Intrademic Genetic Structure and Natural Selection in Insects

1998 ◽  
pp. 181-204 ◽  
Author(s):  
David E. McCauley ◽  
Peter W. Goff
Keyword(s):  
Natural Selection ◽  
Genetic Structure

scholarly journals Patterns of Genome-Wide Variation, Population Differentiation and SNP Discovery of the Red Banded Stink Bug (Piezodorus guildinii)

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Maria I. Zucchi ◽  
Erick M. G. Cordeiro ◽  
Clint Allen ◽  
Mariana Novello ◽  
João Paulo Gomes Viana ◽  
...  
Keyword(s):  
Gene Flow ◽  
Natural Selection ◽  
Genetic Structure ◽  
Insect Pests ◽  
Geographic Origin ◽  
The United States ◽  
Basic Knowledge ◽  
Stink Bug ◽  
Mixed Ancestry ◽  
Significant Genetic Structure

Abstract Unravelling the details of range expansion and ecological dominance shifts of insect pests has been challenging due to the lack of basic knowledge about population structure, gene flow, and most importantly, how natural selection is affecting the adaptive process. Piezodous guildinii is an emerging pest of soybean in the southern region of the United States, and increasingly important in Brazil in recent years. However, the reasons P. guildinii is gradually becoming more of a problem are questions still mostly unanswered. Here, we have genotyped P. guildinii samples and discovered 1,337 loci containing 4,083 variant sites SNPs that were used to estimate genetic structure and to identify gene candidates under natural selection. Our results revealed the existence of a significant genetic structure separating populations according to their broad geographic origin, i.e., U.S. and Brazil, supported by AMOVA (FGT = 0.26), STRUCTURE, PCA, and FST analyses. High levels of gene flow or coancestry within groups (i.e., within countries) can be inferred from the data, and no spatial pattern was apparent at the finer scale in Brazil. Samples from different seasons show more heterogeneous compositions suggesting mixed ancestry and a more complex dynamic. Lastly, we were able to detect and successfully annotated 123 GBS loci (10.5%) under positive selection. The gene ontology (GO) analysis implicated candidate genes under selection with genome reorganization, neuropeptides, and energy mobilization. We discuss how these findings could be related to recent outbreaks and suggest how new efforts directed to better understand P. guildinii population dynamics.

scholarly journals Increased fire frequency promotes stronger spatial genetic structure and natural selection at regional and local scales in Pinus halepensis Mill

2017 ◽  
Vol 119 (6) ◽  
pp. 1061-1072 ◽  
Author(s):  
Katharina B. Budde ◽  
Santiago C. González-Martínez ◽  
Miguel Navascués ◽  
Concetta Burgarella ◽  
Elena Mosca ◽  
...  
Keyword(s):  
Natural Selection ◽  
Genetic Structure ◽  
Pinus Halepensis ◽  
Spatial Genetic Structure ◽  
Fire Frequency

scholarly journals The genetic structure of admixed populations.

Genetics ◽  
1991 ◽  
Vol 127 (2) ◽  
pp. 417-428 ◽  
Author(s):  
J C Long
Keyword(s):  
Natural Selection ◽  
Genetic Structure ◽  
Genetic Drift ◽  
Hybrid Population ◽  
Fixation Index ◽  
Human Populations ◽  
Random Errors ◽  
Chi Square ◽  
Testing Procedures ◽  
Chi Square Test

Abstract A method for simultaneously estimating the admixture proportions of a hybrid population and Wright's fixation index, FST, for that hybrid is presented. It is shown that the variance of admixture estimates can be partitioned into two components: (1) due to sample size, and (2) due to evolutionary variance (i.e., genetic drift). A chi-square test used to detect heterogeneity of admixture estimates from different alleles, or loci, can now be corrected for both sources of random errors. Hence, its value for the detection of natural selection from heterogeneous admixture estimates is improved. The estimation and testing procedures described above are independent of the dynamics of the admixture process. However, when the admixture dynamics can be specified, FST can be predicted from genetic principles. Two admixture models are considered here, gene flow and intermixture. These models are of value because they lead to very different predictions regarding the accumulation of genes from the parental populations and the accumulation of variance due to genetic drift. When there is not evidence for natural selection, and it is appropriate to apply these models to data, the variance effective size (Ne) of the hybrid population can be estimated. Applications are made to three human populations: two of these are Afro-American populations and one is a Yanomamö Indian village. Natural selection could not be detected using the chi-square test in any of these populations. However, estimates of effective population sizes do lead to a richer description of the genetic structure of these populations.

scholarly journals Evolution of multilocus genetic structure in Avena hirtula and Avena barbata.

Genetics ◽  
1993 ◽  
Vol 135 (4) ◽  
pp. 1125-1139 ◽  
Author(s):  
R W Allard ◽  
P García ◽  
L E Sáenz-de-Miera ◽  
M Pérez de la Vega
Keyword(s):  
Natural Selection ◽  
Genetic Structure ◽  
Allelic Diversity ◽  
Adaptive Landscape ◽  
Epistatic Interactions ◽  
Avena Barbata ◽  
Local Populations ◽  
Diploid Ancestor ◽  
Multilocus Genetic Structure

Abstract Avena barbata, an autotetraploid grass, is much more widely adapted than Avena hirtula, its diploid ancestor. We have determined the 14-locus genotype of 754 diploid and 4751 tetraploid plants from 10 and 50 Spanish sites, respectively. Allelic diversity is much greater in the tetraploid (52 alleles) than in the diploid (38 alleles): the extra alleles of the tetraploid were present in nonsegregating heteroallelic quadriplexes. Seven loci were monomorphic for the same allele (genotypically 11) in all populations of the diploid: five of these loci were also monomorphic for the same allele (genotypically 1111) in all populations of the tetraploid whereas two loci each formed a heteroallelic quadriplex (1122) that was monomorphic or predominant in the tetraploid. Seven of the 14 loci formed one or more highly successful homoallelic and/or heteroallelic quadriplexes in the tetraploid. We attribute much of the greater heterosis and wider adaptedness of the tetraploid to favorable within-locus interactions and interlocus (epistatic) interactions among alleles of the loci that form heteroallelic quadriplexes. It is difficult to account for the observed patterns in which genotypes are distributed ecogeographically except in terms of natural selection favoring particular alleles and genotypes in specific habitats. We conclude that natural selection was the predominant integrating force in shaping the specific genetic structure of different local populations as well as the adaptive landscape of both the diploid and tetraploid.

scholarly journals Does natural selection explain the fine scale genetic structure at the nuclear exonGlu-5′in blue mussels from Kerguelen?

2015 ◽  
Vol 5 (7) ◽  
pp. 1456-1473 ◽  
Author(s):  
Karin Gérard ◽  
Charlotte Roby ◽  
Nicolas Bierne ◽  
Philippe Borsa ◽  
Jean-Pierre Féral ◽  
...  
Keyword(s):  
Natural Selection ◽  
Genetic Structure ◽  
Fine Scale ◽  
Blue Mussels
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