scholarly journals The genetic architecture of local adaptation and reproductive isolation in sympatry within theMimulus guttatusspecies complex

2016 ◽  
Vol 26 (1) ◽  
pp. 208-224 ◽  
Author(s):  
Kathleen G. Ferris ◽  
Laryssa L. Barnett ◽  
Benjamin K. Blackman ◽  
John H. Willis
Keyword(s):  
Reproductive Isolation ◽  
Local Adaptation ◽  
Genetic Architecture

scholarly journals The limits to parapatric speciation 3: evolution of strong reproductive isolation in presence of gene flow despite limited ecological differentiation

2020 ◽  
Vol 375 (1806) ◽  
pp. 20190532 ◽  
Author(s):  
Alexandre Blanckaert ◽  
Claudia Bank ◽  
Joachim Hermisson
Keyword(s):  
Gene Flow ◽  
Reproductive Isolation ◽  
Local Adaptation ◽  
Theme Issue ◽  
Genetic Barrier ◽  
Incipient Species ◽  
Postzygotic Reproductive Isolation ◽  
Minimal Configuration ◽  
Parapatric Speciation ◽  
Two Populations

Gene flow tends to impede the accumulation of genetic divergence. Here, we determine the limits for the evolution of postzygotic reproductive isolation in a model of two populations that are connected by gene flow. We consider two selective mechanisms for the creation and maintenance of a genetic barrier: local adaptation leads to divergence among incipient species due to selection against migrants, and Dobzhansky–Muller incompatibilities (DMIs) reinforce the genetic barrier through selection against hybrids. In particular, we are interested in the maximum strength of the barrier under a limited amount of local adaptation, a challenge that many incipient species may initially face. We first confirm that with classical two-locus DMIs, the maximum amount of local adaptation is indeed a limit to the strength of a genetic barrier. However, with three or more loci and cryptic epistasis, this limit holds no longer. In particular, we identify a minimal configuration of three epistatically interacting mutations that is sufficient to confer strong reproductive isolation. This article is part of the theme issue ‘Towards the completion of speciation: the evolution of reproductive isolation beyond the first barriers’.

scholarly journals Genomics of isolation in hybrids

2012 ◽  
Vol 367 (1587) ◽  
pp. 439-450 ◽  
Author(s):  
Zachariah Gompert ◽  
Thomas L. Parchman ◽  
C. Alex Buerkle
Keyword(s):  
Reproductive Isolation ◽  
Genetic Architecture ◽  
Large Scale ◽  
Empirical Studies ◽  
Hybrid Zones ◽  
Direct Measure ◽  
Fitness Effects ◽  
Outlier Loci ◽  
Admixed Population ◽  
Genome Level

Hybrid zones are common in nature and can offer critical insights into the dynamics and components of reproductive isolation. Hybrids between diverged lineages are particularly informative about the genetic architecture of reproductive isolation, because introgression in an admixed population is a direct measure of isolation. In this paper, we combine simulations and a new statistical model to determine the extent to which different genetic architectures of isolation leave different signatures on genome-level patterns of introgression. We found that reproductive isolation caused by one or several loci of large effect caused greater heterogeneity in patterns of introgression than architectures involving many loci with small fitness effects, particularly when isolating factors were closely linked. The same conditions that led to heterogeneous introgression often resulted in a reasonable correspondence between outlier loci and the genetic loci that contributed to isolation. However, demographic conditions affected both of these results, highlighting potential limitations to the study of the speciation genomics. Further progress in understanding the genomics of speciation will require large-scale empirical studies of introgression in hybrid zones and model-based analyses, as well as more comprehensive modelling of the expected levels of isolation with different demographies and genetic architectures of isolation.

scholarly journals The Genetic Architecture of Reproductive Isolation in Louisiana Irises: Flowering Phenology

Genetics ◽  
2007 ◽  
Vol 175 (4) ◽  
pp. 1803-1812 ◽  
Author(s):  
Noland H. Martin ◽  
Amy C. Bouck ◽  
Michael L. Arnold
Keyword(s):  
Reproductive Isolation ◽  
Genetic Architecture ◽  
Flowering Phenology

THE GENETIC ARCHITECTURE OF REPRODUCTIVE ISOLATION IN LOUISIANA IRISES: HYBRID FITNESS IN NATURE

Evolution ◽  
2009 ◽  
Vol 63 (10) ◽  
pp. 2581-2594 ◽  
Author(s):  
Sunni J. Taylor ◽  
Michael Arnold ◽  
Noland H. Martin
Keyword(s):  
Reproductive Isolation ◽  
Genetic Architecture ◽  
Hybrid Fitness

scholarly journals Evolution of polygenic traits under global vs local adaptation

Genetics ◽  
2022 ◽  
Vol 220 (1) ◽  
Author(s):  
Sam Yeaman
Keyword(s):  
Local Adaptation ◽  
Complex Traits ◽  
Genetic Architecture ◽  
Population Genomics ◽  
Natural Populations ◽  
Evolutionary Process ◽  
Frequency Effect ◽  
Theoretical Predictions ◽  
Using Data ◽  
And Migration

Abstract Observations about the number, frequency, effect size, and genomic distribution of alleles associated with complex traits must be interpreted in light of evolutionary process. These characteristics, which constitute a trait’s genetic architecture, can dramatically affect evolutionary outcomes in applications from agriculture to medicine, and can provide a window into how evolution works. Here, I review theoretical predictions about the evolution of genetic architecture under spatially homogeneous, global adaptation as compared with spatially heterogeneous, local adaptation. Due to the tension between divergent selection and migration, local adaptation can favor “concentrated” genetic architectures that are enriched for alleles of larger effect, clustered in a smaller number of genomic regions, relative to expectations under global adaptation. However, the evolution of such architectures may be limited by many factors, including the genotypic redundancy of the trait, mutation rate, and temporal variability of environment. I review the circumstances in which predictions differ for global vs local adaptation and discuss where progress can be made in testing hypotheses using data from natural populations and lab experiments. As the field of comparative population genomics expands in scope, differences in architecture among traits and species will provide insights into how evolution works, and such differences must be interpreted in light of which kind of selection has been operating.

scholarly journals The relative strength of selection on modifiers of genetic architecture under migration load

2021 ◽  
Author(s):  
Stephen R Proulx ◽  
Henrique Teotonio
Keyword(s):  
Local Adaptation ◽  
Genetic Architecture ◽  
Absolute Magnitude ◽  
Relative Strength ◽  
Demographic Stochasticity ◽  
Recombination Rates ◽  
Relative Population ◽  
Population Sizes ◽  
The Mean ◽  
Selection For

Gene flow between populations adapting to differing local environmental conditions creates a "migration load" because individuals might disperse to habitats where their survival is low or because they might reproduce with locally maladapted individuals. The amount by which the mean relative population fitness is kept below one creates an opportunity for modifiers of the genetic architecture to spread due to selection. Prior work that separately considered modifiers changing dispersal or recombination rates, or altering dominance or epistasis, has typically focused on the direction of selection rather than its absolute magnitude. We here develop methods to determine the strength of selection on modifiers of the genetic architecture, including modifiers of the dispersal rate, after populations evolved local adaptation. We consider scenarios with up to five loci contributing to local adaptation and derive a matrix model for the deterministic spread of modifiers. We find that selection for modifiers of epistasis and dominance is stronger than selection for decreased recombination, and that selection for partial reductions in recombination are extremely weak, regardless of the number of loci contributing to local adaptation. The spread of modifiers for a reduction in dispersal depends on the number of loci, pre-existing epistasis and extent of migration load. We identify a novel effect, that modifiers of dominance are more strongly selected when they are unlinked to the locus that they modify. Overall, these results help explain population differentiation and reproductive isolation and provide a benchmark to compare selection on genetic architecture modifiers in finite population sizes and under demographic stochasticity.

scholarly journals Habitat Choice and Speciation

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Sophie E. Webster ◽  
Juan Galindo ◽  
John W. Grahame ◽  
Roger K. Butlin
Keyword(s):  
Reproductive Isolation ◽  
Local Adaptation ◽  
Ecological Speciation ◽  
Habitat Choice ◽  
Current Evidence ◽  
Evolutionary Mechanisms ◽  
Important Challenge ◽  
Intertidal Gastropod ◽  
Underlying Mechanisms

The role of habitat choice in reproductive isolation and ecological speciation has often been overlooked, despite acknowledgement of its ability to facilitate local adaptation. It can form part of the speciation process through various evolutionary mechanisms, yet where habitat choice has been included in models of ecological speciation little thought has been given to these underlying mechanisms. Here, we propose and describe three independent criteria underlying ten different evolutionary scenarios in which habitat choice may promote or maintain local adaptation. The scenarios are the result of all possible combinations of the independent criteria, providing a conceptual framework in which to discuss examples which illustrate each scenario. These examples show that the different roles of habitat choice in ecological speciation have rarely been effectively distinguished. Making such distinctions is an important challenge for the future, allowing better experimental design, stronger inferences and more meaningful comparisons among systems. We show some of the practical difficulties involved by reviewing the current evidence for the role of habitat choice in local adaptation and reproductive isolation in the intertidal gastropodLittorina saxatilis, a model system for the study of ecological speciation, assessing whether any of the proposed scenarios can be reliably distinguished, given current research.

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