Isonymy and population structure of Irish isolates during the 1890s

1982 ◽  
Vol 14 (2) ◽  
pp. 241-247 ◽  
Author(s):  
John H. Relethford
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Isolation By Distance ◽  
Breeding Population ◽  
Isolated Populations ◽  
Estimated Parameters ◽  
Distance Model ◽  
Local Breeding ◽  
And Migration ◽  
Close Fit

SummaryThe estimation of genetic similarity from correspondence of surnames (isonymy) allows investigation of historical population structure. This study uses surname data from seven isolates located along the west coast of Ireland during the 1890s to assess geographic and historic influences on population structure. Observed genetic variation among populations shows a close fit with the expected isolation by distance model, with estimated parameters of isolation and migration being similar to those obtained in other studies of isolated populations. Local genetic variation appears to be due primarily to the size of the local breeding population, with deviations being explained in terms of recent emigration.

scholarly journals Genetic diversity and population structure of the endangered endemic species Paeonia decomposita from China and implications for its conservation

2019 ◽  
Author(s):  
Shi-Quan Wang
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Genetic Distance ◽  
Significant Positive Correlation ◽  
Isolation By Distance ◽  
List Type ◽  
Positive Correlation ◽  
Conservation Measures ◽  
Distance Model

AbstractPaeonia decomposita, endemic to China, has important ornamental, medicinal and economic value and is regarded as a threatened endangered plant. The genetic diversity and structure have seldom been described. A conservation management plan is not currently available. In present study, 16 pairs of SSR primers were used to evaluate genetic diversity and population structure. A total of 122 alleles were obtained with a mean of 7.625 alleles per locus. The expected heterozygosity (He) varied from 0.043 to 0.901 (mean 0.492). Moderate genetic diversity (He=0.405) among populations were revealed, with Danba identified as the center of genetic diversity. Mantel tests revealed a significant positive correlation between geographic and genetic distance among populations (r=0.592, P=0.0001), demonstrating consistency with the isolation by distance model. Analysis of molecular variance (AMOVA) results indicated that the principal genetic variation existed within populations (73.48%) rather than among populations (26.52%). Bayesian structure analysis and principal coordinate analysis (PCoA) supported classification of the populations into three clusters. Based on the level of observed genetic diversity, three management unints were proposed as conservation measures. The results will be beneficial for the conservation and exploitation of the species, providing a theoretical basis for further research on its evolution and phylogeography.HightlightsGenetic diversity among populations was moderate in Paeonia decompositaThere is significant positive correlation between geographic and genetic distance among populations, consistent with the isolation by distance modelPrincipal genetic variation existed within populations rather than among populations.The populations divided into three clusters.Three management unints were proposed as conservation measures.

scholarly journals Effect of population structure and migration when investigating genetic continuity using ancient DNA

2016 ◽  
Author(s):  
NM Silva ◽  
S Kreutzer ◽  
C Papageorgopoulou ◽  
M Currat
Keyword(s):  
Population Structure ◽  
Ancient Dna ◽  
Isolated Populations ◽  
Hunter Gatherers ◽  
History Of ◽  
Genetic Continuity ◽  
Population Continuity ◽  
Local Hunter ◽  
And Migration ◽  
Genetic Pool

AbstractRecent advances in sequencing techniques provide means to access direct genetic snapshots from the past with ancient DNA data (aDNA) from diverse periods of human prehistory. Comparing samples taken in the same region but at different time periods may indicate if there is continuity in the peopling history of that area or if a large genetic input, such as an immigration wave, has occurred. Here we propose a new modeling approach for investigating population continuity using aDNA, including two fundamental elements in human evolution that were absent from previous methods: population structure and migration. The method also considers the extensive temporal and geographic heterogeneity commonly found in aDNA datasets. We compare our spatially-explicit approach to the previous non-spatial method and show that it is more conservative and thus suitable for testing population continuity, especially when small, isolated populations, such as prehistoric ones, are considered. Moreover, our approach also allows investigating partial population continuity and we apply it to a real dataset of ancient mitochondrial DNA. We estimate that 91% of the current genetic pool in central Europe entered the area with immigrant Neolithic farmers, but a genetic contribution of local hunter-gatherers as large as 83% cannot be entirely ruled out.

Allozyme Evidence of Genetic Differentiation Between Populations of Hediste Diversicolor (Polychaeta: Nereididae) from the Western Mediterranean

1996 ◽  
Vol 76 (3) ◽  
pp. 637-647 ◽  
Author(s):  
M. Abbiati ◽  
F. Maltagliati
Keyword(s):  
Genetic Differentiation ◽  
Isolation By Distance ◽  
Western Mediterranean ◽  
Allozyme Electrophoresis ◽  
Isolated Populations ◽  
Hediste Diversicolor ◽  
Dispersal Capacity ◽  
Two Samples ◽  
Distance Model ◽  
Limited Dispersal

The occurrence of genetic differentiation among western Mediterranean Hediste diversicolor (Polychaeta: Nereididae) populations was assessed by allozyme electrophoresis on cellulose acetate. Seventeen loci were analysed in four populations. The level of the genetic variability was markedly low (mean HL range: 0.014–0.034), but comparable to that of other brackish water nereidids. The values of Nei genetic distance index (D) confirm the existence of genetic differentiation between the geographically isolated populations at Venice, Elba, Navicelli and Serchio D range: 0.128–0.356). However, the two samples from Serchio and Navicelli, ~15 km apart, were not genetically different (D=0·00005). The level of genetic differentiation in H. diversicolor populations followed the isolation-by-distance model. Reduced gene flow among H. diversicolor populations may be explained by its limited dispersal capacity and the eco-physiological barriers that occur between different brackish habitats.

Population structure in two geographically sympatric and congeneric ectoparasites (Cimex adjunctus and Cimex lectularius) in the North American Great Lakes region

2017 ◽  
Vol 95 (12) ◽  
pp. 901-907 ◽  
Author(s):  
Benoit Talbot ◽  
Maarten J. Vonhof ◽  
Hugh G. Broders ◽  
M. Brock Fenton ◽  
Nusha Keyghobadi
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
Geographic Area ◽  
Abundant Species ◽  
Cimex Lectularius ◽  
Genetic Structuring ◽  
The North ◽  
Genetic Clusters

Subdivided populations can be described by different models of population structure that reflect population organization, dynamics, and connectivity. We used genetic data to investigate population structure in two geographically sympatric, congeneric species of generalist ectoparasites of warm-blooded animals. We characterized the spatial genetic structure of the eastern bat bug (Cimex adjunctus Barber, 1939), an understudied and fairly abundant species, using microsatellite markers at a spatial scale representing contemporary dispersal of the species. We found seven genetic clusters, global [Formula: see text] of 0.2, 33% of genetic variation among sites, and nonsignificant isolation-by-distance. We compared these results with the common bed bug (Cimex lectularius L., 1758), a closely related but conversely well-known species, in the same geographic area. We found stronger genetic structuring in C. lectularius than in C. adjunctus, with 11 genetic clusters, [Formula: see text] of 0.7, 57% of genetic variation among sites, and significant but weak isolation-by-distance (R2 = 0.09). These results suggest that while both species can be described as having classic metapopulation structure, C. adjunctus leans more towards a patchy population and C. lectularius leans more towards a nonequilibrium metapopulation. The difference in population structure between these species may be attributable to differences in movement potential and extinction–colonization dynamics.

scholarly journals A TEST OF SPATIAL AUTOCORRELATION ANALYSIS USING AN ISOLATION-BY-DISTANCE MODEL

Genetics ◽  
1983 ◽  
Vol 105 (1) ◽  
pp. 219-237
Author(s):  
Robert R Sokal ◽  
Daniel E Wartenberg
Keyword(s):  
Population Structure ◽  
Spatial Autocorrelation ◽  
Process Parameters ◽  
Gene Frequency ◽  
Isolation By Distance ◽  
Neighborhood Size ◽  
Spatial Autocorrelation Analysis ◽  
Autocorrelation Analysis ◽  
Natural Systems ◽  
Distance Model

ABSTRACT Using the isolation-by-distance model as an example, we have examined several assumptions of spatial autocorrelation analysis applied to gene frequency surfaces. Gene frequency surfaces generated by a simulation of Wright's isolation-by-distance model were shown to exhibit spatial autocorrelation, except in the panmictic case. Identical stochastic generating processes result in surfaces with characteristics that are functions of the process parameters, such as parental vagility and neighborhood size. Differences in these parameters are detectable as differences in spatial autocorrelations after only a few generations of the simulations. Separate realizations of processes with identical parameters yield similar spatial correlograms. We have examined the inferences about population structure that could have been made from these observations if they had been real, rather than simulated, populations. From such inferences, we could have drawn conclusions about the presence of selection, migration and drift in given natural systems.

scholarly journals Stable genetic structure and connectivity in pollution-adapted and nearby pollution-sensitive populations of Fundulus heteroclitus

2018 ◽  
Vol 5 (5) ◽  
pp. 171532 ◽  
Author(s):  
Joaquin C. B. Nunez ◽  
Leann M. Biancani ◽  
Patrick A. Flight ◽  
Diane E. Nacci ◽  
David M. Rand ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Fundulus Heteroclitus ◽  
Isolation By Distance ◽  
Spatial Scales ◽  
Purifying Selection ◽  
Spatial Distance ◽  
Estuarine Fish ◽  
Synonymous Mutations ◽  
Microsatellite Analyses

Populations of the non-migratory estuarine fish Fundulus heteroclitus inhabiting the heavily polluted New Bedford Harbour (NBH) estuary have shown inherited tolerance to local pollutants introduced to their habitats in the past 100 years. Here we examine two questions: (i) Is there pollution-driven selection on the mitochondrial genome across a fine geographical scale? and (ii) What is the pattern of migration among sites spanning a strong pollution gradient? Whole mitochondrial genomes were analysed for 133 F. heteroclitus from seven nearby collection sites: four sites along the NBH pollution cline (approx. 5 km distance), which had pollution-adapted fish, as well as one site adjacent to the pollution cline and two relatively unpolluted sites about 30 km away, which had pollution-sensitive fish. Additionally, we used microsatellite analyses to quantify genetic variation over three F. heteroclitus generations in both pollution-adapted and sensitive individuals collected from two sites at two different time points (1999/2000 and 2007/2008). Our results show no evidence for a selective sweep of mtDNA in the polluted sites. Moreover, mtDNA analyses revealed that both pollution-adapted and sensitive populations harbour similar levels of genetic diversity. We observed a high level of non-synonymous mutations in the most polluted site. This is probably associated with a reduction in N e and concomitant weakening of purifying selection, a demographic expansion following a pollution-related bottleneck or increased mutation rates. Our demographic analyses suggest that isolation by distance influences the distribution of mtDNA genetic variation between the pollution cline and the clean populations at broad spatial scales. At finer scales, population structure is patchy, and neither spatial distance, pollution concentration or pollution tolerance is a good predictor of mtDNA variation. Lastly, microsatellite analyses revealed stable population structure over the last decade.

Life-history characteristics and landscape attributes as drivers of genetic variation, gene flow, and fine-scale population structure in northern Dolly Varden (Salvelinus malma malma) in Canada

2015 ◽  
Vol 72 (10) ◽  
pp. 1477-1493 ◽  
Author(s):  
Les N. Harris ◽  
Robert Bajno ◽  
Colin P. Gallagher ◽  
Itsuro Koizumi ◽  
Lucy K. Johnson ◽  
...  
Keyword(s):  
Population Structure ◽  
Genetic Variation ◽  
Life History ◽  
Gene Flow ◽  
Isolation By Distance ◽  
Dolly Varden ◽  
Salvelinus Malma ◽  
Dolly Varden Salvelinus Malma ◽  
Northern Dolly Varden ◽  
Population Demographic

The northern Dolly Varden (Salvelinus malma malma) displays variable life-history types and occupies freshwater habitats with varying levels of connectivity. Here, we assayed microsatellite DNA variation in northern Dolly Varden from the western Canadian Arctic to resolve landscape and life-history variables driving variation in genetic diversity and population structure. Overall, genetic variation was highest in anadromous populations and lowest in those isolated above waterfalls, with stream-resident forms intermediate between the two. Anadromous and isolated populations were genetically divergent from each other, while no genetic differentiation was detectable between sympatric anadromous and stream-resident forms. Population structure was stable over 25 years, hierarchically organized, and conformed to an isolation-by-distance pattern, but stream-isolated forms often deviated from these patterns. Gene flow occurred primarily among Yukon North Slope populations and between sympatric anadromous and resident forms. These results were sex-dependent to some extent, but were influenced more by reproductive status and life history. Our study provides novel insights into the life history, population demographic, and habitat variables that shape the distribution of genetic variation and population structure in Arctic fluvial habitats while providing a spatial context for management and conservation.

scholarly journals Genetic Diversity and Population Structure of a Threatened African Tree Species,Milicia excelsa,Using Nuclear Microsatellites DNA Markers

2009 ◽  
Vol 2009 ◽  
pp. 1-8 ◽  
Author(s):  
Christine Ouinsavi ◽  
Nestor Sokpon ◽  
Damase P. Khasa
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Variation ◽  
Isolation By Distance ◽  
In Situ Conservation ◽  
Agroforestry Systems ◽  
Microsatellites Dna ◽  
Geographical Distances ◽  
Hardy Weinberg Equilibrium ◽  
Milicia Excelsa

To accurately estimate the genetic diversity and population structure for improved conservation planning ofMilicia excelsatree, 212 individuals from twelve population samples covering the species' range in Benin were surveyed at seven specific microsatellite DNA loci. All loci were variable, with the mean number of alleles per locus ranging from 5.86 to 7.69. Considerable genetic variability was detected for all populations at the seven loci (AR=4.60;HE=0.811). Moderate but statistically significant genetic differentiation was found among populations considering bothFST(0.112) andRST(0.342). All of the populations showed heterozygosity deficits in test of Hardy-Weinberg Equilibrium and significantly positiveFISvalues due to inbreeding occurring in the species. PairwiseFSTvalues were positively and significantly correlated with geographical distances (r=0.432;P=.007, Mantel's test) indicating that populations are differentiated by “isolation by distance.” Bayesian analysis of population structure showed division of the genetic variation into four clusters revealing the existence of heterogeneity in population genetic structure. Altogether, these results indicate that genetic variation inMilicia excelsais geographically structured. Information gained from this study also emphasized the need for in situ conservation of the relict populations and establishment of gene flow corridors through agroforestry systems for interconnecting these remnant populations.

scholarly journals Characterizing the genetic diversity of the Andean blueberry (Vaccinium floribundum Kunth.) across the Ecuadorian Highlands

2020 ◽  
Author(s):  
Pamela Vega-Polo ◽  
Maria M. Cobo ◽  
Andrea Argudo ◽  
Bernardo Gutierrez ◽  
Jennifer Rowntree ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Environmental Changes ◽  
Isolation By Distance ◽  
Anthropogenic Activities ◽  
Conservation Status ◽  
Ecological Factors ◽  
Andean Region ◽  
Key Factor ◽  
Distance Model

AbstractThe Ecuadorian páramo, a high altitude tundra-like ecosystem, is a unique source of various ecosystem services and distinct biodiversity. Anthropogenic activities are associated with its fragmentation, which alters ecological factors and directly threatens resident species. Vaccinium floribundum Kunth., commonly known as Andean blueberry or mortiño, is a wild shrub endemic to the Andean region and highly valued in Ecuador for its berries, which are widely used in food preparations and hold an important cultural value. Since it is a wild species, mortiño could be vulnerable to environmental changes, resulting in a reduction of the size and distribution of its populations. To evaluate the extent of these effects on the mortiño populations, we assessed the genetic diversity and population structure of the species along the Ecuadorian highlands. We designed and developed a set of 30 homologous SSR markers and used 16 of these to characterize 100 mortiño individuals from 27 collection sites. Our results revealed a high degree of genetic diversity (HE=0.73) for the Ecuadorian mortiño, and a population structure analyses suggested the existence of distinct genetic clusters present in the northern, central and southern highlands. A fourth, clearly differentiated cluster was also found and included individuals from locations at higher elevations. We suggest that the population structure of the species could be explained by an isolation-by-distance model and can be associated to the geological history of the Andean region. Our results suggest that elevation could also be a key factor in the differentiation of mortiño populations. This study provides an extensive overview of the species across its distribution range in Ecuador, contributing to a better understanding of its conservation status. These results can assist the development of conservation programs for this valuable biological and cultural resource and for the páramo ecosystems as a whole.

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