Relationships Between Wright's FST and FIS Statistics in a Context of Wahlund Effect

Zhivotovsky, Lev A.

doi:10.1093/jhered/esv019

Cited by 23 publications

(9 citation statements)

References 4 publications

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“…the herds exhibited little genetic differentiation (F ST values in the range from 0.01 to 0.09), the Wahlund effect is an unlikely explanation for the observed negative relationship between inbreeding and H O . Furthermore, in contrast to the positive correlation between interlocus f st and f is that is theoretically expected as a result of the Wahlund effect [20,21], here a low negative correlation (r = -0.063, p<0.001) was estimated (results not shown). Finally, cryptic relatedness i.e.…”

Section: Plos Onecontrasting

confidence: 80%

Clustering patterns mirror the geographical distribution and genetic history of Lemnos and Lesvos sheep populations

et al. 2021

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Elucidating the genetic variation and structure of Lemnos and Lesvos sheep is critical for maintaining local genetic diversity, ecosystem integrity and resilience of local food production of the two North Aegean islands. In the present study, we explored genetic diversity and differentiation as well as population structure of the Lemnos and Lesvos sheep. Furthermore, we sought to identify a small panel of markers with the highest discriminatory power to assign animals across islands. A total number of n = 424 (n = 307, Lemnos and n = 117, Lesvos) ewes, sampled from n = 24 herds dispersed at different geographic regions on the two islands, were genotyped with the 50K SNP array. Mean observed heterozygosity was higher (but not statistically significantly different) in Lesvos than in Lemnos population (0.384 vs. 0.377) while inbreeding levels were higher in Lemnos than Lesvos herds (0.065 vs. 0.031). Results of principal components along with that of admixture analysis and estimated genetic distances revealed genetic clusters corresponding to Lesvos and Lemnos origin and the existence of infrastructure within islands that were associated with geographical isolation and genetic history of the studied populations. In particular, genetic analyses highlighted three geographically isolated herds in Lemnos that are located at mountainous areas of the island and are characterized as representatives of the local sheep by historic data and reports. Admixture analysis also showed a shared genetic background between Lemnos and Lesvos sheep attributable to past gene flow. Little overall genetic differentiation was detected between the two island sheep populations, while 150 discriminatory SNPs could accurately assign animals to their origin. Present results are comparable with those reported in the worldwide sheep breeds, suggesting geography related genetic patterns across and within islands and the existence of the local Lemnos sheep.

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Section: Plos Onecontrasting

confidence: 80%

Clustering patterns mirror the geographical distribution and genetic history of Lemnos and Lesvos sheep populations

et al. 2021

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“…For instance, heterozygote deficits could be due to the presence of null alleles 45 or an artificial Wahlund effect caused by non-random sampling of multiple distinct genetic groups of individuals. 70 Although possible, it is unlikely that null alleles could be responsible for the observed heterozygote deficit because there is evidence of significant deviations from HWE in some populations in the overall (Table 1) or per-locus F IS estimates (Table S3 of Supplemental Appendix 1) that had no indication of null alleles in the Micro-Checker analysis in this study (Table S2 of Supplemental Appendix 1), or in past studies. 38 Another possibility is that these population samples were non-random, and included a biased sample from multiple distinct groups (i.e., genetic clusters or families of closely related individuals).…”

Section: Discussionmentioning

confidence: 64%

Genetic Differentiation of Glossina pallidipes Tsetse Flies in Southern Kenya

Okeyo

Saarman

Bateta

et al. 2018

The American Journal of Tropical Medicine and Hygiene

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The tsetse fly , the major vector of the parasite that causes animal African trypanosomiasis in Kenya, has been subject to intense control measures with only limited success. The population dynamics and dispersal patterns that underlie limited success in vector control campaigns remain unresolved, and knowledge on genetic connectivity can provide insights, and thereby improve control and monitoring efforts. We therefore investigated the population structure and estimated migration and demographic parameters in using genotypic data from 11 microsatellite loci scored in 250 tsetse flies collected from eight localities in Kenya. Clustering analysis identified two genetically distinct eastern and western clusters (mean between-cluster = 0.202) separated by the Great Rift Valley. We also found evidence of admixture and migration between the eastern and western clusters, isolation by distance, and a widespread signal of inbreeding. We detected differences in population dynamics and dispersal patterns between the western and eastern clusters. These included lower genetic diversity (allelic richness; 7.48 versus 10.99), higher relatedness (percent related individuals; 21.4% versus 9.1%), and greater genetic differentiation (mean within-cluster ; 0.183 versus 0.018) in the western than the eastern cluster. Findings are consistent with the presence of smaller, less well-connected populations in Western relative to eastern Kenya. These data suggest that recent anthropogenic influences such as land use changes and vector control programs have influenced population dynamics in in Kenya, and that vector control efforts should include some region-specific strategies to effectively control this disease vector.

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“…Further support for substructure is the presence of a Wahlund effect. This is when the subdivision of genetically distinct demes causes a deviation from HWE at the population level resulting in the appearance of a deficit of heterozygotes [42–45]. Across Zambia, mean H O versus H E shows a heterozygote deficiency at the population level, however, when separated into sub-populations, mean values no longer deviate from HWE (Table 4).…”

Section: Discussionmentioning

confidence: 99%

Genetic analysis of African lions (Panthera leo) in Zambia support movement across anthropogenic and geographical barriers

2019

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The Luangwa Valley in eastern Zambia is a transverse offshoot of the Great Rift Valley system. This region appears to have an isolating effect as evidenced by suspected endemic subspecies, such as the Cookson’s wildebeest and Thornicroft’s giraffe. Recent mitochondrial DNA studies demonstrated that African lions in Zambia consist of two highly diverse eastern and western sub-populations. Herein, we report nuclear and mitochondrial DNA results from 409 lions that support this population substructure across Zambia but proposes only partial isolation of the Luangwa Valley with more movement between the populations than previously thought. Population assignment analysis identifies two populations with little evidence of admixture assigning lions to either the eastern or western sub-populations. A high occurrence of private alleles and clear evidence for a Wahlund effect further justify the presence of a highly structured population. But, while mitochondrial DNA analysis still shows little to no matrilineal gene flow (F ST = 0.53) between sub-populations, microsatellite analysis suggests there is gene flow (F ST = 0.04) with low but significant isolation-by-distance and an average of 6 migrants per generation. Evidence of isolation-by-distance is also found in factorial correspondence analysis with the Lower Zambezi National Park and eastern corridor clusters overlapping isolated clusters of the Luangwa Valley and western sub-population. From this evidence, the Luangwa Valley appears separated from the western sub-population with some dispersal through the southern regions of the eastern sub-population. Both the eastern and western sub-populations have high heterozygosity (0.68 and 0.69, respectively) and genetic diversity (0.47 and 0.50, respectively) values, indicative of genetically healthy populations.

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Relationships Between Wright's FST and FIS Statistics in a Context of Wahlund Effect

Cited by 23 publications

References 4 publications

Clustering patterns mirror the geographical distribution and genetic history of Lemnos and Lesvos sheep populations

Clustering patterns mirror the geographical distribution and genetic history of Lemnos and Lesvos sheep populations

Genetic Differentiation of Glossina pallidipes Tsetse Flies in Southern Kenya

Genetic analysis of African lions (Panthera leo) in Zambia support movement across anthropogenic and geographical barriers

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