Journal articles: 'Outbred lines'

1

Phillips, Patrick C., Michael C. Whitlock, and Kevin Fowler. "Inbreeding Changes the Shape of the Genetic Covariance Matrix in Drosophila melanogaster." Genetics 158, no. 3 (July 1, 2001): 1137–45. http://dx.doi.org/10.1093/genetics/158.3.1137.

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Abstract The pattern of genetic covariation among traits (the G matrix) plays a central role in determining the pattern of evolutionary change from both natural selection and random genetic drift. Here we measure the effect of genetic drift on the shape of the G matrix using a large data set on the inheritance of wing characteristics in Drosophila melanogaster. Fifty-two inbred lines with a total of 4680 parent-offspring families were generated by one generation of brother-sister mating and compared to an outbred control population of 1945 families. In keeping with the theoretical expectation for a correlated set of additively determined traits, the average G matrix of the inbred lines remained proportional to the outbred control G matrix with a proportionality constant approximately equal to (1 – F), where F is the inbreeding coefficient. Further, the pattern of covariance among the means of the inbred lines induced by inbreeding was also proportional to the within-line G matrix of the control population with a constant very close to the expectation of 2F. Although the average G of the inbred lines did not show change in overall structure relative to the outbred controls, separate analysis revealed a great deal of variation among inbred lines around this expectation, including changes in the sign of genetic correlations. Since any given line can be quite different from the outbred control, it is likely that in nature unreplicated drift will lead to changes in the G matrix. Thus, the shape of G is malleable under genetic drift, and the evolutionary response of any particular population is likely to depend on the specifics of its evolutionary history.

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Pérez-Enciso, Miguel, and Luis Varona. "Quantitative Trait Loci Mapping in F2 Crosses Between Outbred Lines." Genetics 155, no. 1 (May 1, 2000): 391–405. http://dx.doi.org/10.1093/genetics/155.1.391.

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Abstract We develop a mixed-model approach for QTL analysis in crosses between outbred lines that allows for QTL segregation within lines as well as for differences in mean QTL effects between lines. We also propose a method called “segment mapping” that is based in partitioning the genome in a series of segments. The expected change in mean according to percentage of breed origin, together with the genetic variance associated with each segment, is estimated using maximum likelihood. The method also allows the estimation of differences in additive variances between the parental lines. Completely fixed random and mixed models together with segment mapping are compared via simulation. The segment mapping and mixed-model behaviors are similar to those of classical methods, either the fixed or random models, under simple genetic models (a single QTL with alternative alleles fixed in each line), whereas they provide less biased estimates and have higher power than fixed or random models in more complex situations, i.e., when the QTL are segregating within the parental lines. The segment mapping approach is particularly useful to determining which chromosome regions are likely to contain QTL when these are linked.

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Bolder, N. M., L. L. G. Janss, F. F. Putirulan, and J. A. Wagenaar. "Resistance of broiler outbred lines to infection with Salmonella enteritidis." Avian Pathology 31, no. 6 (December 2002): 581–87. http://dx.doi.org/10.1080/0307945021000024667.

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Weber, K. E., and L. T. Diggins. "Increased selection response in larger populations. II. Selection for ethanol vapor resistance in Drosophila melanogaster at two population sizes." Genetics 125, no. 3 (July 1, 1990): 585–97. http://dx.doi.org/10.1093/genetics/125.3.585.

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Abstract The effect of large population size on selection response was investigated using Drosophila melanogaster, with four "small" lines of 160 selected parents/generation compared to two "large" lines of 1,600 selected parents/generation. All lines were selected under similar conditions at a selection intensity of approximately 0.55 standard deviations, for 65 generations, for increased ethanol vapor resistance (measured in minutes required to become anesthetized). Two unselected control lines of 320 parents/generation were also maintained. A significant effect of population size was found. The final treatment means and standard errors were: 27.91 +/- 1.28 min (two "large" lines); 19.40 +/- 1.54 min (four "small" lines); and 4.98 +/- 0.35 min (two control lines). To estimate the mutation rate for the trait, two isogenic lines of about 400 selected parents were selected for 29 generations. The mean increase in additive genetic variance per generation was 0.0009 times the initial environmental variance of the outbred lines. This is comparable to other reported mutation rates. Mutation can explain part of the difference in evolved resistance between treatments, but it appears that even at rather large population sizes, a large difference in long-term response can be obtained in larger outbred lines, from more complete utilization of the initial genetic variation.

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MINA, N. S., B. L. SHELDON, B. H. YOO, and R. FRANKHAM. "Heterozygosity at Protein Loci in Inbred and Outbred Lines of Chickens." Poultry Science 70, no. 9 (September 1991): 1864–72. http://dx.doi.org/10.3382/ps.0701864.

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6

Curtsinger, James W. "Quantitative wing variation in inbred and outbred lines of Drosophila melanogaster." Journal of Heredity 77, no. 4 (July 1986): 267–71. http://dx.doi.org/10.1093/oxfordjournals.jhered.a110234.

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7

Gonzales, Natalia M., and Abraham A. Palmer. "Fine-mapping QTLs in advanced intercross lines and other outbred populations." Mammalian Genome 25, no. 7-8 (June 7, 2014): 271–92. http://dx.doi.org/10.1007/s00335-014-9523-1.

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8

Haley, C. S., S. A. Knott, and J. M. Elsen. "Mapping quantitative trait loci in crosses between outbred lines using least squares." Genetics 136, no. 3 (March 1, 1994): 1195–207. http://dx.doi.org/10.1093/genetics/136.3.1195.

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Abstract The use of genetic maps based upon molecular markers has allowed the dissection of some of the factors underlying quantitative variation in crosses between inbred lines. For many species crossing inbred lines is not a practical proposition, although crosses between genetically very different outbred lines are possible. Here we develop a least squares method for the analysis of crosses between outbred lines which simultaneously uses information from multiple linked markers. The method is suitable for crosses where the lines may be segregating at marker loci but can be assumed to be fixed for alternative alleles at the major quantitative trait loci (QTLs) affecting the traits under analysis (e.g., crosses between divergent selection lines or breeds with different selection histories). The simultaneous use of multiple markers from a linkage group increases the sensitivity of the test statistic, and thus the power for the detection of QTLs, compared to the use of single markers or markers flanking an interval. The gain is greater for more closely spaced markers and for markers of lower information content. Use of multiple markers can also remove the bias in the estimated position and effect of a QTL which may result when different markers in a linkage group vary in their heterozygosity in the F1 (and thus in their information content) and are considered only singly or a pair at a time. The method is relatively simple to apply so that more complex models can be fitted than is currently possible by maximum likelihood. Thus fixed effects of background genotype can be fitted simultaneously with the exploration of a single linkage group which will increase the power to detect QTLs by reducing the residual variance. More complex models with several QTLs in the same linkage group and two-locus interactions between QTLs can similarly be examined. Thus least squares provides a powerful tool to extend the range of crosses from which QTLs can be dissected whilst at the same time allowing flexible and realistic models to be explored.

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Shackell, Nancy L., and Roger W. Doyle. "Scale Morphology as an Index of Developmental Stability and Stress Resistance of Tilapia (Oreochromis niloticus)." Canadian Journal of Fisheries and Aquatic Sciences 48, no. 9 (September 1, 1991): 1662–69. http://dx.doi.org/10.1139/f91-197.

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Growth and the stabilities of growth and development were examined in inbred, outbred, and interstrain hybrid lines of tilapia (Oreochromus niloticus) under two diet regimes. Developmental stability was quantified as the inverse of the number of deformed scale circuli (calcified ridges). Growth stability was measured as the inverse of the individual variability of circulus spacing (circulus spacing is an indirect measure of growth rate). Each line was fed an alternating diet of low-protein rice bran and high-protein commercial pellet or a constant diet of commercial pellet. Diet regime had a significant effect on growth, developmental stability, and growth stability. Genetic composition of line had a significant effect only on developmental stability. Inbred lines had lower developmental stabilities than outbred lines. Hybrid progeny had higher developmental stability than the average of the parent strain values. Faster growing individuals had higher developmental and growth stabilities and lower growth stabilities (only within the commercial pellet regime). Composite indices of "merit" can be constructed by combining the variables, according to the correlations among variables and breeding objectives.

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Daley, J. W., and R. K. Shepherd. "Utilization of F1information in estimating QTL effects in F2crosses between outbred lines." Journal of Animal Breeding and Genetics 125, no. 1 (February 2008): 35–44. http://dx.doi.org/10.1111/j.1439-0388.2007.00699.x.

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11

Pérez-Enciso, Miguel, Rohan L. Fernando, Jean-Pierre Bidanel, and Pascale Le Roy. "Quantitative Trait Locus Analysis in Crosses Between Outbred Lines With Dominance and Inbreeding." Genetics 159, no. 1 (September 1, 2001): 413–22. http://dx.doi.org/10.1093/genetics/159.1.413.

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Abstract We provide a theoretical framework for quantitative trait locus (QTL) analysis of a crossed population where parental lines may be outbred and dominance as well as inbreeding are allowed for. It can be applied to any pedigree. A biallelic QTL is assumed, and the QTL allele frequencies can be different in each breed. The genetic covariance between any two individuals is expressed as a nonlinear function of the probability of up to 15 possible identity modes and of the additive and dominance effects, together with the allelic frequencies in each of the two parental breeds. The probabilities of each identity mode are obtained at the desired genome positions using a Monte Carlo Markov chain method. Unbiased estimates of the actual genetic parameters are recovered in a simulated F2 cross and in a six-generation complex pedigree under a variety of genetic models (allele fixed or segregating in the parental populations and additive or dominance action). Results from analyzing an F2 cross between Meishan and Large White pigs are also presented.

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Ledur, M. C., N. Navarro, and M. Pérez-Enciso. "Large-scale SNP genotyping in crosses between outbred lines: how useful is it?" Heredity 105, no. 2 (October 21, 2009): 173–82. http://dx.doi.org/10.1038/hdy.2009.149.

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13

Gomez-Raya, Luis, and Erling Sehested. "Power for mapping quantitative trait loci in crosses between outbred lines in pigs." Genetics Selection Evolution 31, no. 4 (1999): 351. http://dx.doi.org/10.1186/1297-9686-31-4-351.

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KIM, JONG-JOO, HONGHUA ZHAO, HAUKE THOMSEN, MAX F. ROTHSCHILD, and JACK C. M. DEKKERS. "Combined line-cross and half-sib QTL analysis of crosses between outbred lines." Genetical Research 85, no. 3 (June 2005): 235–48. http://dx.doi.org/10.1017/s0016672305007597.

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Data from an F2 cross between breeds of livestock are typically analysed by least squares line-cross or half-sib models to detect quantitative trait loci (QTL) that differ between or segregate within breeds. These models can also be combined to increase power to detect QTL, while maintaining the computational efficiency of least squares. Tests between models allow QTL to be characterized into those that are fixed (LC QTL), or segregating at similar (HS QTL) or different (CB QTL) frequencies in parental breeds. To evaluate power of the combined model, data wih various differences in QTL allele frequencies (FD) between parental breeds were simulated. Use of all models increased power to detect QTL. The line-cross model was the most powerful model to detect QTL for FD>0·6. The combined and half-sib models had similar power for FD<0·4. The proportion of detected QTL declared as LC QTL decreased with FD. The opposite was observed for HS QTL. The proportion of CB QTL decreased as FD deviated from 0·5. Accuracy of map position tended to be greatest for CB QTL. Models were applied to a cross of Berkshire and Yorkshire pig breeds and revealed 160 (40) QTL at the 5% chromosome (genome)-wise level for the 39 growth, carcass composition and quality traits, of which 72, 54, and 34 were declared as LC, HS and CB QTL. Fourteen CB QTL were detected only by the combined model. Thus, the combined model can increase power to detect QTL and mapping accuracy and enable characterization of QTL that segregate within breeds.

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Lorthongpanich, Chanchao, Shang-Hsun Yang, Karolina Piotrowska-Nitsche, Rangsun Parnpai, and Anthony W. S. Chan. "Development of single mouse blastomeres into blastocysts, outgrowths and the establishment of embryonic stem cells." REPRODUCTION 135, no. 6 (June 2008): 805–13. http://dx.doi.org/10.1530/rep-07-0478.

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The recently developed technique of establishing embryonic stem (ES) cell lines from single blastomeres (BTMs) of early mouse and human embryos has created significant interest in this source of ES cells. However, sister BTMs of an early embryo might not have equal competence for the development of different lineages or the derivation of ES cells. Therefore, single BTMs from two- and four-cell embryos of outbred mice were individually placed in sequential cultures to enhance the formation of the inner cell mass (ICM) and the establishment of embryonic outgrowth. The outgrowths were then used for the derivation of ES cell lines. Based on the expression of ICM (Sox2) and trophectoderm (Cdx2) markers, it was determined that ICM marker was lacking in blastocysts derived from 12% of BTMs from two-cell stage and 20% from four-cell stage. Four ES cell lines (5.6%; 4/72) were established ater culture of single BTMs from two-cell embryos, and their pluripotency was demonstrated by their differentiation into neuronal cell types. Our results demonstrate that sister BTMs of an early embryo are not equally competent for ICM marker expression. However, we demonstrated the feasibility of establishing ES cells from a single BTM of outbred mice.

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Karpova, Inessa V., Evgenii R. Bychkov, Vera V. Marysheva, Vladimir V. Mikheyev, and Petr D. Shabanov. "The effect of oxytocin on the level and monoamines turnover in the brain of isolated mice of highand low-aggressive lines." Reviews on Clinical Pharmacology and Drug Therapy 15, no. 2 (June 15, 2017): 23–30. http://dx.doi.org/10.17816/rcf15223-30.

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Objective. In the course of the study, the effect of oxytocin on the behavior and level of monoamines of the brain in aggressive male isolates of the initially low-aggressive C57Bl/6 line with similar indices of highly aggressive white outbred mice was compared. Methods. In experiments on isolated male mice of the low-aggressive C57Bl/6 line and highly aggressive white outbred mice, the effects of oxytocin on the aggressive behavior and the activity of monoaminergic systems of the left and right cerebral hemispheres was investigated. After prolonged social isolation, the male mice, who attacked in the resident-intruder test, were selected for further research. Oxytocin (5 IU/ml, 20μl) was admitrated intranasally. Control animals was treated with saline. With the HPLC-method, in the cerebral cortex, hippocampus, olfactory tubercle and striatum of the left and right sides of the brain the concentrations of dopamine, norepinephrine, serotonin and their metabolites of dioxyphenylacetic, homovaniline and 5-hydroxyindoleacetic acids were measured. Results. Among the male isolates of the C57Bl/6 line, the proportion of aggressive individuals was 56.5%, and among white outbred mice 87.5%. The investigated lines also differed in the attack latency time: aggressive C57Bl/6 mice attacked an average on the 113.1±23.5 second, while in white outbred mice the attack followed on the 35.3±14.7 second (p < 0.01). In the aggressive male isolates of the C57Bl/6 line, which received intranasally saline solution, the content of serotonin and 5-hydroxyindoleacetic acid in the hippocampus was significantly higher on the right. In C57Bl/6, oxytocin reduced the manifestation of aggression caused by prolonged social isolation (p < 0.05), but had no absolute ability to stop this type of behavior. Under its influence, the level of dopamine in the left cortex (p = 0.054), as well as serotonin content in the right hippocampus (p < 0.05) and in the left striatum (p < 0.05) decreased. In addition, the use of oxytocin in C57Bl/6 neutralized the asymmetry of serotonin and 5-hydroxyindoleacetic acid levels in the hippocampus. At the same time there was an asymmetry in the content of dopamine in the cerebral cortex with the predominance of this mediator in the right hemisphere (p < 0.05). In male isolates of highly aggressive white outbred mice, the effect of oxytocin on behavior was not found. However, in these animals oxytocin caused certain changes in monoaminergic systems of the brain. Under the action of oxytocin, the inicial right-sided asymmetry of the level of dopamine metabolites in the striatum and left-sided asymmetry in the level of serotonin in the cortex disappeared. Oxytocin caused an increase in the content of 5-hydroxyacetic acid in the right striatum (p < 0.05) and norepinephrine in the left hippocampus (p < 0.05). In addition, white outbred mice under the influence of oxytocin developed asymmetry with the predominance of norepinephrine in the right olfactory tubercle (p < 0.05). Conclusions. It can be assumed that relatively weak changes in the state of serotonergic and dopaminergic systems against the background of high reactivity of the noradrenergic system are a feature of the reaction of the brain of highly aggressive animals to oxytocin. The data obtained are discussed in terms of the lateralization of neurotransmitter systems responsible for intraspecific aggression caused by prolonged social isolation. (For citation: Karpova IV, Bychkov ER, Marysheva VV, et al. The effect of oxytocin on the level and monoamines turnover in the brain of isolated mice of high- and low-aggressive lines. Reviews on Clinical Pharmacology and Drug Therapy. 2017;15(2):23-30. doi: 10.17816/RCF15223-30).

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Sweeney, William E., Linda Kusner, Cathleen R. Carlin, Sharon Chang, Lidia Futey, Calvin U. Cotton, Katherine MacRae Dell, and Ellis D. Avner. "Phenotypic analysis of conditionally immortalized cells isolated from the BPK model of ARPKD." American Journal of Physiology-Cell Physiology 281, no. 5 (November 1, 2001): C1695—C1705. http://dx.doi.org/10.1152/ajpcell.2001.281.5.c1695.

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To study the pathophysiology of autosomal recessive polycystic kidney disease (ARPKD), we sought to develop conditionally immortalized control and cystic murine collecting tubule (CT) cell lines. CT cells were isolated from intercross breedings between BPK mice ( bpk +/−), a murine model of ARPKD, and the Immorto mice (H-2Kb- ts-A58 +/+ ). Second-generation outbred offspring (BPK × Immorto) homozygous for the BPK mutation ( bpk −/−; Im +/±; cystic BPK/H-2Kb- ts-A58), were phenotypically indistinguishable from inbred cystic BPK animals ( bpk −/−). Cystic BPK/H-2Kb- ts-A58 mice developed biliary ductal ectasia and massively enlarged kidneys, leading to renal failure and death by postnatal day 24. Principal cells (PC) were isolated from outbred cystic and noncystic BPK/H-2Kb- ts-A58 littermates at specific developmental stages. Epithelial monolayers were under nonpermissive conditions for markers of epithelial cell polarity and PC function. Cystic and noncystic cells displayed several properties characteristic of PCs in vivo, including amiloride-sensitive sodium transport and aquaporin 2 expression. Cystic cells exhibited apical epidermal growth factor receptor (EGFR) mislocalization but normal expression of ZO-1 and E-cadherin. Hence, these cell lines retain the requisite characteristics of PCs, and cystic BPK/H-2Kb- ts-A58 PCs retained the abnormal EGFR membrane expression characteristic of ARPKD. These cell lines represent important new reagents for studying the pathogenesis of ARPKD.

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Hutchinson, E. W., and M. R. Rose. "Quantitative genetics of postponed aging in Drosophila melanogaster. I. Analysis of outbred populations." Genetics 127, no. 4 (April 1, 1991): 719–27. http://dx.doi.org/10.1093/genetics/127.4.719.

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Abstract Selection has been used to create replicated outbred stocks of Drosophila melanogaster with increased longevity, increased later fecundity, and increased levels of physiological performance at later ages. The present study analyzed the quantitative transmission patterns of such stocks, employing extensive replication in numbers of stocks, individuals, and assayed characters. The populations used derived from five lines with postponed aging and five control lines, all created in 1980 from the same founding base population. The following characters were studied: early 24-hr fecundity, early ovary weight, early female starvation resistance, early male starvation resistance, female longevity and male longevity. Numerous crosses were performed to test for non-Mendelian inheritance, average dominance, maternal effects, sex-linkage and between-line heterogeneity. There was only slight evidence for any of these phenomena arising reproducibly in the characters studied. These findings suggest the value of this set of stocks for studies of the physiological basis of postponed aging.

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AULCHENKO, Y. S., F. TEUSCHER, H. H. SWALVE, and V. GUIARD. "Comparison of methods used for recovering the line origin of alleles in a cross between outbred lines." Genetical Research 79, no. 1 (February 2002): 75–83. http://dx.doi.org/10.1017/s0016672301005432.

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Here, we introduce the idea of probabilities of line origins for alleles in general pedigrees as found in crosses between outbred lines. We also present software for calculating these probabilities. The proposed algorithm is based on the linear regression method of Haley, Knott and Elsen (1994) combined with the Markov chain Monte Carlo (MCMC) method for estimating quantitative trait locus coefficients used as regressors. We compared the relative precision of our method and the original method as proposed by Haley et al. (1994). The scenarios studied varied in the allelic distribution of marker alleles in parental lines and in the frequency of missing marker genotypes. We found that the MCMC method achieves a higher accuracy in all scenarios considered. The benefits of using MCMC approximation are substantial if the frequency of missing marker data is high or the number of marker alleles is low and the allelic frequency distribution is similar in both parental lines.

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de Koning, Dirk J., Luc L. G. Janss, Annemieke P. Rattink, Pieter A. M. van Oers, Beja J. de Vries, Martien A. M. Groenen, Jan J. van der Poel, Piet N. de Groot, E. W. (Pim) Brascamp, and Johan A. M. van Arendonk. "Detection of Quantitative Trait Loci for Backfat Thickness and Intramuscular Fat Content in Pigs (Sus scrofa)." Genetics 152, no. 4 (August 1, 1999): 1679–90. http://dx.doi.org/10.1093/genetics/152.4.1679.

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Abstract In an experimental cross between Meishan and Dutch Large White and Landrace lines, 619 F2 animals and their parents were typed for molecular markers covering the entire porcine genome. Associations were studied between these markers and two fatness traits: intramuscular fat content and backfat thickness. Association analyses were performed using interval mapping by regression under two genetic models: (1) an outbred line-cross model where the founder lines were assumed to be fixed for different QTL alleles; and (2) a half-sib model where a unique allele substitution effect was fitted within each of the 19 half-sib families. Both approaches revealed for backfat thickness a highly significant QTL on chromosome 7 and suggestive evidence for a QTL at chromosome 2. Furthermore, suggestive QTL affecting backfat thickness were detected on chromosomes 1 and 6 under the line-cross model. For intramuscular fat content the line-cross approach showed suggestive evidence for QTL on chromosomes 2, 4, and 6, whereas the half-sib analysis showed suggestive linkage for chromosomes 4 and 7. The nature of the QTL effects and assumptions underlying both models could explain discrepancies between the findings under the two models. It is concluded that both approaches can complement each other in the analysis of data from outbred line crosses.

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Pinard-Van Der Laan, M. H., J. L. Monvoisin, P. Pery, N. Hamet, and M. Thomas. "Comparison of outbred lines of chickens for resistance to experimental infection with coccidiosis (Eimeria tenella)." Poultry Science 77, no. 2 (February 1998): 185–91. http://dx.doi.org/10.1093/ps/77.2.185.

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Leno, M., R. M. Simpson, F. S. Bowers, and T. J. Kindt. "Human T lymphocyte virus 1 from a leukemogenic cell line mediates in vivo and in vitro lymphocyte apoptosis." Journal of Experimental Medicine 181, no. 4 (April 1, 1995): 1575–80. http://dx.doi.org/10.1084/jem.181.4.1575.

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HTLV-1 is implicated in the development of diverse diseases. However, most HTLV-1-infected individuals remain asymptomatic. How HTLV-1 infection leads to disparate consequences remains a mystery, despite extensive investigation of HTLV-1 isolates from infected individuals. As in human infection, experimental HTLV-1 infection in rabbits is generally benign, although HTLV-1-infected rabbit T cell lines that mediate lethal leukemia-like disease have been reported. We report here that thymuses from mature outbred rabbits inoculated with a lethal leukemia-like disease have been reported. We report here that thymuses from mature outbred rabbits inoculated with a lethal HTLV-1 T cell line (RH/K34) showed morphological and biochemical evidence of apoptosis, whereas thymuses from rabbits inoculated with nonlethal HTLV-1 T cell lines showed no signs of apoptosis. Exposure of rabbit or human lymphocytes to purified virus from RH/K34 caused rapid induction of apoptosis, providing an in vitro correlate to the pathogenic effects. By contrast, virus isolated from a nonlethal cell line mediated dose-dependent lymphocyte proliferation. These data implicate lymphocyte apoptosis as a potential mechanism by which the lethal HTLV-1 cell line causes fulminant disease and provide a means to identify factors contributing to HTLV-1 disease. Results from this HTLV-1 infection model can provide insight into variations in HTLV-1 pathogenicity in human infection.

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Keightley, P. D., M. J. Evans, and W. G. Hill. "Effects of multiple retrovirus insertions on quantitative traits of mice." Genetics 135, no. 4 (December 1, 1993): 1099–106. http://dx.doi.org/10.1093/genetics/135.4.1099.

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Abstract To assess the potential to generate quantitative genetic variation by insertional mutagenesis in a vertebrate, lines of mice in which many provirus vector inserts segregated at a low initial frequency on an inbred background (insert lines) were subjected to divergent artificial selection on body weight at 6 weeks and responses and heritability estimates compared to control lines lacking inserts. Heritability estimates were more than 1.5 times greater in the insert lines than in the controls, but because the phenotypic variance was substantially higher in the insert lines the genetic variance was about 3 times greater. Realized heritability estimates tended to be lower than heritabilities estimated by an animal model which utilizes information in covariances between all relatives in the data set. A surprisingly large response to selection occurred in the inbred control line. Insert lines were about 20% less fertile than controls. Division of the selection lines into inbred sublines in the later generations of the experiment revealed substantially greater variation among sublines of the insert lines than among the controls. Heritabilities were similar to typical estimates for the trait in outbred populations. In conclusion, there was clear evidence of extra variation deriving from inserts, which has yet to be attributed to individual genes.

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Whitlock, Michael C., and Kevin Fowler. "The Changes in Genetic and Environmental Variance With Inbreeding in Drosophila melanogaster." Genetics 152, no. 1 (May 1, 1999): 345–53. http://dx.doi.org/10.1093/genetics/152.1.345.

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Abstract We performed a large-scale experiment on the effects of inbreeding and population bottlenecks on the additive genetic and environmental variance for morphological traits in Drosophila melanogaster. Fifty-two inbred lines were created from the progeny of single pairs, and 90 parent-offspring families on average were measured in each of these lines for six wing size and shape traits, as well as 1945 families from the outbred population from which the lines were derived. The amount of additive genetic variance has been observed to increase after such population bottlenecks in other studies; in contrast here the mean change in additive genetic variance was in very good agreement with classical additive theory, decreasing proportionally to the inbreeding coefficient of the lines. The residual, probably environmental, variance increased on average after inbreeding. Both components of variance were highly variable among inbred lines, with increases and decreases recorded for both. The variance among lines in the residual variance provides some evidence for a genetic basis of developmental stability. Changes in the phenotypic variance of these traits are largely due to changes in the genetic variance.

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Shipovalov, A. V., G. А. Kudrov, A. A. Tomilov, S. A. Bodnev, N. D. Boldyrev, A. S. Ovchinnikova, A. V. Zaikovskaya, O. S. Taranov, O. V. P’yankov, and R. A. Maksyutov. "Susceptibility to SARS-CoV-2 Virus Variants of Concern in Mouse Models." Problems of Particularly Dangerous Infections, no. 1 (April 20, 2022): 148–55. http://dx.doi.org/10.21055/0370-1069-2022-1-148-155.

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The aim of the research was to assess the susceptibility of mice of different lines to newly emerging variants of SARS-CoV-2.Materials and methods. The SARS-CoV-2 virus strains belonging to variants of concern (VOC) circulating in the territory of the Russian Federation were used in the study. Experiments involved three inbred mouse lines (BALB/c, CBA and C57Bl/6z) and CD1 outbred mice taken from the nursery of the SSC VB “Vector” of the Rospotrebnadzor. The infectious titer of coronavirus in tissue samples obtained from the laboratory animals was determined on a Vero E6 cell culture. The (Ct) threshold value in RT-PCR was considered an additional parameter for monitoring the viral load in the samples. The severity of lung tissue damage was assessed using histological preparations.Results and discussion. The susceptibility of various mouse lines to the genetic variant Beta of the SARS-CoV-2 virus has been investigated. During intranasal infection of the inbred and outbred mice with strains of VOC at a dose of 2·103 TCID50, the virus replicated in the lungs with maximum concentrations 72 hours after infection. The pathogenicity of genetic variants of the SARS-CoV-2 virus for BALB/c mice has been assessed, a 50 % infectious dose for intranasal infection (ID50) determined. Histological analysis showed COVID-19-specific lung tissue lesions in infected animals. Our study proves that BALB/c mice can be used as a model animal in screening studies when evaluating the effectiveness of therapeutic, vaccine preparations and studying the pathogenesis caused by VOC of the SARS-CoV-2 virus: Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Omicron (B.1.1.529) and the like.

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Dietl, G., M. Langhammer, and U. Renne. "Model simulations for genetic random drift in the outbred strain Fzt:DU." Archives Animal Breeding 47, no. 6 (October 10, 2004): 595–604. http://dx.doi.org/10.5194/aab-47-595-2004.

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Abstract. The mouse outbred stock Fzt:DU has been bred in the Research Institute for the Biology of Farm Animals Dummerstorf, Germany for about 30 years. This paper describes the history and the development of some traits in this stock over 128 generations. It has been used as base population for several lines long-term selected for fertility, growth, fitness and behaviour and has been bred with an average number of 200 breeding pairs per generation using a rotational mating scheme. A simulation study was employed to investigate the effect of genetic random drift on the allele frequencies. The change of the drift variance, the probabilities for allele losses and the development of the effective population size over generations are represented. The effective population size was relatively high, compared to other mouse experiments worldwide, however the genetic variability of the Fzt:DU population is substantially reduced due the high number of generations of isolated reproduction. After 120 generations, the variance effective population size is reduced to approximately 3 animals.

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Langhammer, Martina, Marten Michaelis, Andreas Hoeflich, Alexander Sobczak, Jennifer Schoen, and Joachim M. Weitzel. "High-fertility phenotypes: two outbred mouse models exhibit substantially different molecular and physiological strategies warranting improved fertility." REPRODUCTION 147, no. 4 (April 2014): 427–33. http://dx.doi.org/10.1530/rep-13-0425.

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Animal models are valuable tools in fertility research. Worldwide, there are more than 400 transgenic or knockout mouse models available showing a reproductive phenotype; almost all of them exhibit an infertile or at least subfertile phenotype. By contrast, animal models revealing an improved fertility phenotype are barely described. This article summarizes data on two outbred mouse models exhibiting a ‘high-fertility’ phenotype. These mouse lines were generated via selection over a time period of more than 40 years and 161 generations. During this selection period, the number of offspring per litter and the total birth weight of the entire litter nearly doubled. Concomitantly with the increased fertility phenotype, several endocrine parameters (e.g. serum testosterone concentrations in male animals), physiological parameters (e.g. body weight, accelerated puberty, and life expectancy), and behavioral parameters (e.g. behavior in an open field and endurance fitness on a treadmill) were altered. We demonstrate that the two independently bred high-fertility mouse lines warranted their improved fertility phenotype using different molecular and physiological strategies. The fertility lines display female- as well as male-specific characteristics. These genetically heterogeneous mouse models provide new insights into molecular and cellular mechanisms that enhance fertility. In view of decreasing fertility in men, these models will therefore be a precious information source for human reproductive medicine.Translated abstractA German translation of abstract is freely available athttp://www.reproduction-online.org/content/147/4/427/suppl/DC1.

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Partridge, Linda, Trudy F. C. Mackay, and Susan Aitken. "Male mating success and fertility in Drosophila melanogaster." Genetical Research 46, no. 3 (December 1985): 279–85. http://dx.doi.org/10.1017/s0016672300022783.

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SUMMARYThe male mating ability and male fertility of 40 third chromosome homozygote lines has been measured. There was significant between-line differentiation for both characters, and comparison with a heterozygous stock indicated inbreeding depression and hence dominance variation for them. The characters showed significant positive correlation both with each other and with other fitness components and total fitness, as measured by Mackay (1985). This pattern of large positive correlations between fitness components is not expected to occur in outbred populations.

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Crooks, Lucy, Carl Nettelblad, and Örjan Carlborg. "An Improved Method for Estimating Chromosomal Line Origin in QTL Analysis of Crosses Between Outbred Lines." G3: Genes|Genomes|Genetics 1, no. 1 (June 2011): 57–64. http://dx.doi.org/10.1534/g3.111.000109.

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Michaelis, Marten, Alexander Sobczak, Carolin Ludwig, Hana Marvanová, Martina Langhammer, Jennifer Schön, and Joachim M. Weitzel. "Altered testicular cell type composition in males of two outbred mouse lines selected for high fertility." Andrology 8, no. 5 (May 16, 2020): 1419–27. http://dx.doi.org/10.1111/andr.12802.

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Miyazaki, Kazuhiro, and Hitoshi Neda. "Evaluation of the Use of Outbred Lines for Screening of Genetic Markers in Shiitake (Lentinula edodes)." Breeding Science 54, no. 1 (2004): 75–78. http://dx.doi.org/10.1270/jsbbs.54.75.

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NAGAMINE, Y., and C. S. HALEY. "Using the mixed model for interval mapping of quantitative trait loci in outbred line crosses." Genetical Research 77, no. 2 (April 2001): 199–207. http://dx.doi.org/10.1017/s0016672301004931.

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Interval mapping by simple regression is a powerful method for the detection of quantitative trait loci (QTLs) in line crosses such as F2 populations. Due to the ease of computation of the regression approach, relatively complex models with multiple fixed effects, interactions between QTLs or between QTLs and fixed effects can easily be accommodated. However, polygenic effects, which are not targeted in QTL analysis, cannot be treated as random effects in a least squares analysis. In a cross between true inbred lines this is of no consequence, as the polygenic effect contributes just to the residual variance. In a cross between outbred lines, however, if a trait has high polygenic heritability, the additive polygenic effect has a large influence on variation in the population. Here we extend the fixed model for the regression interval mapping method to a mixed model using an animal model. This makes it possible to use not only the observations from progeny (e.g. F2), but also those from the parents (F1) to evaluate QTLs and polygenic effects. We show how the animal model using parental observations can be applied to an outbred cross and so increase the power and accuracy of QTL analysis. Three estimation methods, i.e. regression and an animal model either with or without parental observations, are applied to simulated data. The animal model using parental observations is shown to have advantages in estimating QTL position and additive genotypic value, especially when the polygenic heritability is large and the number of progeny per parent is small.

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Saxena, Swati, and Geetanjali Mishra. "Inbreeding avoidance in aphidophagous ladybird beetles: a case study inMenochilussexmaculatus." Canadian Journal of Zoology 94, no. 5 (May 2016): 361–65. http://dx.doi.org/10.1139/cjz-2015-0174.

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Relatedness among mates affects reproductive performance in insects. Previous studies indicate that laboratory rearing of a closed population leads to a decline in fitness owing to inbreeding depression. Although females possess the ability to discriminate against unsuitable males, it is not clear whether they have the ability to bias paternity against related males. We investigated whether the zig-zag ladybird beetle (Menochilus sexmaculatus (Fabricius, 1781)) (Coleoptera Coccinellidae) has evolved mechanisms to avoid inbreeding. We performed mating disruption experiments among two lines of inbred and outbred individuals and assessed whether mating behaviour (including mating duration and mate guarding) and reproductive performance were affected. Results indicate that females delay the onset of copula when paired with inbred individuals. Decreased fecundity and percent egg viability following mating with inbred mate is indicative of cost of inbreeding. As trends of spermatophore transfer are similar in inbred and outbred pairs, we assume that females modify their reproductive performance when mated with inbred males. Thus, our study reveals that mating with relatives is likely avoided by females, thus preventing inbreeding depression.

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Wang, Y., X. Cao, X. Gu, and X. Hu. "P5011 Fine mapping the QTL for growth traits in outbred chicken advanced intercross lines by improved ddGBS." Journal of Animal Science 94, suppl_4 (September 1, 2016): 120–21. http://dx.doi.org/10.2527/jas2016.94supplement4120a.

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de Carvalho, Lilian Rego, Andrea Borrego, José Ricardo Jensen, Wafa Hanna Koury Cabrera, Aline Marques Santos, Orlando Garcia Ribeiro, Nancy Starobinas, et al. "Genetic Predisposition to Hepatocarcinogenesis in Inbred and Outbred Mouse Lines Selected for High or Low Inflammatory Response." Journal of Immunology Research 2019 (March 31, 2019): 1–10. http://dx.doi.org/10.1155/2019/5298792.

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AIRmax and AIRmin mouse strains phenotypically selected for high and low acute inflammatory responsiveness (AIR) are, respectively, susceptible or resistant to developing hepatocellular carcinoma (HCC) induced by the chemical carcinogens urethane and diethylnitrosamine (DEN). Early production of TNF-α, IL-1β, and IL-6 in the liver after DEN treatment correlated with tumor development in AIRmax mice. Transcriptome analysis of livers from untreated AIRmax and AIRmin mice showed specific gene expression profiles in each line, which might play a role in their differential susceptibility to HCC. Linkage analysis with SNP markers in F2 (AIRmax×AIRmin) intercross mice revealed two quantitative trait loci (QTL) in chromosomes 2 and 9, which are significantly associated with the number and progression of urethane-induced liver tumors. An independent linkage analysis with an intercross population from A/J and C57BL/6J inbred mice mapped regions in chromosomes 1 and 7 associated with the progression of urethane-induced liver tumors, evidencing the heterogeneity of HCC genetic control.

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Hu, Jiafen, Xuwen Peng, Lynn R. Budgeon, Nancy M. Cladel, Karla K. Balogh, and Neil D. Christensen. "Establishment of a Cottontail Rabbit Papillomavirus/HLA-A2.1 Transgenic Rabbit Model." Journal of Virology 81, no. 13 (April 25, 2007): 7171–77. http://dx.doi.org/10.1128/jvi.00200-07.

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ABSTRACT Three transgenic rabbit lines that express a well-characterized human major histocompatibility complex class I (MHC-I) gene (HLA-A2.1) have been established. All three lines carry the HLA-A2.1 heavy chain and are able to pass the transgene to their offspring with both the outbred and the inbred EIII/JC genetic background. HLA-A2.1 colocalizes exclusively with rabbit MHC-I on the cell surfaces. These HLA-A2.1 transgenic rabbits demonstrated infection patterns similar to those found after cottontail rabbit papillomavirus (CRPV) challenge when compared with results in normal rabbits, although higher regression rates were found in HLA-A2.1 transgenic rabbits. Because the CRPV genome can accommodate significant modifications, the CRPV/HLA-A2.1 rabbit model has the potential to be used to screen HLA-A2.1-restricted immunogenic epitopes from human papillomaviruses in the context of in vivo papillomavirus infection.

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Hughes, Kimberly A. "The inbreeding decline and average dominance of genes affecting male life-history characters in Drosophila melanogaster." Genetical Research 65, no. 1 (February 1995): 41–52. http://dx.doi.org/10.1017/s0016672300032997.

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SummaryThis paper describes the results of assays of male life-history characters in a large outbred laboratory population of D. melanogaster. Lines of flies homozygous for the entire third chromosome and lines of flies carrying two different third chromosomes were assayed for agespecific male mating ability (MMA), age-specific survivorship, male fertility, and body mass. The results of these assays were used to calculate the inbreeding decline associated with each of these traits, the average dominance of deleterious alleles that affect the traits, the genotypic and environmental components of variance for the homozygous lines, and phenotypic and genotypic correlations among the characters. Significant inbreeding decline was found for all characters except the Gompertz intercept and fertility. Early and late MMA show larger effects of inbreeding than any other trait. The inbreeding load for MMA is about the same magnitude as that for egg-to-adult viability, but is substantially less than that associated with total fitness. The estimated inbreeding decline and average dominance of male life-history characters are comparable to estimates for other Drosophila fitness components.

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Wade, Michael J., Norman A. Johnson, Rachel Jones, Vera Siguel, and Michael McNaughton. "Genetic Variation Segregating in Natural Populations of Tribolium castaneum Affecting Traits Observed in Hybrids With T. freemani." Genetics 147, no. 3 (November 1, 1997): 1235–47. http://dx.doi.org/10.1093/genetics/147.3.1235.

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We investigated patterns of within-species genetic variation for traits observed in hybrids (hybrid numbers, hybrid sex ratios, and hybrid male deformities) between two species of flour beetles, Tribolium castaneum and T. freemani. We found genetic variation segregating among four natural populations of T. castaneum as well as within these populations. For some hybrid traits, we observed as much variation among populations 750 km apart as between populations on different continents, suggesting genetic differentiation at a local scale. Within natural populations, the variation segregating among sires is greater than that found in an earlier study for an outbred laboratory population and comparable to that observed between inbred lines derived from the outbred stock by eight generations of brother-sister mating. When sires from T. castaneum are mated to conspecific and heterospecific females, we do not observe a significant correlation at the level of the family mean between the intraspecific and interspecific phenotypes, suggesting the independence of the hybrid traits from comparable traits within species. We discuss our findings in relation to the evolutionary genetics of speciation and the expression of epistatic genetic variance in interspecific crosses.

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Li, Zhiting, Wei Zhao, Jinpeng Zhang, Zhiliang Pan, Shengjun Bai, and Chunfa Tong. "A Novel Strategy to Reveal the Landscape of Crossovers in an F1 Hybrid Population of Populus deltoides and Populus simonii." Plants 11, no. 8 (April 12, 2022): 1046. http://dx.doi.org/10.3390/plants11081046.

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Although the crossover (CO) patterns of different species have been extensively investigated, little is known about the landscape of CO patterns in Populus because of its high heterozygosity and long-time generation. A novel strategy was proposed to reveal the difference of CO rate and interference between Populus deltoides and Populus simonii using their F1 hybrid population. We chose restriction site-associated DNA (RAD) tags that contained two SNPs, one only receiving the CO information from the female P. deltoides and the other from the male P. simonii. These RAD tags allowed us to investigate the CO patterns between the two outbred species, instead of using the traditional backcross populations in inbred lines. We found that the CO rate in P. deltoides was generally greater than that in P. simonii, and that the CO interference was a common phenomenon across the two genomes. The COs landscape of the different Populus species facilitates not only to understand the evolutionary mechanism for adaptability but also to rebuild the statistical model for precisely constructing genetic linkage maps that are critical in genome assembly in Populus. Additionally, the novel strategy could be applied in other outbred species for investigating the CO patterns.

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Falkenberg, H., U. Renne, and M/ Langhammer. "Biochemical characterisation of blood metabolic substances in mice after long-term selection on growth traits." Archives Animal Breeding 43, no. 4 (October 10, 2000): 375–86. http://dx.doi.org/10.5194/aab-43-375-2000.

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Abstract. A biochemical characterisation of blood was done in laboratory mouse lines originating from a heterogeneous outbred strain Fzt:DU which were selected for high body weight at 6 weeks of age (DU-6), for high total protein amount in the carcass (DU-6P) and for an index combining body weight and treadmill Performance (DU-6+TP) over 54 generations, respectively. The level of the following enzymes and Substrates were compared to the unselected control group (Fzt:DU): alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), creatine kinase (CK), y-glutamyl-transpeptidase (GGTP), alkaline Phosphatase (AP), total cholesterol with its components LDL+VLDL- and HDL-cholesterol, triglyceride (Trig.), Creatinine (Crea.), lactate (Lac.) and glucose (Gluc). Concentration of some metabolic substances differed significantly in relation to the specific selection character. It is concluded, that selection indirectly diversified physiological State in the tested long-term selection lines in mice.

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Ward, Colin W., and Barry M. Wagland. "Correlation between gut hypersensitivity and resistance to Trichostrongylus colubriformis infection of outbred and inbred lines of guinea pigs." International Journal for Parasitology 21, no. 4 (July 1991): 455–61. http://dx.doi.org/10.1016/0020-7519(91)90103-e.

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Palmer, Michael R., Anthony S. Basile, William R. Proctor, Rodney C. Baker, and Thomas V. Dunwiddie. "Ethanol Tolerance of Cerebellar Purkinje Neurons from Selectively Outbred Mouse Lines: in Vivo and in Vitro Electrophysiological Investigations." Alcoholism: Clinical and Experimental Research 9, no. 3 (May 1985): 291–96. http://dx.doi.org/10.1111/j.1530-0277.1985.tb05752.x.

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Diez-Tascón, Cristina, Orla M. Keane, Theresa Wilson, Amonida Zadissa, Dianne L. Hyndman, David B. Baird, John C. McEwan, and Allan M. Crawford. "Microarray analysis of selection lines from outbred populations to identify genes involved with nematode parasite resistance in sheep." Physiological Genomics 21, no. 1 (March 21, 2005): 59–69. http://dx.doi.org/10.1152/physiolgenomics.00257.2004.

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Gastrointestinal nematodes infect sheep grazing contaminated pastures. Traditionally, these have been controlled with anthelmintic drenching. The selection of animals resistant to nematodes is an alternative to complete reliance on drugs, but the genetic basis of host resistance is poorly understood. Using a 10,204 bovine cDNA microarray, we have examined differences in gene expression between genetically resistant and susceptible lambs previously field challenged with larval nematodes. Northern blot analysis for a selection of genes validated the data obtained from the microarrays. The results identified over one hundred genes that were differentially expressed based on conservative criteria. The microarray results were further analyzed to identify promoter motifs common to the differentially expressed genes. Motifs identified in upregulated gene promoters were primarily restricted to those promoters; however, motifs identified in downregulated gene promoters were also found in the promoters of upregulated genes but not in the promoters of genes whose expression was unaltered. Protein Annotators’ Assistant was used for lexical analysis of the differentially expressed genes, and Gene Ontology was used to look for metabolic and cell signaling pathways associated with parasite resistance. Two pathways represented by genes differentially expressed in resistant animals were those involved with the development of an acquired immune response and those related to the structure of the intestine smooth muscle. Genes involved in these processes appear from our analysis to be key genetic determinants of parasite resistance.

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Sillanpää, Mikko J., and Elja Arjas. "Bayesian Mapping of Multiple Quantitative Trait Loci From Incomplete Outbred Offspring Data." Genetics 151, no. 4 (April 1, 1999): 1605–19. http://dx.doi.org/10.1093/genetics/151.4.1605.

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Abstract A general fine-scale Bayesian quantitative trait locus (QTL) mapping method for outcrossing species is presented. It is suitable for an analysis of complete and incomplete data from experimental designs of F2 families or backcrosses. The amount of genotyping of parents and grandparents is optional, as well as the assumption that the QTL alleles in the crossed lines are fixed. Grandparental origin indicators are used, but without forgetting the original genotype or allelic origin information. The method treats the number of QTL in the analyzed chromosome as a random variable and allows some QTL effects from other chromosomes to be taken into account in a composite interval mapping manner. A block-update of ordered genotypes (haplotypes) of the whole family is sampled once in each marker locus during every round of the Markov Chain Monte Carlo algorithm used in the numerical estimation. As a byproduct, the method gives the posterior distributions for linkage phases in the family and therefore it can also be used as a haplotyping algorithm. The Bayesian method is tested and compared with two frequentist methods using simulated data sets, considering two different parental crosses and three different levels of available parental information. The method is implemented as a software package and is freely available under the name Multimapper/outbred at URL http://www.rni.helsinki.fi/~mjs/.

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de Koning, Dirk-Jan, Henk Bovenhuis, and Johan A. M. van Arendonk. "On the Detection of Imprinted Quantitative Trait Loci in Experimental Crosses of Outbred Species." Genetics 161, no. 2 (June 1, 2002): 931–38. http://dx.doi.org/10.1093/genetics/161.2.931.

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Abstract In this article, the quantitative genetic aspects of imprinted genes and statistical properties of methods to detect imprinted QTL are studied. Different models to detect imprinted QTL and to distinguish between imprinted and Mendelian QTL were compared in a simulation study. Mendelian and imprinted QTL were simulated in an F2 design and analyzed under Mendelian and imprinting models. Mode of expression was evaluated against the H0 of a Mendelian QTL as well as the H0 of an imprinted QTL. It was shown that imprinted QTL might remain undetected when analyzing the genome with Mendelian models only. Compared to testing against a Mendelian QTL, using the H0 of an imprinted QTL gave a higher proportion of correctly identified imprinted QTL, but also gave a higher proportion of false inference of imprinting for Mendelian QTL. When QTL were segregating in the founder lines, spurious detection of imprinting became more prominent under both tests, especially for designs with a small number of F1 sires.

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Bjork, Adam, William T. Starmer, Dawn M. Higginson, Christopher J. Rhodes, and Scott Pitnick. "Complex interactions with females and rival males limit the evolution of sperm offence and defence." Proceedings of the Royal Society B: Biological Sciences 274, no. 1619 (May 16, 2007): 1779–88. http://dx.doi.org/10.1098/rspb.2007.0293.

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Postcopulatory sexual selection favours males which are strong offensive and defensive sperm competitors. As a means of identifying component traits comprising each strategy, we used an experimental evolution approach. Separate populations of Drosophila melanogaster were selected for enhanced sperm offence and defence. Despite using a large outbred population and evidence of substantive genetic variation for each strategy, neither trait responded to selection in the two replicates of this experiment. Recent work with fixed chromosome lines of D. melanogaster suggests that complex genotypic interactions between females and competing males contribute to the maintenance of this variation. To determine whether such interactions could explain our lack of response to selection on sperm offence and defence, we quantified sperm precedence across multiple sperm competition bouts using an outbred D. melanogaster population exhibiting continuous genetic variation. Both offensive and defensive sperm competitive abilities were found to be significantly repeatable only across matings involving ejaculates of the same pair of males competing within the same female. These repeatabilities decreased when the rival male stayed the same but the female changed, and they disappeared when both the rival male and the female changed. Our results are discussed with a focus on the complex nature of sperm precedence and the maintenance of genetic variation in ejaculate characteristics.

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SACCHERI, ILIK J., RICHARD A. NICHOLS, and PAUL M. BRAKEFIELD. "Effects of bottlenecks on quantitative genetic variation in the butterfly Bicyclus anynana." Genetical Research 77, no. 2 (April 2001): 167–81. http://dx.doi.org/10.1017/s0016672301004906.

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The effects of a single population bottleneck of differing severity on heritability and additive genetic variance was investigated experimentally using a butterfly. An outbred laboratory stock was used to found replicate lines with one pair, three pairs and 10 pairs of adults, as well as control lines with approximately 75 effective pairs. Heritability and additive genetic variance of eight wing pattern characters and wing size were estimated using parent–offspring covariances in the base population and in all daughter lines. Individual morphological characters and principal components of the nine characters showed a consistent pattern of treatment effects in which average heritability and additive genetic variance was lower in one pair and three pair lines than in 10 pair and control lines. Observed losses in heritability and additive genetic variance were significantly greater than predicted by the neutral additive model when calculated with coefficients of inbreeding estimated from demographic parameters alone. However, use of molecular markers revealed substantially more inbreeding, generated by increased variance in family size and background selection. Conservative interpretation of a statistical analysis incorporating this previously undetected inbreeding led to the conclusion that the response to inbreeding of the morphological traits studied showed no significant departure from the neutral additive model. This result is consistent with the evidence for minimal directional dominance for these traits. In contrast, egg hatching rate in the same experimental lines showed strong inbreeding depression, increased phenotypic variance and rapid response to selection, highly indicative of an increase in additive genetic variance due to dominance variance conversion.

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Langhammer, Martina, Erika Wytrwat, Marten Michaelis, Jennifer Schön, Armin Tuchscherer, Norbert Reinsch, and Joachim M. Weitzel. "Two mouse lines selected for large litter size display different lifetime fecundities." Reproduction 161, no. 6 (June 1, 2021): 721–30. http://dx.doi.org/10.1530/rep-20-0563.

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We recently described two outbred mouse lines that were selected for large litter size at first delivery. However, lifetime fecundity appears to be economically more important for the husbandry of many polytocous species for which mouse lines might serve as bona fide animal models (e.g. for pigs). In the present study, we compared the lifetime fecundities of two highly fertile mouse lines (FL1 and FL2: >20 offspring/litter at first delivery) with those of an unselected control line (ctrl) and two lines that were selected for high body weight (DU6) and high protein mass (DU6P) without selection pressure on fertility. We tested the hypothesis that selection for large litter size at first parturition would also increase lifetime fecundity in mice, and we observed very large differences between lines. Whereas FL1 and ctrl delivered up to nine and ten litters, none of the DU6 and DU6P females gave birth to more than five litters. In line with this observation, FL1 delivered the most pups per lifetime (85.7/female). FL2 females produced the largest average litter sizes (20.4 pups/litter) in the first four litters; however, they displayed a reduced number of litters. With the exception of ctrl, litter sizes declined from litter to litter. Repeated delivery of litters with high offspring numbers did not affect the general health of FL females. The presented data demonstrate that two biodiverse, highly fertile mouse lines selected for large litter size at first delivery show different lifetime reproductive fitness levels. Thus, these mouse lines might serve as valuable mouse models for investigating lifetime productivity and longevity in farm animals.

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Duchet-Suchaux, Marion, Florence Mompart, Florence Berthelot, Catherine Beaumont, Patrick Lechopier, and Pierre Pardon. "Differences in Frequency, Level, and Duration of Cecal Carriage between Four Outbred Chicken Lines Infected Orally with Salmonella enteritidis." Avian Diseases 41, no. 3 (July 1997): 559. http://dx.doi.org/10.2307/1592145.

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Shir, Yoram, Rafi Zeltser, Jean-Jacque Vatine, Galia Carmi, Inna Belfer, Abraham Zangen, David Overstreet, Pnina Raber, and Zeʼev Seltzer. "Correlation of intact sensibility and neuropathic pain-related behaviors in eight inbred and outbred rat strains and selection lines." Pain 90, no. 1 (February 2001): 75–82. http://dx.doi.org/10.1016/s0304-3959(00)00388-2.

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Journal articles on the topic 'Outbred lines'

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