Average Relatedness Coefficient Research Articles

Inferring relatedness and heritability using molecular markers in radiata pine

A set of eight unlinked microsatellite markers was used to estimate relatedness among 355 individuals of a Pinus radiata breeding population. The average performance of open-pollinated progeny of each individual, for wood density, was considered to represent the phenotype of all 355 individuals. Marker-based estimates of relationship were compared with the pedigree-based coefficients of relationships. The phenotypic similarity among all pairs of individuals was regressed on marker-estimated relatedness to estimate the inheritance of wood density. The marker-based estimate of heritability was compared with that obtained using classical quantitative genetic methods. Overall, a low correlation (0.13) was observed between marker-based and pedigree-based estimates of relatedness. After discarding negative estimates of relatedness, the average coefficient of relationship among ‘known’ groups of maternal half-sibs, full-sibs and unrelated individuals, increased from 0.24 to 0.29 (0.25 expected), from 0.43 to 0.48 (0.50 expected) and from −0.04 to 0.15 (0 expected), respectively. Marker-based and conventional estimates of heritability of wood density were 0.79 and 0.38, respectively. However, by using only marker loci with expected Hardy–Weinberg frequencies, marker-based estimate of heritability was 0.33, which is very similar to that obtained from conventional approaches. The use of molecular markers to understand quantitative genetic variation is discussed.

Breeding value evaluation in Polish fur animals: Statistical description of fur coat and reproduction traits - relationship and inbreeding

Three data sets were available: records on conformation and coat traits for the arctic fox from one farm (5 540 observations, collected between 1983 and 1997), and the same traits for the silver fox from three farms (8 199 observations, collected between 1984 and 1999). The third set comprised 5 829 observations on reproductive performance of the arctic fox from one farm, collected between 1984 and 1999. The GLM procedure was used to test the significance of fixed effects on the analysed reproduction traits as well as differences between groups. Phenotypic trends as well as relationship and inbreeding across the studied years were computed. Most of the phenotypic trends were positive. Low relationship and inbreeding coefficients in the arctic and silver fox populations under study were estimated. The average relationship coefficients for the silver and arctic fox populations were 0.015 and 0.010, respectively, whereas the average inbreeding coefficients for the same species were 0.0039 and 0.0016, respectively. No inbreeding was found in the arctic fox breeding females.  

Genetische Analyse der Population des Hinterwälder Rindes

Abstract. Title of the paper: Genetic analysis of the population of Hinterwald cattle Since 1994 the Hinterwald population is devided into one of dairy cows and one of suckling cows. The bulls are available to both subpopulations. By means of herdbook records of the year of 2002 there were gained 79 bulls, 698 dairy cows and 517 suckling cows. Considering five generations of ancestors the subpopulations have been investigated with regard to genetic contribution, generation intervals, and circumstances of relationship and inbreeding. The average percentage of Hinterwald blood in the current population amounts to 97 %. The genetic portions of other breeds are low and mostly originating from Vorderwald cattle. The mean generation interval (parents–current animals) is about 5 years. Between the sires and current animals it is shorter (about 4 years) than between the dams and the current animals (about 7 years). The average coefficient of relationship among the bulls is the highest (3.7 %) compared to the dairy cows (2.2 %) and the suckling cows (0.9 %). The mean degree of inbreeding is 1.2 up to 1.3 %, and 37 % of the bulls, 57 % of the dairy cows and 74 % of the suckling cows are not inbred. The increase of inbreeding is rather low and doesn’t surmount 0.7 % in all subpopulations. Therefore it can be assumed that the Hinterwald cattle at present is not subjected to any danger of inbreeding.

Using pedigree information to monitor genetic variability of endangered populations: the Xalda sheep breed of Asturias as an example

SummaryThe aim of this work is to highlight the need of monitoring small populations to conserve their genetic variability by using a set of parameters to characterize both the structure of populations and management practices. As a representative example we analyse the pedigree information of the endangered Xalda sheep breed of Asturias. The herdbook of Xalda sheep included a total of 805 animals and 62 herds. The number of founders was 329. Nowadays, there are 562 live animals and 26 active herds. The breed is in risk of losing genetic diversity because of the abusive use of certain individuals as parents. The effective number of founder animals is 81.1. The effective number of founder herds is 9.9. The average value of inbreeding in the whole Xalda population was 1.5%. The average relatedness (AR) coefficient reached 1.8% in the whole pedigree. The genetic representation of the lines of founders is unbalanced. Inbreeding trends and effective size do not provide realistic information concerning the risk of loss of diversity as a result of the shallowness of the genealogical information. We suggest the monitoring of the breed using AR to unbalance the genetic contributions of specific individuals, equalizing the genetic representation of the founders and lines in the population. In addition, AR can suggest the introduction of new, under‐represented animals in herds showing high average AR values relative to the population. Our results can be useful to improve the development of conservation initiatives involving open herdbooks to avoid the risk of loss of genetic diversity caused by incorrect management practices.

POPULATION STRUCTURE AND COMPETITION AMONG KIN IN THE CHORUS FROG (PSEUDACRIS TRISERIATA).

In natural populations on Isle Royale, tadpoles of the chorus frog live in small pools on the shore of Lake Superior. Hatchling densities are high and sufficient to cause competitive impact on survivorship, growth, and development. The temporal and spatial pattern of egg laying indicates that tadpoles in many of the pools belong to single sibships. I calculated average coefficients of relationship among tadpoles under the assumption that eggs laid together are the products of the same breeding pair; the coefficients indicate that relationship among competing larvae averages approximately 0.35, and varies widely among larval subpopulations, from less than 0.1 to about 0.5. Two growth experiments were carried out in pens to test whether growth trajectories and larval characteristics at metamorphosis are influenced by relationship among competing tadpoles. In both experiments, initial density was crossed with average relationship; relationship was controlled by varying the number of sibships per pen from one to four. The same sibships were used in both experiments, but one experiment had lower initial densities and less water volume per pen than the other. In both experiments, density reduced growth, developmental rate, size at metamorphosis, survivorship to the onset of metamorphosis, and the proportion of survivors which actually attained metamorphosis by the end of the experiment. Kin effects occurred only in the experiment carried out in small pens at high initial densities: in this experiment, pure sib populations grew faster, and a higher proportion attained metamorphosis. However, there were no kin effects on larval period or body size at metamorphosis. The chorus frog appears to have a population structure conducive to kin-group selection. Furthermore, high variance in the average coefficient of relationship among pools should favor kin recognition and kin-specific interference behavior. The growth experiments suggest that the tadpoles respond to the genetic relationship of competitors, with significant effects on the distribution of fitness at metamorphosis among members of the group.

Genetic relatedness in open-pollinated families of two leguminous tree species, Robinia pseudoacacia L. and Gleditsia triacanthos L.

When conducting tree breeding experiments, geneticists often assume that individuals from open-pollinated families are halfsibs. The reliability of this assumption was tested using data from enzyme electrophoresis to estimate the genetic relatedness among progeny within 22 open-pollinated families of Robinia pseudoacacia L. (black locust) and 34 open-pollinated families of Gleditsia triacanthos L. (honey locust) from natural stands. An algorithm employing population estimates of fixation indices, pollen allele frequencies, and selfing rates was used to calculate the mean expected number of alleles in common across loci under assumptions of either full-sib (i.e., a single pollen parent) or half-sib (i.e., random mating) relationships. For each open-pollinated family, the average coefficient of relationship among progeny was calculated by linear interpolation from the observed number of alleles in common. For most families of both species, coefficients were significantly higher than 0.25 (half-sib relation), but were significantly lower than 0.50 (full-sib relation). These results suggest that the assumption of a half-sib relationship among progeny of open-pollinated families is violated for these tree species. More critical to the estimation of heritabilities and the prediction of genetic gains was the observation that estimates of the coefficient of relationship varied widely among open-pollinated families (for R. pseudoacacia r 0=0.20-0.43, mean=0.34; for G. triacanthos r 0=0.29-0.55, mean=0.36).

Heritability and Genetic Progress for a Worker Character inApis Mellifera

SummaryThe classical relationship for genetic progress (ΔG♀ = i h2 σ P) does not apply to a worker character in the honeybee (Apis mellifera) since an aunt-niece relationship takes the place of the parent-offspring relationship. When the genealogy involves only mother-daughter links (no relationship through males), the heritability sensu stricto need not be estimated, but can be substituted by the product φh2, where φ is the average coefficient of relationship between the workers of a colony. This product is equal to the mother—daughter regression coefficient or twice the within-family correlation.

Evolution of eusociality in diploid species

Haplodiploid species are naturally biased by their genetic structure toward the evolution of sterile worker castes, as shown by W. D. Hamilton (1964. J. Theoret. Biol., 7, 1–16, 17–52). Diploid species do not have this intrinsic genetic bias toward eusociality. Nonetheless, true sociality has evolved in the diploid ancestors of the modern termites, and varying degrees of quasisociality are not uncommon in diploid species, including mammals. A genetic bias toward investment in relatives rather than offspring can arise in a diploid species as a result of inbreeding. The consequences of several regular incestuous breeding systems are analyzed in detail. It is shown that, under certain conditions, there is a natural bias toward an alternation of inbred and outbred generations. As this alternation proceeds, the genetic bias toward eusociality rapidly approaches an asymptotic value of 4(1 + 2f 0) 3(1 + 3f 0) , where f 0 is the average coefficient of relationship for the outbreeding pairs. For f 0 close to zero, the genetic bias toward eusociality is close to 1.33, which is even larger than the genetic bias of 1.25 in haplodiploid species. Under other conditions there may be repeated incestuous matings between successive outbreeding generations. In this case the bias toward eusociality can be as large as 2.

Average coefficient of relationship within troops of the Japanese monkey and other primate species with reference to the possibility of group selection

The average coefficient of relationship within troops of the Japanese monkey (Macaca fuscata) is .1667±.0433; this corresponds to anF ST between troops of .0935±.0277. The estimate is based on polymorphic variation at 12 blood protein loci in a sample of about 1,500 individuals distributed over 33 troops. The average coefficient of relationship among adult females (the sedentary sex) is .1886±.0670 and that among adult males (immigrants) is .1067±.0382. The difference, though not statistically significant, is in the direction expected from the observed sex asymmetry in dispersal. We give an approximate formula for the coefficient of relationship between specified relatives. The coefficient of relationship in the Japanese monkey is compared with corresponding estimates in five other terrestrial primate species and in tribal man. It is suggested that the best informed guess of the average coefficient of relationship within bands of Pleistocene man may have been about 10 to 15%. This estimate is relevant to the possibility of the evolution of altruism in our ancestors by group selection.

A sociobiological interpretation of the structures and functions of the human family

Altruism probably had a paramount importance in the development of human societies as a prominent basis of solidarity and social co-operation. Therefore, its evolution may be invoked to explain many aspects of human social organization, especially in simple societies. Evolutionary biology has made it clear that altruism evolves much more easily when directed towards close relatives. The average coefficient of relationship is much higher in a polygamous family than in a promiscuous group, and in a monogamous family than in a polygamous one. This suggests that polygamy must have prevailed over promiscuity, and monogamy over polygamy, by interdemic selection, except where the environment was particularly propitious to the latter. Many forms of preferential and prescriptive marriage, as well as incest taboo and exogamy, may be usefully analysed in this light. The levirate and the sororate raise the coefficient of relationship in the following generation to the highest degree possible in the given situation. The different marriage rules for parallel and cross-cousins discriminate between relatives of the same formal degree, but with different average biological relationship depending on paternity uncertainty. Incest taboo strengthens the avoidance of the closest forms of inbreeding that are already uncommon among lower primates. Exogamy institutionalizes the genetic exchange among groups, allowing for a continual expansion of altruism and the forms of solidarity and co-operation that are based on it. The shift from matrilineal to patrilineal organization profoundly affects the women's social condition by promoting forms of stricter control on their behaviour able to enhance paternity probability.

Surnames in five English villages: relationship to each other, to surrounding areas, and to England and Wales.

SummaryThe surnames of all adult residents of five neighbouring communities in the fenlands of Cambridgeshire are compared with each other and with those of the 165,533 persons married in England and Wales in the period January to March 1975. Among the villages the average coefficient of relationship by isonymy (Ri) is 76 × 10−5. The villages nearer together may have a tendency to higher values of Ri: the correlation of Ri with the natural log of distance between villages is −0·49, p = 0·07. The surnames of the five villages give a weighted average Ri with the whole area about 25 miles of 54 × 10−5 and with a zone 25–40 miles away of 45 × 10−5, whereas Ri with all England and Wales is 42 × 10−5. Rare surnames show a much sharper gradient and contribute approximately twice as much to the coefficient in the 25–40 mile zone and six times as much within 25 miles as found with all England and Wales. Moderately frequent surnames and even common surnames show the same gradient, but to a lesser degree. In the part of Cambridgeshire studied, the present distribution of surnames indicates a slight but appreciable local isolation, with the degree of relationship decreasing from among local villages to that between the villages and all England and Wales. This pattern is consistent with the theory of genetic inbreeding based on distance but there is considerable variability in individual instances.

Density-dependent mortality and the evolution of social interactions

Existing models of kin selection implicitly assume that the intensity of density-dependent mortality depends on the size or density of the entire deme. If individuals compete for locally limited resources, then mortality may also depend on local population density. In this paper, I derive conditions for evolutionary equilibrium when the fitness of an individual depends on (1) the phenotypes of a local group of conspecifics with which it interacts and (2) the size of the local group. In general, altruistic behaviours which reduce the individual fitness of the actor but increase that of the recipient are favoured towards individuals whose coefficient of relationship exceeds a threshold value. ‘Harming’ behaviours which reduce the individual fitness of both the actor and the recipient are favoured towards individuals below this threshold value. The magnitude of this threshold depends on the nature of the processes that cause density-dependent mortality and the average coefficient of relationship in the group.

Estimation of genetic parameters for beef traits from field data

Data of the progeny testing for meat production of the Swiss A.I.-Federation were used in order to estimate genetic parameters. A heritability of carcass gain between 0.21 and 0.25 was found. Very small heritabilities of carcass grades were found (<0.1). Positive genetic correlations between carcass gain and carcass grades seem to exist. The average coefficient of relationship among the sires ( R ) can be considered in the estimation of the heritability by dividing the variance component of sires (σ s 2) by 1 — R. In this analysis the results were hardly influenced at all, due to the very small average relationship of only 1%.

わが国ホルスタイン種の遺伝学的分析

The trends in the values of coefficients of average inbreeding and inter-se relationship in the Holstein cattle in Japan as well as in the degree of subdivision of the population indicated by the relative values of the both coefficients were analyzed in the previous paper. In that analysis, the average relationship coefficients among male parents and among female parents and between male and female parents of the sample heifers, besides the average inbreeding coefficient and inter-se relationship coefficient of the sample heifers themselves, were estimated so that these estimates were used to examine the nature and the influence of different factors affecting the above trends. The first purpose of the present paper is to give a note on the theoretical background for the technique of analysis used there. It was shown in here that any change in value from generation to generation of the coefficients of inter-se relationsoip and average inbreeding of the sample heifers (_??_R and _??_F) and also _??_(F-R/2) could be expressed, in an approximate manner, in terms of separate contributions of the change in each of average male-male, female female, and male-female relationship coefficients brought about by selection and migration in the parent and grand-parent generations and also the contributions from the non-randomness of mating in the both generations, using the values of the above three kinds of average relationship coefficients among the parents of the sample heifers. Then, in the second place, as an example of application of this technique, the contributions of the different factors to some actual values of _??_R, _??_F, and _??_(F-R/2) which appeared in the previous paper were calculated and brief comments were given on some important points suggested by the tabulated results.