scholarly journals Cytonuclear Theory for Haplodiploid Species and X-Linked Genes. I. Hardy-Weinberg Dynamics and Continent-Island, Hybrid Zone Models

Genetics ◽  
1997 ◽  
Vol 147 (1) ◽  
pp. 321-338
Author(s):  
Michael A D Goodisman ◽  
Marjorie A Asmussen
Keyword(s):  
Assortative Mating ◽  
Hybrid Zone ◽  
Random Mating ◽  
Diploid Species ◽  
Specific Gene ◽  
Hybrid Zones ◽  
Pure Type ◽  
Special Cases ◽  
Source Populations ◽  
And Migration

Abstract We develop models that describe the cytonuclear structure for either a cytoplasmic and nuclear marker in a haplodiploid species or a cytoplasmic and X-linked marker in a diploid species. Sex-specific disequilibrium statistics that summarize nonrandom cytonuclear associations in such systems are defined, and their basic Hardy-Weinberg dynamics and admixture formulae are delimited. We focus on the context of hybrid zones and develop continent-island models whereby individuals from two genetically differentiated source populations migrate into and mate within a single zone of admixture. We examine the effects of differential migration of the sexes, assortative mating by pure type females, and census time (relative to mating and migration), as well as special cases of random mating and migration subsumed under the general models. We show that pure type individuals and nonzero cytonuclear disequilibria can be maintained within a hybrid zone if there is continued migration from both source populations, and that females generally have a greater influence over these cytonuclear variables than males. The resulting theoretical framework can be used to estimate the rates of assortative mating and sex-specific gene flow in hybrid zones and other zones of admixture involving haplodiploid or sex-linked cytonuclear data.

scholarly journals The effects of assortative mating and migration on cytonuclear associations in hybrid zones.

Genetics ◽  
1989 ◽  
Vol 122 (4) ◽  
pp. 923-934 ◽  
Author(s):  
M A Asmussen ◽  
J Arnold ◽  
J C Avise
Keyword(s):  
Assortative Mating ◽  
Hybrid Zone ◽  
Evolutionary Dynamics ◽  
Initial Conditions ◽  
Likelihood Method ◽  
Hybrid Population ◽  
Hybrid Zones ◽  
Gene Frequencies ◽  
Nonrandom Mating ◽  
And Migration

Abstract We examine the influence of nonrandom mating and immigration on the evolutionary dynamics of cytonuclear associations in hybrid zones. Recursion equations for allelic and genotypic cytonuclear disequilibria were generated under models of (1) migration alone, assuming hybrid zone matings are random with respect to cytonuclear genotype; and (2) migration in conjunction with refined epistatic mating, in which females of the pure parental species preferentially mate with conspecific males. Major results are as follows: (a) even the slightest migration removes the dependency of the final outcome on initial conditions, producing a unique equilibrium in which both pure parental genotypes are maintained in the hybrid zone; (b) in contrast to nuclear genes, the dynamics of cytoplasmic allele frequencies appear robust to changes in the assumed mating system, yet are particularly sensitive to gene flow; (c) continued immigration can generate permanent cytonuclear disequilibria, whether mating is random or assortative; and (d) the order of population censusing (before versus after reproduction by immigrants) can have a dramatic effect on the magnitude but not the pattern of cytonuclear disequilibria. Using the maximum likelihood method, the parameter space of migration rates and assortative mating rates was examined for best fit to observed cytonuclear disequilibria data in a hybrid population of Hyla tree frogs. An epistatic mating model with a total immigration rate of about 32% per generation produces equilibrium gene frequencies and cytonuclear disequilibria consistent with the empirical observations.

scholarly journals Definition and Properties of Disequilibrium Statistics for Associations Between Nuclear and Cytoplasmic Genotypes

Genetics ◽  
1987 ◽  
Vol 115 (4) ◽  
pp. 755-768
Author(s):  
Marjorie A Asmussen ◽  
Jonathan Arnold ◽  
John C Avise
Keyword(s):  
Assortative Mating ◽  
Initial Conditions ◽  
Random Mating ◽  
Nuclear Gene ◽  
Data Sets ◽  
Mixed Mating ◽  
Hybrid Zones ◽  
Genotype Frequencies ◽  
Conventional Models ◽  
Mixed Mating Model

ABSTRACT We define and establish the interrelationships of four components of statistical association between a diploid nuclear gene and a uniparentally transmitted, haploid cytoplasmic gene: an allelic (gametic) disequilibrium (D), which measures associations between alleles at the two loci; and three genotypic disequilibria (D  1, D  2, D  3), which measure associations between two cytotypes and the three respective nuclear backgrounds. We also consider an alternative set of measures, including D and the residual disequilibrium (d). The dynamics of these disequilibria are then examined under three conventional models of the mating system: (1) random mating; (2a) assortative mating without dominance (the "mixed-mating model"); and (2b) assortative mating with dominance ("O'Donald's model"). The trajectories of gametic disequilibria are similar to those for pairs of unlinked nuclear loci. The dynamics of genotypic disequilibria exhibit a variety of behaviors depending on the model and the initial conditions. Procedures for statistical estimation of cytonuclear disequilibria are developed and applied to several real and hypothetical data sets. Special attention is paid to the biological interpretations of various categories of allelic and genotypic disequilibria in hybrid zones. Genetic systems for which these statistics might be appropriate include nuclear genotype frequencies in conjunction with those for mitochondrial DNA, chloroplast DNA, or cytoplasmically inherited microorganisms.

scholarly journals Patterns of introgression vary within an avian hybrid zone

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Logan M. Maxwell ◽  
Jennifer Walsh ◽  
Brian J. Olsen ◽  
Adrienne I. Kovach
Keyword(s):  
Sexual Selection ◽  
Assortative Mating ◽  
Hybrid Zone ◽  
Spatial Scales ◽  
Random Mating ◽  
Relative Influence ◽  
Hybrid Index ◽  
Interspecific Mating ◽  
Selective Pressures ◽  
Demographic Processes

Abstract Background Exploring hybrid zone dynamics at different spatial scales allows for better understanding of local factors that influence hybrid zone structure. In this study, we tested hypotheses about drivers of introgression at two spatial scales within the Saltmarsh Sparrow (Ammospiza caudacuta) and Nelson’s Sparrow (A. nelsoni) hybrid zone. Specifically, we evaluated the influence of neutral demographic processes (relative species abundance), natural selection (exogenous environmental factors and genetic incompatibilities), and sexual selection (assortative mating) in this mosaic hybrid zone. By intensively sampling adults (n = 218) and chicks (n = 326) at two geographically proximate locations in the center of the hybrid zone, we determined patterns of introgression on a fine scale across sites of differing habitat. We made broadscale comparisons of patterns from the center with those of prior studies in the southern edge of the hybrid zone. Results A panel of fixed SNPs (135) identified from ddRAD sequencing was used to calculate a hybrid index and determine genotypic composition/admixture level of the populations. Another panel of polymorphic SNPs (589) was used to assign paternity and reconstruct mating pairs to test for sexual selection. On a broad-scale, patterns of introgression were not explained by random mating within marshes. We found high rates of back-crossing and similarly low rates of recent-generation (F1/F2) hybrids in the center and south of the zone. Offspring genotypic proportions did not meet those expected from random mating within the parental genotypic distribution. Additionally, we observed half as many F1/F2 hybrid female adults than nestlings, while respective male groups showed no difference, in support of Haldane’s Rule. The observed proportion of interspecific mating was lower than expected when accounting for mate availability, indicating assortative mating was limiting widespread hybridization. On a fine spatial scale, we found variation in the relative influence of neutral and selective forces between inland and coastal habitats, with the smaller, inland marsh influenced primarily by neutral demographic processes, and the expansive, coastal marsh experiencing higher selective pressures in the form of natural (exogenous and endogenous) and sexual selection. Conclusions Multiple drivers of introgression, including neutral and selective pressures (exogenous, endogenous, and sexual selection), are structuring this hybrid zone, and their relative influence is site and context-dependent.

Narrow hybrid zone between two subspecies of big sagebrush (Artemisia tridentata: Asteraceae). VI. Respiration and water potential

1998 ◽  
Vol 76 (4) ◽  
pp. 567-574 ◽  
Author(s):  
E Durant McArthur ◽  
D Carl Freeman ◽  
John H Graham ◽  
Han Wang ◽  
Stewart C Sanderson ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Potential ◽  
Hybrid Zone ◽  
Artemisia Tridentata ◽  
Hybrid Zones ◽  
Stem Water Potential ◽  
Big Sagebrush ◽  
Hybrid Plants ◽  
Apparent Decrease ◽  
Source Populations

Respiration and stem water potential ( psi ) were examined in parental and hybrid big sagebrush (Artemisia tridentata Nutt. ssp. tridentata and Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) grown in common gardens within each parental zone and in the hybrid zone. Plants were sampled in July, August, and September, i.e., immediately before, during, and after flowering. The habitats differed from one another, and there were significant garden by date interactions. The source populations also differed significantly from one another. There were no significant garden by source interactions. Hybrid plants had intermediate respiration rates and did not suffer greater water stress than parental plants. Hybrid plants showed no apparent decrease in adaptation in the important physiological traits respiration and water stress in the hybrid zone.Key words: Artemisia, hybrid zones, respiration, water potential.

scholarly journals Assortative mating by population of origin in a mechanistic model of admixture

2019 ◽  
Author(s):  
Amy Goldberg ◽  
Ananya Rastogi ◽  
Noah A Rosenberg
Keyword(s):  
Assortative Mating ◽  
Mechanistic Model ◽  
Random Mating ◽  
Population History ◽  
Source Population ◽  
Mating Preferences ◽  
Positive Assortative Mating ◽  
Special Cases ◽  
Mating Population ◽  
Over Time

AbstractPopulations whose mating pairs have levels of similarity in phenotypes or genotypes that differ systematically from the level expected under random mating are described as experiencing assortative mating. Excess similarity in mating pairs is termed positive assortative mating, and excess dissimilarity is negative assortative mating. In humans, empirical studies suggest that mating pairs from various admixed populations—whose ancestry derives from two or more source populations—possess correlated ancestry components that indicate the occurrence of positive assortative mating on the basis of ancestry. Generalizing a two-sex mechanistic admixture model, we devise a model of one form of ancestry-assortative mating that occurs through preferential mating based on source population. Under the model, we study the moments of the admixture fraction distribution for different assumptions about mating preferences, including both positive and negative assortative mating by population. We consider the special cases of assortative mating by population that involve a single admixture event and that consider a model of constant contributions to the admixed population over time. We demonstrate that whereas the mean admixture under assortative mating is equivalent to that of a corresponding randomly mating population, the variance of admixture depends on the level and direction of assortative mating. In contrast to standard settings in which positive assortment increases variation within a population, certain assortative mating scenarios allow the variance of admixture to decrease relative to a corresponding randomly mating population: with the three populations we consider, the variance-increasing effect of positive assortative mating within a population might be overwhelmed by a variance-decreasing effect emerging from mating preferences involving other pairs of populations. The effect of assortative mating is smaller on the X chromosome than the autosomes because inheritance of the X in males depends only on the mother’s ancestry, not on the mating pair. Because the variance of admixture is informative about the timing of admixture and possibly about sex-biased admixture contributions, the effects of assortative mating are important to consider in inferring features of population history from distributions of admixture values. Our model provides a framework to quantitatively study assortative mating under flexible scenarios of admixture over time.

Mitochondrial introgression is restricted relative to nuclear markers in a water strider (Hemiptera: Gerridae) hybrid zone

2005 ◽  
Vol 83 (3) ◽  
pp. 432-444 ◽  
Author(s):  
T A Abe ◽  
J R Spence ◽  
F A.H Sperling
Keyword(s):  
Hybrid Zone ◽  
Random Mating ◽  
Experimental Studies ◽  
Hybrid Zones ◽  
Nuclear Markers ◽  
Hybrid Inviability ◽  
Mitochondrial Introgression ◽  
Dna Sequence Variation ◽  
Nuclear Loci ◽  
Mitochondrial Locus

Although cytonuclear incompatibilities between species have been implicated in a variety of theoretical and experimental studies, the influence of such fitness interactions on gene introgression has been demonstrated in very few hybrid zones. We examined patterns of introgression between two species of Limnoporus Stål, 1868 water striders from 10 populations transecting a hybrid zone in Alberta and British Columbia. DNA-sequence variation in mitochondrial locus COI was compared with two nuclear loci, EF1-α and ITS 1. The spatial distribution of haplotype lineages showed strong barriers to gene exchange for mtDNA. Constraints on introgression were weaker for the nuclear markers, particularly ITS 1. The mtDNA from Limnoporus dissortis Drake and Harris, 1930 was associated with nuclear genes from Limnoporus notabilis Drake and Hottes, 1925 less often than expected by random mating, indicating that some cytoplasmic and nuclear combinations are favored over others and that cytonuclear incompatibilities play a role in structuring this hybrid zone. Mitochondrial mobility across the hybrid zone is likely to be restrained by the unusual hybrid inviability of these species. In a reversal of the pattern expected on the basis of Haldane's rule, females are the XX sex and yet hybrid females are much more inviable than males. Differential removal of hybrid females, which carry mtDNA, can explain disproportionately low mitochondrial introgression across the hybrid zone.

scholarly journals The effects of frequency-dependent sexual selection, mating-trait architecture and matching rule on hybrid zone dynamics in crows

2020 ◽  
Author(s):  
Dirk Metzler ◽  
Ulrich Knief ◽  
Joshua V. Peñalba ◽  
Jochen B. W. Wolf
Keyword(s):  
Sexual Selection ◽  
Assortative Mating ◽  
Hybrid Zone ◽  
Secondary Contact ◽  
Hybrid Zones ◽  
Moderate Degree ◽  
Matching Rule ◽  
Trait Loci ◽  
Spatio Temporal ◽  
Hooded Crows

AbstractHybrid zones provide a window into the evolutionary processes governing species divergence. While the role of postzygotic isolation has been extensively characterized in the context of hybrid zones, the contribution of prezygotic isolation is less well explored. In particular, the effect of assortative mate choice, the underlying preference function, the architecture of the mating trait and the strength of sexual selection are worthy of investigation. Here, we explore this question by means of a mathematical model parameterized with empirical data from the hybrid zone between all-black carrion and grey-coated hooded crows. The best-fit model resulted in narrow clines for two mating-trait loci coding for colour phenotype maintained by a moderate degree of assortative mating. Epistasis between the two loci induced hybrid-zone movement in favor of alleles conveying dark plumage followed by a shift in the opposite direction favouring grey-coated phenotypes ∼1,200 generations after secondary contact. Unlinked neutral loci diffused near-unimpeded across the zone. This study demonstrates that sexual selection created by assortative mating can explain steep transitions in mating-trait loci without generalizing to genome-wide reproductive isolation. It further emphasizes the importance of mating-trait architecture for spatio–temporal hybrid-zone dynamics.

Surnames and population structure in the Doctrine of Belén, Altos de Arica, Viceroyalty of Peru (1750–1813)

2021 ◽  
pp. 1-13
Author(s):  
Emma Alfaro ◽  
Xochitl Inostroza ◽  
José E. Dipierri ◽  
Daniela Peña Aguilera ◽  
Jorge Hidalgo ◽  
...  
Keyword(s):  
Population Structure ◽  
Indigenous Population ◽  
Random Mating ◽  
Quantitative Information ◽  
Geographic Space ◽  
Documentary Sources ◽  
Cultural Variables ◽  
The Social ◽  
Population Structures ◽  
And Migration

Abstract The analysis of multiple population structures (biodemographic, genetic and socio-cultural) and their inter-relations contribute to a deeper understanding of population structure and population dynamics. Genetically, the population structure corresponds to the deviation of random mating conditioned by a limited number of ancestors, by restricted migration in the social or geographic space, or by preference for certain consanguineous unions. Through the isonymic method, surname frequency and distribution across the population can supply quantitative information on the structure of a human population, as they constitute universal socio-cultural variables. Using documentary sources to undertake the Doctrine of Belén’s (Altos de Arica, Chile) historical demography reconstruction between 1763 and 1820, this study identified an indigenous population with stable patronymics. The availability of complete marriage, baptism and death records, low rates of migration and the significant percentage of individuals registered and constantly present in this population favoured the application of the isonymic method. The aim of this work was to use given names and surnames recorded in these documentary sources to reconstruct the population structure and migration pattern of the Doctrine of Belén between 1750 and 1813 through the isonymic method. The results of the study were consistent with the ethno-historical data of this ethnic space, where social cohesion was, in multiple ways, related to the regulation of daily life in colonial Andean societies.

Sign in / Sign up

Export Citation Format

Share Document