Significant Effect Of Inbreeding Research Articles

Evaluation of Inbreeding in the Slovak Simmental Breed and Its Effect on Length of Productive Life.

This study aimed to estimate the average inbreeding coefficient in Slovak Simmental dairy cattle and evaluate the effect of inbreeding on the length of productive life. All pedigrees included 463,282 animals dating back to 1914. The inbreeding coefficients for each animal in the pedigree were computed using the software CFC 1.0. Length of productive life (LPL) was defined as the time (days) from the first calving to culling, death, or censoring. The influence of inbreeding on the length of productive life was calculated and tested using the Weibull proportional hazards model. The average inbreeding coefficient, the average number of discrete generation equivalents, and the average longest ancestral path for inbred animals were 0.01, 6.59, and 13.08, respectively. While the largest decrease in the mean coefficient of inbreeding was observed from the year of birth 1995 (F = 1.50%) to 2001 (F = 0.59%), an increasing trend of inbreeding in the population was found from 2003 onwards. A weak but significant effect of inbreeding on the length of productive life of Simmental cows was confirmed using survival analysis.

Effects of inbreeding on reproduction and fitness traits in a closed flock of Nilagiri sheep, an endangered Indian breed

The objective of this study was to investigate the effect of inbreeding on reproductive and fitness traits in Nilagiri sheep. Information on pedigree of 6430 animals collected during the year of 1965–2015 by Sheep Breeding Research Station (SBRS) in Sandynallah were used for analysis. Inbreeding coefficient (F) was calculated from pedigree information using Wright’s method. The average inbreeding per cent was 1.82% in the whole population studies (6430 animals). The average inbreeding per cent was 3.9% for 3007 no. of inbred animals. The effect of inbreeding on most of the reproduction and fitness traits were significant and depression due to inbreeding was evident.The significant effect of inbreeding on reproduction traits viz., age at first service (AFS), weight at first service (WFS), age at first lambing (AFL) and fitness traits viz., tupping percent (TP), number of lambs weaned per ewe mated (NLWEM), number of lambs weaned per ewe lambing (NLWEL) and total lambs weaned per ewe over lifetime (TLWE) was studied using a general linear model, with individual inbreeding coefficient as covariate. The partial regression coefficient for AFC, WFS, AFL, TP, NLWEM, NLWEL and TLWE were 1.28 days, −0.25 kg, 8.13 days, −0.02%, −0.028, −0.017 and −0.182 per 1 per cent increase in inbreeding for Nilagiri sheep. Survival and litter size were not affected by inbreeding. In general, inbreeding had a depressive effect on most of the reproduction and fitness traits. Inbreeding in the population has to be restricted through methods such as introduction of unrelated animals or following co-ancestry based mating system.

Study on Population Dynamics and Effects of Inbreeding on Performance Traits in Indian Murrah Buffalo

Background: A population is continuously facing the changing environment and its directly influencing the production of animal so to adopt these changes population must be flexible and have sufficient variability to overcome the adverse affects of environment. The evaluation of animals in terms of production performance traits along with impact of inbreeding coefficient is essential to formulate breeding and selection strategies for higher genetic improvement. Methods: Genealogy data of 6429 animals maintained at ICAR-NDRI, Karnal, India was analyzed by web-based POPREP application tool (http:// poprep.tzv.fal.de) and ENDOG V5.8 used to study the population structure and genetic diversity and regression model to study the effect of inbreeding on first lactation productive traits in Murrah buffaloes. Result: The result indicated that 91.91% of the individuals had known pedigree. The maximum generation traced was 13 with mean, full and equivalent complete generation as 5.93, 1.67 and 3.25 respectively. The average generation interval was 8.28 years and longer for the sire-son pathway and 2.16% was average inbreeding in whole population. The average genetic diversity loss was 2.10% indicated that the population has been stable with sufficient diversity. The study also revealed non significant effect of inbreeding on all first lactation traits. The low inbreeding was firstly due to introduction of new genetic variant and culling of animals avoiding mating of related ones and secondly due to incompleteness of pedigree in earlier years. This can be used as a base line information of phenomic needs to be generated before applying genomics tools in particular herd to be used as reference population in future for genomic selection.

In-depth Pedigree Analysis and Inbreeding Effect on Reproduction Traits in Sahiwal Nucleus Herd

Background: Loss of genetic diversity is allied with adverse incidents such as inbreeding depression in fitness related traits, addiction of favorable alleles and enhances fluctuation on selection response. Therefore, the study aims to monitor population structure and avoid unfavorable effects of inbreeding for sustainable improvement in breeding programme.Methods: Pedigree information on 3449 animals born from 1955-2018 was analyzed. The effect on inbreeding on Age at first calving (AFC), Service period (SP), Daughter pregnancy rate (DPR), Calving interval (CI) and pregnancy rate was seen by regression analysis.Result: The pedigree completeness index (PCI) were found to be (%) 92.32, 80.26, 65.22, 49.43% and 32.54 respectively from first to fifth generations. The estimated average inbreeding rate was 2.30% and average genetic diversity loss was 2.64%. Study also revealed significant effect of inbreeding on (AFC, CI and SP) with slightly increasing trends. Hence, it is suggested that more precise pedigree recording and planned mating strategies should be adopted to avoid negative effect of inbreeding in future generation.

Runs of homozygosity and analysis of inbreeding depression

Pedigree information was traditionally used to assess inbreeding. The availability of high-density marker panels provides an alternative to assess inbreeding, particularly in the presence of incomplete and error-prone pedigrees. Assessment of autozygosity across chromosomal segments using runs of homozygosity (ROH) has emerged as a valuable tool to estimate inbreeding due to its general flexibility and ability to quantify the chromosomal contribution to genome-wide inbreeding. Unfortunately, the identification of ROH segments is sensitive to the parameters used during the search process. These parameters are heuristically set, leading to significant variation in the results. The minimum length required to identify an ROH segment has major effects on the estimation of inbreeding and inbreeding depression, yet it is arbitrarily set. To overcome this limitation, a search algorithm to approximate mutation enrichment was developed to determine the minimum length of ROH segments. It consists of finding genome segments with significant effect differences in trait means between animals with high and low burdens of autozygous intervals with a specific length. The minimum length could be determined heuristically as the smallest interval at which a significant signal is detected. The proposed method was tested in an inbred Hereford cattle population genotyped for 30,220 SNPs. Phenotypes recorded for six traits were used for the approximation of mutation loads. The estimated minimum length was around 1 Mb for yearling weight (YW) and average daily gain (ADG) and 4 Mb for birth weight and weaning weight. These trait-specific thresholds estimated using the proposed method could be attributed to a trait-dependent effect of homozygosity. The detection of significant inbreeding effects was well aligned with the estimated thresholds, especially for YW and ADG. Although highly deleterious alleles are expected to be more frequent in recent inbreeding (long ROH), short ROH segments (<5 Mb) could contain a large number of less deleterious mutations with substantial joint effects on some traits (YW and ADG). Our results highlight the importance of accurate estimation of the ROH-based inbreeding and the necessity to consider a trait-specific minimum length threshold for the identification of ROH segments in inbreeding depression analyses. These thresholds could be determined using the proposed method provided the availability of phenotypic information.

Negative effect of inbreeding on fitness of an arctic–alpine Hieracium alpinum (Asteraceae), a species with a geographical parthenogenesis distribution pattern

Decreased fitness due to inbreeding in small populations can be a considerable disadvantage in sexually reproducing organisms compared to their asexual relatives. Therefore, inbreeding depression of sexuals could contribute to geographical parthenogenesis (GP) distribution patterns, when sexuals have more restricted distribution than their asexual relatives. In this study, we tested whether biparental inbreeding will lead to decreased fitness in sexual diploids of Hieracium alpinum, a species showing a GP distribution pattern. We performed three types of crosses (inbred, outbred, and interpopulation outbred) and measured eleven fitness traits. A subset of plants was also grown with a natural competitor Nardus stricta to increase any negative effects of inbreeding. We found significant effects of inbreeding in two out of eleven measured traits in the F1 generation. Initial biomass was statistically significantly lower by 9.6% in inbred lineages compared to outbred lineages. Similar trends, i.e., lower values in inbred progeny when compared to outbred one, were found also in final biomass and survival rate (values decreased in inbred progeny by 17.5% and 11.5%, respectively), but these differences were statistically nonsignificant. However, the negative effect of inbreeding on these traits was not increased by the presence of Nardus stricta as a competitor. Our results suggest that biparental inbreeding could to some extent explain a lowered colonizing ability of sexual diploid of H. alpinum, but the GP pattern observed is also likely to be influenced by other processes and their interactions.

The impact of diacylglycerol O-acyltransferase 1 gene polymorphism on carcass traits in cattle

The aim of this study was to identify the K232A polymorphism in gene encoding diacylglycerol O-acyltransferase 1 (DGAT1) and to evaluate its effect on carcass traits in population of Slovak Pinzgau steers. The genotyping data were obtained for totally 56 animals by using PCR-RFLP method. The A allele (0.93) was more frequent in analysed population than K allele (0.07). Even if the expected and observed heterozygosity indicated prevalence of homozygotes, the significant effect of inbreeding on population structure wasn’t found (FIS=-0.08). The decline in effective allele number (Na=1.15) as well as polymorphic information content (PIC=0.12) pointed out to significant decrease of locus effectiveness in population. The effect of DGAT1 gene polymorphism on carcass traits was tested by using the GLM procedure adopted in SAS 9.3. In association analysis the proportion of muscle, fat, bone, and drip loss within the beef three-rib section were evaluated. However, the statistical analysis showed only non-significant impact of DGAT1 gene polymorphism on selected production traits in analysed population.

Effect of inbreeding and individual increase in inbreeding on growth in Nilagiri and Sandyno breeds of sheep

SummaryIndividual increase in inbreeding coefficients (ΔFi) has been recommended as an alternate measure of inbreeding. It can account for the differences in pedigree knowledge of individual animals and avoids overestimation due to increased number of known generations. The effect of inbreeding (F) and equivalent inbreeding (EF) calculated fromΔFi, on growth traits were studied in Nilagiri and Sandyno flocks of sheep. The study was based on data maintained at the Sheep Breeding Research Station, Sandynallah. The pedigree information and equivalent number of generations were less in Sandyno compared with Nilagiri sheep. The average F and EF for the Nilagiri population were 2.17 and 2.44, respectively and the corresponding values for Sandyno sheep were 0.83 and 0.84, respectively. The trend of inbreeding over years in both the populations indicated that EF was higher during earlier generations when pedigree information was shallow. Among the significant effects of inbreeding, the depression in growth per 1 percent increase in inbreeding ranged from 0.04 kg in weaning weight to 0.10 kg in yearling weight. In general, more traits were affected by inbreeding in Nilagiri sheep, in which greater regression of growth traits was noticed with F compared with EF. Higher values of EF than F in earlier generations in both the populations indicate that EF avoided the potential overestimation of inbreeding coefficient during recent generations. In the Sandyno population, the magnitude of depression noticed among growth traits with significant effects of inbreeding was higher. The differences in response to F and EF noticed in the two populations and possible causes for the trait wise differences in response to F and EF are appropriately discussed.

Inbreeding depression and environmental effect on milk traits of the Murciano-Granadina goat breed

The extent of inbreeding as well as environmental factors such as parity order, age at kidding and contemporary group (herd-year-season) was evaluated for their effects on the total production of milk, fat, protein and dry extract in Murciano-Granadina goats in Spain. The pedigrees of 11,926 females were traced to calculate the inbreeding coefficient for each animal. The lactations of these 22,832 females were analysed, standardised to 210 days of lactation, and information on the whole milk, fat, protein and dry extract production was recorded. The least squares method was used, and fixed effects in the model included parity order, the age of goat at kidding and contemporary group, and the inbreeding rate as a continuous variable, considering linear and quadratic effects. Based on this model, only 1.18% of the animals presented inbreeding, and the average population was of low magnitude (0.24%). However, among inbred animals, the average was considered high (20.31%). The total average of milk, fat, protein and dry extract production is within the range considered normal for the breed. The variables of parity order, the age of goat at kidding and contemporary group, exerted a statistically significant influence on the milk production and composition traits. Inbreeding had a quadratic effect on total milk production with a minimum point at 10.59% of inbreeding. Inbreeding had a positive linear correlation with total fat and dry extract yield. There was no statistically significant effect of inbreeding on total protein production. In general, the inbreeding levels in the Murciano-Granadina goat population did not negatively affect milk traits in the evaluated period.

Morphological Traits and Inbreeding Depression in Bracco Italiano Dog Breed

This paper reports the first results of a survey on morphological traits in Bracco Italiano dog breed, and analyzes the effects of various levels of inbreeding on these measures. Traits were taken from 155 adult (mean age 4.18±2.60 years) dogs (79 males and 76 females) belonging to 57 different farms. For each animal, the following biometrical measurements were considered: height at withers (WH), height of chest (ChH), body length (BL), length at rump (RL), height at rump (RH), iliac width of rump (RIlW), ischiatic width of rump (RIsW), circumference of chest (ChC), circumference of cannon (CaC), length of ear (EL), and length of head (HL). The ratio of rump length/withers height (RL/WH), cannon circumference/chest circumference (CaC/ChC) and head length/withers height (HL/WH) were also calculated. ANOVA was used to test the differences between males and females and among farms in terms of morphological measurements and ratios. Significant differences between males and females were observed for many morphological traits. The measures coincided with what reported in the current breed standard, apart from the length of the rump, which was around ¼ of the withers height rather than the 1/3 required in the standard. No significant effect of inbreeding on conformation traits was observed.

Inbreeding Depression under Drought Stress in the Rare Endemic Echium wildpretii (Boraginaceae) on Tenerife, Canary Islands

How climate-change induced environmental stress may alter the effects of inbreeding in patchy populations of rare species is poorly understood. We investigated the fitness of progeny from experimental self- and cross-pollinations in eight populations of different size of Echium wildpretii, a rare endemic plant of the arid subalpine zone of the Canarian island of Tenerife. As control treatments we used open pollination and autonomous selfing. The seed set of open-pollinated flowers was 55% higher than that of autonomously selfed flowers, showing the importance of animal pollination for reproductive success. The seed set, seed mass and germination rate of seedlings of hand-selfed flowers was similar to that of hand-crossed flowers, indicating weak inbreeding depression (seed set –4.4%, seed mass –4.1%, germination –7.3%). Similarly, under normal watering there were no significant effects of inbreeding on seedling survival (–3.0%). However, under low watering of seedlings inbreeding depression was high (survival –50.2%). Seed set of open- and hand-outcrossed-pollinated flowers was higher in large than in small populations, possibly due to more frequent biparental inbreeding in the latter. However, later measures of progeny fitness were not significantly influenced by population size. We predict that increasing drought duration and frequency due to climate change and reductions of population sizes may increase inbreeding depression in this charismatic plant species and thus threaten its future survival in the longer term.

Effects of inbreeding on potential and realized immune responses inTenebrio molitor

Although numerous studies on vertebrates suggest that inbreeding reduces their resistance against parasites and pathogens, studies in insects have found contradictory evidence. In this study we tested the effect of 1 generation of brother-sister mating (inbreeding) on potential and realized immune responses and other life-history traits in Tenebrio molitor. We found that inbreeding reduced adult mass, pre-adult survival and increased development time, suggesting that inbreeding reduced the condition of the adults and thus potentially made them more susceptible to physiological stress. However, we found no significant effect of inbreeding on the potential immune response (encapsulation response), but inbreeding reduced the realized immune response (resistance against the entomopathogenic fungi, Beauveria bassiana). There was a significant family effect on encapsulation response, but no family effect on the resistance against the entomopathogenic fungi. Given that this latter trait showed significant inbreeding depression and that the sample size for the family-effect analysis was small it is likely that the lack of a significant family effect is due to reduced statistical power, rather than the lack of a heritable basis to the trait. Our study highlights the importance of using pathogens and parasites in immunoecological studies.

Inbreeding effects on exterior traits in Polish konik horses

Abstract. Conformation traits of 284 Polish konik mares used in breeding until 2005 were analyzed including pedigree information on 477 individuals. Average inbreeding coefficient was in SK Dobrzyniewo 5.9 %, in SK Kobylniki 5.1 %, and 5.6 % in SO Sieraków. No significant effect of inbreeding on conformation traits was observed. Heritability was estimated as: 0.65 (±0.13) for height at whither, 0.22 (±0.14) for circuit of chest and 0.65 (±0.13) for circuit of cannon. Negative phenotypic trend was observed for girth circumference and positive for circuit of cannon. No significant genetic trends were observed for the analyzed traits, which agrees with the assumption of breeding program in genetic reserve flocks.

Genetic description of a divergent selection experiment in Angora rabbits with overlapping generations

The chief aims of this paper were the following: (i) to describe the demography and genetic structure in two divergent selected lines for total fleece weight (TFW) of French Angora rabbits with overlapping generations; (ii) to describe the effects of inbreeding during an experiment of divergent selection. A study of longevity with the survival kit showed that there was no significant difference in the risk of death or culling between the low line (LL) and high line (HL). A significant effect of inbreeding (p < 0.05) was observed with a 30% higher risk factor in the highest class of inbreeding coefficient compared with the other classes. The means of generation interval were 562 and 601 days in LL and HL, respectively. The numbers of generations for LL and HL were 3.90 and 3.64, respectively. Generation intervals decreased significantly from 1995 to 2000 (p < 0.05). The number of daughters in HL was very variable. The number of animals per generation was higher in HL than in LL. Each buck left nearly three daughters to the next generation (2.52 in LL, 3.24 in HL). In both lines, the effective number of ancestor genomes still present in the genetic pool of the generation was around eight from the reference population of 1995 to that of 2001. Inbreeding in HL was always higher than in LL. The effect of inbreeding was also significant (p < 0.05) on TFW and live weight. The animals with the lowest inbreeding category produced a higher TFW (p < 0.05) than the others. The observed selection differentials were lower than that expected owing to the breeding animal management rules in order to control inbreeding increase.

Relationship of inbreeding with sperm quality and reproductive success in Mexican gray wolves

AbstractThe ultimate goal of the Mexican gray wolf Canis lupus baileyi captive management program is reintroduction of healthy individuals into wild habitats. To this end, zoo population managers work to provide not only for the physical well‐being but also for the genetic health of these animals. However, the very limited genetic founder base, exacerbated by breeding within three distinct lineages, resulted in very high coefficients of inbreeding. Because support for measurable levels of inbreeding depression in the captive wolf population, as defined by reductions in common fitness measures such as juvenile survival or reproductive success, has been weak, we investigated the potential effects on male reproductive capacity. We analyzed semen samples from wolves from all three lineages and compared them with samples from subsequent lineage crosses and from generic gray wolves. We not only found a significant effect of inbreeding on sperm quality but we related both inbreeding and sperm quality to reproductive success. Samples from male offspring of lineage crosses, with inbreeding coefficients of zero were similar in quality to those from generic gray wolves. However, samples from a limited number of offspring from back‐crosses were of extremely poor quality. Although it is reassuring that sperm quality was so much improved in male offspring of lineage crosses, the concomitant reduction in inbreeding coefficient does not eliminate the potentially deleterious alleles. Our results demonstrate that sperm quality is an important indicator of fertility and reproductive success in Mexican wolves. In addition, our data lend further support to the presence of inbreeding depression in this taxon.

Case study: The effect of inbreeding on the production and reproduction traits in the Elsenburg Dormer sheep stud

Data of the Elsenburg Dormer sheep stud, which was kept closed since inception, were collected over a period of 62 years (1941–2002). The breed is a composite, resulting from a cross of Dorset Horn rams with South African Mutton Merino ewes. These data were analysed to quantify the increase in actual level of inbreeding and to investigate the effect of inbreeding on phenotypic values, genetic parameters and estimated breeding values. After editing 11954 pedigree, 11721 birth weight (BW) and survival, 9205 weaning weight (WW) and 7504 reproduction records were available for analysis. The mean level of inbreeding ( F) of all animals over all years was 16%; 14% for dams and 16% for sires. Mean, minimum and maximum F for the lambs in 1997 (when 3 rams from outside were introduced) were 22%, 21% and 24% respectively. Estimates of inbreeding depression for individual inbreeding of 1% were − 0.006 kg for birth and − 0.093 kg for weaning weight respectively. These were the only estimates that were significantly ( P < 0.01) different from zero. No significant effects of inbreeding on the other traits were found. There were virtually no differences in the genetic parameters estimated when fitting the two models (inclusion or exclusion of inbreeding coefficients as covariates). Estimates of the phenotypic variance differed slightly for WW between the two models. Ranking of animals were studied for weaning weight when the two models were considered. The high correlation coefficients (0.990) indicate that the use of inbreeding coefficients did not cause important changes in ranking of animals and sires for WW. It was concluded that slow inbreeding (rate of inbreeding of approximately 1.53% per generation over 19 generations) allows natural selection to operate and to remove the less fit animals. At any given mean level of F, less inbreeding depression would then be expected among the individuals who accumulated the inbreeding over a larger number of generations. Nevertheless, inbreeding coefficients should be considered when mating decisions are made, to limit the possible deleterious effects of inbreeding on productive and reproductive traits and to detect animals “resilient to” higher levels of inbreeding.

Inbreeding in nature: brothers and sisters, do not unite!

Inbreeding, or mating among related individuals, causes problems with viability and fertility in small captive populations. Young inbred ungulates often die in zoos, and the eggs of inbred fruit flies frequently fail to hatch in the laboratory. But what is the role of inbreeding in nature? Does it really affect patterns of population change in the wild, and could it even cause extinctions? These questions were the subject of hot debate in the 1970s. By the late 1980s, many ecologists seemed to agree that other ecological factors were more important than inbreeding in reducing population size and in extinguishing populations. However, we could now be witnessing the revival of interest in inbreeding as a factor to contend with. Whereas theoretical studies have demonstrated how the accumulation of mildly deleterious alleles can lower the fitness of small populations, experiments, both in the laboratory and in the wild, have demonstrated significant effects of inbreeding on the density of several animal and plant species.Observations in 1998 suggested that inbreeding increases the risk of population extinction in the butterfly Melitaea cinxia.1xInbreeding and extinction in a butterfly metapopulation. Saccheri, I et al. Nature. 1998; 392: 491–494Crossref | Scopus (1008)See all References1 Some of the same authors now report experimental evidence2xExperimental confirmation that inbreeding depression increases extinction risk in butterfly populations. Nieminen, M et al. Am. Nat. 2001; 157: 237–244Crossref | PubMed | Scopus (106)See all References2 that not only confirms the earlier results, but also demonstrates when and how inbreeding exerts its harmful effect. Working on small populations of Melitaea cinxia in the laboratory, Nieminen et al. found that inbreeding lowered the proportion of eggs hatched and decreased the survival of over-wintering larvae. The larvae of this butterfly spin communal winter nests, but inbreeding made them spin nests full of holes, which failed to protect them from the elements. And when Nieminen et al. introduced in- and outbred populations into the field, they found that inbred populations had a much higher risk of extinction than did outbred ones.This study suggests that inbreeding in Melitaea cinxia may reduce local survival to the point of local extinction. And as the species occurs as a set of classical metapopulations, where the extinction of small local populations is counterbalanced by the colonization of empty sites, an increased risk of local extinction might ultimately threaten the survival of the species at a landscape level.The work of Nieminen et al. is clearly a case study on a single species with many special features. In their study region, Melitaea cinxia typically occurs as very small local populations, where inbreeding between close relatives is more the rule than an exception. This should keep us from generalizing the current results too broadly. But by identifying inbreeding as a key agent in the dynamics of at least this species, Nieminen et al. do offer an eye opener. With more and more species being split into smaller and more fragmented populations, perhaps inbreeding might soon be a threat to the survival of many wild populations?

Inbreeding and inbreeding depression on reproduction and production traits of White Leghorn lines selected for egg production traits

1. The rate of inbreeding and its effect on reproduction and egg production traits were studied in White Leghorn lines selected for egg production traits. The experiment was carried out for 10 generations in a control line (C) and in lines selected for increased egg number (EN), egg weight (EW) and egg mass (EM). 2. Data were available on reproduction traits, such as percent fertile eggs (PF), percent hatched of fertile eggs (PHF) and percent hatched of total eggs set (PHT), and on egg production traits such as age at 1st egg (AFE), egg number and egg weight. 3. The rate of increase in average inbreeding per generation was 1.50, 1.24, 1.14 and 0.18% for the line EN, EW, EM and C, respectively. The effect of inbreeding on reproduction and production traits was estimated by including the inbreeding coefficient of the hen (Fh), embryo (Fe) and mate (Fs) as a partial linear regression in the model. 4. There was a significant effect of inbreeding on reproduction traits in line EW attributable to the inbreeding of the hen, embryo and mate. No such effect was observed in the other lines. 5. In all lines inbreeding tended to reduce egg number and delay sexual maturity. In general, all lines reacted differently to inbreeding.

Inbreeding effects on mating system traits for two species ofLupinus (Leguminosae)

The consequences of inbreeding for reproductive traits were investigated for two closely related annual lupines that differ in their mating system. Lupinus bicolor (Leguminosae) is a primarily selling species while Lupinus nanus outcrosses at intermediate rates. A controlled crossing program was used for each species to produce selfed and outcrossed progeny. These progeny were then grown in a greenhouse and scored for the date of first flower, flower morphology, and autofertility. Selfed progeny of L. bicolor produced significantly smaller flowers but did not differ from outcrossed progeny for the remaining traits. Selfed progeny of L. nanus produced flowers that significantly differed in shape and had fewer ovules than the flowers of outcrossed progeny. Selfed progeny of L. nanus also had significantly lower rates of autofertility in comparison to outcrossed progeny. The significant effects of inbreeding on these mating system traits may indicate the presence of directional dominance at the loci underlying these characters. The consequences of these direct effects of inbreeding on reproductive traits for plants growing in natural populations may include nonadaptive changes in the outcrossing rate between generations.

Arthritis in the carpal joints of Norwegian trotter — heritability, effects of inbreeding and conformation

Carpal joint arthritis (carpitis) was diagnosed in a sample of 508 four year old Norwegian trotters born in 1980. The Norwegian trotter is a light Döle-horse, and prevalences of 10 and 27% were reported for bilateral and overall carpitis, respectively. Corresponding underlying scale heritability estimates, based on data of 407 horses sired by 34 stallions, were 0.67 and 0.25. Significant effect of inbreeding on bilateral carpitis was estimated on the same scale. The probability of the disease was, respectively, 6.7% and 12.3% among horses with lower or higher inbreeding coefficient than average. The relationship between faults of conformation and variables of carpitis was examined by a logistic regression procedure. On forelimbs, irregular values for calf knees and anterior broken toe-axis were associated with an enhanced prevalence of bilateral carpitis, while corresponding values for calf knees, standing under, toeing out, anterior broken toe-axis and lower circumference on cannon increased the overall carpitis probability.