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PubMed2005

A note on ENDOG: a computer program for analysing pedigree information.

The aim of this note is to describe the program ENDOG (v.3.0). The program handles pedigree information to conduct several demographic and genetic analyses including: (a) the individual inbreeding and average relatedness coefficients; (b) effective population size; (c) parameters characterizing the concentration of both gene and individuals origin such as the effective number of founders and ancestors, the effective number of founder herds; (d) F statistics and paired genetic distances for each subpopulation under study; (e) descriptors of the genetic importance of the herds in a population and (f) generation intervals. The program will help breeders and researchers to monitor the changes in genetic variability and population structure with limited costs of preparing datasets. The program, user's guide and example file can be down-loaded free of charge from the World Wide Web at http://www.ucm.es/ info/prodanim/Endog30.zip.

Animals↗
PubMed2005

Prediction of accuracy of estimated Mendelian sampling terms.

This study describes a general framework for predicting the accuracy of Mendelian sampling terms when truncation selection is applied on best linear unbiased prediction (BLUP) estimated breeding values. A selection index approach is followed. The pseudo-BLUP index is extended to include terms related to the Mendelian sampling term. Predicted accuracies are compared with those obtained through stochastic computer simulation. Good predictions for the accuracy of the Mendelian sampling term were obtained both at selection time and at convergence of long-term contributions of selected candidates for a range of heritabilities and population structures. The prediction approach developed provides a key tool for obtaining predictions of genetic response from quadratic optimization that maximizes the rate of genetic progress while restricting the rate of inbreeding.

Breeding↗
PubMed2006

Genetic variability in French dog breeds assessed by pedigree data.

Pedigree data of nine French dog breeds, namely Barbet (BAR), Basset fauve de Bretagne (BAF), Beauceron (BEN), Berger des Pyrénées (BRP), Bouledogue Français (BUF), Braque Saint-Germain (BQG), Dogue de Bordeaux (DOB), Epagneul Breton (EPB) and Montagne des Pyrénées (MOP), were analysed. The effective numbers of ancestors of dogs born from 1997 to 2001 were equal to 6.7 (BAR), 40.2 (BAF), 36.5 (BEN), 16.0 (BRP), 37.0 (BUF), 13.1 (BQG), 28.9 (DOB), 33.3 (EPB) and 34.0 (MOP). The expected contributions of the major ancestors were found to be highly unbalanced in the EPB and BRP. The average coefficient of inbreeding of dogs born from 1997 to 2001 with both parents known was equal to 12.4% (BAR), 3.9% (BAF), 5.4% (BEN), 7.2% (BRP), 3.3% (BUF), 6.0% (BQG), 4.1% (DOB), 4.5% (EPB) and 4.0% (MOP). These values were found to be significantly higher than the average coefficient of kinship between the male and the female parents of these animals, except in the BAR and BQG, revealing an usual practice of mating between related animals. The results are discussed in relation with the demographic situation and the use of each breed. The method used to class an endangered breed and the ways to preserve the genetic variability, when necessary, are evoked.

Animals↗
PubMed2006

Can low densities of carnivores result in genetic depletion? An investigation within French polecat populations.

Carnivores as top predators are commonly found in relatively low densities even in optimal habitats. Despite a lack of empirical studies, it could be suspected that long-term low density could result in genetic depletion. The genetic structure of European polecat Mustela putorius natural populations was investigated by allozyme electrophoresis in five distinct areas. Density estimates significantly differed among sites from 0.17 to 0.83 individuals/km2 with an average of 0.56 individuals per km2, resulting in a scattered distribution. Genetic structure varied among distinct populations both in number of polymorphic loci and heterozygosity. Polecats from Brittany revealed a very low observed heterozygosity (H(O) = 0.028) whereas mean heterozygosity reached H(O) = 0.072 in Brière. That the lowest heterozygosity levels and highest inbreeding coefficient F(IS) were significantly associated with the lowest densities suggests that low densities may affect populations of carnivores. Both the loss of polymorphic loci and the reduction in heterozygosity rates suggest a density-dependent effect and population density can be arguably regarded as a factor affecting genetic diversity in top carnivores.

Alleles↗
PubMed2006

Major histocompatibility complex alleles, sexual responsivity, and unfaithfulness in romantic couples.

Preferences for mates that possess genes dissimilar to one's own at the major histocompatibility complex (MHC), a polymorphic group of loci associated with the immune system, have been found in mice, birds, fish, and humans. These preferences may help individuals choose genetically compatible mates and may adaptively function to prevent inbreeding or to increase heterozygosity and thereby immunocompetence of offspring. MHC-dissimilar mate preferences may influence the psychology of sexual attraction. We investigated whether MHC similarity among romantically involved couples (N= 48) predicted aspects of their sexual relationship. All women in our sample normally ovulated, and alleles at three MHC loci were typed for each person. As the proportion of MHC alleles couples shared increased, women's sexual responsivity to their partners decreased, their number of extrapair sexual partners increased, and their attraction to men other than their primary partners increased, particularly during the fertile phase of their cycles.

Adolescent↗
PubMed1976

Population structure of Barra (Outer Hebrides).

Historical demography, surname concordance (isonymy), migration, and genealogy give a consistent description of population structure. The census size has averaged about 1400 over the last five centuries. Conjoined with an effective migration rate of 3-05 per generation as estimated by three different methods, this gives an evolutionary size of 638, random kinship of 0-008 and inbreeding of 0-007 relative to the rest of Britain. The population structure of Barra is similar to other British isolates in the recent past, but an order of magnitude less inbred than slash-and-burn agriculturalists and Pacific Islanders. Some consequences for rare genes and polymorphisms are discussed.

Emigration and Immigration↗
PubMed1976

The testing of dominants for heterozygoisty.

A simple method of estimating the frequency of heterozygotes among the dominants by test-making has been described; and then a maximum likelihood estimate is obtained by an iterative counting procedure. Eearly results of Haldane have been review and modified. Methods of estimating the gene frequencies, their ratio, and the inbreeding coefficient from test-mating results have also been given.

Animals↗
PubMed2006

Wild mouse open field behavior is embedded within the multidimensional data space spanned by laboratory inbred strains.

The vast majority of studies on mouse behavior are performed on laboratory mouse strains (Mus laboratorius), while studies of wild-mouse behavior are relatively rare. An interesting question is the relationship between the phenotypes of M. laboratorius and the phenotypes of their wild ancestors. It is commonly believed, often in the absence of hard evidence, that the behavior of wild mice exceeds by far, in terms of repertoire richness, magnitude of variables and variability of behavioral measures, the behavior of the classical inbred strains. Having phenotyped the open field behavior (OF) of eight of the commonly used laboratory inbred strains, two wild-derived strains and a group of first-generation-in-captivity local wild mice (Mus musculus domesticus), we show that contrary to common belief, wild-mouse OF behavior is moderate, both in terms of end-point values and in terms of their variability, being embedded within the multidimensional data space spanned by laboratory inbred strains. The implication could be that whereas natural selection favors moderate locomotor behavior in wild mice, the inbreeding process tends to generate in mice, in some of the features, extreme and more variable behavior.

Animals↗
PubMed2002

A selective advantage to immigrant genes in a Daphnia metapopulation.

Immigrants to habitats occupied by conspecific organisms are usually expected to be competitively inferior, because residents may be locally adapted. If residents are inbred, however, mating between immigrants and residents results in offspring that may enjoy a fitness advantage from hybrid vigor. We demonstrate this effect experimentally in a natural Daphnia metapopulation in which genetic bottlenecks and local inbreeding are common. We estimate that in this metapopulation, hybrid vigor amplifies the rate of gene flow several times more than would be predicted from the nominal migration rate. This can affect the persistence of local populations and the entire metapopulation.

Alleles↗
PubMed1974

Peromyscus: effect of early pairing on reproduction.

Sibling mating in prairie deer mice (Peromyscus maniculatus bairdi) results in poor reproductive performance. Siblings experimentally paired before puberty exhibit delayed reproduction when adult. A behavioral mechanism is involved in this reproductive delay, since prepubertal familiarity also delays reproduction in nonsibling pairs. Such a reproductive delay may act to reduce inbreeding depression and regulate population growth.

Age Factors↗
PubMed2000

Polyploidy and the evolution of gender dimorphism in plants.

Gender dimorphism and polyploidy are important evolutionary transitions that have evolved repeatedly in many plant families. We show that gender dimorphism in North American Lycium (Solanaceae) has evolved in polyploid, self-compatible taxa whose closest relatives are cosexual, self-incompatible diploids. This has occurred independently in South African Lycium. We present additional evidence for this pathway to gender dimorphism from 12 genera involving at least 20 independent evolutionary events. We propose that polyploidy is a trigger of unrecognized importance for the evolution of gender dimorphism, which operates by disrupting self-incompatibility and leading to inbreeding depression. Subsequently, male sterile mutants invade and increase because they are unable to inbreed.

Alleles↗
PubMed1995

Mating patterns in malaria parasite populations of Papua New Guinea.

Description of the genetic structure of malaria parasite populations is central to an understanding of the spread of multiple-locus drug and vaccine resistance. The Plasmodium falciparum mating patterns from madang, Papua New Guinea, where intense transmission of malaria occurs, are described here. A high degree of inbreeding occurs in the absence of detectable linkage disequilibrium. This contrasts with other studies, indicating that the genetic structure of malaria parasite populations is neither clonal nor panmictic but will vary according to the transmission characteristics of the region.

Alleles↗
PubMed1980

Genetic control of susceptibility to Cryptococcus neoformans in mice.

Inbred mice injected intravenously with 5 x 10(6) cells of Cryptococcus neoformans showed two patterns of survival: sensitive (A/WySn, A.BY, A/J, DBA/2J, NZB/B1NJ, and SWR/J) and resistant [C57BL/10Sn, B10.A, B10.A (2R), B10.S (7R),C57BR/cdJ, C58/J, C3H/HeJ, BALB/c, DBA/1J, and SJL/J]. Relative susceptibility based on survival time was shown to correspond to differences obtained for 50% lethal dose values. Either decreasing the dose of organisms or changing to the intraperitoneal route of inoculation resulted in prolonged survival times, but neither change affected the observed patterns of survival. F1 hybrids between different sensitive strains were also sensitive, whereas F1 hybrids between sensitive and resistant strains were resistant, indicating a dominant mode of inheritance. Sensitivity and resistance were shown to be under single gene control by segregation analysis in F2 progeny produced by inbreeding (B10.A x A/WySn)F1 hybrids and in (F1 x A/WySn) backcross progeny. Blood obtained from parental strains, F1, F2, and backcross hybrids was tested for the presence or absence of hemolytic complement. Mice lacking hemolytic complement activity in their sera are homozygous for the Hc(0) allele at the Hc locus on chromosome 2 and are deficient in the complement component C5. A 1:1 correspondence was found between C5 deficiency and sensitivity to C. neoformans. Resistance was shown to cosegregate with the presence of hemolytic complement in the F2 and the backcross progenies.

Animals↗
PubMed1991

Host genetic background effect on the frequency of mouse mammary tumor virus-induced rearrangements of the int-1 and int-2 loci in mouse mammary tumors.

The frequency with which int-1 and int-2 are rearranged in mouse mammary tumors by mouse mammary tumor virus (MMTV)-induced insertional mutagenesis is a consequence of the host genetic background. In 75% of C3H mammary tumors, int-1 is rearranged by MMTV insertion, whereas only 30% of BALB/cfC3H tumors contain a virus-induced rearrangement of int-1. This difference is significant (P less than 0.005) and could not be accounted for by the potentially additive effect of the genetically transmitted Mtv-1-encoded virus in C3H mice. Similarly, MMTV-induced rearrangement of the int-2 gene in mammary tumors of the R111 mouse strain (59%) occurred at a significantly (P less than 0.025) higher frequency than in BALB/cfR111 (25%) mammary tumors. Moreover, in BALB/cfR111 mammary tumors, there is evidence that rearrangement of int-1 and int-2 does not occur independently (P less than 0.025). These results suggest that the long history of inbreeding for high tumor incidence of C3H and R111 mouse strains has selected for the fixation of host mutations which either complement the action of the particular int gene or affect the sensitivity of specific subpopulations of mammary epithelium to infection by particular strains of MMTV.

Animals↗
PubMed1999

Studies on the inheritance of hair loss in the Irish water spaniel.

The inheritance of hair loss in Irish water spaniels has been studied by evaluating the inbreeding levels and genetic relationships in a group of affected and unaffected dogs. A detailed study of the pedigree tree of four families revealed a familial predisposition suggesting a dominant mode of inheritance.

Alopecia↗
PubMed2000

Production of inbred progenies of diploid potatoes using an S-locus inhibitor (Sli) gene, and their characterization.

To develop inbred lines from self-incompatible, cultivated diploid potatoes, an S-locus inhibitor (Sli) gene derived from a self-compatible variant of a wild potato species, Solanum chacoense, was incorporated into various cultivated diploid potatoes. The progeny was selfed twice by the action of the Sli gene to obtain 74 S2 inbred clones belonging to 8 families. More than 40% of them were either non-flowering or pollen sterile. Among the pollen fertile clones, self-compatible clones occurred with a much lower frequency (20.9%) than expected (83.3%). The result demonstrated that self-compatibility was introduced and expressed in the gene pool of cultivated diploid potatoes by an action of the Sli gene, although serious inbreeding depression associated with selfing occurred. The genotypes of S2 inbreds were surveyed using 46 S. chacoense-specific RFLP (restriction fragment length polymorphism) markers covering the whole potato genome. More than half of the markers (67.4%) showed distorted segregation. Particularly, all markers on chromosome 12 were overrepresented in the S2 inbreds. This confirms our earlier finding that the Sli gene locates on chromosome 12 and the alleles linked with this gene are preferentially transmitted because of its essential requirement for selfing.

Animals↗
PubMed1975

Sex differences in gene expression for pupa weight in long term selected lines of Tribolium.

Full-sib matings in two populations of Tribolium which had been selected for increased pupa weight for more than 85 generations resulted in a significant inbreeding depression in male progeny but showed no effect in the female progeny. An analysis of variance of a population produced by backcrossing the selected populations to the inbred lines originally used to establish the select populations (Design-III) indicated some genes were still segregating which produce dominance effects in males but not in females. The data support the hypothesis that a class of genes exists, associated with the autosomes, that differ in their dominance effects of pupa weight in the two sexes.

Animals↗
PubMed1989

Sewall Wright and quantitative genetics.

Some aspects of Wright's great contribution to quantitative genetics and animal breeding are reviewed in relation to current research and practice. Particular aspects discussed are as follows: the utility of his definition of inbreeding coefficient in terms of the correlation of uniting gametes; the maintenance of genetic variation in the optimum model; the inter-relations between past and present animal-breeding practice and the shifting-balance theory of evolution.

Animals↗