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1

Inbreeding effects on lifetime in David?s deer (Elaphurus davidianus, Milne Edwards 1866) population

100%
Sternicki T., Szablewski P., Szwaczkowski T.
Journal of Applied Genetics
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2003
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vol. 44
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issue 2
175-183
EN
The current population of David?s deer is derived from 18 individuals kept in Woburn Abbey Park (England). The aim of this study is to evaluate the inbreeding rate as well as inbreeding depression in longevity. The recorded data have been extracted from the International Species Information System (ISIS). Complete records of 2042 individuals (born in 1947-2000) from zoological gardens were studied. The following four subsets of data were formed: all individuals, individuals over 31 days of life, sexually mature individuals (above 450 days old) and individuals with identified sex. Two models (including inbreeding coefficient as linear and quadratic covariables, respectively) have been employed. These computations were performed by the use of the DFREML package programs. This study has shown that average levels of inbreeding in the David?s deer are relatively low (no exceed 0.028). The highest level of inbreeding was registered for mature individuals. In general, the average inbreeding on length of life was small for the above mentioned the inbreeding level (from 24 days to 77 days). However, on the basis estimated regression coefficients it can be suggested that an increase of inbreeding could lead to a drastic reduction of longevity. Relationships between inbreeding level and longevity are usually better described by quadratic partial regression (except for the oldest individuals). On the other hand, from a statistical point of view, a relatively low inbreeding level of the population studied is not suitable to derive the slope of the dependencies.
2

Genetic differentiation induced by selection in an inbred population of the silkworm Bombyx mori, revealed by RAPDand ISSR marker systems

80%
Pradeep A. R., Chatterjee S. N., Nair C. V.
Journal of Applied Genetics
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2005
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vol. 46
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issue 3
291-298
EN
Artificial selection has been widely utilized in breeding programmes concerning the commercially important silk-producing insect Bombyx mori. Selection increases the frequency of homozygotes and makes homozygous effects stronger. Molecular variation induced by selection in the inbred population of B. mori strain Nistari, was assessed in terms of genic differentiation by using a polymorphic profile generated by RAPD and ISSR marker systems. Artificial selection for longer larval duration (LLD) for 4 generations resulted in a significant prolongation of larval duration (F = 89.28; P = 5.14?10?7). The lines selected for shorter larval duration (SLD) were not significantly different from the control group. RAPD and ISSR primers generated polymorphic profiles when amplified with genomic DNA of individuals of LLD and SLD lines. Distinct markers specific to LLD individuals were observed from the 3rd generation and indicated selection-induced differentiation of allelic variants for longer larval duration. Both SLD and LLD were characterized by high gene diversity (h 0.197) and total heterozygosity (Ht 0.26), low homogeneity (?2 test, p < 0.005) as well as a large coefficient of gene differentiation (Gst 0.42) but low gene flow (Nm 0.42). Genetic distance was the highest (0.824) between 3rd generations of SLD and LLD. High heterozygosity and prolonged larval duration substituted for shorter larval duration (the traditional trait of fitness) in the Nistari LLD larvae.
3

Curvilinear inbreeding effects on some performance traits in laying hens

80%
Szwaczkowski T., Cywa-Benko K., Wezyk S.
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issue 3
341-342
EN
Quadratic partial regression coefficients were estimated for the inbreeding level on five performance traits (body weight, average egg weight, age at first egg, percentage of fertilized eggs, and hatchability of set eggs) of two strains of laying hens. Data on 5631 of H77 layers and 3563 of N88 layers from nine consecutive generations were analysed. Only dams were accounted for. Partial regression coefficients were estimated by REML with a single-trait animal model, which included fixed effects (generation and hatching period) and random effects (additive genetic and error effects). The mean inbreeding level was 0.87% in strain H77 and 1.08% in strain N88. The inbreeding effects were analysed based on the quadratic partial regression equations. A slight inbreeding depression was found for all the traits analysed in N88. In strain H77, negative effects of inbreeding were only noted for body weight and average egg weight. The small inbreeding effects shown here resulted from a relatively low level of homozygosity in the populations studied. The strains were found to differ in the effects of inbreeding. It is worth pointing out that differences were noted both between the inbreeding depression estimated from the partial linear regression equation and the quadratic partial regression equation, as well as different inbreeding levels.
4

Inbreeding and relationship in Polish Black-and-White sires

80%
Kania-Gierdziewicz J.
Journal of Applied Genetics
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2005
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vol. 46
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issue 2
187-193
EN
The aim of the study was to analyse inbreeding and relationship in the Polish population of Black-and-White sires. Data were pedigrees of 25 036 Black-and-White sires born from 1960 through 2000, divided into subsets of 11 447 proven and 13 589 unproven sires, and their 38 228 ancestors, altogether 63 264 animals. Average inbreeding coefficients were about 0.3% for both subsets of sires. Mean relationship coefficients ranged from 0.1% in all animals to 0.7% in the subset of proven sires. Positive time trends in inbreeding coefficients were observed when the subsets of sires were divided into 5-year intervals according to the year of birth and in terms of Holstein Friesian gene contribution. Key words: Black-and-White sires, inbreeding, relationship.
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