scholarly journals Genetic Variation for Phenotypically Invariant Traits Detected in Teosinte: Implications for the Evolution of Novel Forms

Genetics ◽  
2002 ◽  
Vol 160 (1) ◽  
pp. 333-342
Author(s):  
Nick Lauter ◽  
John Doebley
Keyword(s):  
Genetic Variation ◽  
Single Gene ◽  
Phenotypic Expression ◽  
Natural Populations ◽  
Gene Mutations ◽  
Character State ◽  
Multiple Gene ◽  
Cryptic Genetic Variation ◽  
Mapping Strategy ◽  
Discrete Character

Abstract How new discrete states of morphological traits evolve is poorly understood. One possibility is that single-gene changes underlie the evolution of new discrete character states and that evolution is dependent on the occurrence of new single-gene mutations. Another possibility is that multiple-gene changes are required to elevate an individual or population above a threshold required to produce the new character state. A prediction of the latter model is that genetic variation for the traits should exist in natural populations in the absence of phenotypic variation. To test this idea, we studied traits that are phenotypically invariant within teosinte and for which teosinte is discretely different from its near relative, maize. By employing a QTL mapping strategy to analyze the progeny of a testcross between an F1 of two teosintes and a maize inbred line, we identified cryptic genetic variation in teosinte for traits that are invariant in teosinte. We argue that such cryptic genetic variation can contribute to the evolution of novelty when reconfigured to exceed the threshold necessary for phenotypic expression or by acting to modify or stabilize the effects of major mutations.

scholarly journals Cryptic Genetic Variation in Natural Populations: A Predictive Framework

2014 ◽  
Vol 54 (5) ◽  
pp. 783-793 ◽  
Author(s):  
C. C. Ledon-Rettig ◽  
D. W. Pfennig ◽  
A. J. Chunco ◽  
I. Dworkin
Keyword(s):  
Genetic Variation ◽  
Natural Populations ◽  
Cryptic Genetic Variation

scholarly journals Cryptic genetic variation underpins rapid adaptation to ocean acidification

2019 ◽  
Author(s):  
M. C. Bitter ◽  
L. Kapsenberg ◽  
J.-P. Gattuso ◽  
C. A. Pfister
Keyword(s):  
Climate Change ◽  
Genetic Variation ◽  
Natural Populations ◽  
Future Climate Change ◽  
Rapid Adaptation ◽  
Larval Size ◽  
Larval Population ◽  
Cryptic Genetic Variation ◽  
Standing Variation ◽  
Seawater Ph

AbstractGlobal climate change has intensified the need to assess the capacity for natural populations to adapt to abrupt shifts in the environment. Reductions in seawater pH constitute a conspicuous stressor associated with increasing atmospheric carbon dioxide that is affecting ecosystems throughout the world’s oceans. Here, we quantify the phenotypic and genetic modifications associated with rapid adaptation to reduced seawater pH in the marine mussel, Mytilus galloprovincialis. We reared a genetically diverse larval population in ambient and extreme low pH conditions (pHT 8.1 and 7.4) and tracked changes in the larval size and allele frequency distributions through settlement. Additionally, we separated larvae by size to link a fitness-related trait to its underlying genetic background in each treatment. Both phenotypic and genetic data show that M. galloprovincialis can evolve in response to a decrease in seawater pH. This process is polygenic and characterized by genotype-environment interactions, suggesting the role of cryptic genetic variation in adaptation to future climate change. Holistically, this work provides insight into the processes underpinning rapid evolution, and demonstrates the importance of maintaining standing variation within natural populations to bolster species’ adaptive capacity as global change progresses.

scholarly journals C. elegansharbors pervasive cryptic genetic variation for embryogenesis

2014 ◽  
Author(s):  
Annalise Paaby ◽  
Amelia White ◽  
David Riccardi ◽  
Kristin Gunsalus ◽  
Fabio Piano ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Gene Networks ◽  
Genetic Basis ◽  
Disease Susceptibility ◽  
Disease Risk ◽  
Natural Populations ◽  
Cryptic Genetic Variation ◽  
Natural Genetic Variation ◽  
C Elegans ◽  
In The Wild

Conditionally functional mutations are an important class of natural genetic variation, yet little is known about their prevalence in natural populations or their contribution to disease risk. Here, we describe a vast reserve of cryptic genetic variation, alleles that are normally silent but which affect phenotype when the function of other genes is perturbed, in the gene networks ofC. elegansembryogenesis. We find evidence that cryptic-effect loci are ubiquitous and segregate at intermediate frequencies in the wild. The cryptic alleles demonstrate low developmental pleiotropy, in that specific, rather than general, perturbations are required to reveal them. Our findings underscore the importance of genetic background in characterizing gene function and provide a model for the expression of conditionally functional effects that may be fundamental in basic mechanisms of trait evolution and the genetic basis of disease susceptibility.

scholarly journals Genetic Variation Among Natural Populations of Tilletia controversa and T. bromi

2000 ◽  
Vol 90 (4) ◽  
pp. 376-383 ◽  
Author(s):  
Guillermo Pimentel ◽  
Tobin L. Peever ◽  
Lori M. Carris
Keyword(s):  
Genetic Variation ◽  
Genetic Differentiation ◽  
Gene Diversity ◽  
Random Amplified Polymorphic Dna ◽  
Natural Populations ◽  
Host Population ◽  
Natural Hybridization ◽  
Character State ◽  
Phenotypic Analysis ◽  
Tilletia Controversa

Isolates of Tilletia controversa and T. bromi were sampled from wheat and two Bromus species hosts, respectively, in the Pacific Northwest, and genetic variation within and among populations was determined. Fifty-one random amplified polymorphic DNA markers from eleven primers were treated as phenotypic 1 and 0 character state data to estimate similarities and analyze molecular variance (AMOVA) among populations and as putative genetic loci to carry out analyses of gene diversity. Phenotypic analysis of T. controversa and T. bromi isolates revealed two distinct clusters that were 37% similar. The T. bromi cluster was subdivided further into two groups, corresponding to host, with 40% similarity. Cluster analysis based on allele frequencies produced similar results and also supported two T. bromi groups based on host. No evidence of natural hybridization and introgression was detected between the T. controversa and T. bromi populations. Both AMOVA and gene diversity analyses detected moderate levels of differentiation among T. controversa populations, whereas T. bromi populations were highly differentiated. The level of genetic differentiation observed between the T. bromi populations on different Bromus species hosts supports the hypothesis that a high degree of host specificity exists in the wild grass-infecting smuts. We speculate that the higher level of genetic differentiation among the T. bromi populations compared with the T. controversa populations on wheat may be due to selection by a more genetically diverse host population.

scholarly journals Wild worm embryogenesis harbors ubiquitous polygenic modifier variation

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Annalise B Paaby ◽  
Amelia G White ◽  
David D Riccardi ◽  
Kristin C Gunsalus ◽  
Fabio Piano ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Caenorhabditis Elegans ◽  
Gene Function ◽  
Natural Populations ◽  
Complex Trait ◽  
Genetic Modifiers ◽  
Wild Type ◽  
Cryptic Genetic Variation ◽  
Quantitative Genetic ◽  
In The Wild

Embryogenesis is an essential and stereotypic process that nevertheless evolves among species. Its essentiality may favor the accumulation of cryptic genetic variation (CGV) that has no effect in the wild-type but that enhances or suppresses the effects of rare disruptions to gene function. Here, we adapted a classical modifier screen to interrogate the alleles segregating in natural populations of Caenorhabditis elegans: we induced gene knockdowns and used quantitative genetic methodology to examine how segregating variants modify the penetrance of embryonic lethality. Each perturbation revealed CGV, indicating that wild-type genomes harbor myriad genetic modifiers that may have little effect individually but which in aggregate can dramatically influence penetrance. Phenotypes were mediated by many modifiers, indicating high polygenicity, but the alleles tend to act very specifically, indicating low pleiotropy. Our findings demonstrate the extent of conditional functionality in complex trait architecture.

Single-gene mutations in mtDNA-associated proteins are unlikely to be the main cause of sporadic Parkinson's disease. Cumulative genetic variation in numerous genes may be important in neurodegeneration and PD risk

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Genetic Variation ◽  
Mitochondrial Gene ◽  
Single Gene ◽  
Gene Mutations ◽  
Substantia Nigra Pars Compacta ◽  
Mtdna Mutations ◽  
Age Related ◽  
Associated Proteins

More than two decades ago, numerous individuals with mitochondrial abnormalities and Parkinson's disease were reported. Some of these individuals have mtDNA (mtDNA) mutations, which cause instability. Patients who had neurodegeneration in the SNpc showed that mtDNA abnormalities were important in neurodegeneration and PD risk. Similar findings were found in the MitoPark mice as in PD. Single-gene mutations in mtDNA-associated proteins are unlikely to be the main cause of sporadic PD. The mutation in several genes, functioning in concert in intricate functional networks, results in mild to moderate PD symptoms. Single-gene and PD-GWA studies have had little success in uncovering mtDNA risk loci. In this case, mitochondrial biogenesis and compensation processes are associated with the missing compensatory mechanisms in PD. Maintaining a source of wild-type mtDNA helps to fight age-related development of mtDNA abnormalities. PD risk may be enhanced by increasing age-related neuronal loss, if dysregulated or inhibited.Additionally, PD genes, such as PRKN, LRRK2, are multi-taskers. This involves mtDNA participation as well. Some new discoveries connect mtDNA maintenance and mtDNA stress with PRKN/PINK1 PD-mediated inflammation. mtDNA maintenance pathways might potentially be crucial for monogenic PD. How mitochondria can affect monogenic and sporadic kinds of PD is unknown. Continual study only deepens our understanding of the mitochondrial transcriptome. Additionally, mtDNA is known to encode peptides, mRNAs, and small and long noncoding RNAs. These control mitochondrial gene expression, metabolic activity, and stress response. MtDNA mutations impact the nuclear epigenome through creating variations in mitochondrial intermediates that regulate histones. Additionally, mitochondrial DNA polymerases are present. This creates brand-new possibilities for mtDNA replication and repair. We have identified evidence that nDNA that codes for and/or regulates mitochondrial related activities may add to Parkinson's disease (PD) risk. Cumulative genetic variation in numerous genes (including the NRF-1 and NRF-2 pathway) may be important in neurodegeneration and PD risk. It will need more research to figure out which mtDNA gene mutations are responsible for increasing PD risk.The gradual loss of dopaminergic neurons in the substantia nigra pars compacta is one of the defining characteristics of Parkinson's disease (PD) (SNpc). Rigidity, tremor, and bradykinesia are preceded by hallucinations and sleep difficulties as a result of nigrostriatal dopamine depletion. Symptoms vary greatly and their presence and intensity fluctuate over time. Parkinsonism is a catch-all name for a variety of neurological illnesses, including PD, that can cause symptoms that mimic PD. Parkinsonism instances that lack all of the essential symptoms are referred to as parkinsonism instances.

scholarly journals Compensatory evolution via cryptic genetic variation: Distinct trajectories to phenotypic and fitness recovery

2017 ◽  
Author(s):  
Sudarshan Chari ◽  
Christian Marier ◽  
Cody Porter ◽  
Emmalee Northrop ◽  
Alexandra Belinky ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Natural Selection ◽  
Allelic Variation ◽  
Courtship Behavior ◽  
Natural Populations ◽  
Wing Morphology ◽  
Cryptic Genetic Variation ◽  
Compensatory Evolution ◽  
Compensatory Adaptation ◽  
Deleterious Alleles

AbstractPopulations are constantly exposed to deleterious alleles, most of which are purged via natural selection. However, deleterious fitness effects of alleles can also be suppressed by compensatory adaptation. Compensatory mutations can act directly to reduce deleterious effects of an allele. Alternatively, compensation may also occur by altering other aspects of an organisms’ phenotype or performance, without suppressing the phenotypic effects of the deleterious allele. Moreover, the origin of allelic variation contributing to compensatory adaptation remains poorly understood. Compensatory evolution driven by mutations that arise during the selective process are well studied. However less is known about the role standing (cryptic) genetic variation plays in compensatory adaptation. To address these questions, we examined evolutionary trajectories of natural populations of Drosophila melanogaster fixed for mutations that disrupt wing morphology, resulting in deleterious effects on several components of fitness. Lineages subjected only to natural selection, evolved modifications to courtship behavior and several life history traits without compensation in wing morphology. Yet, we observed rapid phenotypic compensation of wing morphology under artificial selection, consistent with segregating variation for compensatory alleles. We show that alleles contributing to compensation of wing morphology have deleterious effects on other fitness components. These results demonstrate the potential for multiple independent avenues for rapid compensatory adaptation from standing genetic variation, which ultimately may reveal novel adaptive trajectories.

scholarly journals POPULATION GENETICS OF ALLOZYME VARIATION IN NEUROSPORA INTERMEDIA

Genetics ◽  
1975 ◽  
Vol 80 (4) ◽  
pp. 785-805
Author(s):  
P T Spieth
Keyword(s):  
Genetic Variation ◽  
Vegetative Reproduction ◽  
Vascular Plant ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Regular Feature ◽  
Local Populations ◽  
Neurospora Intermedia ◽  
Pattern Of Variation ◽  
High Level

ABSTRACT Electrophoretically detectable variation in the fungus Neurospora intermedia has been surveyed among isolates from natural populations in Malaya, Papua, Australia and Florida. The principal result is a pattern of genetic variation within and between populations that is qualitatively no different than the well documented patterns for Drosophila and humans. In particular, there is a high level of genetic variation, the majority of which occurs at the level of local populations. Evidence is presented which argues that N. intermedia has a population structure analogous to that of an annual vascular plant with a high level of vegetative reproduction. Sexual reproduction appears to be a regular feature in the biology of the species. Substantial heterokaryon function seems unlikely in natural populations of N. intermedia. Theoretical considerations concerning the mechanisms underlying the observed pattern of variation most likely should be consistent with haploid selection theory. The implications of this constraint upon the theory are discussed in detail, leading to the presentation of a model based upon the concept of environmental heterogeneity. The essence of the model, which is equally applicable to haploid and diploid situations, is a shifting distribution of multiple adaptive niches among local populations such that a given population has a small net selective pressure in favor of one allele or another, depending upon its particular distribution of niches. Gene flow among neighboring populations with differing net selective pressures is postulated as the principal factor underlying intrapopulational allozyme variation.

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