scholarly journals Selection for mitonuclear co-adaptation could favour the evolution of two sexes

2011 ◽  
Vol 279 (1734) ◽  
pp. 1865-1872 ◽  
Author(s):  
Zena Hadjivasiliou ◽  
Andrew Pomiankowski ◽  
Robert M. Seymour ◽  
Nick Lane
Keyword(s):  
Mutation Rates ◽  
Mitochondrial Genomes ◽  
Uniparental Inheritance ◽  
Mating Types ◽  
Mitochondrial Inheritance ◽  
Free Living ◽  
Critical Function ◽  
Ploidy Levels ◽  
Wide Range ◽  
Selection For

Mitochondria are descended from free-living bacteria that were engulfed by another cell between one and a half to two billion years ago. A redistribution of DNA led to most genetic information being lost or transferred to a large central genome in the nucleus, leaving a residual genome in each mitochondrion. Oxidative phosphorylation, the most critical function of mitochondria, depends on the functional compatibility of proteins encoded by both the nucleus and mitochondria. We investigate whether selection for adaptation between the nuclear and mitochondrial genomes (mitonuclear co-adaptation) could, in principle, have promoted uniparental inheritance of mitochondria and thereby the evolution of two mating types or sexes. Using a mathematical model, we explore the importance of the radical differences in ploidy levels, sexual and asexual modes of inheritance, and mutation rates of the nucleus and mitochondria. We show that the major features of mitochondrial inheritance, notably uniparental inheritance and bottlenecking, enhance the co-adaptation of mitochondrial and nuclear genes and therefore improve fitness. We conclude that, under a wide range of conditions, selection for mitonuclear co-adaptation favours the evolution of two distinct mating types or sexes in sexual species.

scholarly journals Rapid, Selective Digestion of Mitochondrial DNA in Accordance With the matA Hierarchy of Multiallelic Mating Types in the Mitochondrial Inheritance of Physarum polycephalum

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 963-975 ◽  
Author(s):  
Y Moriyama ◽  
S Kawano
Keyword(s):  
Mitochondrial Dna ◽  
Physarum Polycephalum ◽  
Nuclear Fusion ◽  
The Other ◽  
Pcr Analysis ◽  
Uniparental Inheritance ◽  
Mating Types ◽  
Mitochondrial Inheritance ◽  
Biparental Inheritance ◽  
Mitochondrial Nucleoids

Abstract Although mitochondria are inherited uniparentally in nearly all eukaryotes, the mechanism for this is unclear. When zygotes of the isogamous protist Physarum polycephalum were stained with DAPI, the fluorescence of mtDNA in half of the mitochondria decreased simultaneously to give small spots and then disappeared completely ∼1.5 hr after nuclear fusion, while the other mitochondrial nucleoids and all of the mitochondrial sheaths remained unchanged. PCR analysis of single zygote cells confirmed that the loss was limited to mtDNA from one parent. The vacant mitochondrial sheaths were gradually eliminated by 60 hr after mating. Using six mating types, the transmission patterns of mtDNA were examined in all possible crosses. In 39 of 60 crosses, strict uniparental inheritance was confirmed in accordance with a hierarchy of relative sexuality. In the other crosses, however, mtDNA from both parents was transmitted to plasmodia. The ratio of parental mtDNA was estimated to be from 1:1 to 1:10-4. Nevertheless, the matA hierarchy was followed. In these crosses, the mtDNA was incompletely digested, and mtDNA replicated during subsequent plasmodial development. We conclude that the rapid, selective digestion of mtDNA promotes the uniparental inheritance of mitochondria; when this fails, biparental inheritance occurs.

scholarly journals Germline Bottlenecks and the Evolutionary Maintenance of Mitochondrial Genomes

Genetics ◽  
1998 ◽  
Vol 149 (4) ◽  
pp. 2135-2146 ◽  
Author(s):  
Carl T Bergstrom ◽  
Jonathan Pritchard
Keyword(s):  
Equilibrium Distribution ◽  
Genetic Model ◽  
Mutation Rates ◽  
Mitochondrial Genomes ◽  
Uniparental Inheritance ◽  
Small Populations ◽  
Deleterious Mutations ◽  
Muller's Ratchet ◽  
Large Populations ◽  
Muller’S Ratchet

Abstract Several features of the biology of mitochondria suggest that mitochondria might be susceptible to Muller's ratchet and other forms of evolutionary degradation: Mitochondria have predominantly uniparental inheritance, appear to be nonrecombining, and have high mutation rates producing significant deleterious variation. We demonstrate that the persistence of mitochondria may be explained by recent data that point to a severe “bottleneck” in the number of mitochondria passing through the germline in humans and other mammals. We present a population-genetic model in which deleterious mutations arise within individual mitochondria, while selection operates on assemblages of mitochondria at the level of their eukaryotic hosts. We show that a bottleneck increases the efficacy of selection against deleterious mutations by increasing the variance in fitness among eukaryotic hosts. We investigate both the equilibrium distribution of deleterious variation in large populations and the dynamics of Muller's ratchet in small populations. We find that in the absence of the ratchet, a bottleneck leads to improved mitochondrial performance and that, over a longer time scale, a bottleneck acts to slow the progression of the ratchet.

scholarly journals Ecological selection for small microbial genomes along a temperate-to-thermal soil gradient

2018 ◽  
Author(s):  
Jackson W. Sorensen ◽  
Taylor K. Dunivin ◽  
Tammy C. Tobin ◽  
Ashley Shade
Keyword(s):  
Genome Size ◽  
Inverse Relationship ◽  
Microbial Genome ◽  
Ancestral State ◽  
Free Living ◽  
Ecological Selection ◽  
Wide Range ◽  
Pearson's R ◽  
Selection For ◽  
Pearson’S R

SummarySmall bacterial and archaeal genomes provide insights into the minimal requirements for life1and seem to be widespread on the microbial phylogenetic tree2. We know that evolutionary processes, mainly selection and drift, can result in microbial genome reduction3,4. However, we do not know the precise environmental pressures that constrain genome size in free-living microorganisms. A study including isolates5has shown that bacteria with high optimum growth temperatures, including thermophiles, often have small genomes6. It is unclear how well this relationship may extend generally to microorganisms in nature7,8, and in particular to those microbes inhabiting complex and highly variable environments like soil3,6,9. To understand the genomic traits of thermally-adapted microorganisms, here we investigated bacterial and archaeal metagenomes from a 45°C gradient of temperate-to-thermal soils overlying the ongoing Centralia, Pennsylvania (USA) coal seam fire. There was a strong relationship between average genome size and temperature: hot soils had small genomes relative to ambient soils (Pearson’s r = −0.910, p < 0.001). There was also an inverse relationship between soil temperature and cell size (Pearson’s r = −0.65, p = 0.021), providing evidence that cell and genome size in the wild are together constrained by temperature. Notably, hot soils had different community structures than ambient soils, implicating ecological selection for thermo-tolerant cells that had small genomes, rather than contemporary genome streamlining within the local populations. Hot soils notably lacked genes for described two-component regulatory systems and antimicrobial production and resistance. Our work provides field evidence for the inverse relationship between microbial genome size and temperature requirements in a diverse, free-living community over a wide range of temperatures that support microbial life. Our findings demonstrate that ecological selection for thermophiles and thermo-tolerant microorganisms can result in smaller average genome sizesin situ, possibly because they have small genomes reminiscent of a more ancestral state.

scholarly journals Evidence for mitochondrial DNA polymorphism and uniparental inheritance in the cellular slime mold Polysphondylium pallidum: effect of intraspecies mating on mitochondrial DNA transmission.

Genetics ◽  
1990 ◽  
Vol 124 (3) ◽  
pp. 607-613
Author(s):  
M Mirfakhrai ◽  
Y Tanaka ◽  
K Yanagisawa
Keyword(s):  
Mitochondrial Dna ◽  
Slime Mold ◽  
Cellular Slime Mold ◽  
Uniparental Inheritance ◽  
Mating Types ◽  
Mitochondrial Inheritance ◽  
Mitochondrial Dna Polymorphism ◽  
Polysphondylium Pallidum ◽  
Length Polymorphisms ◽  
Cellular Slime

Abstract Restriction fragment length polymorphisms (RFLPs) were used as markers to monitor mitochondrial inheritance in the cellular slime mold, Polysphondylium pallidum. When two opposite mating types (mat1 and mat2) of closely related strains were crossed, all the haploid progeny regardless of mating type inherited their mitochondrial DNA from the mat2 parent only. When opposite mating types from more distantly related strains were crossed, most of the progeny also inherited their mitochondrial DNA from the mat2 parent, but some inherited their mitochondrial DNA from the mat1 parent. In both cases however, the transmission of mitochondrial DNA was uniparental, since in every individual progeny only one type of mitochondrial DNA exists. Moreover, in crosses involving more distantly related strains all the progeny of a single macrocyst were shown to contain the same type of mitochondrial DNA. These findings are discussed in regard to mechanisms of transmission and the possible involvement of nuclear genes in the control of transmission of mitochondrial DNA in Polysphondylium.

Le fonti, i metodi e le narrazioni della storia della videoarte in Italia negli anni Settanta

2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Lisa Parola
Keyword(s):  
Comparative Study ◽  
Contemporary Art ◽  
Narrative Structure ◽  
Video Art ◽  
Wide Range ◽  
History Of ◽  
Selection For ◽  
The Many ◽  
Art And Architecture ◽  
Selection Of

This essay derives from the primary need to make order between direct and indirect sources available for the reconstruction of the history of video art in Italy in the seventies. In fact, during the researches for the Ph.D. thesis it became clear that in most cases it is difficult to define, in terms of facts, which of the different historiographies should be taken into consideration to deepen the study of video art in Italy. Beyond legitimate differences of perspectives and methods, historiographical narratives all share similar issues and narrative structure. The first intention of the essay is, therefore, to compare the different historiographic narratives on Italian video art of the seventies, verifying their genealogy, the sources used and the accuracy of the narrated facts. For the selection of the corpus, it was decided to analyze in particular monographic volumes dealing with the history of the origins of video art in Italy. The aim was, in fact, to get a wide range of types of "narrations", as in the case of contemporary art and architecture magazines, which are examined in the second part of the essay. After the selection, for an analytical and comparative study of the various historiography, the essay focuses only on the Terza Biennale Internazionale della Giovane Pittura. Gennaio ’70. Comportamenti, oggetti e mediazioni (Third International Biennial of Young Painting. January '70. Behaviors, Objects and Mediations, 1970, Bologna), the exhibition which - after Lucio Fontana's pioneering experiments - is said to be the first sign of the arrival of videotape in Italy (called at the time videorecording), curated by Renato Barilli, Tommaso Trini, Andrea Emiliani and Maurizio Calvesi. The narration given so far of this exhibition appeared more mythological than historical and could be compared structurally to that of the many numerous beginnings that historiographyies on international video art identify as ‘first’ and ‘generative’. In the first part of the essay the 'facts' related to Gennaio ’70, as narrated by historiography on video art, are compared. In the second part the survey is carried out through some of the direct sources identified during the research, with the aim of answering to questions raised by the comparison between historiographies. Concluding, it is important to underline that the tapes containing the videos transmitted have not been found and seem to have disappeared since the ending of the exhibition. Nevertheless, the deepening of the works and documentation transmitted during the exhibition is possible thanks to other types of sources which give us many valuable information regarding video techniques and practices at the beginning of 1970 in Italy.

scholarly journals Pioneer: A New Tool for Coding of Multi-Level Finite State Machines Based on Evolution Programming

VLSI Design ◽  
1994 ◽  
Vol 2 (2) ◽  
pp. 105-116
Author(s):  
S. Muddappa ◽  
R. Z. Makki ◽  
Z. Michalewicz ◽  
S. Isukapalli
Keyword(s):  
Finite State Machines ◽  
Mutation Rates ◽  
Natural Phenomenon ◽  
State Machines ◽  
State Assignment ◽  
Wide Range ◽  
Finite State ◽  
Multi Level ◽  
Crossover And Mutation ◽  
Evolution Programs

In this paper we present a new tool for the encoding of multi-level finite state machines based on the concept of evolution programming. Evolution programs are stochastic adaptive algorithms, based on the paradigm of genetic algorithms whose search methods model some natural phenomenon: genetic inheritance and Darwinian strife for survival. Crossover and mutation rates were tailored to the state assignment problem experimentally. We present results over a wide range of MCNC benchmarks which demonstrate the effectiveness of the new tool. The results show that evolution programs can be effectively applied to state assignment.

scholarly journals Why and How to Switch to Genomic Selection: Lessons From Plant and Animal Breeding Experience

2021 ◽  
Vol 12 ◽  
Author(s):  
◽  
Aline Fugeray-Scarbel ◽  
Catherine Bastien ◽  
Mathilde Dupont-Nivet ◽  
Stéphane Lemarié
Keyword(s):  
Genetic Diversity ◽  
Genomic Selection ◽  
Plant Species ◽  
Animal Species ◽  
Animal Breeding ◽  
Breeding Cycle ◽  
Breeding Programs ◽  
The Third ◽  
Wide Range ◽  
Selection For

The present study is a transversal analysis of the interest in genomic selection for plant and animal species. It focuses on the arguments that may convince breeders to switch to genomic selection. The arguments are classified into three different “bricks.” The first brick considers the addition of genotyping to improve the accuracy of the prediction of breeding values. The second consists of saving costs and/or shortening the breeding cycle by replacing all or a portion of the phenotyping effort with genotyping. The third concerns population management to improve the choice of parents to either optimize crossbreeding or maintain genetic diversity. We analyse the relevance of these different bricks for a wide range of animal and plant species and sought to explain the differences between species according to their biological specificities and the organization of breeding programs.

Molecular and physiological comparison ofAzospirillumspp. isolated fromRhizoctonia solanimycelia, wheat rhizosphere, and human skin wounds

2004 ◽  
Vol 50 (4) ◽  
pp. 291-297 ◽  
Author(s):  
Michael F Cohen ◽  
Xiang Y Han ◽  
Mark Mazzola
Keyword(s):  
Rhizoctonia Solani ◽  
Azospirillum Brasilense ◽  
Type Strain ◽  
Apple Orchard ◽  
Rrna Gene ◽  
Bacterial Strains ◽  
Free Living ◽  
Root Pathogen ◽  
Wide Range ◽  
Orchard Soil

Four phenotypically similar bacterial strains isolated from fungal, plant, and human sources were identified as Azospirillum species. Strains RC1 and LOD4 were isolated from the mycelium of the apple root pathogen Rhizoctonia solani AG 5 and from the rhizosphere of wheat grown in apple orchard soil, respectively. Strains C610 and F4626 isolated from human wounds were previously misclassified as Roseomonas genomospecies 3 and 6. All four strains demonstrated close similarities in 16S rRNA gene sequences, having [Formula: see text]97% identity to Azospirillum brasilense type strain ATCC 29145 and <90% identity to Roseomonas gilardii, the Roseomonas type strain. Extensive phenotypic similarities among the four strains included the ability of free-living cells to fix N2. Cells of strains RC1, LOD4, and C610 but not of strain F4626 could be induced to flocculate by incubation with 10 mmol·L–1glycerol or fructose in medium containing 0.5 mmol·L–1NO3–. Our results indicate a wide range of potential sources for Azospirillum spp. with the isolation of Azospirillum spp. from human wounds warranting further investigation.Key words: Azospirillum brasilense, Roseomonas fauriae, flocculation, Rhizoctonia solani.

scholarly journals Evolution of pathogen and parasite avoidance behaviours

2018 ◽  
Vol 373 (1751) ◽  
pp. 20170256 ◽  
Author(s):  
Cecile Sarabian ◽  
Val Curtis ◽  
Rachel McMullan
Keyword(s):  
Avoidance Behaviour ◽  
Disease Avoidance ◽  
Behavioural Science ◽  
Free Living ◽  
Society Meeting ◽  
Neural Architecture ◽  
Trade Offs ◽  
Wide Range ◽  
Parasite Avoidance ◽  
Behavioural Adaptations

All free-living animals are subject to intense selection pressure from parasites and pathogens resulting in behavioural adaptations that can help potential hosts to avoid falling prey to parasites. This special issue on the evolution of parasite avoidance behaviour was compiled following a Royal Society meeting in 2017. Here we have assembled contributions from a wide range of disciplines including genetics, ecology, parasitology, behavioural science, ecology, psychology and epidemiology on the disease avoidance behaviour of a wide range of species. Taking an interdisciplinary and cross-species perspective allows us to sketch out the strategies, mechanisms and consequences of parasite avoidance and to identify gaps and further questions. Parasite avoidance strategies must include avoiding parasites themselves and cues to their presence in conspecifics, heterospecifics, foods and habitat. Further, parasite avoidance behaviour can be directed at constructing parasite-retardant niches. Mechanisms of parasite avoidance behaviour are generally less well characterized, though nematodes, rodents and human studies are beginning to elucidate the genetic, hormonal and neural architecture that allows animals to recognize and respond to cues of parasite threat. While the consequences of infection are well characterized in humans, we still have much to learn about the epidemiology of parasites of other species, as well as the trade-offs that hosts make in parasite defence versus other beneficial investments like mating and foraging. Finally, in this overview we conclude that it is legitimate to use the word ‘ disgust' to describe parasite avoidance systems, in the same way that ‘fear' is used to describe animal predator avoidance systems. Understanding disgust across species offers an excellent system for investigating the strategies, mechanisms and consequences of behaviour and could be a vital contribution towards the understanding and conservation of our planet's ecosystems. This article is part of the Theo Murphy meeting issue ‘Evolution of pathogen and parasite avoidance behaviours'.

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