Mean Kinship Research Articles

Genome Resource Banking for Species Conservation: Selection of Sperm Donors

The systematic banking of genome resources using cryopreserved germ plasm offers the opportunity to further conservation strategies of endangered species by assisting in the effective genetic management of captive populations. Cryopreserved germ plasm will allow indefinite preservation of the presently available gene diversity represented in either captive or wild populations. If properly utilized, genome resource banks have the potential to decelerate the loss of gene and allelic diversity in captive populations through reintroducing "original" genetic material through time to counter genetic drift. However, in order for any genome resource bank to be effective, strategies need to be developed to identify genetically valuable individuals to bank which will represent optimal gene diversity of the specific population. Four selection strategies were evaluated to identify individual donors from four North American captive populations representing differently structured pedigrees. The strategies consisted of selecting: (1) all males in the population ("All Male Bank"); (2) only living founders and early generation descendents ("Founder Method Bank." FMB); (3) males remaining after culling to minimize mean kinship ("Culled Male Bank 1"); and (4) males remaining after culling to minimize mean kinship with the males reduced to the number in the FMB ("Culled Male Bauk 2"). The effectiveness of each strategy was based on the comparison of genetic variation metrics in each bank with the genetic variation in the present living managed population. Althougb maximal retention of allelic diversity was achieved by banking genes from all living animals, nearly optimal retention of allelic and gene diversity was obtained by utilizing the selection strategy based on minimizing mean kinships. As a consequence, properly designed and utilized, genome resouce banks cnn become effective tools for preserving gene diversity in future generations of living populations.

Clarification of genetic terms and their use in the management of captive populations

AbstractSome of the concepts, terms, and methods used in the genetic management of captive populations have not been defined precisely in the scientific literature and consequently have been misunderstood and misused. The definitions and interrelationships among gene diversity, effective population size, founder genome equivalents, inbreeding, allelic diversity, mean kinship, and kinship value are presented here. It is important to understand what populations and generations are used as the baselines against which losses of genetic variation are measured. Gene diversity and founder genome equivalents are defined relative to a source population from which founders of the captive population were randomly sampled. Inbreeding and allelic diversity are assessed relative to the founders. The potential gene diversity that would result from an equalization of frequencies of founder alleles retained in the population can never be achieved because, among other limitations, the random process of gene transmission will prevent equalization of allele frequencies even if animals are bred optimally. The gene diversity achievable with the population can be determined by iterative production of hypothetical offspring from the pairs with lowest mean kinship. The long‐term objective for offspring production from each animal is also thereby generated. Mean kinships should be recalculated with each real or hypothetical birth and death, because offspring objectives based on current mean kinships might correlate poorly with the optimal long‐term offspring objectives. © 1995 Wiley‐Liss, Inc.

A Linear Time Algorithm for Calculation of Multiple Pairwise Kinship Coefficients and the Genetic Index of Familiality

We present an algorithm that calculates the mean kinship coefficient between all pairs of individuals in a given set relative to a known pedigree. The time required to make the calculations is proportional to the size of the set. The constant of proportionality is determined by the number of generations that the pedigree spans. A simple alteration to the algorithm allows efficient calculation of all pairwise kinship coefficients within a set of individuals.

Identification of kin structure among Guam rail founders: a comparison of pedigrees and DNA profiles

Kin structure among founders can have a significant effect on subsequent population structure. Here we use the correlation between DNA profile similarity and relatedness calculated from pedigrees to test hypotheses regarding kin structure among founders to the captive Guam rail (Rallus owstoni) population. Five different pedigrees were generated under the following hypotheses: (i) founders are unrelated; (ii) founders are unrelated except for same-nest chicks; (iii) founders from the same major site are siblings; (iv) founders from the same local site are siblings; and (v) founders are related as defined by a UPGMA cluster analysis of DNA similarity data. Relatedness values from pedigrees 1, 2 and 5 had the highest correlation with DNA similarity but the correlation between relatedness and similarity were not significantly different among pedigrees. Pedigree 5 resulted in the highest correlation overall when using only relatedness values that changed as a result of different founder hypotheses. Thus, founders were assigned relatedness based on pedigree 5 because it had the highest correlations with DNA similarity, was the most conservative approach, and incorporated all field data. The analyses indicated that estimating relatedness using DNA profiles remains problematic, therefore we compared mean kinship, a measure of genetic importance, with mean DNA profile similarity to determine if genetic importance among individuals could be determined via use of DNA profiles alone. The significant correlation suggests this method may provide more information about population structure than was previously thought. Thus, DNA profiles can provide a reasonable explanation for founder relatedness and mean DNA profile similarity may be helpful in determining relative genetic importance of individuals when detailed pedigrees are absent.

Genetic epidemiology of sensorimotor polyneuropathy with or without agenesis of the corpus callosum in northeastern Quebec.

Sensorimotor polyneuropathy with or without agenesis of the corpus callosum (McKusick number 218000) is a disorder that has a high frequency in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of north-eastern Quebec. The incidence at birth and the carrier rate were estimated, respectively, at 1/2117 liveborns and 1/23 inhabitants. Remote consanguinity was found in several polyneuropathic families while the mean kinship coefficient was 2.7 times higher in the polyneuropathic group than in control groups. The birth places of the individuals with sensorimotor polyneuropathy and their parents did not show a clustered nonuniform distribution. The genealogical reconstruction suggests that the high incidence of polyneuropathy in SLSJ is likely to be the result of a founder effect. It also suggests that a unique mutation accounts for most, if not all, of the cases of sensorimotor polyneuropathy known in this region.

Kinship bioassay on hypervariable loci in blacks and Caucasians.

Four hypervariable loci were examined in DNA samples of American Blacks and Caucasians. Genetic diversity, measured by mean kinship within race, is 0.004 for a sliding window equal to twice the radius of coalescence of the autoradiographic bands. Kinship increases with the width of a window or bin, but it is an order of magnitude less than for blood groups and isozymes. This must reflect the greater mutability of hypervariable loci and absence of divergent selection. Low kinship implies that matching probabilities do not depend critically on race. Complete matching between pairs of loci shows deviations from independence, presumably because of inadvertent inclusion of replicated samples or related individuals. Multilocus matching probabilities were corrected for this (possibly spurious) dependence; the correction is negligible. When the complexities of coalescence, kinship, and dependent matching are allowed for, the probability calculations used in forensic identification are reliable. Recent counterarguments without theoretical basis or empirical support are discussed.

Genetic epidemiology of autosomal recessive spastic ataxia of Charlevoix-Saguenay in northeastern Quebec.

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a disorder that has an elevated frequency in Saguenay-Lac-St-Jean (SLSJ) and Charlevoix, two geographically isolated regions in the past of northeastern Quebec. The incidence at birth and the carrier rate in SLSJ were estimated at 1/1,932 liveborn infants and 1/22 inhabitants, respectively, for the period 1941-1985. The mean inbreeding coefficient was twice higher and the mean kinship coefficient 3 times higher among the ARSACS families than among control families. In the SLSJ region, the birth places of the ARSACS individuals and their parents did not show a clustered distribution. The genealogical reconstruction suggests that the high incidence of ARSACS in SLSJ and Charlevoix is likely to be the result of a founder effect. Because the disease is apparently unknown elsewhere in the world and a high proportion of French Canadians presently living in eastern Quebec have ancestors coming from Perche, a small region in France, it also suggests that a unique mutation accounts for most, if not all, of the ARSACS cases known in these regions.

Inbreeding and kinship in Saguenay-Lac-St-Jean: a study of newborn samples 1956-1971.

Samples of individuals born between 1956 and 1971 proportional to the population size of each parish of Saguenay-Lac-St-Jean (SLSJ) were extracted from a computerized population register. The mean inbreeding and kinship coefficients were calculated for each sample. Our results showed that inbreeding and kinship were unevenly distributed in the SLSJ region. The highest values of inbreeding and kinship were found in Bas-Saguenay, an isolated subregion of SLSJ, and in rural parishes. It was also found that the mean inbreeding and kinship coefficients had higher values in parishes that opened between 1872 and 1901 than those opened earlier or later.

Genetic epidemiology of cystic fibrosis in Saguenay‐Lac‐St‐Jean (Quebec, Canada)

Cystic fibrosis (CF) is an autosomal recessive disorder with a prevalence at birth estimated at 1/2000-1/2500 livebirths in Caucasian populations. Some 127 CF individuals are known in Saguenay-Lac-St-Jean (SLSJ), a geographically isolated region of Quebec. The prevalence at birth was estimated at 1/902 live borns, and the carrier rate was estimated at 1/15 inhabitants in the SLSJ region. The mean inbreeding coefficient was only slightly elevated in the CF group compared with three control groups, and was due to remote consanguinity. The mean kinship coefficient was 2.4 times higher in the CF group than in the control groups. In SLSJ region, the places of origin of the CF individuals and their parents did not show a clustered nonuniform distribution. Endogamy was not higher in the CF group than in control groups.

Genetic epidemiology of Down's syndrome in Shetland

Pedigrees of all known cases, on Shetland, of Down's syndrome, cytogenetically confirmed as trisomy 21, and of a control for each patient matched by birth date, sex and birth place, were traced over a minimum of eight generations. Mean kinship coefficients in all pairs of Down's syndrome patients and in all pairs of controls were similar. The kinship between the father and mother of each case shows that the parents are more closely related than the general level of relationship in the population, suggesting some recessive element in the etiology. It is argued that the effect of the resulting increased homozygosity would be to prevent the loss of the conceptus that occurs in the majority of trisomy 21 conceptions.

Inbreeding and prereproductive mortality in the Old Order Amish. I. Genealogic epidemiology of inbreeding.

Epidemiologic patterns of inbreeding in the Old Order Amish were investigated using a unique genealogic registry of Lancaster County, Pennsylvania, Amish that contains information on 8,163 marriages, dating back to the time of the pioneer migrants in the 1700s and spanning more than 10 generations. The kinship coefficient for each marriage was computed using the path method of tracing common ancestors in the multigenerational pedigrees. Because of extensive genealogic connections, mean kinship coefficients and the proportion of related marriages have increased significantly over time, from 0.004 and 37%, respectively, for marriages before 1850 to 0.012 and 98%, respectively, for marriages after 1950. Demographic factors related to higher kinship levels include young age at marriage, large sibship size for both husband and wife, husband being a farmer, and marriages occurring in the marriage season (November or December). The rise in inbreeding levels in the Amish over time can be uniquely contrasted with the decline in inbreeding in most areas of the world. Furthermore, because some of the demographic factors related to high inbreeding levels may be associated with levels of mortality, such factors have to be taken into account when studying the effects of inbreeding on mortality in the Amish. This study uses an epidemiologic approach to the evaluation of inbreeding patterns in a population over time.

Predicting the genetic drift in small populations

Predicting the genetic drift in small populations is considered over a short interval of time. A detailed description of the dynamic and spatial structure of the population is used, together with several measures of the change of genetic variability with time: mean inbreeding and kinship coefficients within and between groups of animals; percentages of genes contributed by the various foundation groups that made up the initial population; rate of loss of founder genes; joint distribution and random fluctuations of allelic frequencies. This approach is illustrated by means of two theoretical populations that model actual cattle breeds, and is applied to two problems: the conservation of a small population with or without freezing of semen, and the conflict between diffusion of genetic progress and random drift in a selected population conducted with or without superovulation and embryo transfer. Two main conclusions were drawn from these examples: 1. (a) Drift should not be characterized by single values (genetic effective size, or mean inbreeding coefficients), but rather by a set of criteria that have differentiated sensitivities to variations in demographic structure, mating scheme and gene diffusion. 2. (b) Quite large random variations in gene frequencies can be promoted by selection in seemingly large populations.

Bioassay of kinship in Micronesia.

AbstractPhenotype bioassay agrees with clan isonymy, anthropometrics, and migration in estimating the mean kinship within a Micronesian population, relative to large distances, as 0.05. Various calculations of occupancy for the Eastern Carolines from ethnohistory, kinship, and glottochronology average around 1,000 years. Estimates of isolation by distance are in agreement for different indicators of population structure. Problems of kinship bioassay are discussed.