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da Silva VS, Machado CR. Sex in protists: A new perspective on the reproduction mechanisms of trypanosomatids. Genet Mol Biol 2022; 45:e20220065. [PMID: 36218381 PMCID: PMC9552303 DOI: 10.1590/1678-4685-gmb-2022-0065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/07/2022] [Indexed: 11/04/2022] Open
Abstract
The Protist kingdom individuals are the most ancestral representatives of
eukaryotes. They have inhabited Earth since ancient times and are currently
found in the most diverse environments presenting a great heterogeneity of life
forms. The unicellular and multicellular algae, photosynthetic and heterotrophic
organisms, as well as free-living and pathogenic protozoa represents the protist
group. The evolution of sex is directly associated with the origin of eukaryotes
being protists the earliest protagonists of sexual reproduction on earth. In
eukaryotes, the recombination through genetic exchange is a ubiquitous mechanism
that can be stimulated by DNA damage. Scientific evidences support the
hypothesis that reactive oxygen species (ROS) induced DNA damage can promote
sexual recombination in eukaryotes which might have been a decisive factor for
the origin of sex. The fact that some recombination enzymes also participate in
meiotic sex in modern eukaryotes reinforces the idea that sexual reproduction
emerged as consequence of specific mechanisms to cope with mutations and
alterations in genetic material. In this review we will discuss about origin of
sex and different strategies of evolve sexual reproduction in some protists such
that cause human diseases like malaria, toxoplasmosis, sleeping sickness, Chagas
disease, and leishmaniasis.
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Affiliation(s)
- Verônica Santana da Silva
- Universidade Federal de Minas Gerais, Departamento de Genética,
Ecologia e Evolução, Belo Horizonte, MG, Brazil
| | - Carlos Renato Machado
- Universidade Federal de Minas Gerais, Departamento de Bioquímica e
Imunologia, Belo Horizonte, MG, Brazil
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Cisternas‐Fuentes A, Jogesh T, Broadhead GT, Raguso RA, Skogen KA, Fant JB. Evolution of selfing syndrome and its influence on genetic diversity and inbreeding: A range-wide study in Oenothera primiveris. AMERICAN JOURNAL OF BOTANY 2022; 109:789-805. [PMID: 35596689 PMCID: PMC9320852 DOI: 10.1002/ajb2.1861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 06/15/2023]
Abstract
PREMISE To avoid inbreeding depression, plants have evolved diverse breeding systems to favor outcrossing, such as self-incompatibility. However, changes in biotic and abiotic conditions can result in selective pressures that lead to a breakdown in self-incompatibility. The shift to increased selfing is commonly associated with reduced floral features, lower attractiveness to pollinators, and increased inbreeding. We tested the hypothesis that the loss of self-incompatibility, a shift to self-fertilization (autogamy), and concomitant evolution of the selfing syndrome (reduction in floral traits associated with cross-fertilization) will lead to increased inbreeding and population differentiation in Oenothera primiveris. Across its range, this species exhibits a shift in its breeding system and floral traits from a self-incompatible population with large flowers to self-compatible populations with smaller flowers. METHODS We conducted a breeding system assessment, evaluated floral traits in the field and under controlled conditions, and measured population genetic parameters using RADseq data. RESULTS Our results reveal a bimodal transition to the selfing syndrome from the west to the east of the range of O. primiveris. This shift includes variation in the breeding system and the mating system, a reduction in floral traits (flower diameter, herkogamy, and scent production), a shift to greater autogamy, reduced genetic diversity, and increased inbreeding. CONCLUSIONS The observed variation highlights the importance of range-wide studies to understand breeding system variation and the evolution of the selfing syndrome within populations and species.
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Affiliation(s)
- Anita Cisternas‐Fuentes
- Negaunee Institute for Plant Conservation Science and ActionChicago Botanic Garden1000 Lake Cook RoadGlencoeIllinois60035USA
- Plant Biology and ConservationNorthwestern University2205 Tech DriveEvanstonIllinois60208USA
- Department of Biological ScienceClemson University132 Long HallClemsonSouth Carolina29631USA
| | - Tania Jogesh
- Negaunee Institute for Plant Conservation Science and ActionChicago Botanic Garden1000 Lake Cook RoadGlencoeIllinois60035USA
| | - Geoffrey T. Broadhead
- Department of Entomology and NematologyUniversity of Florida1881 Natural Area DriveGainesvilleFlorida32611USA
| | - Robert A. Raguso
- Department of Neurobiology and BehaviorCornell UniversityW361 Mudd HallIthacaNew York14853USA
| | - Krissa A. Skogen
- Negaunee Institute for Plant Conservation Science and ActionChicago Botanic Garden1000 Lake Cook RoadGlencoeIllinois60035USA
- Plant Biology and ConservationNorthwestern University2205 Tech DriveEvanstonIllinois60208USA
| | - Jeremie B. Fant
- Negaunee Institute for Plant Conservation Science and ActionChicago Botanic Garden1000 Lake Cook RoadGlencoeIllinois60035USA
- Plant Biology and ConservationNorthwestern University2205 Tech DriveEvanstonIllinois60208USA
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Kim JH, Ajani P, Murray SA, Kim JH, Lim HC, Teng ST, Lim PT, Han MS, Park BS. Sexual reproduction and genetic polymorphism within the cosmopolitan marine diatom Pseudo-nitzschia pungens. Sci Rep 2020; 10:10653. [PMID: 32606343 PMCID: PMC7326933 DOI: 10.1038/s41598-020-67547-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 06/10/2020] [Indexed: 01/10/2023] Open
Abstract
Different clades belonging to the cosmopolitan marine diatom Pseudo-nitzschia pungens appear to be present in different oceanic environments, however, a ‘hybrid zone’, where populations of different clades interbreed, has also been reported. Many studies have investigated the sexual reproduction of P. pungens, focused on morphology and life cycle, rather than the role of sexual reproduction in mixing the genomes of their parents. We carried out crossing experiments to determine the sexual compatibility/incompatibility between different clades of P. pungens, and examined the genetic polymorphism in the ITS2 region. Sexual reproduction did not occur only between clades II and III under any of experimental temperature conditions. Four offspring strains were established between clade I and III successfully. Strains established from offspring were found interbreed with other offspring strains as well as viable with their parental strains. We confirmed the hybrid sequence patterns between clades I and III and found novel sequence types including polymorphic single nucleotide polymorphisms (SNPs) in the offspring strains. Our results implicate that gene exchange and mixing between different clades are still possible, and that sexual reproduction is a significant ecological strategy to maintain the genetic diversity within this diatom species.
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Affiliation(s)
- Jin Ho Kim
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea.,Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje, 53201, Republic of Korea.,DNA Analysis Division, National Forensic Service, Seoul, 158-707, Republic of Korea
| | - Penelope Ajani
- Climate Change Cluster, University of Technology, Sydney, 2007, Australia
| | - Shauna A Murray
- Climate Change Cluster, University of Technology, Sydney, 2007, Australia
| | - Joo-Hwan Kim
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea
| | | | - Sing Tung Teng
- Faculty of Research Science and Technology, University Malaysia Sarawak, 94300, Kota Samarahan, Malaysia
| | - Po Teen Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, 16020, Bachok, Kelantan, Malaysia
| | - Myung-Soo Han
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea.
| | - Bum Soo Park
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea. .,Marine Ecosystem Research Center, Korea Institute of Ocean Science and Technology, Busan, 49111, Republic of Korea.
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Karnaukhova N, Selyutina I, Syeva S. Some of issues of endemic species reproductive biology of Southern Siberia Hedysarum L. BIO WEB OF CONFERENCES 2020. [DOI: 10.1051/bioconf/20202400032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The seed productivity of endemic species of the genus Hedysarum L. in southern Siberia was studied. It is established that the reproduction of these species is carried out only by seed. Flowering occurs in June, the number of flowers in the inflorescence ranges from 12.3 to 19.1. The efficiency of fruit formation (% of the set beans from the number of flowers) differs significantly: the maximum values are marked for H. austrosibiricum, H. turczaninovii and H. sangilense (90.7-74.1 %), the minimum values are marked for the rare H. minussinense, H. chaiyrakanicum, H. zundukii (35.3 – 47.2 %). A decrease in the number of seeds that are set compared to the number of ovules, caused by various reasons, leads to a significant decrease in the RSP compared to the PSP. The percentage of semenification in the studied species is highest in the endemics H. austrosibiricum, H. sangilense and H. turczaninovii (56.545.1 %), the minimum – in the rare H. zundukii, H. minussinense and H. chaiyrakanicum (9.8-36.5 %).
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de Meeûs T, Balloux F. Clonal reproduction and linkage disequilibrium in diploids: a simulation study. INFECTION GENETICS AND EVOLUTION 2004; 4:345-51. [PMID: 15374532 DOI: 10.1016/j.meegid.2004.05.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Revised: 04/30/2004] [Accepted: 05/03/2004] [Indexed: 11/17/2022]
Abstract
Estimating the rate of clonal reproduction in natural population of diploid organisms is recognised as being problematic and even the detection of strictly clonal populations is often controversial. One well-acknowledged signature of clonal reproduction is the generation of non-random associations between loci. Linkage disequilibrium (LD) is thus often used for estimating the amount of clonal reproduction. Here we explore with computer simulations the effect of the rate of clonal reproduction on LD estimates obtained from different estimators within a comprehensive parameter range. None of the LD estimators studied is able to accurately measure the proportion of clonal (or sexual) reproduction on its own, due to strong bias, incoherent behaviour, or huge variances. The joint use of several statistics is thus recommended for the estimation rates of clonal reproduction in natural populations. We hope that our work will provide useful tools for the study of clonal diploids, many of which can only be studied with molecular markers, as it is the case for medically important parasites.
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Affiliation(s)
- Thierry de Meeûs
- Génétique et Evolution des Maladies Infectieuses, Equipe Evolution des Systèmes Symbiotiques, UMR 2724 CNRS-IRD, BP 64501, 911 Av. Agropolis, 34394 Montpellier Cedex 5, France.
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Abstract
The consequences of variable rates of clonal reproduction on the population genetics of neutral markers are explored in diploid organisms within a subdivided population (island model). We use both analytical and stochastic simulation approaches. High rates of clonal reproduction will positively affect heterozygosity. As a consequence, nearly twice as many alleles per locus can be maintained and population differentiation estimated as F(ST) value is strongly decreased in purely clonal populations as compared to purely sexual ones. With increasing clonal reproduction, effective population size first slowly increases and then points toward extreme values when the reproductive system tends toward strict clonality. This reflects the fact that polymorphism is protected within individuals due to fixed heterozygosity. Contrarily, genotypic diversity smoothly decreases with increasing rates of clonal reproduction. Asexual populations thus maintain higher genetic diversity at each single locus but a lower number of different genotypes. Mixed clonal/sexual reproduction is nearly indistinguishable from strict sexual reproduction as long as the proportion of clonal reproduction is not strongly predominant for all quantities investigated, except for genotypic diversities (both at individual loci and over multiple loci).
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Affiliation(s)
- François Balloux
- I.C.A.P.B., University of Edinburgh, Edinburgh EH9 3JT, Scotland, United Kingdom.
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Ryndin A, Kirzhner V, Nevo E, Korol A. Polymorphism maintenance in populations with mixed random mating and apomixis subjected to stabilizing and cyclical selection. J Theor Biol 2001; 212:169-81. [PMID: 11531383 DOI: 10.1006/jtbi.2001.2365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We analysed a diploid population model with a mixed breeding system that includes panmixia and apomixis. Each individual produces a part (ss) of its progeny by random mating, the remainder (1-ss) being a result of precise copying (vegetative reproduction or apomixis) of the parental genotype. Both constant and periodically varying selection regimes were considered. In the main model, the selected trait was controlled by two diallelic additive or semidominant loci, A/a and B/b, whereas the parameter of breeding system (ss) was genotype-independent. A numerical iteration of the evolutionary equations were used to evaluate the proportion (V) of population trajectories converging to internal (polymorphic) fixed points. The results were the following. (a) A complex pattern of dependence of polymorphism stability on interaction among the breeding system, recombination rate, and the genetic architecture of the selected trait emerged. (b) The recombination provided some advantage to sex at intermediate period lengths and strong-to-moderate selection intensities. (c) The complex limiting behavior (CLB) was quite compatible with sexual reproduction, at least within the framework of pure genetic (not including variations in population density) models of multilocus varying selection.
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Affiliation(s)
- A Ryndin
- Department of Mathematics, Institute of Evolution, University of Haifa, Mount Carmel, Haifa 31905, Israel
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Abstract
The idea that sex functions to provide variation for natural selection to act upon was first advocated by August Weismann and it has dominated much discussion on the evolution of sex and recombination since then. The goal of this paper is to further extend this hypothesis and to assess its place in a larger body of theory on the evolution of sex and recombination. A simple generic model is developed to show how fitness variation and covariation interact with selection for recombination and illustrate some important implications of the hypothesis: (1) the advantage of sex and recombination can accrue both to reproductively isolated populations and to modifiers segregating within populations, but the former will be much larger than the latter; (2) forces of degradation that are correlated across loci within an individual can reduce or reverse selection for increased recombination; and (3) crossing-over (which can occur at different places in different meioses) will create more variability than having multiple chromosomes and so will have more influence on the efficacy of selection. Several long-term selection experiments support Weismann's hypothesis, including those showing a greater response to selection in populations with higher rates of recombination and higher rates of recombination evolving as a correlated response to selection for some other character. Weismann's hypothesis is also consistent with the sporadic distribution of obligate asexuality, which indicates that clones have a higher rate of extinction than sexuals. Weismann's hypothesis is then discussed in light of other patterns in the distribution of sexuality versus asexuality. To account for variation in the frequency of obligate asexuality in different taxa, a simple model is developed in which this frequency is a function of three parameters: the rate of clonal origin, the initial fitness of clones when they arise, and the rate at which that fitness declines over time. Variation in all three parameters is likely to be important in explaining the distribution of obligate asexuality. Facultative asexuality also exists, and for this to be stable it seems there must be ecological differences between the sexual and asexual propagules as well as genetic differences. Finally, the timing of sex in cyclical parthenogens is most likely set to minimize the opportunity costs of sex. None of these patterns contradict Weismann's hypothesis, but they do show that many additional principles unrelated to the function of sex are required to fully explain its distribution. Weismann's hypothesis is also consistent with what we know about the mechanics and molecular genetics of recombination, in particular the tendency for chromatids to recombine with a homolog rather than a sister chromatid at meiosis, which is opposite to what they do during mitosis. However, molecular genetic studies have shown that cis-acting sites at which recombination is initiated are lost by gene conversion as a result, a factor that can be expected to affect many fine details in the evolution of recombination. In summary, although Weismann's hypothesis must be considered the leading candidate for the function of sex and recombination, nevertheless, many additional principles are needed to fully account for their evolution.
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Affiliation(s)
- A Burt
- Department of Biology, Imperial College, United Kingdom.
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Charlesworth B, Barton NH. Recombination load associated with selection for increased recombination. Genet Res (Camb) 1996; 67:27-41. [PMID: 8919888 DOI: 10.1017/s0016672300033450] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Experiments on Drosophila suggest that genetic recombination may result in lowered fitness of progeny (a 'recombination load'). This has been interpreted as evidence either for a direct effect of recombination on fitness, or for the maintenance of linkage disequilibria by epistatic selection. Here we show that such a recombination load is to be expected even if selection favours increased genetic recombination. This is because of the fact that, although a modifier may suffer an immediate loss of fitness if it increases recombination, it eventually becomes associated with a higher additive genetic variance in fitness, which allows a faster response to direction selection. This argument applies to mutation-selection balance with synergistic epistasis, directional selection on quantitative traits, and ectopic exchange among transposable elements. Further experiments are needed to determine whether the selection against recombination due to the immediate load is outweighed by the increased additive variance in fitness produced by recombination.
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Affiliation(s)
- B Charlesworth
- Department of Ecology and Evolution, University of Chicago, IL 60637-1573, USA.
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Abstract
Models of the evolutionary advantages of sex and genetic recombination due to directional selection on a quantitative trait are analysed. The models assume that the trait is controlled by many additive genes. A nor-optimal selection function is used, in which the optimum either moves steadily in one direction, follows an autocorrelated linear Markov process or a random walk, or varies cyclically. The consequences for population mean fitness of a reduction in genetic variance, due to a shift from sexual to asexual reproduction are examined. It is shown that a large reduction in mean fitness can result from such a shift in the case of a steadily moving optimum, under light conditions. The conditions are much more stringent with a cyclical or randomly varying environment, especially if the autocorrelation for a random environment is small. The conditions for spread of a rare modifier affecting the rate of genetic recombination are also examined, and the strength of selection on such a modifier determined. Again, the case of a steadily moving optimum is most favourable for the evolution of increased recombination. The selection pressure on a recombination modifier when a trait is subject to strong truncation selection is calculated, and shown to be large enough to account for observed increases in recombination associated with artificial selection. Theoretical and empirical evidence relevant to evaluating the importance of this model for the evolution of sex and recombination is discussed.
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Affiliation(s)
- B Charlesworth
- Department of Ecology and Evolution, University of Chicago, IL 60637-1573
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Abstract
We review what is known about the transcriptional inactivation and condensation of heteromorphic sex chromosomes in contrast to the activation of homomorphic sex chromosomes during meiotic prephase in animals. We relate these cytological and transcriptional features to the recombination status of the sex chromosomes. We propose that sex chromosome condensation is a meiotic adaptation to prevent the initiation of potentially damaging recombination events in nonhomologous regions of the X and Y chromosome.
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Affiliation(s)
- B D McKee
- Department of Zoology, University of Tennessee, Knoxville 37996
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DYER PAULS, INGRAM DAVIDS, JOHNSTONE KEITH. THE CONTROL OF SEXUAL MORPHOGENESIS IN THE ASCOMYCOTINA. Biol Rev Camb Philos Soc 1992. [DOI: 10.1111/j.1469-185x.1992.tb01189.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ash C. Sex: why bother? PARASITOLOGY TODAY (PERSONAL ED.) 1992; 8:291. [PMID: 15463643 DOI: 10.1016/0169-4758(92)90094-i] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
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Mutation-selection balance and the evolutionary advantage of sex and recombination. Genet Res (Camb) 1990; 55:199-221. [PMID: 2394378 DOI: 10.1017/s0016672300025532] [Citation(s) in RCA: 273] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Mutation-selection balance in a multi-locus system is investigated theoretically, using a modification of Bulmer's infinitesimal model of selection on a normally-distributed quantitative character, taking the number of mutations per individual (n) to represent the character value. The logarithm of the fitness of an individual with n mutations is assumed to be a quadratic, decreasing function of n. The equilibrium properties of infinitely large asexual populations, random-mating populations lacking genetic recombination, and random-mating populations with arbitrary recombination frequencies are investigated. With 'synergistic' epistasis on the scale of log fitness, such that log fitness declines more steeply as n increases, it is shown that equilibrium mean fitness is least for asexual populations. In sexual populations, mean fitness increases with the number of chromosomes and with the map length per chromosome. With 'diminishing returns' epistasis, such that log fitness declines less steeply as n increases, mean fitness behaves in the opposite way. Selection on asexual variants and genes affecting the rate of genetic recombination in random-mating populations was also studied. With synergistic epistasis, zero recombination always appears to be disfavoured, but free recombination is disfavoured when the mutation rate per genome is sufficiently small, leading to evolutionary stability of maps of intermediate length. With synergistic epistasis, an asexual mutant is unlikely to invade a sexual population if the mutation rate per diploid genome greatly exceeds unity. Recombination is selectively disadvantageous when there is diminishing returns epistasis. These results are compared with the results of previous theoretical studies of this problem, and with experimental data.
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