recessive deleterious mutations in populations, so we argue that the same applies to heterosis and that the appearance of overdominance is often due to pseudo-overdominance. 7. This suggestion is consistent with fine-mapping data from genetic analyses of heterosis and with molecular evolutionary data that suggests that purifying selection is pervasive in functional genes but that long-term balancing selection (of which overdominance is a sub-category) is infrequent.}, day = {01}, doi = {10.1038/nrg2664}, issn = {1471-0056}, journal = {Nature Reviews Genetics}, keywords = {consanguineous, evolution, genetics, genomics, review}, month = {November}, number = {11}, pages = {783--796}, posted-at = {2009-11-05 13:18:39}, priority = {2}, publisher = {Nature Publishing Group}, title = {The genetics of inbreeding depression}, url = {http://dx.doi.org/10.1038/nrg2664}, volume = {10}, year = {2009} }

TY - JOUR ID - citeulike:5977248 L3 - citeulike-article-id:5977248 N2 - Inbreeding depression — the reduced survival and fertility of offspring of related individuals — occurs in wild animal and plant populations as well as in humans, indicating that genetic variation in fitness traits exists in natural populations. Inbreeding depression is important in the evolution of outcrossing mating systems and, because intercrossing inbred strains improves yield (heterosis), which is important in crop breeding, the genetic basis of these effects has been debated since the early twentieth century. Classical genetic studies and modern molecular evolutionary approaches now suggest that inbreeding depression and heterosis are predominantly caused by the presence of recessive deleterious mutations in populations. IS - 11 JF - Nature Reviews Genetics SN - 1471-0056 EP - 796 TI - The genetics of inbreeding depression PB - Nature Publishing Group VL - 10 SP - 783 KW - consanguineous KW - evolution KW - genetics KW - genomics KW - review N1 - 1. Inbreeding depression is the reduced survival and fertility of offspring of related individuals. Large effects are documented in wild animal and plant populations, as well as in humans. Intercrossing inbred strains improves yield (heterosis). 2. Inbreeding depression implies that genetic variation exists in species for alleles that affect fitness. It is important for the evolutionary maintenance of outcrossing mating systems. 3. Inbreeding depression and heterosis could be caused either by the presence of (largely recessive) deleterious mutations that are present at low frequencies in populations (so that inbreeding increases the frequency of individuals expressing their effects; the 'dominance hypothesis') or by alleles with heterozygote advantage that are maintained by balancing selection at intermediate frequencies (here, homozygotes would have lower fitness; the 'overdominance hypothesis'). 4. These two hypotheses are genetically distinct but, if deleterious mutations are common, genome regions may frequently carry mutations in different genes in repulsion. Therefore, homozygotes for each chromosome type might express fitness-reducing recessive mutations, and heterozygotes (with wild-type function of both genes) would have higher fitness owing to complementation. The region would therefore show heterozygote advantage even though no overdominant gene is present. Distinguishing this 'pseudo-overdominance' from true overdominance is difficult. 5. Rather than excluding overdominance, much work has focused on assessing the extent to which genetic variation in populations can be accounted for purely by deleterious mutations. 6. The overall data suggest that inbreeding depression is predominantly caused by recessive deleterious mutations in populations, so we argue that the same applies to heterosis and that the appearance of overdominance is often due to pseudo-overdominance. 7. This suggestion is consistent with fine-mapping data from genetic analyses of heterosis and with molecular evolutionary data that suggests that purifying selection is pervasive in functional genes but that long-term balancing selection (of which overdominance is a sub-category) is infrequent. AU - Charlesworth, Deborah AU - Willis, John PY - 2009/11/01/ UR - http://dx.doi.org/10.1038/nrg2664 ER -