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Title: Selection strategies in marker assisted introgression, with special reference to pig breeding
Author: van Heelsum, Anna Maria
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1997
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In this thesis several aspects of Marker Assisted Introgression (MAI) are investigated, keeping in mind the application of the methods to pig breeding. During the process of introgression of a desirable gene from a donor population into a recipient population, markers were used to identify the gene of interest as well as the background genome. The first part of this study deals with consequences of using markers of which the alleles could occur in both base populations. The effects were studied over 5 generations of backcrossing. Using a marker bracket was a much more reliable way to identify the introgressed allele than using a single marker. Applying selection on background (recipient) genotype gave a rapid decrease in the frequency of the introgressed allele, even when the marker alleles were nearly unique to the base populations. Selection on the probability of presence of the desired trait allele while giving preference to heterozygotes (that produce informative gametes that can more often be traced to the correct parent) gave a better retention of the introgressed allele. If possible it would be better to preselect each parental pair on uniqueness of their marker alleles. The second part of the thesis deals with fine mapping a QTL during its introgressing. First a tool was developed to measure the accuracy of the QTL position estimate and then different selection strategies were compared with respect to their ability to map to QTL as precisely as possible, their ability to rapidly recover the background (recipient) genotype and their ability to retain the desired QTL allele. A dense map of fully informative markers was assumed. Some of the simulations used modelled an idealised situation, nonetheless, the conclusions provide valuable information for current pig breeding practice. Furthermore, the rapid development of marker technology and maps means the methods can probably be applied in the near future with relatively minor modifications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available