scholarly journals FACTORS INFLUENCING THE EFFECT OF SEGREGATION DISTORTION IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1984 ◽  
Vol 107 (3) ◽  
pp. 375-393
Author(s):  
Rayla Greenberg Temin ◽  
Marta Marthas
Keyword(s):  
Segregation Distortion ◽  
Pericentric Inversion ◽  
Natural Populations ◽  
Special Test ◽  
Recessive Lethal ◽  
Factors Influencing ◽  
Direct Measurements ◽  
Tight Linkage ◽  
In The Wild

ABSTRACT The major components of the SD system have been examined in two natural populations of D. melanogaster to investigate how SD behaves and is maintained in nature and to estimate its impact and efficiency. A twofold approach was used: (1) direct measurements of segregation distortion in wild males and (2) measurement of sensitivity of wild SD  + chromosomes to SD action. Characterization of newly isolated SD chromosomes and of a large number of SD  + chromosomes from nature demonstrated that (1) SD can operate efficiently in the wild genome: 45% of SD/SD  + males collected from nature had k values larger than 0.70. (2) Forty-three of 44 newly recovered SD chromosomes are of the SD-72 type, having a small pericentric inversion that maintains tight linkage among the Sd, E(SD) and Rsp loci in the SD complex. In 1956, most SD chromosomes in Madison lacked this inversion. (3) Only 12 of the 44 SD chromosomes carried a recessive lethal (compared with five of six in 1956), and many of the viable SD chromosomes were fertile as homozygotes, indicating that SD homozygotes need not have obvious reductions in fitness. (4) Among more than 500 wild chromosomes assayed for response to distortion by a strong SD, at least 40-50% were sensitive, about 33% were partially sensitive and 17% were insensitive. This frequency of sensitives is higher than in reports from some other populations. An estimated 12% of the wild chromosomes were classified as true Rspi by their constellation of effects, including a special test of ability to cause self-distortion of a "suicide" chromosome, R(cn)-10. In a direct assay with R(cn)-10, an independent sample of 99 chromosomes from nature gave 30% putative Rspi. Thus, these populations contain in the range of 12-30% Rspi. (5) Chromosomes supersensitive to SD, previously described for certain laboratory stocks, were also found to coexist in nature with SD. (6) Profiles of wild chromosomes with a panel of three or four different SD testers suggest a series of allelic alternatives at the Rsp locus including supersensitive, sensitive, semisensitive and insensitive, and that loci other than Rsp may also be important in determining the effect of SD in nature.

scholarly journals HIGH-RESOLUTION CHARACTERIZATION OF MALE ORNAMENTATION AND REEVALUATION OF SEX LINKAGE IN GUPPIES

2020 ◽  
Author(s):  
Jake Morris ◽  
Iulia Darolti ◽  
Wouter van der Bijl ◽  
Judith E. Mank
Keyword(s):  
High Resolution ◽  
Natural Populations ◽  
Colour Pattern ◽  
Sexually Dimorphic ◽  
Animal Colouration ◽  
In The Wild ◽  
Colour Changes ◽  
Colour Patterns ◽  
Male Ornaments

AbstractColouration plays a key role in the ecology of many species, influencing how an organism interacts with its environment, other species and conspecifics. Guppies are sexually dimorphic, with males displaying sexually selected colouration resulting from female preference. Previous work has suggested that much of guppy colour pattern variation is Y-linked. However, it remains unclear how many individual colour patterns are Y-linked in natural populations as much of the previous work has focused on phenotypes either not found in the wild, or aggregate measures such as total colour area. Moreover, ornaments have traditionally been identified and delineated by hand, and computational methods now make it possible to extract pixels and identify ornaments more automatedly, reducing the potential for human bias. Here we developed a pipeline for automated ornament identification and high-resolution image analysis of male guppy colour patterns and applied it to a multigenerational pedigree. Our results show that loci controlling the presence or absence of individual male ornaments in our population are not predominantly Y-linked. However, we find that ornaments of similar colour are not independent of each other, and modifier loci that affect whole animal colouration appear to be at least partially Y-linked. Considering these results, Y-linkage of individual ornaments may not be important in driving colour changes in natural populations of guppies, or in expansions of the non-recombining Y region, while Y-linked modifier loci that affect aggregate traits may well play an important role.

scholarly journals High-resolution characterization of male ornamentation and re-evaluation of sex linkage in guppies

2020 ◽  
Vol 287 (1937) ◽  
pp. 20201677
Author(s):  
Jake Morris ◽  
Iulia Darolti ◽  
Wouter van der Bijl ◽  
Judith E. Mank
Keyword(s):  
High Resolution ◽  
Natural Populations ◽  
Colour Pattern ◽  
Sexually Dimorphic ◽  
In The Wild ◽  
Colour Changes ◽  
Colour Patterns ◽  
Male Ornaments ◽  
Automated Methods

Coloration plays a key role in the ecology of many species, influencing how an organism interacts with its environment, other species and conspecifics. Guppies are sexually dimorphic, with males displaying sexually selected coloration resulting from female preference. Previous work has suggested that much of guppy colour pattern variation is Y-linked. However, it remains unclear how many individual colour patterns are Y-linked in natural populations as much of the previous work has focused on phenotypes either not found in the wild, or aggregate measures such as total colour area. Moreover, ornaments have traditionally been identified and delineated by hand, and computational methods now make it possible to extract pixels and identify ornaments with automated methods, reducing the potential for human bias. Here we developed a pipeline for semi-automated ornament identification and high-resolution image analysis of male guppy colour patterns and applied it to a multigenerational pedigree. Our results show that loci controlling the presence or the absence of individual male ornaments in our population are not predominantly Y-linked. However, we find that ornaments of similar colour are not independent of each other, and modifier loci that affect whole animal coloration appear to be at least partially Y-linked. Considering these results, Y-linkage of individual ornaments may not be important in driving colour changes in natural populations of guppies, or in expansions of the non-recombining Y region, while Y-linked modifier loci that affect aggregate traits may well play an important role.

scholarly journals Multi-Camera Based Setup for Geometrical Measurement of Free-Falling Molten Glass Gob

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1041
Author(s):  
Mazhar Hussain ◽  
Mattias O’Nils ◽  
Jan Lundgren
Keyword(s):  
Free Fall ◽  
Frame Rate ◽  
Geometrical Parameters ◽  
Contactless Method ◽  
Molten Material ◽  
Dynamic Changes ◽  
Direct Measurements ◽  
Molten Materials ◽  
Free Falling

High temperatures complicate the direct measurements needed for continuous characterization of the properties of molten materials such as glass. However, the assumption that geometrical changes when the molten material is in free-fall can be correlated with material characteristics such as viscosity opens the door to a highly accurate contactless method characterizing small dynamic changes. This paper proposes multi-camera setup to achieve accuracy close to the segmentation error associated with the resolution of the images. The experimental setup presented shows that the geometrical parameters can be characterized dynamically through the whole free-fall process at a frame rate of 600 frames per second. The results achieved show the proposed multi-camera setup is suitable for estimating the length of free-falling molten objects.

scholarly journals Evolutionary dynamics of spore killers.

Genetics ◽  
1993 ◽  
Vol 135 (3) ◽  
pp. 923-930 ◽  
Author(s):  
M J Nauta ◽  
R F Hoekstra
Keyword(s):  
Life Cycle ◽  
Segregation Distortion ◽  
Population Genetic ◽  
Field Data ◽  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Additional Advantage ◽  
Genetic Modeling ◽  
Spore Killing ◽  
Ascospore Formation

Abstract Spore killing in ascomycetes is a special form of segregation distortion. When a strain with the Killer genotype is crossed to a Sensitive type, spore killing is expressed by asci with only half the number of ascospores as usual, all surviving ascospores being of the Killer type. Using population genetic modeling, this paper explores conditions for invasion of Spore killers and for polymorphism of Killers, Sensitives and Resistants (which neither kill, nor get killed), as found in natural populations. The models show that a population with only Killers and Sensitives can never be stable. The invasion of Killers and stable polymorphism only occur if Killers have some additional advantage during the process of spore killing. This may be due to the effects of local sib competition or some kind of "heterozygous" advantage in the stage of ascospore formation or in the short diploid stage of the life cycle. This form of segregation distortion appears to be essentially different from other, well-investigated forms, and more field data are needed for a better understanding of spore killing.

Genetic characterization of novel polymorphic microsatellite markers for Epilobium nankotaizanense (Onagraceae), an endemic and threatened herb in Taiwan

2021 ◽  
pp. 1-4
Author(s):  
Yu-Wei Tseng ◽  
Chi-Chun Huang ◽  
Chih-Chiang Wang ◽  
Chiuan-Yu Li ◽  
Kuo-Hsiang Hung
Keyword(s):  
Microsatellite Markers ◽  
Natural Populations ◽  
Conservation Strategy ◽  
Sequencing Data ◽  
Germplasm Collections ◽  
The Family ◽  
Conservation Genetic ◽  
Population Sizes ◽  
Polymorphic Microsatellite

Abstract Epilobium belongs to the family Onagraceae, which consists of approximately 200 species distributed worldwide, and some species have been used as medicinal plants. Epilobium nankotaizanense is an endemic and endangered herb that grows in the high mountains in Taiwan at an elevation of more than 3300 m. Alpine herbs are severely threatened by climate change, which leads to a reduction in their habitats and population sizes. However, only a few studies have addressed genetic diversity and population genetics. In the present study, we developed a new set of microsatellite markers for E. nankotaizanense using high-throughput genome sequencing data. Twenty polymorphic microsatellite markers were developed and tested on 30 individuals collected from three natural populations. These loci were successfully amplified, and polymorphisms were observed in E. nankotaizanense. The number of alleles per locus (A) ranged from 2.000 to 3.000, and the observed (Ho) and expected (He) heterozygosities ranged from 0.000 to 0.929 and from 0.034 to 0.631, respectively. The developed polymorphic microsatellite markers will be useful in future conservation genetic studies of E. nankotaizanense as well as for developing an effective conservation strategy for this species and facilitating germplasm collections and sustainable utilization of other Epilobium species.

Characterization of Enterococcus faecium mutants resistant to mundticin KS, a class IIa bacteriocin

Microbiology ◽  
2003 ◽  
Vol 149 (10) ◽  
pp. 2901-2908 ◽  
Author(s):  
Youko Sakayori ◽  
Mizuho Muramatsu ◽  
Satoshi Hanada ◽  
Yoichi Kamagata ◽  
Shinichi Kawamoto ◽  
...  
Keyword(s):  
Enterococcus Faecium ◽  
Antimicrobial Agents ◽  
Wild Type Strain ◽  
Unsaturated Fatty Acids ◽  
Class I ◽  
Wild Type ◽  
Food Preservatives ◽  
In The Wild ◽  
Resistant Mutants

The emergence and spread of mutants resistant to bacteriocins would threaten the safety of using bacteriocins as food preservatives. To determine the physiological characteristics of resistant mutants, mutants of Enterococcus faecium resistant to mundticin KS, a class IIa bacteriocin, were isolated. Two types of mutant were found that had different sensitivities to other antimicrobial agents such as nisin (class I) and kanamycin. Both mutants were resistant to mundticin KS even in the absence of Mg2+ ions. The composition of unsaturated fatty acids in the resistant mutants was significantly increased in the presence of mundticin KS. The composition of the phospholipids in the two resistant mutants also differed from those in the wild-type strain. The putative zwitterionic amino-containing phospholipid in both mutants significantly increased, whereas amounts of phosphatidylglycerol and cardiolipin decreased. These changes in membrane structure may influence resistance of enterococci to class IIa and class I bacteriocins.

An ecological explanation for hyperallometric scaling of reproduction

2021 ◽  
Author(s):  
Tomos Potter ◽  
Anja Felmy
Keyword(s):  
Body Size ◽  
Reproductive Output ◽  
Resource Competition ◽  
Natural Populations ◽  
Scaling Exponent ◽  
Wild Populations ◽  
Wet Season ◽  
Size Dependent ◽  
In The Wild ◽  
The Relationship

AbstractIn wild populations, large individuals have disproportionately higher reproductive output than smaller individuals. We suggest an ecological explanation for this observation: asymmetry within populations in rates of resource assimilation, where greater assimilation causes both increased reproduction and body size. We assessed how the relationship between size and reproduction differs between wild and lab-reared Trinidadian guppies. We show that (i) reproduction increased disproportionately with body size in the wild but not in the lab, where effects of resource competition were eliminated; (ii) in the wild, the scaling exponent was greatest during the wet season, when resource competition is strongest; and (iii) detection of hyperallometric scaling of reproduction is inevitable if individual differences in assimilation are ignored. We propose that variation among individuals in assimilation – caused by size-dependent resource competition, niche expansion, and chance – can explain patterns of hyperallometric scaling of reproduction in natural populations.

The Role of Fluid Flow Phenomena in the Czochralski Growth of Oxides.

1981 ◽  
Vol 9 ◽  
Author(s):  
D.C. Miller
Keyword(s):  
Fluid Flow ◽  
Defect Density ◽  
Major Effect ◽  
Czochralski Growth ◽  
Simulation Experiments ◽  
Direct Measurements ◽  
Flow Geometry ◽  
Flow Phenomena

ABSTRACTIn the Czochralski growth of single crystals from large melts, fluid flow phenomena have a major effect on interface shape, growth striations, defect density and the length of crystals which can be grown from a melt of given volume and thermal geometry. Because of the technical difficulties encountered in making direct measurements in molten oxides, simulation experiments have been extensively utilized to gain insight into melt behavior.Both temperature profile and flow geometry results from simulation experiments are discussed. This data is supported by direct melt observations and results from the characterization of grown crystals. When reviewed together, this information offers new insights into the complex behavior of Czochralski growth processes, including the role of thermal gradients, crystal rotation, and surface tension driven (Marangoni) convection.

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