scholarly journals History of Click-Speaking Populations of Africa Inferred from mtDNA and Y Chromosome Genetic Variation

2007 ◽  
Vol 24 (10) ◽  
pp. 2180-2195 ◽  
Author(s):  
S. A. Tishkoff ◽  
M. K. Gonder ◽  
B. M. Henn ◽  
H. Mortensen ◽  
A. Knight ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Y Chromosome ◽  
History Of

Population Genetics ofCaenorhabditis elegans: The Paradox of Low Polymorphism in a Widespread Species

Genetics ◽  
2003 ◽  
Vol 163 (1) ◽  
pp. 147-157 ◽  
Author(s):  
Arjun Sivasundar ◽  
Jody Hey
Keyword(s):  
Genetic Variation ◽  
Microsatellite Loci ◽  
Population Expansion ◽  
Widespread Species ◽  
C Elegans ◽  
Model Research ◽  
The World ◽  
Natural Isolates ◽  
History Of ◽  
Low Levels

AbstractCaenorhabditis elegans has become one of the most widely used model research organisms, yet we have little information on evolutionary processes and recent evolutionary history of this widespread species. We examined patterns of variation at 20 microsatellite loci in a sample of 23 natural isolates of C. elegans from various parts of the world. One-half of the loci were monomorphic among all strains, and overall genetic variation at microsatellite loci was low, relative to most other species. Some population structure was detected, but there was no association between the genetic and geographic distances among different natural isolates. Thus, despite the nearly worldwide occurrence of C. elegans, little evidence was found for local adaptation in strains derived from different parts of the world. The low levels of genetic variation within and among populations suggest that recent colonization and population expansion might have occurred. However, the patterns of variation are not consistent with population expansion. A possible explanation for the observed patterns is the action of background selection to reduce polymorphism, coupled with ongoing gene flow among populations worldwide.

Y-chromosome genetic variation in Rio De Janeiro population

2006 ◽  
Vol 18 (6) ◽  
pp. 829-837 ◽  
Author(s):  
Dayse A. Silva ◽  
Elizeu Carvalho ◽  
Guilherme Costa ◽  
Lígia Tavares ◽  
António Amorim ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Y Chromosome ◽  
Rio De Janeiro

Genetic variation in allozymes of western larch

1986 ◽  
Vol 16 (5) ◽  
pp. 1013-1018 ◽  
Author(s):  
Lauren Fins ◽  
Lisa W. Seeb
Keyword(s):  
Genetic Variation ◽  
Genetic Drift ◽  
Fire History ◽  
Glacial History ◽  
Geographic Proximity ◽  
Electrophoretic Variation ◽  
Inland Empire ◽  
Genetic History ◽  
Expected Heterozygosity ◽  
History Of

Seed samples from 19 stands of Larixoccidentalis Nutt. were analyzed for electrophoretic variation at 23 loci. Because sample sizes consisted of only 9 or 10 trees per stand (18–20 alleles per locus per stand), samples were grouped by geographic proximity into four larger samples. For all measures of variation, this species scored lower than most, but within the range observed for other western conifers. Most of the variation was found within rather than between the population groups. The single southern sample appeared to be genetically distinct from the others. Although some variation was observed between individual stand samples in expected heterozygosity, the consistently low values for all samples suggest that genetic drift has played a major role in the genetic history of the species in the Inland Empire, both through its glacial history in postulated refugia and through fire history in recent times.

scholarly journals Genetic variation in native and farmed populations of Tambaqui (Colossoma macropomum) in the Brazilian Amazon: regional discrepancies in farming systems

2013 ◽  
Vol 85 (4) ◽  
pp. 1439-1447 ◽  
Author(s):  
Jonas Aguiar ◽  
Horacio Schneider ◽  
Fatima Gomes ◽  
Jeferson Carneiro ◽  
Simoni Santos ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Dna Sequences ◽  
Amazon Basin ◽  
Farming Systems ◽  
Wild Populations ◽  
The West ◽  
Colossoma Macropomum ◽  
Breeding Stock ◽  
History Of

The tambaqui, Colossoma macropomum, is the most popular fish species used for aquaculture in Brazil but there is no study comparing genetic variation among native and farmed populations of this species. In the present study, we analyzed DNA sequences of the mitochondrial DNA to evaluate the genetic diversity among two wild populations, a fry-producing breeding stock, and a sample of fish farm stocks, all from the region of Santarém, in the west of the Brazilian state of Pará. Similar levels of genetic diversity were found in all the samples and surprisingly the breeding stock showed expressive representation of the genetic diversity registered on wild populations. These results contrast considerably with those of the previous study of farmed stocks in the states of Amapá, Pará, Piauí, and Rondônia, which recorded only two haplotypes, indicating a long history of endogamy in the breeding stocks used to produce fry. The results of the two studies show two distinct scenarios of tambaqui farming in the Amazon basin, which must be better evaluated in order to guarantee the successful expansion of this activity in the region, and the rest of Brazil, given that the tambaqui and its hybrids are now farmed throughout the country.

scholarly journals The role of matrilineality in shaping patterns of Y chromosome and mtDNA sequence variation in southwestern Angola

2018 ◽  
Author(s):  
Sandra Oliveira ◽  
Alexander Hübner ◽  
Anne-Maria Fehn ◽  
Teresa Aço ◽  
Fernanda Lages ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Sequence Data ◽  
Population History ◽  
Female Population ◽  
Bantu Languages ◽  
Mtdna Sequence ◽  
Population Sizes ◽  
Group Variation ◽  
History Of ◽  
Previous Demonstration

AbstractSouthwestern Angola is a region characterized by contact between indigenous foragers and incoming food-producers, involving genetic and cultural exchanges between peoples speaking Kx’a, Khoe-Kwadi and Bantu languages. Although present-day Bantu-speakers share a patrilocal residence pattern and matrilineal principle of clan and group membership, a highly stratified social setting divides dominant pastoralists from marginalized groups that subsist on alternative strategies and have previously been though to have pre-Bantu origins. Here, we compare new high-resolution sequence data from 2.3 Mb of the non-recombining Y chromosome (NRY) from 170 individuals with previously reported mitochondrial genomes (mtDNA), to investigate the population history of seven representative southwestern Angolan groups (Himba, Kuvale, Kwisi, Kwepe, Twa, Tjimba, !Xun) and to study the causes and consequences of sex-biased processes in their genetic variation. We found no clear link between the formerly Kwadi-speaking Kwepe and pre-Bantu eastern African migrants, and no pre-Bantu NRY lineages among Bantu-speaking groups, except for small amounts of “Khoisan” introgression. We therefore propose that irrespective of their subsistence strategies, all Bantu-speaking groups of the area share a male Bantu origin. Additionally, we show that in Bantu-speaking groups, the levels of among-group and between-group variation are higher for mtDNA than for NRY. These results, together with our previous demonstration that the matriclanic systems of southwestern Angolan Bantu groups are genealogically consistent, suggest that matrilineality strongly enhances both female population sizes and interpopulation mtDNA variation.

scholarly journals Genetic variation in alcohol dehydrogenase is associated with neurocognition in men with HIV and history of alcohol use disorder: preliminary findings

2020 ◽  
Vol 26 (2) ◽  
pp. 214-225 ◽  
Author(s):  
Rowan Saloner ◽  
Emily W. Paolillo ◽  
Maulika Kohli ◽  
Sarah S. Murray ◽  
David J. Moore ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Alcohol Use ◽  
Alcohol Dehydrogenase ◽  
Alcohol Use Disorder ◽  
History Of

scholarly journals Tracing the genetic history of the ‘Cañaris’ from Ecuador and Peru using uniparental DNA markers

BMC Genomics ◽  
2020 ◽  
Vol 21 (S7) ◽  
Author(s):  
José R. Sandoval ◽  
Daniela R. Lacerda ◽  
Marilza M. S. Jota ◽  
Paulo Robles-Ruiz ◽  
Pierina Danos ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Y Chromosome ◽  
Genetic Relationship ◽  
Tandem Repeats ◽  
Geographic Proximity ◽  
Lake Titicaca ◽  
Control Region Sequences ◽  
History Of ◽  
Historical Question ◽  
Close Genetic Relationship

Abstract Background According to history, in the pre-Hispanic period, during the conquest and Inka expansion in Ecuador, many Andean families of the Cañar region would have been displaced to several places of Tawantinsuyu, including Kañaris, a Quechua-speaking community located at the highlands of the Province of Ferreñafe, Lambayeque (Peru). Other families were probably taken from the Central Andes to a place close to Kañaris, named Inkawasi. Evidence of this migration comes from the presence near the Kañaris–Inkawasi communities of a village, a former Inka camp, which persists until the present day. This scenario could explain these toponyms, but it is still controversial. To clarify this historical question, the study presented here focused on the inference of the genetic relationship between ‘Cañaris’ populations, particularly of Cañar and Ferreñafe, compared to other highland populations. We analysed native patrilineal Y chromosome haplotypes composed of 15 short tandem repeats, a set of SNPs, and maternal mitochondrial DNA haplotypes of control region sequences. Results After the genetic comparisons of local populations—three from Ecuador and seven from Peru—, Y chromosome analyses (n = 376) indicated that individuals from the Cañar region do not share Y haplotypes with the Kañaris, or even with those of the Inkawasi. However, some Y haplotypes of Ecuadorian ‘Cañaris’ were associated with haplotypes of the Peruvian populations of Cajamarca, Chivay (Arequipa), Cusco and Lake Titicaca, an observation that is congruent with colonial records. Within the Kañaris and Inkawasi communities there are at least five clans in which several individuals share haplotypes, indicating that they have recent common ancestors. Despite their relative isolation, most individuals of both communities are related to those of the Cajamarca and Chachapoyas in Peru, consistent with the spoken Quechua and their geographic proximity. With respect to mitochondrial DNA haplotypes (n = 379), with the exception of a shared haplotype of the D1 lineage between the Cañar and Kañaris, there are no genetic affinities. Conclusion Although there is no close genetic relationship between the Peruvian Kañaris (including Inkawasi) and Ecuadorian Cañar populations, our results showed some congruence with historical records.

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