scholarly journals Epistasis can accelerate adaptive diversification in haploid asexual populations

2015 ◽  
Vol 282 (1802) ◽  
pp. 20142648 ◽  
Author(s):  
Cortland K. Griswold
Keyword(s):  
Biological Sciences ◽  
Genetic Basis ◽  
Balancing Selection ◽  
Ecological Process ◽  
Frequency Dependent ◽  
Bacterial Populations ◽  
Frequency Dependent Selection ◽  
Adaptive Diversification ◽  
Fundamental Goal ◽  
Asexual Populations

A fundamental goal of the biological sciences is to determine processes that facilitate the evolution of diversity. These processes can be separated into ecological, physiological, developmental and genetic. An ecological process that facilitates diversification is frequency-dependent selection caused by competition. Models of frequency-dependent adaptive diversification have generally assumed a genetic basis of phenotype that is non-epistatic. Here, we present a model that indicates diversification is accelerated by an epistatic basis of phenotype in combination with a competition model that invokes frequency-dependent selection. Our model makes use of a genealogical model of epistasis and insights into the effects of balancing selection on the genealogical structure of a population to understand how epistasis can facilitate diversification. The finding that epistasis facilitates diversification may be informative with respect to empirical results that indicate an epistatic basis of phenotype in experimental bacterial populations that experienced adaptive diversification.

scholarly journals Negative frequency dependent selection contributes to the maintenance of a global polymorphism in mitochondrial DNA

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Zorana Kurbalija Novičić ◽  
Ahmed Sayadi ◽  
Mihailo Jelić ◽  
Göran Arnqvist
Keyword(s):  
Mitochondrial Dna ◽  
Genetic Variation ◽  
Life History ◽  
Balancing Selection ◽  
Food Resource ◽  
Ecological Processes ◽  
Central Process ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection

Abstract Background Understanding the forces that maintain diversity across a range of scales is at the very heart of biology. Frequency-dependent processes are generally recognized as the most central process for the maintenance of ecological diversity. The same is, however, not generally true for genetic diversity. Negative frequency dependent selection, where rare genotypes have an advantage, is often regarded as a relatively weak force in maintaining genetic variation in life history traits because recombination disassociates alleles across many genes. Yet, many regions of the genome show low rates of recombination and genetic variation in such regions (i.e., supergenes) may in theory be upheld by frequency dependent selection. Results We studied what is essentially a ubiquitous life history supergene (i.e., mitochondrial DNA) in the fruit fly Drosophila subobscura, showing sympatric polymorphism with two main mtDNA genotypes co-occurring in populations world-wide. Using an experimental evolution approach involving manipulations of genotype starting frequencies, we show that negative frequency dependent selection indeed acts to maintain genetic variation in this region. Moreover, the strength of selection was affected by food resource conditions. Conclusions Our work provides novel experimental support for the view that balancing selection through negative frequency dependency acts to maintain genetic variation in life history genes. We suggest that the emergence of negative frequency dependent selection on mtDNA is symptomatic of the fundamental link between ecological processes related to resource use and the maintenance of genetic variation.

Frequency-dependent selection in bacterial populations

1988 ◽  
Vol 319 (1196) ◽  
pp. 459-472 ◽  
Keyword(s):  
Natural Selection ◽  
Genetic Variability ◽  
Mass Culture ◽  
Experimental Studies ◽  
Frequency Dependent ◽  
Bacterial Populations ◽  
Frequency Dependent Selection ◽  
Selection For ◽  
Restriction Modification ◽  
Restriction Modification Systems

There are many situations in which the direction and intensity of natural selection in bacterial populations will depend on the relative frequencies of genotypes. In some cases, this selection will favour rare genotypes and result in the maintenance of genetic variability; this is termed stabilizing frequency-dependent selection. In other cases, selection will only favour genotypes when they are common. Rare types cannot invade and genetic variability will not be maintained; this is known as disruptive frequency-dependent selection. Phage-mediated selection for bacteria with novel restriction-modification systems is frequency-dependent and stabilizing. In mass culture, selection for the production of toxins and allelopathic agents is likely to be frequency-dependent but disruptive. This also occurs in selection favouring genes and transposable elements that cause mutations. Here I review the results of theoretical and experimental studies of stabilizing and disruptive frequency-dependent selection in bacterial populations, and speculate on the importance of this kind of selection in the adaptation and evolution of these organisms and their accessory elements (plasmid, phage and transposons).

scholarly journals Predicting evolution using frequency-dependent selection in bacterial populations

2018 ◽  
Author(s):  
Taj Azarian ◽  
Pamela P Martinez ◽  
Brian J Arnold ◽  
Lindsay R Grant ◽  
Jukka Corander ◽  
...  
Keyword(s):  
Gene Products ◽  
Human Pathogen ◽  
Population Composition ◽  
Frequency Dependent ◽  
Bacterial Populations ◽  
Conjugate Vaccines ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection ◽  
Pathogen Populations ◽  
The Impact

AbstractPredicting how pathogen populations will change over time is challenging. Such has been the case with Streptococcus pneumoniae, an important human pathogen, and the pneumococcal conjugate vaccines (PCVs), which target only a fraction of the strains in the population. Here, we use the frequencies of accessory genes to predict changes in the pneumococcal population after vaccination, hypothesizing that these frequencies reflect negative frequency-dependent selection (NFDS) on the gene products. We find that the standardized predicted fitness of a strain estimated by an NFDS-based model at the time the vaccine is introduced enables to predict whether the strain increases or decreases in prevalence following vaccination. Further, we are able to forecast the equilibrium post-vaccine population composition and assess the invasion capacity of emerging lineages. Overall, we provide a method for predicting the impact of an intervention on pneumococcal populations with potential application to other bacterial pathogens in which NFDS is a driving force.

scholarly journals Elevated Heterozygosity in Adults Relative to Juveniles Provides Evidence of Viability Selection on Eagles and Falcons

2019 ◽  
Vol 110 (6) ◽  
pp. 696-706 ◽  
Author(s):  
Jacqueline M Doyle ◽  
Janna R Willoughby ◽  
Douglas A Bell ◽  
Peter H Bloom ◽  
Evgeny A Bragin ◽  
...  
Keyword(s):  
Genetic Variability ◽  
Balancing Selection ◽  
Spatial Scales ◽  
Heterozygote Advantage ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Viability Selection ◽  
Subsequent Decrease ◽  
Genome Wide ◽  
Imperial Eagle

Abstract Viability selection yields adult populations that are more genetically variable than those of juveniles, producing a positive correlation between heterozygosity and survival. Viability selection could be the result of decreased heterozygosity across many loci in inbred individuals and a subsequent decrease in survivorship resulting from the expression of the deleterious alleles. Alternatively, locus-specific differences in genetic variability between adults and juveniles may be driven by forms of balancing selection, including heterozygote advantage, frequency-dependent selection, or selection across temporal and spatial scales. We use a pooled-sequencing approach to compare genome-wide and locus-specific genetic variability between 74 golden eagle (Aquila chrysaetos), 62 imperial eagle (Aquila heliaca), and 69 prairie falcon (Falco mexicanus) juveniles and adults. Although genome-wide genetic variability is comparable between juvenile and adult golden eagles and prairie falcons, imperial eagle adults are significantly more heterozygous than juveniles. This evidence of viability selection may stem from a relatively smaller imperial eagle effective population size and potentially greater genetic load. We additionally identify ~2000 single-nucleotide polymorphisms across the 3 species with extreme differences in heterozygosity between juveniles and adults. Many of these markers are associated with genes implicated in immune function or olfaction. These loci represent potential targets for studies of how heterozygote advantage, frequency-dependent selection, and selection over spatial and temporal scales influence survivorship in avian species. Overall, our genome-wide data extend previous studies that used allozyme or microsatellite markers and indicate that viability selection may be a more common evolutionary phenomenon than often appreciated.

scholarly journals BALANCING SELECTION, INVERSION POLYMORPHISM AND ADAPTATION IN DDT-RESISTANT POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1983 ◽  
Vol 105 (1) ◽  
pp. 87-104
Author(s):  
Phillip T Barnes
Keyword(s):  
Drosophila Melanogaster ◽  
Balancing Selection ◽  
Aldehyde Oxidase ◽  
Selective Advantage ◽  
Heterozygote Advantage ◽  
Allozyme Polymorphism ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Laboratory Populations ◽  
Environmental Component

ABSTRACT The modes of selection important in maintaining an inversion-allozyme polymorphism in two laboratory populations of Drosophila melanogaster were examined. The populations, 731R and J2, are highly resistant to DDT. The polymorphism involves the Standard and In(3R)P chromosomal arrangements in very strong linkage association with the AO  1 and AO  4 allozymes, respectively, of the aldehyde oxidase locus—The mean fertilities of the three karyotypes were not significantly different in 731R, but, in J2, In/In was significantly inferior to St/St and St/In. Egg-to-adult viability tests indicated very strong heterozygote advantage at all frequency combinations of the karyotypes in both populations when DDT was present. When DDT was excluded, the viabilities varied over the frequency combinations but were not inversely correlated with karyotype frequency, as predicted by balancing frequency-dependent selection. Discrete, multiple-generation experiments showed a rapid increase in heterozygote frequency to about 80% in both populations when DDT was present. Without DDT, 731R showed apparent directional selection favoring St, whereas J2 showed persistence of the polymorphism, although with extensive fluctuation.—Thus, the inversion-allozyme polymorphism is directly involved in the adaptation to a specific environmental component, DDT, and the selective advantage of the heterozygotes is the important balancing force. Balancing frequency-dependent selection was not observed, which suggests the hypothesis that this form of selection may not be involved in adaptation to novel environmental conditions.

scholarly journals Preserving genes: a model of the maintenance of genetic variation in a metapopulation under frequency-dependent selection

1995 ◽  
Vol 65 (3) ◽  
pp. 175-191 ◽  
Author(s):  
Olivia P. Judson
Keyword(s):  
Genetic Variation ◽  
Natural Populations ◽  
Practical Interest ◽  
Strong Interactions ◽  
Population Subdivision ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Maintenance Of Sex ◽  
Negative Frequency Dependent Selection ◽  
Asexual Populations

SummaryUnderstanding how genetic variability is maintained in natural populations is of both theoretical and practical interest. In particular, the subdivision of populations into demes linked by low levels of migration has been suggested to play an important role. But the maintenance of genetic variation in populations is also often linked to the maintenance of sexual reproduction: any force that acts to maintain sex should also act to maintain variation. One theory for the maintenance of sex, the Red Queen, states that sex and variation are maintained by antagonistic coevolutionary interactions – especially those between hosts and their harmful parasites – that give rise to negative frequency-dependent selection. In this paper I present a model to examine the relationships between population subdivision, negative frequency-dependent selection due to parasites, the maintenance of sex, and the preservation of alleles from fixation. The results show strong interactions between migration rates, negative frequency-dependent selection, and the maintenance of variability for sexual and asexual populations.

scholarly journals Dynamics of Laterality in Lake Tanganyika Scale-Eaters Driven by Cross-Predation

Symmetry ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 119
Author(s):  
Michio Hori ◽  
Masanori Kohda ◽  
Satoshi Awata ◽  
Satoshi Takahashi
Keyword(s):  
Rocky Shore ◽  
Genetic Basis ◽  
Lake Tanganyika ◽  
Prey Species ◽  
Temporal Changes ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Cichlid Fishes ◽  
The Right

Scale-eating cichlid fishes, Perissodus spp., in Lake Tanganyika have laterally asymmetrical bodies, and each population is composed of righty and lefty morphs. Righty morphs attack the right side of prey and lefty morphs do the opposite. This anti-symmetric dimorphism has a genetic basis. Temporal changes in the frequencies of morphs in two cohabiting scale-eating species (Perissodus microlepis and P. straeleni) were investigated over a 31-year period on a rocky shore at the southern end of the lake. Dimorphism was maintained dynamically during the period in both species, and the frequencies oscillated with a period of about four years in a semi-synchronized manner. Recent studies have indicated that this type of anti-symmetric dimorphism is shared widely among fishes, and is maintained by frequency-dependent selection between predator and prey species. The combinations of laterality in each scale-eater and its victim were surveyed. The results showed that “cross-predation”, in which righty predators catch lefty prey and lefty predators catch righty prey, occurred more frequently than the reverse combination (“parallel-predation”). The cause of the predominance of cross-predation is discussed from the viewpoint of the physical and sensory abilities of fishes.

Adaptive Diversification (MPB-48)

2011 ◽  
Author(s):  
Michael Doebeli
Keyword(s):  
Evolutionary Biology ◽  
Biological Diversity ◽  
Adaptive Dynamics ◽  
Theoretical Treatment ◽  
Mathematical Framework ◽  
Evolutionary Branching ◽  
Rare Type ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Adaptive Diversification

Understanding the mechanisms driving biological diversity remains a central problem in ecology and evolutionary biology. Traditional explanations assume that differences in selection pressures lead to different adaptations in geographically separated locations. This book takes a different approach and explores adaptive diversification—diversification rooted in ecological interactions and frequency-dependent selection. In any ecosystem, birth and death rates of individuals are affected by interactions with other individuals. What is an advantageous phenotype therefore depends on the phenotype of other individuals, and it may often be best to be ecologically different from the majority phenotype. Such rare-type advantage is a hallmark of frequency-dependent selection and opens the scope for processes of diversification that require ecological contact rather than geographical isolation. This book investigates adaptive diversification using the mathematical framework of adaptive dynamics. Evolutionary branching is a paradigmatic feature of adaptive dynamics that serves as a basic metaphor for adaptive diversification, and the book explores the scope of evolutionary branching in many different ecological scenarios, including models of coevolution, cooperation, and cultural evolution. It also uses alternative modeling approaches. Stochastic, individual-based models are particularly useful for studying adaptive speciation in sexual populations, and partial differential equation models confirm the pervasiveness of adaptive diversification. Showing that frequency-dependent interactions are an important driver of biological diversity, the book provides a comprehensive theoretical treatment of adaptive diversification.

scholarly journals Two modes of balancing selection in Drosophila melanogaster: overcompensation and overdominance.

Genetics ◽  
1991 ◽  
Vol 128 (2) ◽  
pp. 381-391
Author(s):  
T X Peng ◽  
A Moya ◽  
F J Ayala
Keyword(s):  
Drosophila Melanogaster ◽  
Balancing Selection ◽  
Natural Populations ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Designed Experiments ◽  
Two Temperatures ◽  
Limiting Resources ◽  
Uniform Population

Abstract Overdominance is often invoked to account for the extensive polymorphisms found in natural populations of organisms; overcompensation, however, may be equally or more important. Overcompensation occurs when limiting resources are better exploited by a genetically mixed than by a uniform population, and is often causally related to frequency-dependent selection. We have designed experiments to test whether overcompensation occurs in Drosophila melanogaster, using the Sod locus as a marker. Tests are made at each of two densities and two temperatures for cultures with desired genetic compositions. Both temperature and density have statistically significant effects on the per-female productivity of the cultures. More important, there are strong effects due to overcompensation. Cultures that are more polymorphic are also more productive than less polymorphic ones even when the level of individual heterozygosity is the same in all. There is also overdominance for the Sod locus: the heterozygotes are more productive than either homozygote at every temperature and density, and the differences are statistically significant in several cases. These results corroborate previous studies showing that overdominance may contribute to the maintenance of the Sod polymorphisms. Moreover, our results indicate that the significance of overcompensation as a mechanism to account for polymorphism in natural populations deserves further investigation.

scholarly journals Negative frequency-dependent selection is frequently confounding

2017 ◽  
Author(s):  
Dustin Brisson
Keyword(s):  
Genetic Diversity ◽  
Evolutionary Biology ◽  
Balancing Selection ◽  
Natural Populations ◽  
Research Progress ◽  
Selective Force ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Negative Frequency Dependent Selection ◽  
Peer Community

AbstractThis preprint has been reviewed and recommended by Peer Community in Evolutionary Biology (http://dx.doi.org/10.24072/pci.evolbiol.100024).The existence of persistent genetic variation within natural populations presents an evolutionary problem as natural selection and genetic drift tend to erode genetic diversity. Models of balancing selection were developed to account for the high and sometimes extreme levels of polymorphism found in many natural populations. Negative frequency-dependent selection may be the most powerful selective force maintaining balanced natural polymorphisms but it is also commonly misinterpreted. The aim of this review is to clarify the processes underlying negative frequency-dependent selection, describe classes of natural polymorphisms that can and cannot result from these processes, and discuss observational and experimental data that can aid in accurately identifying the processes that generated or are maintain diversity in nature. Finally, I consider the importance of accurately describing the processes affecting genetic diversity within populations as it relates to research progress.

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