scholarly journals Evolutionary mysteries in meiosis

2016 ◽  
Author(s):  
Thomas Lenormand ◽  
Jan Engelstadter ◽  
Susan E. Johnston ◽  
Erik Wijnker ◽  
Christoph R. Haag
Keyword(s):  
Life Cycles ◽  
Sexual Life ◽  
Model Organisms ◽  
Evolutionary Significance ◽  
Crossover Interference ◽  
Selective Pressures

AbstractMeiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often “weird” features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.

scholarly journals Evolutionary mysteries in meiosis

2016 ◽  
Vol 371 (1706) ◽  
pp. 20160001 ◽  
Author(s):  
Thomas Lenormand ◽  
Jan Engelstädter ◽  
Susan E. Johnston ◽  
Erik Wijnker ◽  
Christoph R. Haag
Keyword(s):  
Sexual Reproduction ◽  
Life Cycles ◽  
Sexual Life ◽  
Model Organisms ◽  
Evolutionary Significance ◽  
Crossover Interference ◽  
Selective Pressures

Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often ‘weird’ features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes. This article is part of the themed issue ‘Weird sex: the underappreciated diversity of sexual reproduction’.

Dormant plasticity of rotifer diapausing eggs in response to predator kairomones

2021 ◽  
Vol 17 (11) ◽  
Author(s):  
Xuwang Yin ◽  
Yuecen Zhao ◽  
Shuang Tian ◽  
Xiaochun Li
Keyword(s):  
Life Cycles ◽  
Freshwater Ecosystems ◽  
Sexual Life ◽  
Hatching Rate ◽  
Ecological Implication ◽  
Maternal Environment ◽  
Predator Prey ◽  
Diapausing Eggs ◽  
Embryonic Exposure ◽  
Phenotypic Responses

In freshwater ecosystems, hatching strategy of diapausing eggs (DEs) under predation risk has important ecological implication for zooplankters. Although kairomones released by predators can induce phenotypic responses of prey, hatching patterns of DEs in response to kairomones have received contradictory conclusions in zooplankters. Maternal environment may also affect hatching strategy of DEs during predator–prey interactions. We used classical Brachionus calyciflorus – Asplanchna models to determine the timing and proportion of DE hatching in association with parental and embryonic exposure to kairomones. Results obtained from two Brachionus clones supported the hypothesis that DEs could detect Asplanchna kairomones and adjust hatching patterns. DEs showed early and synchronous hatching patterns in the environment with kairomones. Data also supported the prediction that DEs could gain information about predators from maternal environments and adjusted their hatching pattern in response to the presence of kairomones. Compared with DEs from Brachionus mothers not exposed to kairomones, DEs produced by mothers that were experienced with kairomones attained a higher hatching rate when both of them hatched in the environment either with or without kairomones. Our results suggest that DEs of B . calyciflorus possess dormant plasticity to defend against predation from Asplanchna , which may be regulated by maternal environmental effects during sexual life cycles.

scholarly journals Genome sequence of the model rice variety KitaakeX

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Rashmi Jain ◽  
Jerry Jenkins ◽  
Shengqiang Shu ◽  
Mawsheng Chern ◽  
Joel A. Martin ◽  
...  
Keyword(s):  
Functional Genomics ◽  
De Novo ◽  
Rice Variety ◽  
Rice Genome ◽  
Life Cycles ◽  
Model Organisms ◽  
High Quality ◽  
Rice Varieties ◽  
Protein Coding ◽  
High Quality Genome

Abstract Background The availability of thousands of complete rice genome sequences from diverse varieties and accessions has laid the foundation for in-depth exploration of the rice genome. One drawback to these collections is that most of these rice varieties have long life cycles, and/or low transformation efficiencies, which limits their usefulness as model organisms for functional genomics studies. In contrast, the rice variety Kitaake has a rapid life cycle (9 weeks seed to seed) and is easy to transform and propagate. For these reasons, Kitaake has emerged as a model for studies of diverse monocotyledonous species. Results Here, we report the de novo genome sequencing and analysis of Oryza sativa ssp. japonica variety KitaakeX, a Kitaake plant carrying the rice XA21 immune receptor. Our KitaakeX sequence assembly contains 377.6 Mb, consisting of 33 scaffolds (476 contigs) with a contig N50 of 1.4 Mb. Complementing the assembly are detailed gene annotations of 35,594 protein coding genes. We identified 331,335 genomic variations between KitaakeX and Nipponbare (ssp. japonica), and 2,785,991 variations between KitaakeX and Zhenshan97 (ssp. indica). We also compared Kitaake resequencing reads to the KitaakeX assembly and identified 219 small variations. The high-quality genome of the model rice plant KitaakeX will accelerate rice functional genomics. Conclusions The high quality, de novo assembly of the KitaakeX genome will serve as a useful reference genome for rice and will accelerate functional genomics studies of rice and other species.

scholarly journals From single nuclei to whole genome assemblies

2019 ◽  
Author(s):  
Merce Montoliu-Nerin ◽  
Marisol Sánchez-García ◽  
Claudia Bergin ◽  
Manfred Grabherr ◽  
Barbara Ellis ◽  
...  
Keyword(s):  
Single Cell ◽  
Large Scale ◽  
Genomic Data ◽  
Life Cycles ◽  
Genomic Research ◽  
Metagenomic Data ◽  
Model Organisms ◽  
Genomic Study ◽  
And Function ◽  
Genome Assemblies

SummaryA large proportion of Earth's biodiversity constitutes organisms that cannot be cultured, have cryptic life-cycles and/or live submerged within their substrates1–4. Genomic data are key to unravel both their identity and function5. The development of metagenomic methods6,7 and the advent of single cell sequencing8–10 have revolutionized the study of life and function of cryptic organisms by upending the need for large and pure biological material, and allowing generation of genomic data from complex or limited environmental samples. Genome assemblies from metagenomic data have so far been restricted to organisms with small genomes, such as bacteria11, archaea12 and certain eukaryotes13. On the other hand, single cell technologies have allowed the targeting of unicellular organisms, attaining a better resolution than metagenomics8,9,14–16, moreover, it has allowed the genomic study of cells from complex organisms one cell at a time17,18. However, single cell genomics are not easily applied to multicellular organisms formed by consortia of diverse taxa, and the generation of specific workflows for sequencing and data analysis is needed to expand genomic research to the entire tree of life, including sponges19, lichens3,20, intracellular parasites21,22, and plant endophytes23,24. Among the most important plant endophytes are the obligate mutualistic symbionts, arbuscular mycorrhizal (AM) fungi, that pose an additional challenge with their multinucleate coenocytic mycelia25. Here, the development of a novel single nuclei sequencing and assembly workflow is reported. This workflow allows, for the first time, the generation of reference genome assemblies from large scale, unbiased sorted, and sequenced AM fungal nuclei circumventing tedious, and often impossible, culturing efforts. This method opens infinite possibilities for studies of evolution and adaptation in these important plant symbionts and demonstrates that reference genomes can be generated from complex non-model organisms by isolating only a handful of their nuclei.

Advances in the Evolution and Ecology of 13- and 17-Year Periodical Cicadas

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Chris Simon ◽  
John R. Cooley ◽  
Richard Karban ◽  
Teiji Sota
Keyword(s):  
Character Displacement ◽  
Prime Numbers ◽  
Life Cycles ◽  
Model Organisms ◽  
Annual Review ◽  
Publication Date ◽  
Reproductive Character Displacement ◽  
Temporal Isolation ◽  
Periodical Cicadas ◽  
Major Review

Apart from model organisms, 13- and 17-year periodical cicadas (Hemiptera: Cicadidae: Magicicada) are among the most studied insects in evolution and ecology. They are attractive subjects because they predictably emerge in large numbers; have a complex biogeography shaped by both spatial and temporal isolation; and include three largely sympatric, parallel species groups that are, in a sense, evolutionary replicates. Magicicada are also relatively easy to capture and manipulate, and their spectacular, synchronized mass emergences facilitate outreach and citizen science opportunities. Since the last major review, studies of Magicicada have revealed insights into reproductive character displacement and the nature of species boundaries, provided additional examples of allochronic speciation, found evidence for repeated and parallel (but noncontemporaneous) evolution of 13- and 17-year life cycles, quantified the amount and direction of gene flow through time, revealed phylogeographic patterning resulting from paleoclimate change, studied the timing of juvenile development, and created hypotheses for the evolution of life-cycle control and the future effects of climate change on Magicicada life cycles. New ecological studies have supported and questioned the role of prime numbers in Magicicada ecology and evolution, found bidirectional shifts in population size over generations, quantified the contribution of Magicicada to nutrient flow in forest ecosystems, and examined behavioral and biochemical interactions between Magicicada and their fungal parasites and bacterial endosymbionts. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Life Histories

2018 ◽  
Keyword(s):  
Life Histories ◽  
Evolutionary Ecology ◽  
Life Cycles ◽  
Model Organisms ◽  
High Mountain ◽  
Comprehensive Overview ◽  
Animal Physiology ◽  
Wide Range ◽  
Terrestrial Environments ◽  
Territorial Behaviors

Crustaceans are increasingly being used as model organisms in all fields of biology, including neurobiology, developmental biology, animal physiology, evolutionary ecology, biogeography, and resource management. Crustaceans have a very wide range of phenotypes and inhabit a diverse array of environments, ranging from the deep sea to high mountain lakes and even deserts. The evolution of their life histories has permitted crustaceans to successfully colonize this variety of habitats. Few other taxa exhibit such a variety of life histories and behavior. A comprehensive overview of their life histories is essential to the understanding of many aspects of their success in marine and terrestrial environments. This book provides a general overview of crustacean life histories. Crustaceans have particular life history adaptations that have permitted them to conquer all environments on earth. Crustacean life cycles have evolved to maximize fecundity, growth, and ageing, in a wide range of environmental conditions. Individual contributions contrast benefits and costs of different life histories including sexual versus asexual production, semelparity versus iteroparity, and planktonic larvae versus direct development. Important aspects of particular behaviors are presented (e.g. migrations, defense and territorial behaviors, anti-predator behavior, symbiosis).

scholarly journals Sexual conflict and the evolution of asexuality at low population densities

2016 ◽  
Vol 283 (1841) ◽  
pp. 20161280 ◽  
Author(s):  
Nina Gerber ◽  
Hanna Kokko
Keyword(s):  
Sexual Harassment ◽  
Sexual Reproduction ◽  
Sexual Conflict ◽  
Life Cycles ◽  
Sexual Life ◽  
Relative Advantage ◽  
Male Mating ◽  
Population Densities ◽  
Asexual Populations ◽  
Sexual Life Cycle

Theories for the evolution of sex rarely include facultatively sexual reproduction. Sexual harassment by males is an underappreciated factor: it should at first sight increase the relative advantage of asexual reproduction by increasing the cost of sex. However, if the same females can perform either sexual or asexual life cycles, then females trying to reproduce asexually may not escape harassment. If resisting male harassment is costly, it might be beneficial for a female to accept a mating and undertake a sexual life cycle rather than ‘insist’ on an asexual one. We investigate the effects of sexual harassment on the maintenance of sex under different population densities. Our model shows that resisting matings pays off at low population densities, which leads to the complete extinction of males, and thus to the evolution of completely asexual populations. Facultative sex persists in a narrow range of slightly higher densities. At high densities, selection favours giving up resisting male mating attempts and thus sexual reproduction takes over. These interactions between the outcomes of sexual conflict and population density suggest an explanation for the rarity of facultative sex and also patterns of geographical parthenogenesis, where marginal environments with potentially low densities are associated with asexuality.

Defining and Disrupting Species Boundaries in Saccharomyces

2020 ◽  
Vol 74 (1) ◽  
pp. 477-495
Author(s):  
Jasmine Ono ◽  
Duncan Greig ◽  
Primrose J. Boynton
Keyword(s):  
Reproductive Isolation ◽  
Evolutionary History ◽  
Life Cycles ◽  
Sexual Life ◽  
Evolutionary Mechanisms ◽  
History Of ◽  
The One ◽  
Reproductive Isolation Mechanisms ◽  
Evolutionary Consequences ◽  
Isolation Mechanisms

The genus Saccharomyces is an evolutionary paradox. On the one hand, it is composed of at least eight clearly phylogenetically delineated species; these species are reproductively isolated from each other, and hybrids usually cannot complete their sexual life cycles. On the other hand, Saccharomyces species have a long evolutionary history of hybridization, which has phenotypic consequences for adaptation and domestication. A variety of cellular, ecological, and evolutionary mechanisms are responsible for this partial reproductive isolation among Saccharomyces species. These mechanisms have caused the evolution of diverse Saccharomyces species and hybrids, which occupy a variety of wild and domesticated habitats. In this article, we introduce readers to the mechanisms isolating Saccharomyces species, the circumstances in which reproductive isolation mechanisms are effective and ineffective, and the evolutionary consequences of partial reproductive isolation. We discuss both the evolutionary history of the genus Saccharomyces and the human history of taxonomists and biologists struggling with species concepts in this fascinating genus.

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