Abstract
Simple SummaryLosses of genetic diversity have a particular impact on breed populations in countries with a small breeding base or national breeds with a small registry. Among them, it is possible to include the breed of the Czech Spotted Dog (CSD), whose variability has been low since the beginning of breeding due to the small number of founders and mating of close relatives. Through study of its pedigree records, we recorded a severe loss of genetic variability and high relatedness between animals. Moreover, the population is not free of genetic diseases; therefore, future existence of the breed is in danger.Loss off genetic diversity negatively affects most of the modern dog breeds. However, no breed created strictly for laboratory purposes has been analyzed so far. In this paper, we sought to explore by pedigree analysis exactly such a breed—the Czech Spotted Dog (CSD). The pedigree contained a total of 2010 individuals registered since the second half of the 20th century. Parameters such as the mean average relatedness, coefficient of inbreeding, effective population size, effective number of founders, ancestors and founder genomes and loss of genetic diversity—which was calculated based on the reference population and pedigree completeness—were used to assess genetic variability. Compared to the founding population, the reference population lost 38.2% of its genetic diversity, of which 26% is due to random genetic drift and 12.2% is due to the uneven contribution of the founders. The reference population is highly inbred and related. The average inbreeding coefficient is 36.45%, and the mean average relatedness is 74.83%. The effective population size calculated based on the increase of inbreeding coefficient is 10.28. Thus, the Czech Spotted Dog suffered significant losses of genetic diversity that threaten its future existence.
Highlights
Many dog breeds suffer from limited genetic diversity
The bottleneck effect, use of favored sires, inbreeding and genetic drift are the main mechanisms of the loss of genetic diversity
Many small-registry dog breeds face a shortage of breeding individuals, and this may have consequences in the form of inbreeding depression
Summary
Many dog breeds suffer from limited genetic diversity. Due to their current use as human companions, they are selected by humans—and not by nature—for specific phenotypes. The strict division into breeds and forms causes irreversible loss of alleles and, in most cases, vitality as well. The bottleneck effect, use of favored sires, inbreeding and genetic drift are the main mechanisms of the loss of genetic diversity. Genetic drift is a significant evolutionary force that is the functional essence of all of the other causes of the loss of genetic variability listed above [1]. The bottleneck effect occurs by selecting a low number of animals for breeding or subdividing a population. The current dispersion of dog hobby breeding all over the world creates a new form of the bottleneck effect—the national bottleneck [2]
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