EPISTATIC KINSHIP - A NEW MEASURE FOR THE ASSESSMENT OF GENETIC DIVERSITY IN LIVESTOCK POPULATIONS

The main goal of this thesis was the extension of the single locus concept of the kinship coefficient to chromosomal segments of length x in Morgan. The metric - called epistatic kinship - describes the probability that two randomly drawn segments are identical by descent. In a simulation study the genetic properties of chromosomal segments were investigated theoretically. Further the use of marker based epistatic kinship was investigated for situations where pedigree information is not available. Finally the marker based epistatic kinship was evaluated on practical data. Therefore DNA-samples from three subpopulations of the Goettingen minipig were genotyped for six chromosomal segments defined with microsatellites. The statistical analysis revealed a remarkable variability of epistatic kinship between segments. The variability decreased applying a correction factor for identity by state. To estimate genetic diversity a genetic distance measure considering the epistatic kinship between and within populations was proposed. The distances for the three subpopulations of the Goettingen minipig resulted in the same order for the pedigree based expectations and the marker based epistatic kinship distances. Based on the results the epistatic kinship is proposed as a new measure for the assessment of genetic diversity for short term phylogenies, which are often found in livestock populations.