Population structure in the Connecticut Valley. I. Marital migration

This study reports on an analysis of marital migration among 12 communities in the Connecticut River Valley of Massachusetts during the years 1790-1849. Genetic inferences are drawn, and the requisite assumptions considered. The effect of geographic distance on genetic kinship is predicted using Malécot's isolation-by-distance model. The resulting estimates are discussed in terms of geographic and historical factors. The configuration of communities as predicted by kinship values approximates closely their actual geographic locations. Estimated genetic heterogeneity was low for the historical Connecticut Valley population, and community isolation breaks down rapidly over time. The region thus assumes its place among a number of sedentary, agricultural populations for which the isolation-by-distance model provides an adequate representation. A regression analysis which includes variables in addition to distance indicates that historical and economic factors contribute some additional explanatory power to the distribution of mating frequencies.     

Isonymous structure in the white population of Córdoba, Argentina, in 1813

Surnames analysis is useful for populations in which only written documents remain, as is the case for historical populations. In Córdoba province, Argentina, census records contain nominal data of inhabitants, including information on sex, age, ethnosocial category, civil status, occupation, place of birth, and residence, that can be analyzed using surnames. Relationship indicators within and among ecclesiastic units in Córdoba were estimated by isonymy for the adult white population registered in the 1813 census. The Rii, Rij, and R(ST) coefficients and the surname abundance indicator (a) were calculated. Lasker's distances among categories of population units were used to cluster the 16 provincial population categories. Gradients for kinship within population and for surname diversity were in agreement with the principal areas and waves of original settlement in the province. The main population clusters reflect those areas, whereas minor clusters coincide with the network of roads existing in the territory by 1813. The structure of the white population in Córdoba province was determined by the geographic location of the original waves of settlement, and it followed a pattern of relationships conditioned by the routes connecting population units in the Colonial period.     

Genetic structure of the human population in the Po delta

The genetic structure of the population of Ferrara Province in the Po delta in Italy was investigated using chi 2 analysis, kinship analysis, analysis of correspondences, and geographical mapping of principal components of gene frequencies. chi 2 Analysis tests for Hardy-Weinberg equilibrium and for heterogeneity of gene and phenotype frequencies; kinship analysis tests for association between indicators of genetic and geographic proximity; analysis of correspondences relates localities and genetic systems in an eigenvectorial space; and geographic mapping displays the principal components of gene frequencies in the real space. In 1,364 adults in 26 residential units, seven presumably neutral isoenzyme systems were typed; ACP1 ESD, GLO I, GPT, PGD, PGM1 and PGP. It was found that average kinship for these neutral systems is correlated with geographic distance in this small area, but not as strongly as kinship for beta-thalassemia. A north-south gradient was observed for ESD. Analysis of correspondences indicated GPT, PGM1, and GLO I as the systems contributing most to differentiation within the province. The maps obtained from principal components of gene frequencies were consistent with the migrational history of the area.     

Contribución al conocimiento de los líquenes epifíticos del Valle de Sanabria (Zamora,España)

A catalogue of epiphytic lichens from the Sanabria valley (Zamora) is presented in this study. A total of 145 taxa are reported. According to our data, 137 taxa are new records for Zamora Province. For each species, ecological and chorological remarks are included. Chaenotheca furfuracea, Chromatochlamys muscorum, Cladina arbuscula subsp. mitis, Degelia atlantica, Julella lactea, Mycobilimbia hypnorum, Nephroma parile, Pannaria ignobilis, Pannaria pezizoides, Peltigera britannica, P. hymenina, Pertusaria ophthalmiza, Rinodina archaea, R. conradii, Thelenella modesta and Xylographa abietina are specially considered, due to their chorological implications in the Iberian Peninsula. We highlight the area “arroyo de las Truchas”, in Cobreros, because of the particularly wide diversity of epiphytic lichens.     

Phytoplankton structure and dynamics in Lake Sanabria and Valparaíso reservoir (NW Spain)

The aim of this work is to compare the composition and seasonality of the phytoplankton population in a natural oligotrophic lake (Lake Sanabria) and a mesotrophic reservoir (Valparaíso). Both ecosystems are located on the Tera river course (NW Spain), which runs along an area of ancient metamorphic and plutonic rocks. Some physical and chemical parameters, chlorophyll a and phytoplankton biovolume were studied from monthly samples collected at different depths during the periods 1987–1989 (Lake Sanabria) and 1991–1992 (Valparaíso). Phytoplankton biovolume and chlorophyll a concentration were about five times higher in Valparaíso than in Lake Sanabria. Species composition (and main phytoplankton groups) were different. Valparaíso was highly dominated by diatoms and Lake Sanabria by cryptophytes and small chlorophytes. In spite of the fact that both sites were nitrogen limited, heterocystous cyanophytes (Anabaena sp.) were detected only in Valparaíso. The relationships between phytoplankton structure and trophic level, hydrological conditions and nitrate content are discussed.     

Genetic structure of La Cabrera, Spain, from surnames and migration matrices

The genetic structure of La Cabrera (province of Léon, Spain), a highly isolated and inbred population (alpha3 = 0.00482), is analyzed by applying multivariate methods (nonmetric multidimensional scaling, Mantel test, Monmonier's algorithm) to different biodemographic data sets. Isonymy, parent-offspring migration (total, males, females), and marital migration matrices were obtained from 5,714 marriages recorded in 37 parishes (clustered in 4 municipalities) between 1880 and 1989. The aim of the study is to investigate the relationships between the genetic and geographic structures of the area. Endemicity values (diagonal of parent-offspring migration matrices), calculated for both sexes at two hierarchical levels (parishes and municipalities), show that female mobility follows the virilocal migration model at the higher (municipalities) level and the uxorilocal model at the parish level. Analysis of isonymy and parent-offspring migration matrices shows high correspondence between the genetic structure and geographic location of the parishes. In fact, the main reproductive barriers, constructed using Monmonier's algorithm, generally coincide with geographic barriers, highlighting increasing isolation patterns from northwest to southeast. Moreover, the analysis of isonymous relationships, which are influenced by earlier population movements, identifies three parishes whose outlier positions are explained by historical-cultural or geographic reasons. The positive and highly significant values (0.32 < or = r < or = 0.51;p < or = 0.001) given by the Mantel tests underline the dependence of the genetic structure on geographic distance. In confirmation of the endemicity results, the lowest correlation value (r = 0.32) is given by the female migration matrix. When the outlier parishes are omitted from the analysis, the correlation between isonymy and geographic distance increases from 0.35 to 0.46, and the values from the other migration matrices remain unchanged. In conclusion, the combination of different data sets and methods allows a wider and more coherent reconstruction of the historical changes in the genetic structure of the La Cabrera population.     

Geographic, demographic and inbreeding patterns in a Basque mountainous region of Guipuzcoa

The Goierri, a mountain region within the Basque Hills of Guipúzcoa, includes one of the most culturally controlled autochthonous populations within the Basque area, mainly from linguistic point of view. The effects of geography and demographic changes (1862–1995) on consanguinity variables over its 21 Municipalities have been investigated. Rates of consanguineous marriages and mean inbreeding levels recorded in some of the southern villages can be considered high but, average values for the entire region were lowered due to the early industrialization of the province. In spite of that, consanguinity in the study area has been, for a long time, a prevailing and conspicuous phenomenon when compared to the other Guipúzcoa regions. The impact of marriages between first cousins from immigrant groups on the regional inbreeding levels represents an interesting result as well. Geographic and demographic factors seem to be related both to the extent of marriages as well as to the number of potential mates within populations, which, in turn, are associated with mean inbreeding levels. Altitude seems to show weak relationship with population distribution and population consanguinity variables. Nevertheless, levels of endogamy appear positively correlated with consanguinity rates and mean inbreeding coefficient and, inversely related-but not statistically significant- to mean village sizes. First cousin marriages yield the highest levels of exogamy and exogamous M22 marriages were mostly concentrated within short (1–10 km) and long-range marital distances (>50 km). The aveaage values of Goierri have been compared with a consanguinity data set of some selected Spanish mountain populations taken from the literature. One of the main results is that geographic and demographic variables are poorly correlated with the most important inbreeding parameters. However, different clusters of populations can be observed with specific characteristics for each of them, not highly correlated with geography.     

Fine-Scale Genetic Structure in the United Arab Emirates Reflects Endogamous and Consanguineous Culture,Population History,and Geography

The indigenous population of the United Arab Emirates (UAE) has a unique demographic and cultural history. Its tradition of endogamy and consanguinity is expected to produce genetic homogeneity and partitioning of gene pools while population movements and intercontinental trade are likely to have contributed to genetic diversity. Emiratis and neighboring populations of the Middle East have been underrepresented in the population genetics literature with few studies covering the broader genetic history of the Arabian Peninsula. Here, we genotyped 1,198 individuals from the seven Emirates using 1.7 million markers and by employing haplotype-based algorithms and admixture analyses, we reveal the fine-scale genetic structure of the Emirati population. Shared ancestry and gene flow with neighboring populations display their unique geographic position while increased intra- versus inter-Emirati kinship and sharing of uniparental haplogroups, reflect the endogamous and consanguineous cultural traditions of the Emirates and their tribes.     

EXAMINATION OF POPULATION STRUCTURE IN RED-COCKADED WOODPECKERS USING DNA PROFILES

The degree to which DNA similarity is related to kinship and population structure in natural populations was investigated for a small population of cooperatively-breeding Red-cockaded Woodpeckers (Picoides borealis) in the western Piedmont region of South Carolina. An independent pedigree was established from records of color-banded individuals. Results of DNA profiles were then examined relative to this pedigree. DNA similarity among unrelated woodpeckers averaged 0.55 ± 0.01 (SE). The mean number of DNA bands scored and similarity did not significantly differ between founders and the current population. Examination of parentage in 10 families indicated that multiple paternity did not occur when band by band comparisons or similarity values were compared among parents, helpers, and offspring. Thus, Red-cockaded Woodpeckers were monogamous in this population. DNA similarity among all individuals ranged from 0.32-0.78. Distribution of these similarity values by kinship resulted in some overlap with other kin values. Therefore, specific similarity values could not be assigned a kinship value without knowledge of the pedigree. However, least-squares linear regression indicated that similarity was significantly related to kinship (P < 0.05). These results indicate that use of DNA profiles may be important in quantifying population structure, however, they must be used in conjunction with a known pedigree before any assessment of kinship among individuals is made. Band by band comparisons remain a viable technique for examination of parentage when all putative parents have been sampled.     

Comparison of sexual compatibility in crosses between the southern and northern populations of the cabbage beetle Colaphellus bowringi

It is widely accepted that the genetic divergence and reproductive incompat- ibility between closely related species and/or populations is often viewed as an important step toward speciation. In this study, sexual compatibility in crosses between the southern XS population and the northern TA population of the polyandrous cabbage beetle Co- laphellus bowringi was investigated by testing their mating preferences, mating latency, copulation duration, and reproductive performances of post-mating. In choice mating ex- periments, the percentages ofmatings were significantly higher in intra-population crosses than in inter-population crosses. Both isolation index （/） and index of pair sexual isolation （/PSi） indicated partial mating incompatibility or assortative mating in crosses between the two different geographical populations. In single pair mating experiments, XS females in inter-population crosses mated significantly later and copulated significantly shorter than those in intra-population crosses. However, TA females in inter-population crosses mated significantly earlier and copulated longer than those in intra-population crosses, suggesting that larger XS males may enhance heterotypic mating. The lifetime fecundity was highest in XS homotypic matings, lowest in TA homotypic matings, and intermedi- ate in heterotypic rnatings between their parents. The inter-population crosses resulted in significantly lower egg hatching rate and shorter female longevity than intra-population crosses. These results demonstrated that there exist some incompatibilities in premating, postmating-prezygotic, and postzygotic stages between the southern XS population and northern TA population of the cabbage beetle Colaphellus bowringi.     

Bighorn Sheep Genetic Structure in Wyoming Reflects Geography and Management

Aligning wildlife management boundaries with accurate biological units promotes effective conservation and management practices that reflect ecological and evolutionary processes. Neutral genetic markers allow for quantitative delineation of population structure without a priori assumptions or biases. In the United States, bighorn sheep (Ovis canadensis) are a charismatic component of Wyoming's biodiversity and a species that provides important viewing and hunting opportunities. Bighorn sheep abundances are relatively stable throughout Wyoming, and the species is managed by administrative units identified using expert knowledge, distribution and movement data, and geographic and administrative boundaries. We used a panel of 38 variable microsatellite loci and 512 base pairs of mitochondrial DNA sequence to identify the genetic structure throughout the state and in translocation source herds, quantify the extent of genetic diversity within each genetic cluster, and estimate the degree of gene flow among herds using blood and tissue samples collected 1989–2017. We identified genetic structure of Rocky Mountain bighorn sheep in the major mountain ranges of Wyoming, with strong support for ≥5 genetic clusters using microsatellite loci. These genetic clusters generally aligned with current management units, whereas mitochondrial data showed a more complex mosaic that was not geographically patterned. Genetic variation estimated from both markers was high within each herd and comparable among herds. The assignment of individuals reflected a combination of geographic isolation and translocation, which has been extensive. Our results provide a state-wide assessment of genetic diversity and structure that will enhance management by understanding the outcomes of translocation, identifying the source of unknown individuals, and parameterizing disease ecology models. © 2020 The Wildlife Society.     

Inbreeding in Finland

We have compiled data on the frequency of first-cousin marriages in Finland using royal dispensation records for the time period 1810-1872 and national population statistics for the time period 1878-1920. For the earlier period, 0.315% of Finland's marriages were contracted between first cousins (2,331 of 739,387). During the second time period, 0.174% of Finland's marriages took place between first cousins (1,325 of 761,976). These figures, which yield average kinship coefficients of 0.00020 and 0.00011, respectively, show that the level of inbreeding in Finland due to first-cousin marriage has been quite low. An analysis of individual parishes shows that first-cousin marriages are, on average, substantially less frequent than predicted by a random-mating model. In order to evaluate determinants of first-cousin marriage, several predictive variables have been examined: parish ethnic composition (proportion of Swedish and Finnish speakers), husband's occupation (graded into 6 socioeconomic levels), geographic distance between spouses' premarital residences, population density, parish endogamy, and urban vs. rural residence. Various logistic and linear regression models were analyzed in which consanguinity was the dependent variable. The best predictors of consanguinity were ethnic composition and occupation. The other variables were not in general significant predictors. These results show that many of the "mate availability" factors that would be predicted theoretically to account for consanguinity variation (population density, geographic isolation, urban vs. rural residence) do not. Instead, the best predictors of consanguinity at the first-cousin level are cultural factors such as ethnicity and occupation. Evaluation of cultural variables can provide a greatly enriched interpretation of complex biosocial phenomena such as inbreeding.     

CROSS ABILITY OF MIMULUS GUTTATUS IN RELATION TO COMPONENTS OF GENE FIXATION

The joint effects of parental gene fixation and consanguinity of mates upon the fitness of matings was examined in Mimulus guttatus. Plants from four populations were crossed at five levels of genetic relatedness, and five viability characters were scored in progeny. Parental gene fixation at 12 polymorphic allozyme loci was partitioned into local, subpopulation, and population components. A model is proposed wherein parental gene fixation influences distance-dependent crossing success. At a fixed locus, inbreeding is favored if natural selection caused allele fixation, or is disfavored if gene fixation was random. The distance between mates required to eliminate gene fixation depends upon patch size of fixation. When selective fixation and patch size differ among loci, an optimal crossing distance is possible. In M. guttatus, progeny viability generally decreased with greater relatedness between mates, but this decrease was often heterogeneous among populations. The highest pollen viability and the lowest seed set were found at an intermediate relatedness between mates. To determine whether parental gene fixation influences these crossing patterns, a type of mutational-load analysis was performed. Progeny fitness was regressed on parent F and fitness estimated at F = 1. This was done for each component of F, for a) crosses that maintain gene fixation and b) crosses that eliminate gene fixation. A multiplicative, composite measure of fitness indicates that, in M. guttatus, genes fixed during local or population differentiation favor outbreeding, while genes fixed during subpopulation differentiation favor inbreeding. This predicts that random mating within subpopulations confers highest progeny fitness, exclusive of between-population matings. However, predictions did not fit the observed patterns of crossing success very well, perhaps because gene fixation was relatively low or was not adequately measured at loci influencing fitness.     

Is the Central Valley of Costa Rica a genetic isolate?

In the last decade, the Costa Rican Central Valley population (CRCV), has received considerable scientific attention, attributed in part to a particularly interesting population structure. Two different and contradictory explanations have emerged: (1) An European-Amerindian-African admixed population, with some regional genetic heterocigosity and moderate degrees of consanguinity, similar to other Latin-American populations. (2) A genetic isolate, with a recent founder effect of European origin, genetically homogeneous, with a high intermarriage rate, and with a high degree of consanguinity. Extensive civil and religious documentation, since the settlement of the current population, allows wide genealogy and isonymy studies useful in the analysis of both hypotheses. This paper reviews temporal and spatial aspects of endogamy and consanguinity in the CRCV as a key to understand population history. The average inbreeding coefficients (a) between 1860 and 1969 show a general decrease within time. The consanguinity in the CRCV population is not homogeneous, and it is related to a variable geographic pattern. Results indicate that the endogamy frequencies are high but in general it was not correlated with a values. The general tendency shows a consanguinity decrease in time, and from rural to urban communities, repeating the tendencies observed in other countries with the same degree of development, and follows the general Western World tendency. Few human areas or communities in the world can be considered true genetic isolates. As shown, during last century, the CRCV population has had consanguinity values that definitively do not match those of true genetic isolates. A clear knowledge of the Costa Rican population genetic structure is needed to explain the origin of genetic diseases and its implications to the health system.     

Estimation of inbreeding from ecclesiastical dispensations: application of three procedures to a Spanish case

The inbreeding coefficient of a population, estimated from ecclesiastical Roman Catholic dispensations, results from the relative contribution of different degrees of relationships (uncle-niece, first cousin, etc.). The interpopulation comparisons of consanguinity patterns may be obscured by the fact that in 1918 the Roman Catholic Church norm regulating the closest marriageable kinship was modified, limiting the application for an ecclesiastical dispensation to relatives of third degree (second cousins) or closer. Depending on the length of the period before or after the change of regulation, coefficients and rates may differ. Deviation of frequencies for multiple marriages may also occur. The aim of the present paper is to determine how the chosen procedure based on ecclesiastical dispensations may affect results, regarding the inbreeding coefficient, the consanguinity rate, the structure of consanguinity and the close/remote kinship ratio. As a sample case, information from the Gredos mountain range (central Spain) has been used.     

Population structure in the Connecticut Valley: II. A comparison of multidimensional scaling solutions of migration matrices and isonymy

In a previous paper (Swedlund et al., 1984) we have described the population structure of the historical Connecticut River Valley of Massachusetts in terms of matrimonial migration matrices. Using procedures described by Morton (1973), Harpending and Jenkins (1974), Jorde (1980), and others the exchanges between subdivisions which make up the matrices are made column stochastic and analyzed to predict genetic kinship. Subsequently the kinship estimates within and between subdivisions can be interpreted as genetic covariance and compared to the actual geographic distances between the respective subdivisions using a principal components analysis. In the present paper we extend these results by applying nonmetric multidimensional scaling to the migration matrices, and to isonymy matrices based on the same communities. We demonstrate that the multidimensional scaling configurations of marital migration represent the actual geographic relationships between the communities quite effectively for this particular case study from historical Massachusetts. Moreover, we argue that while these migration data may provide good estimates of social and genetic exchange between the subdivisions, surname analysis may also be informative of processes not revealed in the migration matrices alone.     

Population relationships by isonymy in frontier Pennsylvania.

Data from the 1800 US census were used to study relationships by isonymy among 7 civil subdivisions of Bedford County, Pennsylvania. Two analyses of the data were conducted. In the first analysis heads of household served as the unit of analysis. In the second analysis the total number of individuals in each household was used to correct for varying family sizes. All measures of internal differentiation were approximately doubled when the complete population numbers were used. The head-of-household analysis produced FST and RST values of 0.0012 and 0.0007, respectively; the complete population analysis yielded 0.0021 for FST and 0.0015 for RST. Interpopulation a priori kinship estimations were similar using both methods. Conditional kinship estimations varied more, with almost all values negative, but the head-of-household estimates were less negative. Multidimensional scaling of isonymy values coincided fairly well with actual geographic relationships, but a Mantel test revealed no significant relationship between geographic distances and isonymy, and isolation by distance values indicated a low relationship between the 2 measures. The population of the county was heterogeneous, with low kinship between its constituent communities. This appears to be a result of kin-structured long-distance migration rather than of local processes. The head-of-household values are more comparable with other studies and more representative of population relationships; complete population values exaggerate heterogeneity because of random fluctuations in household size.     

Ethnicity and biodemographic structure in the Arbëreshe of the province of Cosenza, southern Italy, in the XIX century

Cultural and environmental factors interact in determining the genetic structure of human populations. Bio-demographic investigations of ethnic minorities are able to disentangle the influences that these two components have on the evolution of the genetic structure of a population. The ethnic minority of the Arb?reshe of the province of Cosenza (Calabria, southern Italy) is analyzed in this paper and its bio-demographic structure in the early 1800s is compared with that of neighboring Italian populations. The data derive from surnames recorded in the birth registers of the 19 Arbdreshe municipalities of the province of Cosenza and in 5 non-Arb?reshe municipalities of the same province. Isonymy and repeated pairs of surnames are used to analyze the bio-demographic structure of these populations, while analysis of isonymic relationships is used to investigate the variability between populations. Higher values of marital isonymy and subdivision into subpopulations characterize the Arb?reshe populations with respect to their non-Arb?reshe neighbors. However, the high range of variability of these parameters suggests a strong influence of geographic location on the marriage pattern of each community. At the same time, cultural differences linked to group identity had a strong impact in limiting marriage exchanges between the different ethnic groups living in the province of Cosenza in the early 1800s. In fact, the analysis of isonymic relationships demonstrates that geographic location shaped kinship patterns among the Arbereshe communities, but it also shows that the non-Arb?reshe neighbors formed a clearly separate reproductive cluster.     

Inbreeding patterns in La Cabrera, Spain: dispensations, multiple consanguinity analysis, and isonymy

Marital structure and inbreeding coefficients were analyzed in La Cabrera, an isolated mountain region in northwestern Spain. A total of 5,714 marriages were celebrated from 1880 to 1989 in the 37 parishes of the area. The total frequency of consanguineous marriages (up to the fourth degree) is 23.05%; multiple consanguineous marriages are remarkably common, reaching 5.43% of the total. The first cousin/second cousin ratio (referred to as kinship-type frequencies) is 0.43. The inbreeding values are the highest recorded in Spain and in Europe: alpha3 is 4.82 x 10(-3) for the whole period and alpha4 is 6.78 x 10(-3) for 1880--1919. The temporal trend of inbreeding shows high values (alpha3 > 4.5 x 10(-3)) for a particularly long period (1900--1959) and a rapid decline from 1960 onward. This historical inbreeding trend is clearly related to changes in population size. The frequencies of multiple consanguineous marriages and the analysis of isonymy show that the inbreeding structure is related to geographic and demographic factors. Comparing the results at two hierarchical levels (La Cabrera as a whole and the 37 parishes individually), we conclude that the inbreeding values are affected by internal geographic subdivision of the population (Wahlund effect). Social and cultural factors, such as avoidance of or preference for consanguineous marriages, are less important but depend on the kinship type involved.     

Mitochondrial DNA patterns in the Iberian Northern plateau: Population dynamics and substructure of the Zamora province

Several studies have shown the importance of recent events in the configuration of the genetic landscape of a specific territory. In this context, due to the phenomena of repopulation and demographic fluctuations that took place in recent centuries, the Iberian Northern plateau is a very interesting case study. The main aim of this work is to check if recent population movements together with existing boundaries (geographical and administrative) have influenced the current genetic composition of the area. To accomplish this general purpose, mitochondrial DNA variations of 214 individuals from a population located in the Western region of the Iberian Northern plateau (the province of Zamora) were analyzed. Results showed a typical Western European mitochondrial DNA haplogroup composition. However, unexpected high frequencies of U5, HV0, and L haplogroups were found in some regions. The analyses of microdifferentiation showed that there are differences between regions, but no geographic substructure organization can be noticed. It can be stated that the differences observed in the genetic pool of the sampled area at regional level results from the mixture of different populations carrying new lineages into this area at different points in history. Am J Phys Anthropol 142:531–539, 2010. © 2010 Wiley‐Liss, Inc.