scholarly journals Long-term balancing selection drives evolution of immunity genes in Capsella

2018 ◽  
Author(s):  
Daniel Koenig ◽  
Jörg Hagmann ◽  
Rachel Li ◽  
Felix Bemm ◽  
Tanja Slotte ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Natural Selection ◽  
Balancing Selection ◽  
Population Bottleneck ◽  
Genomic Variability ◽  
Immune Systems ◽  
Immunity Genes ◽  
Evolution Of Immunity

ABSTRACTGenetic drift is expected to remove polymorphism from populations over long periods of time, with the rate of polymorphism loss being accelerated when species experience strong reductions in population size. Adaptive forces that maintain genetic variation in populations, or balancing selection, might counteract this process. To understand the extent to which natural selection can drive the retention of genetic diversity, we document genomic variability after two parallel species-wide bottlenecks in the genus Capsella. We find that ancestral variation preferentially persists at immunity related loci, and that the same collection of alleles has been maintained in different lineages that have been separated for several million years. Our data point to long term balancing selection as an important factor shaping the genetics of immune systems in plants and as the predominant driver of genomic variability after a population bottleneck.

scholarly journals Long-term balancing selection drives evolution of immunity genes in Capsella

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Daniel Koenig ◽  
Jörg Hagmann ◽  
Rachel Li ◽  
Felix Bemm ◽  
Tanja Slotte ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Balancing Selection ◽  
Protein Sequences ◽  
Population Bottleneck ◽  
Genomic Variability ◽  
Immune Systems ◽  
Immunity Genes ◽  
Evolution Of Immunity

Genetic drift is expected to remove polymorphism from populations over long periods of time, with the rate of polymorphism loss being accelerated when species experience strong reductions in population size. Adaptive forces that maintain genetic variation in populations, or balancing selection, might counteract this process. To understand the extent to which natural selection can drive the retention of genetic diversity, we document genomic variability after two parallel species-wide bottlenecks in the genus Capsella. We find that ancestral variation preferentially persists at immunity related loci, and that the same collection of alleles has been maintained in different lineages that have been separated for several million years. By reconstructing the evolution of the disease-related locus MLO2b, we find that divergence between ancient haplotypes can be obscured by referenced based re-sequencing methods, and that trans-specific alleles can encode substantially diverged protein sequences. Our data point to long-term balancing selection as an important factor shaping the genetics of immune systems in plants and as the predominant driver of genomic variability after a population bottleneck.

scholarly journals Author response: Long-term balancing selection drives evolution of immunity genes in Capsella

2019 ◽  
Author(s):  
Daniel Koenig ◽  
Jörg Hagmann ◽  
Rachel Li ◽  
Felix Bemm ◽  
Tanja Slotte ◽  
...  
Keyword(s):  
Balancing Selection ◽  
Author Response ◽  
Immunity Genes ◽  
Evolution Of Immunity

Individual differences: Variation by design

2000 ◽  
Vol 23 (5) ◽  
pp. 676-677 ◽  
Author(s):  
Anthony J. Greene ◽  
William B. Levy
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Individual Differences ◽  
Natural Selection ◽  
Individual Variation ◽  
Mate Selection ◽  
Behavioral Variability ◽  
Behavioral Variation ◽  
Absolute Necessity

Stanovich & West (S&W) appear to overlook the adaptivity of variation. Behavioral variability, both between and within individuals, is an absolute necessity for phylogenetic and ontological adaptation. As with all heritable characteristics, inter-individual behavioral variation is the foundation for natural selection. Similarly, intra-individual variation allows a broad exploration of potential solutions. Variation increases the likelihood that more optimal behaviors are available for selection. Four examples of the adaptivity of variation are discussed: (a) Genetic variation as it pertains to behavior and natural selection; (b) behavioral and cognitive aspects of mate selection which may facilitate genetic diversity; (c) variation as a strategy for optimizing learning through greater exploration; and (d) behavioral variation coupled with communication as a means to propagate individually discovered behavioral success.

Mosaic microecological differential stress causes adaptive microsatellite divergence in wild barley, Hordeum spontaneum, at Neve Yaar, Israel

Genome ◽  
2002 ◽  
Vol 45 (6) ◽  
pp. 1216-1229 ◽  
Author(s):  
Qingyang Huang ◽  
Alex Beharav ◽  
Youchun Li ◽  
Valery Kirzhner ◽  
Eviatar Nevo
Keyword(s):  
Genetic Diversity ◽  
Natural Selection ◽  
Wild Barley ◽  
Permutation Test ◽  
Balancing Selection ◽  
Real Data ◽  
Hordeum Spontaneum ◽  
Data Sets ◽  
Total Genetic Diversity ◽  
Ssr Loci

Genetic diversity at 38 microsatellite (short sequence repeats (SSRs)) loci was studied in a sample of 54 plants representing a natural population of wild barley, Hordeum spontaneum, at the Neve Yaar microsite in Israel. Wild barley at the microsite was organized in a mosaic pattern over an area of 3180 m2 in the open Tabor oak forest, which was subdivided into four microniches: (i) sun–rock (11 genotypes), (ii) sun–soil (18 genotypes), (iii) shade–soil (11 genotypes), and (iv) shade–rock (14 genotypes). Fifty-four genotypes were tested for ecological–genetic microniche correlates. Analysis of 36 loci showed that allele distributions at SSR loci were nonrandom but structured by ecological stresses (climatic and edaphic). Sixteen (45.7%) of 35 polymorphic loci varied significantly (p < 0.05) in allele frequencies among the microniches. Significant genetic divergence and diversity were found among the four subpopulations. The soil and shade subpopulations showed higher genetic diversities at SSR loci than the rock and sun subpopulations, and the lowest genetic diversity was observed in the sun–rock subpopulation, in contrast with the previous allozyme and RAPD studies. On average, of 36 loci, 88.75% of the total genetic diversity exists within the four microniches, while 11.25% exists between the microniches. In a permutation test, GST was lower for 4999 out of 5000 randomized data sets (p < 0.001) when compared with real data (0.1125). The highest genetic distance was between shade-soil and sun–rock (D = 0.222). Our results suggest that diversifying natural selection may act upon some regulatory regions, resulting in adaptive SSR divergence. Fixation of some loci (GMS61, GMS1, and EBMAC824) at a specific microniche seems to suggest directional selection. The pattern of other SSR loci suggests the operation of balancing selection. SSRs may be either direct targets of selection or markers of selected haplotypes (selective sweep).Key words: natural selection, genetic diversity, microsatellites, adaptation, Hordeum spontaneum, wild barley, microsite divergence.

Genetic polymorphism in Proteocephalus exiguus shown by enzyme electrophoresis

1996 ◽  
Vol 70 (4) ◽  
pp. 345-349 ◽  
Author(s):  
V. Šnábel ◽  
V. Hanzelová ◽  
S. Mattiucci ◽  
S. D'Amelio ◽  
L. Paggi
Keyword(s):  
Genetic Diversity ◽  
Genetic Variation ◽  
Genetic Polymorphism ◽  
Genetic Variability ◽  
Balancing Selection ◽  
Outcrossing Rate ◽  
Enzyme Electrophoresis ◽  
Factors Affecting ◽  
Hardy Weinberg Equilibrium ◽  
Coregonid Fishes

AbstractEnzyme electrophoresis has been used to examine genetic diversity in a population of Proteocephalus exiguus La Rue, 1911 (Cestoda: Proteocephalidae), parasitizing salmonid and coregonid fishes. Among 16 loci tested, three polymorphic loci (Ada, Got, Pgm-2) were found. Six different genotypes at the Got locus distributed in Hardy-Weinberg equilibrium suggest remarkable genetic flexibility of P. exiguus. Balancing selection is proposed as the mechanism maintaining genetic variation within the species. Data of genetic variability parameters (Ho = 0.064; He = 0.07; P = 0.19) and outcrossing rate (t = 0.842) of P. exiguus population have been provided. Possible factors affecting these data are discussed.

scholarly journals Signatures of natural selection are not uniform across genes of innate immune system, but purifying selection is the dominant signature

2009 ◽  
Vol 106 (17) ◽  
pp. 7073-7078 ◽  
Author(s):  
Souvik Mukherjee ◽  
Neeta Sarkar-Roy ◽  
Diane K. Wagener ◽  
Partha P. Majumder
Keyword(s):  
Innate Immunity ◽  
Immune System ◽  
Natural Selection ◽  
Innate Immune System ◽  
Rare Variants ◽  
Balancing Selection ◽  
Purifying Selection ◽  
Innate Immune ◽  
Extended Haplotype ◽  
Immunity Genes

We tested the opposing views concerning evolution of genes of the innate immune system that (i) being evolutionary ancient, the system may have been highly optimized by natural selection and therefore should be under purifying selection, and (ii) the system may be plastic and continuing to evolve under balancing selection. We have resequenced 12 important innate-immunity genes (CAMP, DEFA4, DEFA5, DEFA6, DEFB1, MBL2, and TLRs 1, 2, 4, 5, 6, and 9) in healthy volunteers (n = 171) recruited from a region of India with high microbial load. We have compared these data with those of European-Americans (EUR) and African-Americans (AFR). We have found that most of the human haplotypes are many mutational steps away from the ancestral (chimpanzee) haplotypes, indicating that humans may have had to adapt to new pathogens. The haplotype structures in India are significantly different from those of EUR and AFR populations, indicating local adaptation to pathogens. In these genes, there is (i) generally an excess of rare variants, (ii) high, but variable, degrees of extended haplotype homozygosity, (iii) low tolerance to nonsynonymous changes, (iv) essentially one or a few high-frequency haplotypes, with star-like phylogenies of other infrequent haplotypes radiating from the modal haplotypes. Purifying selection is the most parsimonious explanation operating on these innate immunity genes. This genetic surveillance system recognizes motifs in pathogens that are perhaps conserved across a broad range of pathogens. Hence, functional constraints are imposed on mutations that diminish the ablility of these proteins to detect pathogens.

scholarly journals Spatio-Temporal Ecological and Evolutionary Dynamics in Natural Butterfly Populations (2015 Field Season)

2015 ◽  
Vol 38 ◽  
pp. 29-32
Author(s):  
Zachariah Gompert ◽  
Lauren Lucas
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Molecular Evolution ◽  
Natural Populations ◽  
Spatial And Temporal Variation ◽  
Long Term Study ◽  
Genome Wide ◽  
In The Wild ◽  
Long Term Studies

The study of evolution in natural populations has advanced our understanding of the origin and maintenance of biological diversity. For example, long term studies of wild populations indicate that natural selection can cause rapid and dramatic changes in traits, but that in some cases these evolutionary changes are quickly reversed when periodic variation in weather patterns or the biotic environment cause the optimal trait value to change (e.g., Reznick et al. 1997, Grant and Grant 2002). In fact, spatial and temporal variation in the strength and nature of natural selection could explain the high levels of genetic variation found in many natural populations (Gillespie 1994, Siepielski et al. 2009). Long term studies of evolution in the wild could also be informative for biodiversity conservation and resource management, because, for example, data on short term evolutionary responses to annual fluctuations in temperature or rainfall could be used to predict longer term evolution in response to directional climate change. Most previous research on evolution in the wild has considered one or a few observable traits or genes (e.g., Kapan 2001, Grant and Grant 2002, Barrett et al. 2008). We believe that more general conclusions regarding the rate and causes of evolutionary change in the wild and selection’s contribution to the maintenance of genetic variation could be obtained by studying genome-wide molecular evolution in a suite of natural populations. Thus, in 2012 we began a long term study of genome-wide molecular evolution in a series of natural butterfly populations in the Greater Yellowstone Area (GYA). This study will allow us to quantify the contribution of environment-dependent natural selection to evolution in these butterfly populations and determine whether selection consistently favors the same alleles across space and through time.

scholarly journals Spatio-Temporal Evolutionary Dynamics in Natural Butterfly Populations (2012 Field Season)

2012 ◽  
Vol 35 ◽  
pp. 73-76
Author(s):  
Zachariah Gompert ◽  
Lauren Lucas
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Molecular Evolution ◽  
Natural Populations ◽  
Spatial And Temporal Variation ◽  
Long Term Study ◽  
Genome Wide ◽  
In The Wild ◽  
Long Term Studies

The study of evolution in natural populations has advanced our understanding of the origin and maintenance of biological diversity. For example, long term studies of wild populations indicate that natural selection can cause rapid and dramatic changes in traits, but that in some cases these evolutionary changes are quickly reversed when periodic variation in weather patterns or the biotic environment cause the optimal trait value to change (e.g., Reznick et al. 1997; Grant and Grant 2002). In fact, spatial and temporal variation in the strength and nature of natural selection could explain the high levels of genetic variation found in many natural populations (Gillespie 1994; Siepielski et al. 2009). Long term studies of evolution in the wild could also be informative for biodiversity conservation and resource management, because, for example, data on short term evolutionary responses to annual fluctuations in temperature or rainfall could be used to predict longer term evolution in response to directional climate change. Most previous research on evolution in the wild has considered one or a few observable traits or genes (Kapan 2001; Grant and Grant 2002; Barrett et al. 2008). We believe that more general conclusions regarding the rate and causes of evolutionary change in the wild and selection’s contribution to the maintenance of genetic variation could be obtained by studying genome-wide molecular evolution in a suite of natural populations. Thus, we have begun a long term study of genome-wide molecular evolution in a series of natural butterfly populations in the Greater Yellowstone Area (GYA). This study will allow us to quantify the contribution of environment-dependent natural selection to evolution in these butterfly populations and determine whether selection consistently favors the same alleles across space and through time.

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