scholarly journals Parthenogenesis and the Evolution of Anisogamy

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2467
Author(s):  
George W. A. Constable ◽  
Hanna Kokko
Keyword(s):  
Mating Type ◽  
Positive Feedback ◽  
The Other ◽  
Recent Analysis ◽  
Mating Types ◽  
Additional Costs ◽  
Progeny Size ◽  
Parthenogenetic Reproduction ◽  
The Relationship ◽  
Equal Contribution

Recently, it was pointed out that classic models for the evolution of anisogamy do not take into account the possibility of parthenogenetic reproduction, even though sex is facultative in many relevant taxa (e.g., algae) that harbour both anisogamous and isogamous species. Here, we complement this recent analysis with an approach where we assume that the relationship between progeny size and its survival may differ between parthenogenetically and sexually produced progeny, favouring either the former or the latter. We show that previous findings that parthenogenesis can stabilise isogamy relative to the obligate sex case, extend to our scenarios. We additionally investigate two different ways for one mating type to take over the entire population. First, parthenogenesis can lead to biased sex ratios that are sufficiently extreme that one type can displace the other, leading to de facto asexuality for the remaining type that now lacks partners to fuse with. This process involves positive feedback: microgametes, being numerous, lack opportunities for syngamy, and should they proliferate parthenogenetically, the next generation makes this asexual route even more prominent for microgametes. Second, we consider mutations to strict asexuality in producers of micro- or macrogametes, and show that the prospects of asexual invasion depend strongly on the mating type in which the mutation arises. Perhaps most interestingly, we also find scenarios in which parthenogens have an intrinsic survival advantage yet facultatively sexual isogamous populations are robust to the invasion of asexuals, despite us assuming no genetic benefits of recombination. Here, equal contribution from both mating types to zygotes that are sufficiently well provisioned can outweigh the additional costs associated with syngamy.

scholarly journals Parthenogenesis and the Evolution of Anisogamy

2021 ◽  
Author(s):  
George W. A. Constable ◽  
Hanna Kokko
Keyword(s):  
Mating Type ◽  
Positive Feedback ◽  
The Other ◽  
Entire Population ◽  
Mating Types ◽  
Additional Costs ◽  
Progeny Size ◽  
Parthenogenetic Reproduction ◽  
The Relationship ◽  
Equal Contribution

Recently, it was pointed out (Lehtonen et al., 2021) that classic models for the evolution of anisogamy do not take into account the possibility of parthenogenetic reproduction, even though sex is facultative in many relevant taxa (e.g. algae) that harbour both anisogamous and isogamous species. Here we complement the analysis of (Lehtonen et al., 2021) with an approach where we assume that the relationship between progeny size and its survival may differ between parthenogenetically and sexually produced progeny, favouring either the former or the latter. We show that the findings of (Lehtonen et al., 2021), that parthenogenesis can stabilise isogamy relative to the obligate sex case, extend to our scenarios. We additionally investigate two different ways for one mating type to take over the entire population. First, parthenogenesis can lead to biased sex ratios that are sufficiently extreme that one type can displace the other, leading to de facto asexuality for the remaining type that now lacks partners to fuse with. This process involves positive feedback: microgametes, being numerous, lack opportunities for syngamy, and should they proliferate parthenogenetically, the next generation makes this asexual route even more prominent for microgametes. Second, we consider mutations to strict asexuality in producers of micro- or macrogametes, and show that the prospects of asexual invasion depend strongly on the mating type in which the mutation arises. Perhaps most interestingly, we also find scenarios in which parthenogens have an intrinsic survival advantage yet facultatively sexual isogamous populations are robust to the invasion of asexuals, despite us assuming no genetic benefits of recombination. Here equal contribution from both mating types to zygotes that are sufficiently well provisioned to outweigh the additional costs associated with syngamy.

scholarly journals Phytophthora infestans Mating Types on Tomato (Solanum lycopersicum) in Southern Spain

Plant Disease ◽  
2007 ◽  
Vol 91 (1) ◽  
pp. 109-109 ◽  
Author(s):  
J. M. Segura ◽  
M. de Cara ◽  
M. Santos ◽  
J. Tello
Keyword(s):  
Phytophthora Infestans ◽  
Mating Type ◽  
Agar Medium ◽  
The Other ◽  
Southern Spain ◽  
White Mold ◽  
Mating Types ◽  
Tomato Plants ◽  
Cornell University ◽  
Tomato Seeds

During 2004, an unusual spread of Phytophthora infestans on tomato plants in greenhouses located in Almería and Granada provinces, southern Spain, was observed. Infected plants had water-soaked, brown spots on leaves and stems and necrotic areas with white mold on the surface of fruits. Three isolates were obtained by plating diseased tissue on V8 juice agar medium and maintained on rye agar at 18°C. These isolates were analyzed for the mating type. Crosses were carried out using V8 juice agar and rye agar. The two parental isolates US1 (A1) and US8 (A2) were both provided by W. E. Fry, Cornell University, Ithaca, NY. Two of the Spanish isolates were homothallic and the other isolate belonged to the uncommon mating type A1A2. To confirm the occurrence of the two mating types, 43 single-sporangium progeny were produced and analyzed from the A1A2 mating type. Thirty eight isolates were A1, two were A2, one was A1A2 mating type, and two were sterile. Assessment of five single-sporangium progeny from the homothallic type resulted in two A1, two homothallic, and one sterile isolate. A1A2 isolates produced oospores when crossed with either A1 or A2, but not when self-crossed. Previously, the A1A2 mating type has been found in Israel in the field and was obtained from oospores produced on tomato seeds (2,3). Since 2003, mating types of P. infestans isolates recovered from potato (60) and tomato (8) in southern Spain have been characterized. Seventy-five percent of the isolates recovered from potato were A1 and 25% were A2 mating types. Isolates recovered from tomato were 50% A1 and 50% A2 (1). To our knowledge, this is the first report of the occurrence of the A1A2 mating type and homothallic P. infestans isolates on tomato in Spain. References: (1) E. Andujar et al. Congr. Sociedad Española de Fitopatol. 12:244, 2004. (2) E. Rubin and Y. Cohen. Phytoparasitica 32:237, 2004. (3) E. Rubin and Y. Cohen. Plant Dis. 90:741, 2006.

scholarly journals Cloning the mating types of the heterothallic fungus Podospora anserina: developmental features of haploid transformants carrying both mating types.

Genetics ◽  
1991 ◽  
Vol 128 (3) ◽  
pp. 539-547 ◽  
Author(s):  
M Picard ◽  
R Debuchy ◽  
E Coppin
Keyword(s):  
Mating Type ◽  
Gene Replacement ◽  
Podospora Anserina ◽  
The Other ◽  
Mating Types ◽  
Body Development ◽  
Fruiting Body Development ◽  
Mat Locus ◽  
Functional Analyses ◽  
Developmental Features

Abstract DNAs that encode the mating-type functions (mat+ and mat-) of the filamentous fungus Podospora anserina were cloned with the use of the mating-type A probe from Neurospora crassa. Cloning the full mat information was ascertained through gene replacement experiments. Molecular and functional analyses of haploid transformants carrying both mating types lead to several striking conclusions. Mat+ mat- strains are dual maters. However, the resident mat information is dominant to the mat information added by transformation with respect to fruiting body development and ascus production. Moreover, when dual mating mat+ mat- strains are crossed to mat+ or mat- testers, there is strong selection, after fertilization, that leads to the loss from the mat+ mat- nucleus of the mat information that matches that of the tester. Finally, the mat locus contains at least two domains, one sufficient for fertilization, the other necessary for sporulation.

scholarly journals Frequency and Genetic Diversity of theMAT1Locus of Histoplasma capsulatum Isolates in Mexico and Brazil

2013 ◽  
Vol 12 (7) ◽  
pp. 1033-1038 ◽  
Author(s):  
Gabriela Rodríguez-Arellanes ◽  
Carolina Nascimento de Sousa ◽  
Mauro de Medeiros-Muniz ◽  
José A. Ramírez ◽  
Cláudia V. Pizzini ◽  
...  
Keyword(s):  
Mating Type ◽  
Internal Transcribed Spacer ◽  
Histoplasma Capsulatum ◽  
Geographical Origin ◽  
Soil Samples ◽  
The Other ◽  
Clinical Samples ◽  
Mating Types ◽  
Content Type ◽  
Type Strains

ABSTRACTTheMAT1-1andMAT1-2idiomorphs associated with theMAT1locus ofHistoplasma capsulatumwere identified by PCR. A total of 28 fungal isolates, 6 isolates from human clinical samples and 22 isolates from environmental (infected bat and contaminated soil) samples, were studied. Among the 14 isolates from Mexico, 71.4% (95% confidence interval [95% CI], 48.3% to 94.5%) were of theMAT1-2genotype, whereas 100% of the isolates from Brazil were of theMAT1-1genotype. EachMAT1idiomorphic region was sequenced and aligned, using the sequences of the G-217B (+ mating type) and G-186AR (− mating type) strains as references. BLASTn analyses of theMAT1-1andMAT1-2sequences studied correlated with their respective + and − mating type genotypes. Trees were generated by the maximum likelihood (ML) method to search for similarity among isolates of eachMAT1idiomorph. AllMAT1-1isolates originated from Brazilian bats formed a well-defined group; three isolates from Mexico, the G-217B strain, and a subgroup encompassing all soil-derived isolates and two clinical isolates from Brazil formed a second group; last, one isolate (EH-696P) from a migratory bat captured in Mexico formed a third group of theMAT1-1genotype. TheMAT1-2idiomorph formed two groups, one of which included twoH. capsulatumisolates from infected bats that were closely related to the G-186AR strain. The other group was formed by two human isolates and six isolates from infected bats. Concatenated ML trees, with internal transcribed spacer 1 (ITS1) -5.8S-ITS2 andMAT1-1orMAT1-2sequences, support the relatedness ofMAT1-1orMAT1-2isolates.H. capsulatummating types were associated with the geographical origin of the isolates, and all isolates from Brazil correlated with their environmental sources.

scholarly journals Formation of the phenotypic structure of Phytophthora infestans population in Poland during 1987-2001

2013 ◽  
Vol 55 (1) ◽  
pp. 389-400 ◽  
Author(s):  
Hanna Zarzycka ◽  
Sylwester Sobkowiak ◽  
Renata Lebecka ◽  
Beata Tatarowska
Keyword(s):  
Phytophthora Infestans ◽  
Virulence Factors ◽  
Mating Type ◽  
The Other ◽  
Mating Types ◽  
Polish Population ◽  
Other Hand ◽  
Sexual Recombination ◽  
Phenotypic Structure ◽  
High Level

The formation of phenotypic structure of <i>P.infestans</i> population in Poland was determined by analyzing 1603 isolates collected from 1987 to 2001. The race complexity, low at the beginning of experiment, has been increasing from year to year and reached in 2001 a high level 7,2 virulence factors per isolate. The single and less composed races dominating firstly in the population were replaced gradually by more composed races. The virulence factors 1, 2, 3, 4, 7 and 11 occurred most frequently, but factors 5 and 8 were noted sporadically. The A2 mating type was detected in 1988 at first and since that time its occurrence has been noted in Polish population each year. The oospores were formed in potato tissues. Race diversity, low at the beginning of the investigation, reached a peak in 1996-2001 . During 1987-1990 weakly and middly aggressive phenotypes dominated in Polish population. In the later period very aggressive isolates were more frequent. Phenotypic race similarity of <i>P.infestans</i> populations in 1987 and 2001 was very low. The race structure of 1987 population was totally different from the race structure of populations of the next years. It was probably due to migration of new pathotypes. On the other hand the variation in complexity, diversity and similarity of races, as well as in aggressiveness observed in later years of investigation can be caused by the presence of both mating types and sexual recombination.

scholarly journals Distribution of Mating Type and Sexual Status in Chinese Rice Blast Populations

Plant Disease ◽  
2009 ◽  
Vol 93 (3) ◽  
pp. 238-242 ◽  
Author(s):  
Jing Zeng ◽  
Shujie Feng ◽  
Jiangqiao Cai ◽  
Ling Wang ◽  
Fei Lin ◽  
...  
Keyword(s):  
Mating Type ◽  
Magnaporthe Oryzae ◽  
Rice Blast ◽  
Rice Blast Fungus ◽  
The Other ◽  
Fertility Level ◽  
Mating Types ◽  
Field Isolates ◽  
Sexual Status ◽  
Blast Fungus

A collection of 520 field isolates of the rice blast fungus (Magnaporthe oryzae) originating from five provinces in China was assessed for mating type and sexual fertility. One of the two tester sets was composed of isolates collected from barley and the other from rice. Two mating types (MAT1-1 and MAT1-2) were identified among the 443 fertile isolates. The two mating types were roughly in balance with one another in the southwestern region but one or the other predominated in the southeastern and southern regions. Male-only fertile isolates were the most common, and only a few hermaphroditic and no female only fertile isolates were detected. The fertility level of the isolates was variable. Isolates from Jiangsu were more fertile than those from Fujian. The mating capacity of the testers collected from barley was higher than that of those collected from rice, but this was because the MAT1-2 testers differed very significantly from one another. In contrast, the mating capacities of the two MAT1-1 testers were similar to one another.

TIME-LAPSE STUDIES OF CONJUGATION IN COSMARIUM BOTRYTIS: II. PSEUDOCONJUGATION AND AN ANISOGAMOUS MATING BEHAVIOR INVOLVING CHEMOTAXIS

1967 ◽  
Vol 45 (4) ◽  
pp. 483-493 ◽  
Author(s):  
P. E. Brandham
Keyword(s):  
Cell Division ◽  
Mating Behavior ◽  
Mating Type ◽  
Time Lapse ◽  
The Other ◽  
Mating Types ◽  
Continuous Observation ◽  
Gamete Fusion ◽  
Use Of Time ◽  
Morphological Variants

Techniques were devised for the continuous observation of the 24-hour process of cell pairing and gamete fusion in the morphologically isogamous heterothallic desmid Cosmarium botrytis by the use of time-lapse ciné-photomicrography. Several stages of early conjugation are described and their duration measured. Many pairings are temporary and the cells dissociate after a few hours. This phenomenon is termed pseudoconjugation. Dissociation is frequently caused by the nuclear or cell division of one partner. By the use of morphological variants to determine the mating type of individual cells observed in a mixture of two mating types, an anisogamous behavior during pairing was noted. In any particular cross between two compatible clones, cells of one clone become relatively immobile or passive during conjugation while those of the other clone are attracted towards them, probably by chemotaxis. This anisogamous behavior is not rigidly linked with mating type since some plus clones are either passive or chemo-tactically active, depending upon which minus clone they are crossed with. An interim explanation of the mechanism is given.NoteThe term “anisogamous” is usually defined as a difference in size or morphology between compatible gametes. In this paper the definition is extended to cover differences in the mating behavior of gametes that are otherwise identical.

The Relationship Between Suicidal Thinking and Dating Violence in a Sample of Adolescent Abortion Patients

Crisis ◽  
2011 ◽  
Vol 32 (5) ◽  
pp. 246-253 ◽  
Author(s):  
Gretchen E. Ely ◽  
William R. Nugent ◽  
Julie Cerel ◽  
Mholi Vimbba
Keyword(s):  
Unintended Pregnancy ◽  
Dating Violence ◽  
Young Women ◽  
Psychosocial Problems ◽  
The Other ◽  
Assessment Scale ◽  
Adolescent Dating Violence ◽  
Adolescent Relationships ◽  
Suicidal Thinking ◽  
The Relationship

Background: The relationship between suicidal thinking and adolescent dating violence has not been previously explored in a sample of adolescent abortion patients. Aims: This paper highlights a study where the relationship between dating violence and severity of suicidal thinking was examined in a sample of 120 young women ages 14–21 seeking to terminate an unintended pregnancy. Methods: The Multidimensional Adolescent Assessment Scale and the Conflict in Adolescent Relationships Scale was used to gather information about psychosocial problems and dating violence so that the relationship between the two problems could be examined, while controlling for the other psychosocial problems. Results: The results suggest that dating violence was related to severity of suicidal thinking, and that the magnitude of this relationship was moderated by the severity of problems with aggression. Conclusions: Specifically, as the severity of participant’s general problems with aggression increased, the magnitude of the relationship between dating violence and severity of suicidal thinking increased. Limitations of the study and implications for practice are discussed.

Emotional Impact Feedback Changes How We Remember Negative Autobiographical Experiences

2010 ◽  
Vol 57 (5) ◽  
pp. 354-359 ◽  
Author(s):  
Melanie K. T. Takarangi ◽  
Deryn Strange
Keyword(s):  
Well Being ◽  
The Other ◽  
Personal Perspective ◽  
Emotional Impact ◽  
Potential Mechanism ◽  
Negative Experiences ◽  
Negative Memory ◽  
The Relationship ◽  
Negative Memories ◽  
Over Time

When people are told that their negative memories are worse than other people’s, do they later remember those events differently? We asked participants to recall a recent negative memory then, 24 h later, we gave some participants feedback about the emotional impact of their event – stating it was more or less negative compared to other people’s experiences. One week later, participants recalled the event again. We predicted that if feedback affected how participants remembered their negative experiences, their ratings of the memory’s characteristics should change over time. That is, when participants are told that their negative event is extremely negative, their memories should be more vivid, recollected strongly, and remembered from a personal perspective, compared to participants in the other conditions. Our results provide support for this hypothesis. We suggest that external feedback might be a potential mechanism in the relationship between negative memories and psychological well-being.

Haematocrit: Relationships with Blood Lipids, Blood Pressure and other Cardiovascular Risk Factors

1994 ◽  
Vol 72 (01) ◽  
pp. 058-064 ◽  
Author(s):  
Goya Wannamethee ◽  
A Gerald Shaper
Keyword(s):  
Physical Activity ◽  
Risk Factors ◽  
Blood Pressure ◽  
Body Mass Index ◽  
Cardiovascular Risk ◽  
Cardiovascular Risk Factors ◽  
Alcohol Intake ◽  
Blood Lipids ◽  
The Other ◽  
The Relationship

SummaryThe relationship between haematocrit and cardiovascular risk factors, particularly blood pressure and blood lipids, has been examined in detail in a large prospective study of 7735 middle-aged men drawn from general practices in 24 British towns. The analyses are restricted to the 5494 men free of any evidence of ischaemic heart disease at screening.Smoking, body mass index, physical activity, alcohol intake and lung function (FEV1) were factors strongly associated with haematocrit levels independent of each other. Age showed a significant but small independent association with haematocrit. Non-manual workers had slightly higher haematocrit levels than manual workers; this difference increased considerably and became significant after adjustment for the other risk factors. Diabetics showed significantly lower levels of haematocrit than non-diabetics. In the univariate analysis, haematocrit was significantly associated with total serum protein (r = 0*18), cholesterol (r = 0.16), triglyceride (r = 0.15), diastolic blood pressure (r = 0.17) and heart rate (r = 0.14); all at p <0.0001. A weaker but significant association was seen with systolic blood pressure (r = 0.09, p <0.001). These relationships remained significant even after adjustment for age, smoking, body mass index, physical activity, alcohol intake, lung function, presence of diabetes, social class and for each of the other biological variables; the relationship with systolic blood pressure was considerably weakened. No association was seen with blood glucose and HDL-cholesterol. This study has shown significant associations between several lifestyle characteristics and the haematocrit and supports the findings of a significant relationship between the haematocrit and blood lipids and blood pressure. It emphasises the role of the haematocrit in assessing the risk of ischaemic heart disease and stroke in individuals, and the need to take haematocrit levels into account in determining the importance of other cardiovascular risk factors.

Sign in / Sign up

Export Citation Format

Share Document