Evolving gene banks: improving diverse populations of crop and exotic germplasm with optimal contribution selection.

We simulated pre-breeding in evolving gene banks - populations of exotic and crop types undergoing optimal contribution selection for long-term genetic gain and management of population genetic diversity. The founder population was based on crosses between elite crop varieties and exotic lines of field pea (Pisum sativum) from the primary genepool, and was subjected to 30 cycles of recurrent selection for an economic index composed of four traits with low heritability: black spot resistance, flowering time and stem strength (measured on single plants), and grain yield (measured on whole plots). We compared a small population with low selection pressure, a large population with high selection pressure, and a large population with moderate selection pressure. Single seed descent was compared with S0-derived recurrent selection. Optimal contribution selection achieved higher index and lower population coancestry than truncation selection, which reached a plateau in index improvement after 40 years in the large population with high selection pressure. With optimal contribution selection, index doubled in 38 years in the small population with low selection pressure and 27-28 years in the large population with moderate selection pressure. Single seed descent increased the rate of improvement in index per cycle but also increased cycle time.

Prediction of heterosis using genome-wide SNP-marker data: application to egg production traits in white Leghorn crosses.

Prediction of heterosis has a long history with mixed success, partly due to low numbers of genetic markers and/or small data sets. We investigated the prediction of heterosis for egg number, egg weight and survival days in domestic white Leghorns, using ∼400 000 individuals from 47 crosses and allele frequencies on ∼53 000 genome-wide single nucleotide polymorphisms (SNPs). When heterosis is due to dominance, and dominance effects are independent of allele frequencies, heterosis is proportional to the squared difference in allele frequency (SDAF) between parental pure lines (not necessarily homozygous). Under these assumptions, a linear model including regression on SDAF partitions crossbred phenotypes into pure-line values and heterosis, even without pure-line phenotypes. We therefore used models where phenotypes of crossbreds were regressed on the SDAF between parental lines. Accuracy of prediction was determined using leave-one-out cross-validation. SDAF predicted heterosis for egg number and weight with an accuracy of ∼0.5, but did not predict heterosis for survival days. Heterosis predictions allowed preselection of pure lines before field-testing, saving ∼50% of field-testing cost with only 4% loss in heterosis. Accuracies from cross-validation were lower than from the model-fit, suggesting that accuracies previously reported in literature are overestimated. Cross-validation also indicated that dominance cannot fully explain heterosis. Nevertheless, the dominance model had considerable accuracy, clearly greater than that of a general/specific combining ability model. This work also showed that heterosis can be modelled even when pure-line phenotypes are unavailable. We concluded that SDAF is a useful predictor of heterosis in commercial layer breeding.

Genomic evaluations using similarity between haplotypes.

Long-range phasing and haplotype library imputation methodologies are accurate and efficient methods to provide haplotype information that could be used in prediction of breeding value or phenotype. Modelling long haplotypes as independent effects in genomic prediction would be inefficient due to the many effects that need to be estimated and phasing errors, even if relatively low in frequency, exacerbate this problem. One approach to overcome this is to use similarity between haplotypes to model covariance of genomic effects by region or of animal breeding values. We developed a simple method to do this and tested impact on genomic prediction by simulation. Results show that the diagonal and off-diagonal elements of a genomic relationship matrix constructed using the haplotype similarity method had higher correlations with the true relationship between pairs of individuals than genomic relationship matrices built using unphased genotypes or assumed unrelated haplotypes. However, the prediction accuracy of such haplotype-based prediction methods was not higher than those based on unphased genotype information.

A major SNP resource for dissection of phenotypic and genetic variation in Pacific white shrimp (Litopenaeus vannamei).

Bioinformatics and re-sequencing approaches were used for the discovery of sequence polymorphisms in Litopenaeus vannamei. A total of 1221 putative single nucleotide polymorphisms (SNPs) were identified in a pool of individuals from various commercial populations. A set of 211 SNPs were selected for further molecular validation and 88% showed variation in 637 samples representing three commercial breeding lines. An association analysis was performed between these markers and several traits of economic importance for shrimp producers including resistance to three major viral diseases. A small number of SNPs showed associations with test weekly gain, grow-out survival and resistance to Taura Syndrome Virus. Very low levels of linkage disequilibrium were revealed between most SNP pairs, with only 11% of SNPs showing an r(2)-value above 0.10 with at least one other SNP. Comparison of allele frequencies showed small changes over three generations of the breeding programme in one of the commercial breeding populations. This unique SNP resource has the potential to catalyse future studies of genetic dissection of complex traits, tracing relationships in breeding programmes, and monitoring genetic diversity in commercial and wild populations of L. vannamei.

A method to detect recombination between a genetic marker and the QTL that it marks.

Some individual genetic markers show strong and apparently consistent effects on trait merit and are taken as causative mutations that can be used directly as fixed effects in marker-assisted selection programs. If the effect of such a marker is seen to decrease over time, key reasons include epistasis, where the effect depends on genetic background, and recombination, where the marker is in fact not causative, and strong linkage disequilibrium between the marker and the causative QTL is breaking down. This paper presents a method to detect the latter scenario, including calculation of the probability of a recombinant haplotype for each gamete contributing to each individual in a pedigree. This method requires only pedigree, phenotypes and genotypic information on the single marker. Missing marker genotypes are handled by the method, but with diminishing power. For biallelic markers, strong QTL effects are needed for the method to be of clear value. Given suitable results, breeders may chose to eliminate certain individuals from the breeding program in order to continue using the single genetic marker under high linkage disequilibrium with the causative QTL. Alternatively, other linked markers might be sought that can be used individually or in haplotype tests to restore strong LD for marker-assisted selection.

Cyclic genotyping strategies. III: A comparison of predictive methods for group genotyping.

This paper provides an investigation into some of the key practical issues for minimizing the cost of DNA testing. Previous studies focused on maximizing the utility of genotyping by prioritizing individuals for genotyping. For logistical reasons, individuals may have to be genotyped in groups rather than individually, and the best group to genotype is expected to differ from the same-sized group chosen when individuals are genotyped sequentially. In a calibration step, simulated populations and full knowledge of genotypes were used to discover the best group(s) to genotype. The characteristics of these groups were then targeted in an optimization step, using normally available information for group formation in targeted populations. Contrasts were made among predictive indices for: (i) individuals, with genotyping between each individual; (ii) individuals, with genotyping occurring group-at-a-time; and (iii) groups, using group variables as criteria. The results of this investigation allow the determination of the value of moving from individual to group genotyping, reveal the favourable attributes of individuals for group formation, and lead to methods to form groups for genotyping. The approach used has applications in reducing genotyping costs in both experimental and commercial populations for both quantitative trait loci (QTL) detection and monitoring.

A simple genetic algorithm for multiple sequence alignment.

Multiple sequence alignment plays an important role in molecular sequence analysis. An alignment is the arrangement of two (pairwise alignment) or more (multiple alignment) sequences of 'residues' (nucleotides or amino acids) that maximizes the similarities between them. Algorithmically, the problem consists of opening and extending gaps in the sequences to maximize an objective function (measurement of similarity). A simple genetic algorithm was developed and implemented in the software MSA-GA. Genetic algorithms, a class of evolutionary algorithms, are well suited for problems of this nature since residues and gaps are discrete units. An evolutionary algorithm cannot compete in terms of speed with progressive alignment methods but it has the advantage of being able to correct for initially misaligned sequences; which is not possible with the progressive method. This was shown using the BaliBase benchmark, where Clustal-W alignments were used to seed the initial population in MSA-GA, improving outcome. Alignment scoring functions still constitute an open field of research, and it is important to develop methods that simplify the testing of new functions. A general evolutionary framework for testing and implementing different scoring functions was developed. The results show that a simple genetic algorithm is capable of optimizing an alignment without the need of the excessively complex operators used in prior study. The clear distinction between objective function and genetic algorithms used in MSA-GA makes extending and/or replacing objective functions a trivial task.

An index of information content for genotype probabilities derived from segregation analysis.

A genotype probability index (GPI) is proposed to indicate the information content of genotype probabilities derived from a segregation analysis. Typically, some individuals are genotyped at a marker locus or a quantitative trait locus, and segregation analysis is used to make genotype inferences about ungenotyped relatives. Genotype probabilities for a two-allele autosomal locus are plotted on a triangular surface. The GPI has a value of zero at the point corresponding to Hardy-Weinberg frequencies, and a value of 100% at the vertices of the triangle. Trigonometric functions are used to help calculate intermediate index values. It is proposed that such an index can be useful to help identify which ungenotyped individuals or loci should be genotyped to maximize the benefit/cost of genotyping operations.

A method of screening for genes of major effect.

This paper describes a method for screening animal populations on an index of calculated probabilities of genotype status at an unknown single locus. Animals selected by such a method might then be candidates in test matings and genetic marker analyses for major gene detection. The method relies on phenotypic measures for a continuous trait plus identification of sire and dam. Some missing phenotypes and missing pedigree information are permitted. The method is an iterative two-step procedure, the first step estimates genotype probabilities and the second step estimates genotypic effects by regressing phenotypes on genotype probabilities, modeled as true genotype status plus error. Prior knowledge or choice of major locus-free heritability for the trait of interest is required, plus initial starting estimates of the effect on phenotype of carrying one and two copies of the unknown gene. Gene frequency can be estimated by this method, but it is demonstrated that the consequences of using an incorrect fixed prior for gene frequency are not particularly adverse where true frequency of the allele with major effect is low. Simulations involving deterministic sampling from the normal distribution lead to convergence for estimates of genotype effects at the true values, for a reasonable range of starting values, illustrating that estimation of major gene effects has a rational basis. In the absence of polygenic effects, stochastic simulations of 600 animals in five generations resulted in estimates of genotypic effects close to the true values. However, stochastic simulations involving generation and fitting of both major genotype and animal polygenic effects showed upward bias in estimates of major genotype effects. This can be partially overcome by not using information from relatives when calculating genotype probabilities-a result which suggests a route to a modified method which is unbiased and yet does use this information.

Use of multiple genetic markers in prediction of breeding values.

Genotypes at a marker locus give information on transmission of genes from parents to offspring and that information can be used in predicting the individuals' additive genetic value at a linked quantitative trait locus (MQTL). In this paper a recursive method is presented to build the gametic relationship matrix for an autosomal MQTL which requires knowledge on recombination rate between the marker locus and the MQTL linked to it. A method is also presented to obtain the inverse of the gametic relationship matrix. This information can be used in a mixed linear model for simultaneous evaluation of fixed effects, gametic effects at the MQTL and additive genetic effects due to quantitative trait loci unlinked to the marker locus (polygenes). An equivalent model can be written at the animal level using the numerator relationship matrix for the MQTL and a method for obtaining the inverse of this matrix is presented. Information on several unlinked marker loci, each of them linked to a different locus affecting the trait of interest, can be used by including an effect for each MQTL. The number of equations per animal in this case is 2m + 1 where m is the number of MQTL. A method is presented to reduce the number of equations per animal to one by combining information on all MQTL and polygenes into one numerator relationship matrix. It is illustrated how the method can accommodate individuals with partial or no marker information. Numerical examples are given to illustrate the methods presented. Opportunities to use the presented model in constructing genetic maps are discussed.

Optimal utilization of non-additive quantitative trait locus in animal breeding programs.

Optimal selection on a single identified quantitative trait locus (QTL) with four modes of inheritance: normal autosomal, sex-limited, imprinting and X-linked, was evaluated in four breeding structures: single line selection (SLS), two-way crossing (2WC), three-way crossing (3WC) and reciprocal crossing (RC) by comparing extra benefit from mate selection over index selection to demonstrate effectiveness of mate selection in exploiting non-additive QTL. The results showed that the superiority varied at different QTL inheritance modes, initial favourable allele frequencies and breeding structures. The superiority tended to decrease with the increase of the favourable allele frequency except for over-dominant QTL and imprinted QTL in all breeding structures. Less superiority (below 9%) was observed for a recessive and a fully dominant QTL than for an over-dominant QTL (up to 27.11%). Normal autosomal and sex-linked QTL led to a similar trend of superiority from mate selection but the magnitude of the superiority with the latter was slightly higher than with the former for most combinations of the parameters. A high superiority (6.41-41.54%) was observed from mate selection over index selection for an imprinted QTL. A maternally imprinted QTL tended to lead to higher superiority from mate selection than a paternally imprinted QTL. X-linked QTL led to less superiority from mate selection than the other modes of QTL. A larger superiority from mate selection was observed for a recessive and a fully dominant QTL in structures 3WC and 2WC than structures RC and SLS. The superiority from autosomal QTL and X-linked QTL was lower in the structure RC than in other structures examined.

Using mechanistic animal growth models to estimate genetic parameters of biological traits.

Mechanistic animal growth models can incorporate a description of the genotype as represented by underlying biological traits that aim to specify the animal's genetic potential for performance, independent from the environmental factors captured by the models. It can be argued that these traits may therefore be more closely associated to genetic potential, or components of genetic merit that are more robust across environments, than the environmentally dependent phenotypic traits currently used for genetic evaluation. The prediction of merit for underlying biological traits can be valuable for breeding and development of selection strategies across environments.Model inversion has been identified as a valid method for obtaining estimates of phenotypic and genetic components of the biological traits representing the genotype in the mechanistic model. The present study shows how these estimates were obtained for two existing pig breeds based on genetic and phenotypic components of existing performance trait records. Some of the resulting parameter estimates associated with each breed differ substantially, implying that the genetic differences between the breeds are represented in the underlying biological traits. The estimated heritabilities for the genetic potentials for growth, carcass composition and feed efficiency as represented by biological traits exceed the heritability estimates of related phenotypic traits that are currently used in evaluation processes for both breeds. The estimated heritabilities for maintenance energy requirements are however relatively small, suggesting that traits associated with basic survival processes have low heritability, provided that maintenance processes are appropriately represented by the model.The results of this study suggest that mechanistic animal growth models can be useful to animal breeding through the introduction of new biological traits that are less influenced by environmental factors than phenotypic traits currently used. Potential value comes from the estimation of underlying biological trait components and the explicit description of their expression across a range of environments as predicted by the model equations.

A genotype probability index for multiple alleles and haplotypes.

We use linear algebra to calculate an index of information content in genotype probabilities which has previously been calculated using trigonometry. The new method can be generalized allowing the index to be calculated for loci with more than two alleles. Applications of this index include its use in genotyping strategies, strategies to manage genetic disorders and in estimation of genotype effects.

The nature of 2-locus epistatic interactions in animals: evidence from Sewall Wright's guinea pig data.

The nature of epistatic interactions affects covariance between relatives and the expression of heterosis in various crossbred genotypes. The investigation of these interactions for metric traits requires large data sets of a suitable type. Data from Sewall Wright's early work with guinea pigs are used to compare the goodness-of-fit of seven biological models of 2-locus interaction for the six out of eleven traits in which epistatic effects are apparent. The model equivalent to additive x additive epistasis gives the best general fit over traits, with an average transformed R(2) value significantly greater than that of the next best fitting model (P<0.05). This result is compatible with results from the one other study in this area, using data from mice. It is concluded that, based on results available to date, the additive x additive 2-locus model of epistatic interaction appears most suitable for reduced genetic models.

Mate selection by groups.

The two key components in a breeding program can be described as the development of an objective function and the implementation of an algorithm for mate selection to target the objective function. However, mate selection is unacceptably slow for objective functions that involve longer term aims, such as engineering a good connection between herds. This paper proposes animal clustering to facilitate group mate selection, plus a step to refine mate selection for individual animals. Cluster analysis is used to form groups of animals within each sex based on nominated factors such as breed, herd, age, and EBV. Mate selection is then performed on groups, reducing the size of the problem considerably. The example used involved a three-breed crossbred population with a simple objective function to maximize predicted progeny merit. Twenty sires and 500 dams were to be selected from 816 and 1784 candidates. Group mate selection achieved 96.9% efficiency (random selection, 0%; full mate selection, 100%) and took 0.28 s to compute (394.2 s for full mate selection). Permitting more candidates to reach the individual mate selection stage increased efficiency to, for example, 98.9% at the cost of an extra 1.15 s. Efficiency was also improved by permitting more clusters.

Optimising multi-tier open nucleus breeding schemes.

The constant migration (CM) method and the ebv migration (EBVM) method of optimising the design of multi-tier open nucleus breeding schemes are presented and compared. The equation for the equilibrium rate of genetic gain of a three-tier open nucleus scheme is determined using the CM method. The major advantage of the EBVM method is the reduction in the number of parameters which have to be varied in order to locate the maximum equilibrium rate of genetic gain. For the CM method for the number of variable parameters is 5, 14, 27 and (2n + 1) (n - 1) for unrestricted male and female migration in schemes with 2, 3, 4 and n tiers respectively. The corresponding number of variable parameters for the EBVM method is 1, 2, 3 and n-1 respectively. A procedure is given for the EBVM method so as to accomodate variance loss due to selection and variance gain due to the mixing of groups with a different mean breeding value.

The value of accuracy in making selection decisions.

SUMMARY: A stochastic simulation was carried out to investigate the impact of using an index of ehvs and accuracy on genetic response and utility. Two population types were considered based on the range of accuracy used (Type A: 0-1.0 and B: 0.5-1.0). Five hundred replications were carried out leading to the evaluation of the sample mean response and its variance. The index weightings defining plateaux within 1% and 5% of the maximum response were identified, these suggesting that for population Types A and B, minimal loss in response will occur if weightings on accuracy of up to ± 0.5 σ and ± 1.5σ are selected. These weightings result in relatively minor changes in the ranking of animals, particularly where only a small number of animals are selected. Utility was defined as a function of the mean and variance of the sample response. The index weightings leading to the maximal utility were identified for seven utility functions (three risk averse, three risk preferring and a risk neutral function). Placing some weighting on accuracy when making selection decisions can be done with little compromise in expected mean response. This gives opportunity to reflect risk preferring or risk averse attitudes through the use of negative or positive weightings on accuracy. However, it seems that somewhat extreme utility functions are required before this opportunity can result in significant benefit. ZUSAMMENFASSUNG: Der Wert von Genauigkeit bei Selektionsentscheidungen Zur Untersuchung des Einflusses eines Index aus geschätzten Zuchtwerten und Genauigkeit auf genetischen Fortschritt und Nützlichkeit wurde durch stochastische Simulation durchgeführt. Es wurden zwei Populationstypen untersucht, die einen Bereich von 0-1 (A) in der Genauigkeit oder 0.5-1 (B) haben. Fünfhundert Wiederholungen wurden zur Bewertung des Stichprobendurchschnitts hinsichtlich Erfolg und Varianz durchgeführt. Die Indexgewichtung, die zu einem Plateau innerhalb 1% bzw. 5% des Maximalfortschrittes führte, wurde identifiziert und ließ darauf schließen, daß für Populationen des Typus A und B minimaler Erfolgsverlust vorhanden ist, wenn Gewichtungen der Genauigkeit von bis zu ± 0,5 und ± 1,5 σ ausgewählt wurden. Diese Gewichtungen resultierten in relativ geringfügigen Änderungen in der Rangierung von Tieren, besonders bei geringer Zahl von Kandidaten. Nützlichkeit wurde als eine Funktion von Mittelwert und Varianz des Stichprobenerfolges betrachtet. Indexgewichtungen für maximale Nützlichkeit wurden für sieben Nützlichkeitsfunktionen (drei Risikoabwendungen, drei Risikoerwählungen und eine risikoneutrale Funktion) identifiziert. Eine gewisse Gewichtung der Genauigkeit bei Selektionsentscheidungen kann mit wenig Verminderung des erwarteten mittleren Erfolges vorgenommen werden, so daß Risikobevorzugungen oder Risikoabwendungen durch Veränderung negativer oder positiver Gewichtungen der Genauigkeit möglich und überlegenswert sind. Allerdings scheint es, daß eher extreme Nützlichkeitsfunktionen vorhanden sein müssen, bevor diese Änderungen in signifikanten Vorteilen resultieren.

Effects of strains, strain crosses and environments on additive genetic and phenotypic variances in Drosophila melanogaster.

SUMMARY: The stability of phenotypic, additive genetic and environmental variances of thorax length of Drosophila melanogaster in pure and synthetic strains was examined in two different environments. Two pure strains from different geographic locations (Melbourne and Townsville) were used, together with three synthetic populations formed from them. The existence of differences in thorax length between the Melbourne and Townsville populations, genotype by environment interaction, and heterosis in crosses between these populations indicate that they are genetically different. Thus geographic separation can cause differences in mean thorax length of flies from different populations. Both the difference in selection histories between the two localities and drift could lead to these differences. Up to the thirty fifth generation there was no evidence of any reduction in the difference between the Melbourne and Townsville populations, in either laboratory environment. The genetic differentiation of strains therefore may be maintained over many generations under new environmental conditions. The fluctuation over generations of heterosis of thorax length is possibly caused by the fluctuation of the rate of loss of favourable epistatic interaction in crossbred genotypes in combination with natural selection effects. V(p) was significantly higher in poor than in the good environment. This higher V(p) in the poor environment is most likly due to higher non additive genetic variance. V(p) was also significantly influenced by strain. In general, V(p) values of synthetic strains were higher than those of pure strains in both environments. Finally, the additive and environmental variances of thorax length were relatively stable across strains, generations and environments. ZUSAMMENFASSUNG: Wirkung von Herkünften, Kreuzungen und Umwelten auf additiv-genetische und phänotypische Varianzen in Drosophila melanogaster Die Stabilität phänotypischer, additiv-genetischer und umweltbedingter Varianzen der Thoraxlänge von Drosophila melanogaster in reinen und synthetischen Herkünften wurde in zwei verschiedenen Umwelten überprüft. Zwei reine Herkünfte von verschiedenen Gegenden (Melboune und Townsville) wurden zusammen mit drei zwischen ihnen gebildeten synthetischen Populationen untersucht. Unterschiede in Thoraxlänge zwischen Melbourne- und Townsvilleherkünften, Genotypumweltinteraktionen und Heterosis in Kreuzungen zwischen diesen Populationen zeigen, daß sie sich genetisch unterscheiden. Die geographische Trennung kann also Unterschiede in der mittleren Thoraxlänge zur Folge haben, wobei unterschiedliche Selektionsgeschichte in beiden Gegenden und Drift dies verursachen können. Bis zur 35. Generation gab es in keinem Labormilieu einen Hinweis auf eine Reduktion der Unterschiede zwischen den beiden Populationen. Die genetische Differenz der Herkünfte erhält sich daher auch unter neuen Umweltverhältnissen über viele Generationen. Die Schwankung in Heterosis für Thoraxlänge ist möglicherweise durch Schwankungen in der Verlustrate günstiger epistatischer Interaktionswirkungen in Kreuzungsgenotypen zusammen mit natürlichen Selektionswirkungen verursacht. V(p) war durch Umweltbedingungen signifikant beeinflußt und höher in schlechtem als in gutem Milieu. Der hohe Wert in schlechtem Milieu ist wahrscheinlich auf nicht-additiv-genetische Varianz zurückzuführen. V(p) wurde auch signifikant durch Herkunft beeinflußt und Werte in synthetischen Linien waren höher Linien in beiden Milieus. Additive und umweltbedingte Varianzen waren über Linie, Generationen und Umwelt relativ stabil.

A note on the formation of optimal composite populations.

Two recently proposed methods for predicting the optimal breed contributions to a new composite breed are discussed. It is shown that these can both lead to incorrect solutions, and a reliable method is proposed.

The joint regulation of genetic gain and inbreeding under mate selection.

SUMMARY: Stochastic simulation was used to evaluate a range of selection strategies with respect to both additive genetic response and inbreeding. Strategies involving selection on BLUP ebvs or individual phenotype, followed by random mating, were compared with mate selection strategies which used portfolio analysis to give joint consideration to genetic merit and inbreeding. An adapted Mean Of Total Absolute Deviations (MOTAD) method was used in a mate selection model to define optimal matings with regard to aggregate genetic merit and inbreeding for a base population h(2) of 0.2. Compared with random mating following selection on BLUP ebvs, inbreeding levels after 10 years of selection were able to be reduced under BLUP plus mate selection from ∼.23 to as little as .11. Additive genetic gain was either little compromised or increased. The results suggest that information linking expected levels of genetic merit and inbreeding can be used to find the preferred selection strategy. ZUSAMMENFASSUNG: Gemeinsame Kontrolle von Zuchtfortschritt und Inzucht bei Partnerselektion Es wurde stochastische Simulation zur Auswertung einer Reihe von Selektionsstrategien hinsichtlich Zuchtwertzuwachs und Inzucht verwendet. Strategien mit Selektion auf der Basis von BLUP ebvs oder individuellem Phänotyp mit nachfolgender Zufallspaarung wurden mit Partnerselektionsstrategien verglichen, die Portfolioanalyse zur gemeinsamen Beachtung von Zuchtwert und Inzucht verwendeten. Eine Methode adaptierter MITTELWERTE TOTALER ABSOLUTER ABWEICHUNGEN (MOTAD) Methode wurde beim Partnerselektionsmodell zur Definition optimaler Paarungen in Hinblick auf Gesamtzuchtwert und Inzucht bei einer Populationsheritabilität von 0,2 verwendet. Verglichen mit Zufallspaarung nach Selektion auf BLUP ebvs waren die Inzuchtgrade nach 10 Selektionsjahren von 0,23 auf 0,11 reduziert und additiver Zuchtfortschritt war dabei wenig beeinträchtigt oder nahm sogar zu. Die Ergebnisse weisen darauf hin, daß Information, die Zuchtwert und Inzucht verbindet, zur Identifikation erwünschter Selektionsstrategien führen kann.