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PubMed1979

P phenotype observed in two generations of Tunisian family with a high rate of inbreeding.

A p phenotype was discovered in a Tunisian woman and in three of her seven children. This paradoxical result challenges the known hypotheses on this phenotype, which generally recognise that it is determined by the existence of a very rare allele in a double dose. The computation of the coefficient of inbreeding of these subjects showed that repeated intermarriages increased the coefficient of kinship of the propositus and her husband to 0.116 (if unknown women of the ancestry were assumed to be different for each child) through 0,1362 (if unknown women of the ancestry were assumed to be the same for sibs). Therefore inbreeding was proved to be so high as to induce the presence of a recessively defined phenotype in two successive generations. Moreover, the search for probability of origin of genes of the last generation showed that the BCH ancestor was probably the carrier of the p allele.

Alleles↗
PubMed1981

[Consanguineous marriages, inbreeding and its effects in the Taimyr Nganasans].

Genealogy, marriage structure, inbreeding and its effects in Taimyr Nganasans have been studied in detail. The population size in 715. 223 pairs were analysed. Uncle-niece and first cousin marriages were absent. Marriage frequency of second cousins and more remote relatives is 20.0%. Average inbreeding coefficient of the population is 0.0022 with some variation among three subpopulations (0.0015-0.0027). Consanguineous marriages are characterized by lower average number of livebirths, living children, stillbirths and miscarriages. There are some difficulties in the interpretation of the differences received because of a higher incidence of repeated marriages between relatives; 6 cases of hereditary diseases were registered among the offsprings of nonconsanguineous marriages, including two cases with one parent inbred.

Consanguinity↗
PubMed1981

Inbreeding, mortality and genetic load in families with congenital heart diseases.

A total of 93 cases of congenital heart diseases (CHD) were studied for the effects of inbreeding on the incidence of these diseases. Sib mortality and genetic load in families with CHD were estimated. This study indicated (1) involvement of recessive genes in causation of CHD, (2) lack of inbreeding effects on sib mortality in CHD, and (3) the nature of genetic load to be segregational.

Consanguinity↗
PubMed1993

[Migration structure and inbreeding in the Talysh population].

The origin of genes in Talysh population (South Azerbaijan Republic) is considered. During 11 generations of population history more than 100 unrelated persons supplied the genes to the population. At present, the population is highly isolated: the endogamy index is 0.878, gametic index being 0.935. Inbreeding is estimated both ty means of genealogy and from the frequency of marriages between the persons of the same kin. The inbreeding coefficient is FIT = 0.026-0.030, its random component is FST = 0.01-0.02 and non-random component is FIS = 0.026-0.020.

Azerbaijan↗
PubMed1977

Inbreeding in Norway.

In Norway specified information of marriages between second cousins and closer relations has been recorded in the marriage certificates since January 1889. In addition, information was collected in the 1891 census and in the Medical Registration of Births (established in 1967). A ratio of second- to first-cousin marriages equal to or greater than 2 has been taken as some evidence indicating reliability of the source of data. Using this criterion, the information in the Medical Registration of Births seems most reliable, and that in the 1891 census possibly of similar accuracy. On the other hand, from 1890 the marriage certificates are unreliable with regard to the proportion of second-cousin marriages (ratio less than 1), and with regard to the proportion of first-cousin marriages from 1919. The present inbreeding in Norway is low (alpha4 = 0-000242), approximately one-eighth of the estimated level according to the 1891 census. The greatest reduction in inbreeding probably occurred after 1920.

Consanguinity↗
PubMedDate not supplied

[Bite anomalies and inbreeding].

For the first time, the population investigation on frequency and structure of patho-occlusion in schoolchildren in complex with inbreeding has been carried out in 9 regions of Azerbaijan Republic. The frequency of these pathologies ranged between 22.59-39.94%, at the average frequency 28.03%. Correlation between frequencies of patho-occlusion and inbreeding coefficient in the studied regions was found.

Adolescent↗
PubMed1993

Inbreeding avoidance in rhesus macaques: whose choice?

Whether nonhuman primates avoid copulating with close kin living in their social group is controversial. If sexual aversion to relatives occurs, it should be stronger in females than in males because of females' greater investment in each offspring and hence greater costs resulting from less viable offspring. Data presented here show that adult male rhesus macaques breeding in their natal groups at Cayo Santiago experienced high copulatory success, but copulated less with females of their own matrilineages than with females of other matrilineages. Adult females were never observed to copulate with males of their own matrilineage during their fertile periods. Although natal males sometimes courted their relatives, examination of two measures of female mate choice showed that females chose unrelated natal males over male kin. Female aversion to male kin was specific to the sexual context; during the birth season, females did not discriminate against their male relatives in distributing grooming. Evolved inbreeding avoidance mechanisms probably produce different outcomes at Cayo Santiago than in wild rhesus macaque populations. Gender differences in sexual aversion to relatives may be partly responsible for differences between studies in reported frequency of copulations by related pairs.

Animals↗
PubMedDate not supplied

Analysis of inbreeding in a colonizing population of Drosophila subobscura.

An analysis of the effects of inbreeding on the genetic structure of a colonizing population of Drosophila subobscura has been carried out. Species of Drosophila, particularly D. subobscura, may have lethal alleles associated with chromosomal inversions and our aim was to assess the extent to which the genome is balanced in this way. The frequencies of chromosomal inversions were compared between a large population and a set of 72 lines that were maintained by brother-sister mating for 10 generations. Fisher's matrix method was used to calculate the expected homozygosity in these inbred lines for 5 allozyme loci (Aph, Hk-1, Lap, Odh, and Pept-1) used as markers of large chromosomal segments. Furthermore, the expected rates of fixation corresponding to these allozyme loci were also calculated. The results show that the amount of homozygosis observed did not differ significantly from expectations (with the corresponding loss of lines as a consequence of the reduction in viability). However, two deviations from strict neutrality were observed: there was a heterozygote excess at the Lap locus, and the frequency of the O5 inversion (always associated with a lethal gene in colonizing populations) was higher than expected.

Animals↗
PubMed1990

On the classification of regular systems of inbreeding.

Regular systems of inbreeding are defined as those with discrete, nonoverlapping generations and with the same number of individuals and mating pattern in every generation. Given the number of individuals in a generation, there are many possible regular mating systems. A notion of when two such mating systems are equivalent is introduced, and several necessary conditions are given for such an equivalence. The use of these conditions is illustrated for N = 2, 3, 4 and 5 individuals, and a complete enumeration has been found for these cases: the numbers of inequivalent mating systems are 1, 5, 57 and 858, respectively. The maximal eigenvalue of the matrix q that specifies the recursion relations satisfied by the probabilities of identity have also been found for these cases. For N = 3 and 4 (and 2 trivially), circular mating gives the slowest rate of approach to genetic uniformity of those systems that do evolve to uniformity, but for N = 5 there are two other mating systems that have a slower rate of convergence, and for N = 6 partial results show that there are many such examples.

Animals↗
PubMed1980

Aanlysis of some regular systems of inbreeding.

A probabilistic method is used to calculate the asymptotic rate of loss of genetic variability for half-sib and first-cousin mating of an infinite number of individuals. For both systems of inbreeding, all probabilities of nonidentity by descent converge to zero at ultimate rate proportional to t-1/2, where t is the time in generations. The rate of decay is faster for half-sibs than for first cousins, the respective asymptotic allozygosities being 4(pit)-1/2 and 8(pi t)-1/2.

Animals↗
PubMed1988

Regular systems of inbreeding.

Regular systems of inbreeding with discrete, nonoverlapping generations and the same number of individuals and mating pattern in every generation are studied. The matrix Q that specifies the recursion relations satisfied by the probabilities of identity is expressed in terms of the matrix M that describes the mating system. Necessary and sufficient conditions for convergence to genetic uniformity are given, and it is determined which probabilities of identity approach one. If the mating system has certain symmetries and these are imposed initially, then a matrix R, of lower dimension than Q, specifies the recursion relations. For such a mating system, for generic initial conditions, the condensed matrix R suffices for determining whether convergence to uniformity occurs and which probabilities of identity approach one. If Q is irreducible, the maximal eigenvalue of R is the same as that of Q. If Q is also aperiodic, this implies that the asymptotic rate of convergence to homogeneity of the condensed system is the same as that of the complete one. The above results apply to autosomal loci in monoecious (with or without selfing) and dioecious populations and to X-linked loci. As an example, all the eigenvalues and right and left eigenvectors of Q for circular mating are found.

Animals↗
PubMed1979

Inbreeding and copulatory behavior in house mice: a further consideration.

Comparisons were made of the copulatory behavior of randomly bred (one population: WRL) and inbred wild (five strains: PAA, ab, ac, ad, and PAE) male house mice. All inbred and randomly bred stocks were derived from a single foundation population. The inbred males tended to have shorter latencies to the first mount and intromission, longer latencies to ejaculation, and more preejaculatory mounts and thrusts than randomly bred males. All these effects parallel those observed in a previous study in which a wild population was compared with various domestic inbred strains. If inbreeding depression is related to adaptive significance, these data suggest that, although rapid initiation of copulation in a novel environment may not be adaptive, it may be adaptive for mice to ejaculate rapidly once copulation is initiated.

Adaptation, Psychological↗
PubMed1993

Inbreeding depression and male-mating behavior in Drosophila melanogaster.

There have been relatively few studies designed to investigate the effects of inbreeding on behavioral traits. To study this phenomenon, five experimental lines of Drosophila melanogaster made isogenic for chromosome 2 were evaluated for their male-mating ability and, subsequently, male courtship behavior. All lines showed significant reductions in overall mating ability, and males from all of these lines displayed impaired mating behavior, with two lines displaying particularly aberrant courtship patterns. Line 16 displayed an inability to successfully initiate copulation following successful courtship, while line 17 displayed significant reduction in locomotor activity, resulting in virtually no successful courtship or copulatory activity. The implications of these findings for competitive mating ability in wild Drosophila populations are presented. Further, the importance of mating success as a fitness component in the management of potentially highly inbred populations of endangered species is discussed.

Animals↗
PubMed1980

Serial inbreeding of rabbits with hereditary hyperlipidemia (WHHL-rabbit).

The WHHL-rabbit (Watanabe-heritable hyperlipidemic rabbit) is a strain of rabbit with a consistently inherited hyperlipidemic trait produced by inbreeding from a mutant discovered in 1973. (1) The alleles for this trait have been inherited unfailingly to yield a total of 154 WHHL-rabbits to date. (2) These rabbits showed abnormally increased serum levels of cholesterol (S-Ch) and triglyceride (S-TG) at various ages, increased approximately 8- to 14-fold in comparison with control levels in normal Japanese white rabbits. The serum lipoproteins displayed an electrophoretic pattern characterized by a broad beta-lipoprotein band a markedly diminished alpha-lipoprotein band. (3) Necropsy examination performed on 75 WHHL-rabbits showed spontaneous development of aortic atherosclerosis in all cases over 5 months of age (63/63) and xanthoma of digital joints in 60% of cases from the ages of about 16 months.

Animals↗
PubMed1988

Regular systems of inbreeding with mutation.

Probability of identity by type is studied for regular systems of inbreeding in the presence of mutation. Analytic results are presented for half-sib mating, first cousin mating, and half nth cousin mating under both infinite allele and two allele (back mutation) models. Reasonable rates of mutation do not provide significantly different results from probability of identity by descent in the absence of mutation. Homozygosity is higher under half-sib mating than under first cousin mating, but the expected number of copies of a gene in the population is higher under first cousin mating than under half-sib mating.

Genetics, Population↗
PubMed1988

On the evolution of genetic incompatibility systems. III. Introduction of weak gametophytic self-incompatibility under partial inbreeding.

I explore the proposition that genetic incompatibility systems serve as a means for parents to evaluate and discriminate among their own offspring. Conditions for the initial increase of gametophytic self-incompatibility in a self-compatible population undergoing selfing, sibmating, and random outcrossing are reported. The adaptive value of reducing the concordance between offspring and maternal genotypes depends upon the relative changes in the numbers of offspring derived by the three modes, parent-offspring relatedness, and the magnitude of distortion of transmission ratios through pollen. Recessivity of stylar expression and low rates of receipt of pollen from related individuals facilitate the evolution of self-incompatibility. Viewed as a means of preferential maternal investment in offspring of high quality, self-incompatibility may be regarded as serving a function in common with diverse phenomena, including sexual selection, brood reduction, and other forms of prezygotic and postzygotic incompatibility. Associations between incompatibility loci and loci expressing inbreeding depression are expected to improve the reliability of the level of concordance at incompatibility loci as a measure of genomic homozygosity and offspring quality.

Female↗