scholarly journals Comparative effects of pollen and seed migration on the cytonuclear structure of plant populations. II. Paternal cytoplasmic inheritance.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 253-267
Author(s):  
A Schnabel ◽  
M A Asmussen
Keyword(s):  
Gene Flow ◽  
De Novo ◽  
Life Stage ◽  
Cytoplasmic Inheritance ◽  
Island Population ◽  
Mixed Mating ◽  
Plant Populations ◽  
Seed Migration ◽  
Self Fertilization ◽  
The Relationship

Abstract We continue our study of the effects of pollen and seed migration on the cytonuclear structure of mixed-mating plant populations by analyzing two deterministic continent-island models under the critical assumption of paternal cytoplasmic inheritance. The major results of this study that contrast with our previous conclusions based on maternal cytoplasmic inheritance are (i) pollen gene flow can significantly affect the cytonuclear structure of the island population, and in particular can help to generate cytonuclear disequilibria that greatly exceed the magnitude of those that would be produced by seed migration or mixed mating alone; (ii) with simultaneous pollen and seed migration, nonzero cytonuclear disequilibria will be maintained not only when there is disequilibrium in the immigrant pollen or seeds, but also through a variety of intermigrant admixture effects when the two pools of immigrants differ appropriately in their cytonuclear compositions; (iii) either immigrant pollen or immigrant seeds can generate disequilibria de novo in populations with initially random cytonuclear associations, but pollen migration alone generally produces lower levels of disequilibrium than does comparable seed migration, especially at high levels of self-fertilization when the overall fraction of immigrant pollen is low; (iv) the equilibrium state of the island population will be influenced by the rate of pollen gene flow whenever there is either allelic disequilibrium in the immigrant pollen or simultaneous seed migration coupled with different cytoplasmic or nuclear allele frequencies in immigrant pollen and seeds or nonzero allelic disequilibrium in either immigrant pool. The estimation of pollen migration should therefore be facilitated with paternal cytoplasmic inheritance relative to the case of maternal cytoplasmic inheritance. These basic conclusions hold whether the population is censused as seeds or as adults, but with simultaneous pollen and seed migration, the relationship between census time and the ability to detect nonrandom cytonuclear associations is complex. When migration is through pollen alone, however, the cytonuclear structure of the island population is independent of the life stage censused.

scholarly journals Comparative effects of pollen and seed migration on the cytonuclear structure of plant populations. I. Maternal cytoplasmic inheritance.

Genetics ◽  
1991 ◽  
Vol 128 (3) ◽  
pp. 639-654
Author(s):  
M A Asmussen ◽  
A Schnabel
Keyword(s):  
De Novo ◽  
Life Stage ◽  
Random Mating ◽  
Cytoplasmic Inheritance ◽  
Island Population ◽  
Mixed Mating ◽  
Seed Migration ◽  
Self Fertilization ◽  
Basic Behavior ◽  
Special Case

Abstract We explicitly solve and analyze a series of deterministic continent-island models to delimit the effects of pollen and seed migration on cytonuclear frequencies and disequilibria in random-mating, mixed-mating and self-fertilized populations. Given the critical assumption of maternal cytoplasmic inheritance, five major findings are (i) nonzero cytonuclear disequilibria will be maintained in the island population if and only if at least some migration occurs each generation through seeds with nonrandom cytonuclear associations; (ii) immigrant seeds with no cytonuclear disequilibria can strongly affect the genetic structure of the island population by generating significant and long-lasting transient associations; (iii) with all else being equal, substantially greater admixture disequilibria are generally found with higher rates of seed migration into, or higher levels of self-fertilization within, the island population (with the possible exception of the heterozygote disequilibrium); (iv) pollen migration can either enhance or reduce the cytonuclear disequilibria caused by seed migration, or that due to mixed-mating in the absence of seed migration, but the effect is usually small and appears primarily to make a noticeable difference in predominantly outcrossing populations; and (v) pollen migration alone cannot generate even transient disequilibria de novo in populations with completely random associations. This same basic behavior is exhibited as long as there is some random outcrossing in the island population. Self-fertilized populations represent a special case, however, in that they are necessarily closed to pollen migration, and nonzero disequilibria can be maintained even in the absence of seed migration. All of these general results hold whether the population is censused as adults or as seeds, but the ability to detect nonrandom cytonuclear associations can depend strongly on the life stage censused in populations with a significant level of random outcrossing. We suggest how these models might be used for the estimation of seed and pollen migration.

The consequences of self-fertilization and outcrossing of the cestode Schistocephalus solidus in its second intermediate host

Parasitology ◽  
2003 ◽  
Vol 126 (4) ◽  
pp. 369-378 ◽  
Author(s):  
M. CHRISTEN ◽  
M. MILINSKI
Keyword(s):  
Intermediate Host ◽  
Gasterosteus Aculeatus ◽  
Life Stage ◽  
Life History Strategy ◽  
Body Cavity ◽  
Infected Fish ◽  
Mixed Mating ◽  
Schistocephalus Solidus ◽  
Self Fertilization ◽  
Second Intermediate Host

Many hermaphroditic parasites reproduce by both cross-fertilization and self-fertilization. To understand the maintenance of such mixed mating systems it is necessary to compare the fitness consequences of the two reproductive modes. This has, however, almost never been done in the context of host–parasite coevolution. Here we show the consequences of outcrossing and selfing in an advanced life-stage of the cestode Schistocephalus solidus, i.e. in its second intermediate host, the three-spined stickleback (Gasterosteus aculeatus). Each juvenile stickleback was simultaneously exposed to 2 experimentally infected copepods, one harbouring outcrossed the other selfed parasites. At 60 days p.i. parasites were removed from the fish's body cavity and, with microsatellite markers, assigned to either outcrossed or selfed origin. Prevalence was not significantly higher in outcrossed parasites. However, those fish that were infected contained significantly more outcrossed than selfed parasites. Thus the probability of a selfed parasite to progress in the life-cycle is reduced in the second intermediate host. Furthermore, we found that even the multiply infected fish increased in weight during the experiment. Nevertheless, total worm weight in multiply infected fish was significantly lower than in singly infected ones, which thus might be a parasite life-history strategy.

scholarly journals The Effects of Pollen and Seed Migration on Nuclear-Dicytoplasmic Systems. II. A New Method for Estimating Plant Gene Flow From Joint Nuclear-Cytoplasmic Data

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 833-854 ◽  
Author(s):  
Maria E Orive ◽  
Marjorie A Asmussen
Keyword(s):  
Gene Flow ◽  
Simulated Data ◽  
Likelihood Method ◽  
Data Sets ◽  
Mixed Mating ◽  
Hybrid Zones ◽  
Plant Gene ◽  
Seed Migration ◽  
Genotype Frequencies ◽  
Source Populations

Abstract A new maximum-likelihood method is developed for estimating unidirectional pollen and seed flow in mixed-mating plant populations from counts of joint nuclear-cytoplasmic genotypes. Data may include multiple unlinked nuclear markers with a single maternally or paternally inherited cytoplasmic marker, or with two cytoplasmic markers inherited through opposite parents, as in many conifer species. Migration rate estimates are based on fitting the equilibrium genotype frequencies under continent-island models of plant gene flow to the data. Detailed analysis of their equilibrium structures indicates when each of the three nuclear-cytoplasmic systems allows gene flow estimation and shows that, in general, it is easier to estimate seed than pollen migration. Three-locus nuclear-dicytoplasmic data only increase the conditions allowing seed migration estimates; however, the additional dicytonuclear disequilibria allow more accurate estimates of both forms of gene flow. Estimates and their confidence limits for simulated data sets confirm that two-locus data with paternal cytoplasmic inheritance provide better estimates than those with maternal inheritance, while three-locus dicytonuclear data with three modes of inheritance generally provide the most reliable estimates for both types of gene flow. Similar results are obtained for hybrid zones receiving pollen and seed flow from two source populations. An estimation program is available upon request.

scholarly journals Inbreeding depression and heterosis in a subdivided population: influence of the mating system

2002 ◽  
Vol 80 (2) ◽  
pp. 107-116 ◽  
Author(s):  
KONSTANTINOS THEODOROU ◽  
DENIS COUVET
Keyword(s):  
Gene Flow ◽  
Mating System ◽  
Inbreeding Depression ◽  
Genetic Load ◽  
Negative Influence ◽  
Point Of View ◽  
Mixed Mating ◽  
Isolated Populations ◽  
Seed Migration ◽  
Subdivided Population

We investigate the joint effects of gene flow and selfing on the level of inbreeding depression, heterosis and genetic load in a subdivided population at equilibrium. Low gene flow reduces inbreeding depression and substantially increases heterosis. However, in highly self-fertilizing populations, inbreeding depression is independent of the amount of gene flow. When migration occurs via pollen, consanguinity of the reproductive system could have a negative influence on subpopulation persistence, in contrast to the case of isolated populations. However, with only seed migration, genetic load and heterosis depend mildly on the mating system. From an evolutionary point of view, we reach two main conclusions: first, outcrossing is selected for if gene flow is low; second, intermediate levels of gene flow could promote mixed mating systems, especially when migration occurs through pollen.

scholarly journals The Effects of Pollen and Seed Migration on Nuclear-Dicytoplasmic Systems. I. Nonrandom Associations and Equilibrium Structure With Both Maternal and Paternal Cytoplasmic Inheritance

Genetics ◽  
2000 ◽  
Vol 155 (2) ◽  
pp. 813-831 ◽  
Author(s):  
Marjorie A Asmussen ◽  
Maria E Orive
Keyword(s):  
Gene Flow ◽  
Theoretical Foundation ◽  
Random Mating ◽  
Equilibrium Structure ◽  
Higher Order ◽  
Plant Population ◽  
New Method ◽  
Mixed Mating ◽  
Seed Migration ◽  
Special Cases

AbstractWe determine the nuclear-dicytoplasmic effects of unidirectional gene flow via pollen and seeds upon a mixed-mating plant population, focusing on nuclear-mitochondrial-chloroplast systems where mitochondria are inherited maternally and chloroplasts paternally, as in many conifers. After first delineating the general effects of admixture (via seeds or individuals) on the nonrandom associations in such systems, we derive the full dicytonuclear equilibrium structure, including when disequilibria may be indicators of gene flow. Substantial levels of permanent two- and three-locus disequilibria can be generated in adults by (i) nonzero disequilibria in the migrant pools or (ii) intermigrant admixture effects via different chloroplast frequencies in migrant pollen and seeds. Additionally, three-locus disequilibria can be generated by higher-order intermigrant effects such as different chloroplast frequencies in migrant pollen and seeds coupled with nuclear-mitochondrial disequilibria in migrant seeds, or different nuclear frequencies in migrant pollen and seeds coupled with mitochondrial-chloroplast disequilibria in migrant seeds. Further insight is provided by considering special cases with seed or pollen migration alone, complete random mating or selfing, or migrant pollen and seeds lacking disequilibria or intermigrant admixture effects. The results complete the theoretical foundation for a new method for estimating pollen and seed migration using joint cytonuclear or dicytonuclear data.

scholarly journals THE EFFECTIVE PROPORTION OF SELF-FERTILIZATION WITH CONSANGUINEOUS MATINGS IN INBRED POPULATIONS

Genetics ◽  
1984 ◽  
Vol 106 (1) ◽  
pp. 139-152
Author(s):  
Kermit Ritland
Keyword(s):  
Mixed Mating ◽  
Selfing Rate ◽  
Genotypic Distribution ◽  
Self Fertilization ◽  
Allelic Segregation ◽  
Mixed Mating Model ◽  
Mating Model ◽  
Inbred Populations ◽  
Biased Estimates ◽  
Independent Parameters

ABSTRACT Allelic segregation at a single locus among offspring derived from matings, including those between inbred relatives, is a combination of two patterns, corresponding to self-fertilization and random outcrossing. The proportion of effective self-fertilization is termed the "effective selfing rate," and it is specified with identity coefficients. The description of the offspring genotypic distribution for a population with mating among relatives requires a set of three independent parameters of genetic and mating structure. One such set is the inbreeding coefficient of parents, the coefficient of kinship between mates and the effective selfing rate. The model used to derive the effective selfing rate distinguishes between the effective selfing rates of inbred vs. outbred parents; the mixed mating model does not distinguish between these two rates. As a result, the mixed mating model usually gives biased estimates of effective selfing, if there is mating among inbred relatives. The procedure for estimation of effective selfing, based upon progeny array data distributed according to the "effective selfing model," is presented, and an example is given.

scholarly journals The Rubisco small subunits in the green algal genus Chloromonas provide insights into evolutionary loss of the eukaryotic carbon-concentrating organelle, the pyrenoid

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ryo Matsuzaki ◽  
Shigekatsu Suzuki ◽  
Haruyo Yamaguchi ◽  
Masanobu Kawachi ◽  
Yu Kanesaki ◽  
...  
Keyword(s):  
Evolutionary Biology ◽  
De Novo ◽  
Small Subunit ◽  
Plant Evolution ◽  
Reaction Products ◽  
Photosynthetic Organisms ◽  
Green Algal ◽  
Interesting Study ◽  
Algal Genus ◽  
The Relationship

Abstract Background Pyrenoids are protein microcompartments composed mainly of Rubisco that are localized in the chloroplasts of many photosynthetic organisms. Pyrenoids contribute to the CO2-concentrating mechanism. This organelle has been lost many times during algal/plant evolution, including with the origin of land plants. The molecular basis of the evolutionary loss of pyrenoids is a major topic in evolutionary biology. Recently, it was hypothesized that pyrenoid formation is controlled by the hydrophobicity of the two helices on the surface of the Rubisco small subunit (RBCS), but the relationship between hydrophobicity and pyrenoid loss during the evolution of closely related algal/plant lineages has not been examined. Here, we focused on, the Reticulata group of the unicellular green algal genus Chloromonas, within which pyrenoids are present in some species, although they are absent in the closely related species. Results Based on de novo transcriptome analysis and Sanger sequencing of cloned reverse transcription-polymerase chain reaction products, rbcS sequences were determined from 11 strains of two pyrenoid-lacking and three pyrenoid-containing species of the Reticulata group. We found that the hydrophobicity of the RBCS helices was roughly correlated with the presence or absence of pyrenoids within the Reticulata group and that a decrease in the hydrophobicity of the RBCS helices may have primarily caused pyrenoid loss during the evolution of this group. Conclusions Although we suggest that the observed correlation may only exist for the Reticulata group, this is still an interesting study that provides novel insight into a potential mechanism determining initial evolutionary steps of gain and loss of the pyrenoid.

Metabolism-driven post-translational modifications of H3K9 in early bovine embryos

Reproduction ◽  
2021 ◽  
Vol 162 (3) ◽  
pp. 181-191
Author(s):  
Jessica Ispada ◽  
Aldcejam Martins da Fonseca Junior ◽  
Otávio Luiz Ramos Santos ◽  
Camila Bruna de Lima ◽  
Erika Cristina dos Santos ◽  
...  
Keyword(s):  
Metabolic Pathways ◽  
Developmental Stages ◽  
De Novo ◽  
Blastocyst Stage ◽  
Developmental Model ◽  
Bovine Embryos ◽  
Acetyl Coa ◽  
Post Translational Modifications ◽  
The Relationship ◽  
Different Levels

Metabolic and molecular profiles were reported as different for bovine embryos with distinct kinetics during the first cleavages. In this study, we used this same developmental model (fast vs slow) to determine if the relationship between metabolism and developmental kinetics affects the levels of acetylation or tri-methylation at histone H3 lysine 9 (H3K9ac and H3K9me3, respectively). Fast and slow developing embryos presented different levels of H3K9ac and H3K9me3 from the earliest stages of development (40 and 96 hpi) and up to the blastocyst stage. For H3K9me3, both groups of embryos presented a wave of demethylation and de novo methylation, although it was more pronounced in fast than slow embryos, resulting in blastocysts with higher levels of this mark. The H3K9ac reprogramming profile was distinct between kinetics groups. While slow embryos presented a wave of deacetylation, followed by an increase in this mark at the blastocyst stage, fast embryos reduced this mark throughout all the developmental stages studied. H3K9me3 differences corresponded to writer and eraser transcript levels, while H3K9ac patterns were explained by metabolism-related gene expression. To verify if metabolic differences could alter levels of H3K9ac, embryos were cultured with sodium-iodoacetate (IA) or dichloroacetate (DCA) to disrupt the glycolytic pathway or increase acetyl-CoA production, respectively. IA reduced H3K9ac while DCA increased H3K9ac in blastocysts. Concluding, H3K9me3 and H3K9ac patterns differ between embryos with different kinetics, the second one explained by metabolic pathways involved in acetyl-CoA production. So far, this is the first study demonstrating a relationship between metabolic differences and histone post-translational modifications in bovine embryos.

scholarly journals Impacts of soil moisture on de novo monoterpene emissions from European beech, Holm oak, Scots pine, and Norway spruce

2015 ◽  
Vol 12 (1) ◽  
pp. 177-191 ◽  
Author(s):  
C. Wu ◽  
I. Pullinen ◽  
S. Andres ◽  
G. Carriero ◽  
S. Fares ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Norway Spruce ◽  
Scots Pine ◽  
De Novo ◽  
European Beech ◽  
Holm Oak ◽  
Factorial Approach ◽  
Moisture Dependence ◽  
The Relationship ◽  
Mild Drought

Abstract. Impacts of soil moisture on de novo monoterpene (MT) emissions from Holm oak, European beech, Scots pine, and Norway spruce were studied in laboratory experiments. The volumetric water content of the soil, Θ, was used as the reference quantity to parameterize the dependency of MT emissions on soil moisture and to characterize the severity of the drought. When Θ dropped from 0.4 m3 × m−3 to ~0.2 m3 × m−3 slight increases of de novo MT emissions were observed but with further progressing drought the emissions decreased to almost zero. In most cases the increases of MT emissions observed under conditions of mild drought were explainable by increases of leaf temperature due to lowered transpirational cooling. When Θ fell below certain thresholds, MT emissions decreased simultaneously with Θ and the relationship between Θ and MT emissions was approximately linear. The thresholds of Θ (0.044–0.19 m3 × m−3) were determined, as well as other parameters required to describe the soil moisture dependence of de novo MT emissions for application in the Model of Emissions of Gases and Aerosols from Nature, MEGAN. A factorial approach was found appropriate to describe the impacts of Θ, temperature, and light. Temperature and Θ influenced the emissions largely independently from each other, and, in a similar manner, light intensity and Θ acted independently on de novo MT emissions. The use of Θ as the reference quantity in a factorial approach was tenable in predicting constitutive de novo MT emissions when Θ changed on a time scale of days. Empirical parameterization with Θ as a reference was only unsuccessful when soil moisture changed rapidly

Genetic Differentiation in Isolated Populations of Hakea carinata (Proteaceae)

1998 ◽  
Vol 46 (6) ◽  
pp. 671 ◽  
Author(s):  
G. J. Starr ◽  
S. M. Carthew
Keyword(s):  
Gene Flow ◽  
Habitat Fragmentation ◽  
Gene Diversity ◽  
South Australia ◽  
Similar Species ◽  
Isolated Populations ◽  
Plant Populations ◽  
Evolutionary Condition ◽  
Private Alleles

Fragmentation of the landscape by human activity has created small, isolated plant populations. Hakea carinata F. Muell. ex Meissner, a sclerophyllous shrub, is common in isolated fragments of vegetation in South Australia. This study investigated whether habitat fragmentation has caused restrictions to gene flow between populations. Gene diversity (HT = 0.317) is average for similar species but little is held within populations (HS = 0.168) and 46.9% of gene diversity is accounted for between populations. Estimates of gene flow are NM = 0.270 (based on FST) and NM = 0.129 (based on private alleles). Populations are substantially selfing (t = 0.111). Small isolated populations appears to be a long-term evolutionary condition in this species rather than a consequence of habitat fragmentation; however, population extinctions are occurring. Conservation will require the reservation of many populations to represent the genetic variation present in the species.

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