Association of Polymorphic Blood Group Systems and Relative Fitness in Pigs
Yau, Francis Dick-Woon
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https://hdl.handle.net/2142/69998
Description
Title
Association of Polymorphic Blood Group Systems and Relative Fitness in Pigs
Author(s)
Yau, Francis Dick-Woon
Issue Date
1982
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Genetics
Abstract
A total of 9563 pigs from 1328 familes comprising 3 replicate lines of 5 breed classes (Duroc unselected, Duroc selected, Yorkshire unselected, Yorkshire selected, and Duroc-Yorkshire crossbred selected) over 7 generations were typed for blood factors in 12 blood group systems using 33 reagents. Boars in the selected lines were selected for high ('40)K count per unit weight. Both segregation analyses and least squares analyses of litter size and perinatal and preweaning survivabilities were used to study possible mechanisms of natural selection with respect to polymorphic blood group systems. In the G and H systems, parental incompatibility appeared to be the major cause for reducing the overall biological fitness of the conceptuses, where heterosis had apparently produced significant differences in the ratios of heterozygotes in homozygotes. In the E system, parental incompatibility seemed to be responsible for differences in litter size and survivability of offspring and there was no heterosis. Maternal-fetal incompatibility was found to be a source of selection against heterozygotes in the K system. There was evidence for prezygotic selection (meiotic drive) in the B system. The method of maximum likelihood was used to estimate relative fitness of blood group genotypes from segregation data where a consistent heterotic effect was obtained in the H system with heterozygote superiority across all breed classes. Lower fitness was identified with the B('b) and G('a) alleles in Yorkshires. An overall fitness index to rank blood group genotypes was formulated based on litter size and perinatal and preweaning survivabilities of offspring. This index could be used to support a selection program, but its usefulness was limited because of inconsistent results in most blood group systems.
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