Effects Of Maternal Inbreeding Research Articles

Male Assistance in Parental Care Does Not Buffer Against Detrimental Effects of Maternal Inbreeding on Offspring

The severity of inbreeding depression often varies across environments and recent work suggests that social interactions can aggravate or reduce inbreeding depression. For example, stressful interactions such as competition can exacerbate inbreeding depression, whereas benign interactions such as parental care can buffer against inbreeding depression in offspring. Here, we test whether male assistance in parental care can buffer against the detrimental effects of maternal inbreeding on offspring fitness in the burying beetle Nicrophorus vespilloides. Our results confirm that maternal inbreeding had detrimental effects on offspring survival. However, we found no evidence that male assistance in parental care buffered against those effects on offspring fitness. Outbred females benefitted from male assistance, gaining more weight over the breeding attempt when assisted by a male. In contrast, inbred females did not benefit from male assistance, gaining as much weight regardless of whether they were assisted by a male or not. Surprisingly, we find that males gained more weight during the breeding attempt when mated to an inbred female, suggesting that males benefitted from assisting an inbred female partner in terms of their weight gain. Overall, our findings suggest that parental care or other benign social interactions may not always buffer against detrimental effects of inbreeding depression.

Consequences of long-term inbreeding accumulation on preweaning traits in a closed nucleus Angus herd1

The effect of individual and dam (maternal) inbreeding was quantified for preweaning traits in an Angus nucleus herd that has been closed to outside breeding for 70 yr. The effectiveness of 5 models (linear, quadratic, exponential, Michaelis-Menten, and Rumford-Newton) was evaluated for describing the effect of inbreeding on growth traits, hock length (HL), and scrotal circumference (SC). Pedigree information and production records were retrieved for 10,938 animals and analyzed in an animal model that included the fixed effects of year of birth, age of the dam, sex, and age at weaning (for traits measured at weaning). Average individual and maternal inbreeding in the herd were 0.068 and 0.066, respectively, for all animals; in the last calf crop these values were 0.120 for the calves and 0.121 for their dams. Inbreeding depression was observed for BW at birth (WB), weaning weight (WW), BW adjusted to 205 d of age (W205), ADG, HL, and SC. The effect of maternal inbreeding was smaller than for individual inbreeding for WB, WW, W205, and ADG. Nonlinear prediction was done more effectively by the exponential and Michaelis-Menten models. Quadratic polynomials were an inadequate descriptor of inbreeding effects. Genetic gain from selection at an intensity equivalent to 0.25 can be nullified by an inbreeding accumulation of 0.187 (WB), 0.056 (WW), 0.068 (W205), 0.065 (ADG), or 0.092 (SC). Inbreeding accumulation of 0.018 is required to nullify genetic gain for HL; this particular prediction is valid for non-inbred cows due to an observed interaction between individual and maternal inbreeding. At current inbreeding accumulation levels in this herd, 7 generations of inbreeding accumulation will be necessary to nullify the genetic progress from 1 generation of selection in growth traits.

Effects of rapid inbreeding and of crossing inbred lines on the growth of linear body dimensions of sheep

AbstractSheep of three hill breeds and the crosses among them were closely inbred for four generations to create five levels with inbreeding coefficients 0·0 (F2/O2), 0·25 (I1,), 0·375 (I2), 0·50 (I3), and 0·59 (I4). Inbred females were also mated to unrelated inbred males of the same breed or crossbred type to produce line-crosses (LC). Mating was arranged so that the effects of inbreeding on the individual could be differentiated from maternal inbreeding. A total of 2369 animals were available up to 78 weeks of age and 1062 to the age of 4 years. This study examines the effects on six linear body dimensions and draws comparison with the effects on body weight. There were significant reductions in the size of the body dimensions with increasing inbreeding but the maximum depression was usually at the I2 stage for individual inbreeding and the I3 stage for maternal inbreeding. Most of the linear and many of the non-linear effects of inbreeding of the individual were significant and the effects of maternal inbreeding were also significant in a majority of cases. Inbreeding effects were more marked for relatively late-maturing parts (shoulder and hook widths) than for early-maturing (cannon bone and tibia lengths) with head width and body length intermediate but closer to the early-maturing parts. This was seen separately at each age, and in the effects of advancing age. By 78 weeks of age, the effects of inbreeding of the individual on absolute size had increased with age and by 4 years of age, in spite of a small recovery in size relative to F2/O2, was still greater than in early life. The effects of maternal inbreeding became progressively less with advancing age relative to non-inbreds. The changes with inbreeding could not be explained by dominance effects alone and epistasis is therefore likely also to be involved.

Effects of rapid inbreeding and of crossing of inbred lines on the body weight growth of sheep

AbstractSheep of three hill breeds, Scottish Blackface, Cheviot and Welsh Mountain and the reciprocal crosses among these breeds were inbred (mostly by parent × offspring mating) for four generations to five levels with inbreeding coefficients ofO, 0·25 (I1), 0·38 (I2), 0·50 (I3) and 0·59 (I4). Inbred females were also mated to unrelated inbred males of the same breed type to produce line crosses (LC). Each type of dam (except LC and I4) was mated to produce lambs of up to three different inbreeding levels thus allowing the effects of the individual's own inbreeding to be separately assessed from the effects of maternal inbreeding. This study examined body weight at a sequence of ages from birth to 4 years of age with 2369 animals (ages up to 78 weeks old) or 1062 animals (2 to 4 years old) contributing to the analyses.Inbreeding of the individual had a highly significant retarding effect on body weight and growth rate up to the I2 level for weights of lambs up to 24 weeks old, with a slight recovery in performance thereafter. For the later ages examined, the maximum depression was reached at the I3 stage. The partial recovery in performance at the higher levels of inbreeding for lambs less than 24 weeks of age was also noted within lines and did not therefore appear to arise only from a loss of lines as inbreeding proceeded. The effect of dam's inbreeding was to depress growth up to the I3 level and at most ages up to I4. Line-cross lambs were generally heavier (but not significantly so) than non-inbred (F2 and the pure equivalent, O2) and progeny of line-cross dams were similar in weight to those from other non-inbred (F1, or F2 and O1, or O2 dams) or slightly better. The more highly inbred the individuals the more, in general, they fell behind the weights of the corresponding non-inbreds as they grew older. Inbreeding may thus have permanently stunted the sheep.There were no significant differences between purebred and crossbred sheep in the rate of inbreeding depression. Only at the ages of 3 and 6 weeks was there a significant difference between the three pure breeds in the changes in weight attributable to inbreeding. Up to the age of weaning (15 weeks) the changes with inbreeding of individuals could not be explained statistically in terms of dominance effects alone and non-allelic interactions may therefore also be involved. At all ages the effect of inbreeding of the dam was consistent with dominance effects alone.

Effects of Maternal Inbreeding on Prenatal Deaths in Man

Effects of Maternal Inbreeding on Prenatal Deaths in Man

Down's Syndrome and Maternal Inbreeding

SummaryIn order to test the possible effect of maternal inbreeding upon non-disjunction, ancestors of 104 children with Down's syndrome born to younger mothers were identified on the basis of official records. Among them, 6 had related parents, while 10 of the fathers and 12 of the mothers had also such parents. The relationship comprises first-cousins, first-cousins once removed, and second cousins. It was concluded that recessive genes are unlikely to be involved in the aetiology of non-disjunction of the 21st autosome, at least in younger mothers.