Tags: Mirela petrean album 2013, Bug out vehicle loadout, Asexual Reproduction PowerPoint Presentation Lesson Plan. Natural Vegetative Propagation, Artificial Vegetative Propagation. $ Asexual Reproduction In Animals Vegetative Reproduction Teacher Resources Biology Presentation Life Science Science Lessons Activities Education. Sexual and Asexual Reproduction Concept Sort. Apr 12, · Asexual vs Sexual Reproduction 1. Asexual vs. Sexual Reproduction Note: If you are viewing this PPT at home, some videos may not play. 2. Asexual Reproduction• Asexual reproduction is the process by which a single organism produces genetically identical offspring.•. Methods of Reproduction Sexual and Asexual Reproduction Asexual Reproduction: requires only 1 parent and the offspring are an exact copy of the parenta clone Asexual Reproduction: Organisms that reproduce asexually cannot develop much variety, . Reproduction Sexual Reproduction Asexual Reproduction Asexual Reproduction: Genetically Identical ...
Asexual reproduction is the mode of reproduction in prokaryotes. In particular, prokaryotes reproduce through binary fission. Eukaryotes, especially higher forms of animals, reproduce through sexual means, i.e. by sexual reproduction. In sexual reproduction, gametes are produced by meiosis. A male gamete fertilizes the female gamete, forming a zygote. Some eukaryotes are capable of asexual reproduction. In asexual reproduction, the organism is capable of reproducing an offspring in the absence of a mate. As a result, the offspring is a clone of the parent and therefore results in low genetic variation in the species as a whole. Some species are capable of heterogamy, i.e. the ability to alternate between sexual and asexual reproduction. ...
4. The type of division, in which two individuals are formed from a single individual, is … Budding 3. The segments rapidly grow new cells to constitute their muscle fiber and internal structure through mitosis. These are binary fission, budding, vegetative reproduction, fragmentation and by spores. Segmented worms and many echinoderms such as starfish reproduce asexually via fragmentation. Organisms produced by asexual reproduction are the product of mitosis. There are two types of reproduction - sexual reproduction and asexual reproduction. Asexual reproduction is the primary form of reproduction for single-celled organisms such the archaea, bacteria, and protists. Natural selection, the mechanism for evolution, chooses which traits are favorable adaptations for a given environment and which are unfavorable. A particular type of cell known as a gemmule can develop into a new organism. But in the long term (over several generations), lack of sexual reproduction compromises their ability to ...
Are you two twins? Asexual Reproduction: Asexual Reproduction: -Used by many unicellular organisms, plants, and lower animals. -Involves only mitotic cell division = each offspring has exactly the same heredity as its parent. -Usually rapid compared to sexual reproduction. Types of Asexual Reproduction Include:
In this podcast Mark Carrigan (a researcher focused on asexuality) and Michael Dore (an asexual mathematician) lead an introductory workshop about asexuality. For more information about asexuality visit www.asexuality.org, the Asexuality Visibility and Education Network. An introduction to Asexuality A couple of articles about asexuality which have featured on Sociological Imagination: Reflections on a year…
Reproduction (or procreation or breeding) is the biological process by which new individual organisms - offspring - are produced from their parents. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction. By asexual reproduction, an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sexual reproduction is that only 50% of organisms reproduce and organisms only pass on 50% of their genes. Sexual reproduction typically requires the sexual interaction of two specialized organisms, called gametes, which contain half the number of chromosomes of normal ...
State Standard 2E. Compare the advantages of sexual reproduction and asexual reproduction in different situations. Meiosis & Sexual Reproduction (10.1)
Living organisms have good reason for engaging in sexual, rather than asexual, reproduction according to Maurine Neiman, assistant professor of biology in the UI College of Liberal Arts and Sciences and researcher in the Roy J. Carver Center for Genomics.. In an article published in a recent issue of the journal Molecular Biology and Evolution, she and her colleagues, including John M. Logsdon Jr., associate professor of biology, examined the theory that sexual reproduction, while requiring more time and energy than asexual reproduction, is also much more common among living organisms and, therefore, must be very beneficial.. The study looked at sexual, as well as asexual, varieties of a New Zealand freshwater snail (left), Potamopyrgus antipodarum, by sequencing mitochondrial genomes and found that the sexually reproducing snails had accumulated harmful DNA mutations at about half the rate of the asexual snails.. This is the first study to compare mutation accumulation in a species where ...
The evolution and maintenance of sexual reproduction may involve important tradeoffs because asexual reproduction can double an individuals contribution to the gene pool but reduces diversity. Moreover, in social insects the maintenance of genetic diversity among workers may be important for colony growth and survival. We identified a previously unknown termite breeding system in which both parthenogenesis and sexual reproduction are conditionally used. Queens produce their replacements asexually but use normal sexual reproduction to produce other colony members. These findings show how eusociality can lead to extraordinary reproductive systems and provide important insights into the advantages and disadvantages of sex.. ...
In evolutionary genetics, Mullers ratchet (named after Hermann Joseph Muller, by analogy with a ratchet effect) is a process by which the genomes of an asexual population accumulate deleterious mutations in an irreversible manner. Muller proposed this mechanism as one reason why sexual reproduction may be favored over asexual reproduction. The negative effect of accumulating irreversible deleterious mutations may not be prevalent in organisms which, while they reproduce asexually, also undergo other forms of recombination. This effect has also been observed in those regions of the genomes of sexual organisms which do not undergo recombination. Although Muller discussed the advantages of sexual reproduction in his 1932 talk, it does not contain the word ratchet. Muller first introduced the term ratchet in his 1964 paper, and the phrase Mullers ratchet was coined by Joe Felsenstein in his 1974 paper, The Evolutionary Advantage of Recombination. Asexual reproduction compels genomes to be ...
Asexual Reproduction Study Guide Vocabulary: asexual reproduction, binary fission.. 1. Offspring resulting from asexual reproduction and those resulting from sexual reproduction differ in one major way. What is the difference?. 2. Sketch and describe the three steps of binary fission. Fill in the chart below to highlight the advantage and disadvantages of asexual reproduction. Advantages, Disadvantages,. 3. , , 4. , , 5. , ,. 6. If a eukaryotic organism reproduces through mitosis, what is true about the offspring and the parent organism?. 7. In what types of organisms is mitotic reproduction most common?. 8. List three examples of mitotic reproduction. 9. What forms of reproduction does the sea anemone use?. 10. Write a word that starts with the letters bi. Explain what is similar between the meaning of the word you wrote and the meaning of binary fission.. 11. What is the creation of offspring form only one parent organism called?. Multicellular Life Study Guide Vocabulary: tissue, organ, ...
Official asexual reproduction bacteria called h-pylori pron pictures - Helicobacter pylori (H. pylori) is a microaerophilic Gram (-) bacterium. The bacterium is detected more frequently in the developing world. . permitting all non-commercial use, distribution, and reproduction in any medium.
Native Prickly Stick-insect (Acanthoxyla geisovii, order Phasmatodea). No males in species, reproduces via asexual reproduction or parthenogenesis, New Zealand (NZ) stock photo. Quality New Zealand images by well known photographer Rob Suisted, Natures Pic Images.
Selective advantage of sexual over asexual reproduction (rmm = 0, rmM = 0, rMM = 0.1) (a,c) and of high over low recombination (b,d) in both the standard model
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Hey, this is pretty good :) , Maybe find even someone close somehow to my age even though age is just a number lol. I am a 52 (Aug. 12th of this year 20...
Jun 08, · For plants that rely on sexual reproduction, the maturity process for a crop yield can be several months. This shortened growing time makes it possible for multiple yields in some environments. What Are the Disadvantages of Asexual Reproduction? 1. Negative mutations linger longer in asexual . Jan 28, · Asexual reproducers do not have to carry their offspring for a long amount of time and produce more than one at a time. This makes it a quick and inexpensive process for them in the terms of time. The Disadvantages of Asexual Reproduction. 1. No Diversity Since the traits of only one parent is passed on, all of the offspring are exactly.. Disadvantages of sexual reproduction and asexual reproduction in Long Beach
Reproduction is to create or recreate something, usually a new living thing, such as a baby. In biology, the two types of reproduction are sexual and asexual reproduction. Sexual reproduction involves two organisms of the same species, each supplying half the genes for the descendant. Asexual reproduction only involves a single organism; it works by division (or splitting) of the cell. Most bacteria reproduce by asexual reproduction. Some organisms can either reproduce sexually or asexually. ...
Its tempting, though ultimately pointless, to try and correct this situation. You could crash into the asexual community wielding badges of scientific, medical or imagined authority and demand that all of the masturbating asexuals pack their bags and truck off to a conceptually consistent set of terms. Not only would this be wrong (because it would deny masturbating asexuals their right to self-identity) and pointless (because theres no way to create a division in the community if masturbating and non-masturbating asexuals dont see one), its a textbook case of changing the facts to fit the theory. To make sense of this paradox, lets take a step back to our ideas about sexuality and sexual desire.. In the asexual community, asexuality is about more than how you feel about sex. There is no litmus test, no way to examine your own internal wiring (or lack of wiring) around sexuality and scientifically state whether or not you are asexual. Asexual identity is viewed less as a label and more as a ...
In nature, some plants and single-celled organisms produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism. For example, water hyacinth produces multiple copies of genetically-identical plants through a process known as apomixis, or asexual seed formation.. Archaea, bacteria, and protists reproduce asexually by binary fission, where a cell divides giving rise to two cells, each having the potential to grow to the size of the original cell. Finally, some plants, invertebrates (such as water fleas, aphids, stick insects, some ants, bees and parasitic wasps), and vertebrates (such as some reptiles, amphibians, fish, and few birds) reproduce using parthenogenesis, a form of asexual reproduction where an unfertilized egg develops into a new individual in the absence of the male gamete.. Natural clones, also known as identical twins, occur in humans and other ...
In nature, some plants and single-celled organisms produce genetically identical offspring through a process called asexual reproduction. In asexual reproduction, a new individual is generated from a copy of a single cell from the parent organism. For example, water hyacinth produces multiple copies of genetically-identical plants through a process known as apomixis, or asexual seed formation.. Archaea, bacteria, and protists reproduce asexually by binary fission, where a cell divides giving rise to two cells, each having the potential to grow to the size of the original cell. Finally, some plants, invertebrates (such as water fleas, aphids, stick insects, some ants, bees and parasitic wasps), and vertebrates (such as some reptiles, amphibians, fish, and few birds) reproduce using parthenogenesis, a form of asexual reproduction where an unfertilized egg develops into a new individual in the absence of the male gamete.. Natural clones, also known as identical twins, occur in humans and other ...
Asexual Reproduction Asexual reproduction involving only one parent organism. The offspring created through asexual reproduction have the exact same genetic material as the parent; the offspring is a clone of its parent. The production of offspring is usually external so the parent can have lots of offspring in a very short amount of time. There is no parental care required; […]. ...
Here I present a deterministic model of the coevolution of parasites with the acquired immunity of their hosts, a system in which coevolutionary oscillations can be maintained. These dynamics can confer an advantage to sexual reproduction within the parasite population, but the effect is not strong enough to outweigh the twofold cost of sex. The advantage arises primarily because sexual reproduction impedes the response to fluctuating epistasis and not because it facilitates the response to directional selection-in fact, sexual reproduction often slows the response to directional selection. Where the cost of sexual reproduction is small, a polymorphism can be maintained between the sexuals and the asexuals. A polymorphism is maintained in which the advantage gained due to recombination is balanced by the cost of sex. At much higher costs of sex, a polymorphism between the asexual and sexual populations can still be maintained if the asexuals do not have a full complement of genotypes available to them,
I noticed that lots of people have partners here. Are there any sexuals out there who just want to be asexual and try to be like that but they dont have p...
Chaos has been found in many mathematical models of population dynamics. This suggests that it should be a common feature of natural populations, quite in contrast to the scarcity of systems where it has been demonstrated. We suggest in this paper that the reason for this contrast may lie in the reproductive system. Whereas ecological modelling traditionally deals with asexual organisms, we introduce sexual reproduction (and thus explicit population genetics) into the population dynamic models. As specific examples, we describe the effect of sexual reproduction on two models (a host-parasite model and a predator-prey model) which exhibit chaotic behaviour for many sets of parameters. The results show that sexual reproduction generally reduces the complexity of the system, leading to a stable equilibrium or other forms of simple dynamics, or at least reducing the fluctuations of the system. Thus the chaotic behaviour predicted by many population dynamic models may be restricted to systems with ...
Epigenetic inheritance can be important for adaptation, especially in cases where the available genetic variation is limited. Firstly, epigenetic inheritance, like phenotypic plasticity, can enable survival in new environments before genetic adaptation evolves (Burggren 2016). Secondly, the rate of spontaneous gains and losses of individually methylated sites (i.e. the epimutation rate) is estimated to be substantially higher than the genetic mutation rate (Graaf et al. 2015), creating new heritable variation that can ultimately enable adaptation. Finally, for small populations with limited genetic variation, or asexual organisms, epigenetic variation can be a major source of heritable variation that can enable adaptation to new environments.. The realisation that natural populations harbour substantial amounts of epigenetic variation (e.g. Herrera et al. 2016; Thorson et al. 2017) raises the question of what degree this epigenetic variation can contribute to phenotypic variation, the actual ...
REPRODUCTION IN PLANTS. Sexual reproduction in plants occurs when a detached reproductive cell unites with another reproductive cell. Unlike animals, plants do not have to have separate male and female sexes, in many plants both sexes are located on the same species. In asexual reproduction, the cell, tissue, or organ develops directly into a new organism. Sexual reproduction allows combinations of different genetic material to be introduced into a new individual (this is the method by which humans reproduce and provides for genetic rearrangement and assortment.) In asexual reproduction an exact copy is made from the mother cell, therefore, the genetic material remains the same. Vascular plants are more complicated than non-vascular plants. The development of complex tissues and organs in vascular plants to aid in the movement of water and food, created the need for different strategies to reproduce ...
BALANOGLOSSUS-REPRODUCTION Balanoglossus performs asexual and sexual reproduction Asexual reproduction: Gilchrist described asexual reproduction in Balanoglossus capsensis. In the summer season its posterior end will divide into a number of bits. Each bit will develop into a new individual. Sexual Reproduction : Sexes are separate, sexual dimorphism is absent. The gonads are simple. They are present in one or many rows in the branchio-genital region. Each gonad will give gonoduct. This gonoduct will open out through a pore externally. In male the gonads are called testes. They produce sperms. In female the gonads are called ovaries. They produce ova. They are liberated into water. Fertilization will take place in water. It is called external fertilization. The fertilized zygote will undergo holoblastic clevage. 1. In Balanoglossus kowaiowsley the development is direct. No larval form is seen in its life history. 2. In other species of Balanoglossus a larval form called Tonaria is seen in the ...
For asexual organisms point mutations correspond to local displacements in the genotypic space, while other genotypic rearrangements represent long-range jumps. We investigate the spreading properties of an initially homogeneous population in a flat fitness landscape, and the equilibrium properties on a smooth fitness landscape. We show that a small-world effect is present: even a small fraction of quenched long-range jumps makes the results indistinguishable from those obtained by assuming all mutations equiprobable. Moreover, we find that the equilibrium distribution is a Boltzmann one, in which the fitness plays the role of an energy, and mutations that of a temperature.. Type: article. Keywords: genotypic, rearrangements, mutation, jumps, Boltzmann. ...
In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. For example, a great number of snails and slugs are hermaphrodites. Hermaphroditism is also found in some fish species and to a lesser degree in other vertebrates, he acknowledges. The evolution of sexual reproduction is still a major puzzle for biologists, he admits.. The first account of self-fertilization in history is ascribed to Juanita Franciscella, a Spanish street artist also known as the bearded woman of Castilla, who in 1483 is said to have given birth to a child of her own conception. The birth was judged heretical by the Spanish Inquisition and she was burned with her child at the stake.. ...
Evolution by mutation occurs whenever a mistake in the DNA occurs in the heritable cells of an organism. In the single-celled asexual organisms, such as bacterial, the whole cell and its DNA is passed on to the next generation because these organisms reproduce via binary fission. For sexual organisms, mutations are passed to the next generation if they occur in the egg or sperm cells used to create offspring. Mutations occur at random in the genome, but mutations of large effect are often so bad for the organism that the organism dies as it develops, so mutations of smaller effect or even neutral mutations are theoretically more common in a population. The variation that is created in a population through the random process of mutation is called standing genetic variation, and it must be present for evolution to occur. Mutation is the raw stuff of evolution because it creates new heritable phenotypes, irrespective of fitness or adaptation. Mutation rates are actually pretty low for most genes, ...
the offspring are identical to the parent!. By cell division, one cell divides to become two. This process is used by some organisms, such as protozoans, to reproduce. In other, multicellular organisms, this process is used to grow in size or to replace tissues.. * when offspring are produced from two parents, it is called sexual reproduction ...
There are several genetic mechanisms by which genomes may change and phenotypic diversity emerge. Mutations or alterations of the coding sequence of the parental DNA can arise either due to DNA damage caused by external agents or more commonly by the oxidative intermediates of metabolism or errors in DNA replication or repair. Mutations may be beneficial, neutral, or detrimental to the cell depending upon its environment. Thus heterozygosity, the occurrence of allele diversity for a specific gene, happens naturally in yeast populations of individuals giving rise to genomic variation. Both sexual and asexual reproduction contribute to further population diversity. Recombination between chromosomes and loss of chromosome integrity can occur during asexual reproduction. Chromosomal repair mechanisms may introduce further genetic change or lead to the loss of one of a pair of alleles, termed gene conversion. Sexual reproduction by design leads to a reshuffling of genetic material across homologous ...
Heritable differences in ecologically important traits can allow distinct lineages to arise and coexist. In sexual organisms, divergence typically occurs when populations are geographically separated, and the lineages may or may not persist in the event of later contact (1, 2). In asexual organisms, divergent lineages can arise and persist even in sympatry if ecological opportunities are available (3-7). Divergent lineages have been seen to evolve in environments with unexploited resources (4, 6) or spatial gradients (3); these opportunities are sometimes generated by the organisms themselves through secretion of metabolites (5, 7) and other forms of niche construction (8). Selective processes, including character displacement and trade-offs in life-history traits or metabolic functions, can promote divergence by causing negative frequency-dependent interactions between nascent lineages (1-7, 9). However, the genetic changes necessary to construct an ecologically distinct lineage are ...
We now know that structures and functions at the molecular and cellular levels provide the mechanism for reproduction and the continuity of species. Instructions for development are passed from parents to offspring in thousands of discrete genes, each of which is a segment of a molecule of DNA. An organisms particular genetic information, coded in its DNA (genotype), contains genes that provide the information necessary to assemble proteins. Offspring of asexual organisms inherit all of the parents genes. In organisms that reproduce sexually, specialized female and male sex cells (gametes) are formed during a process of cell division called meiosis. Each of these sex cells contains a random half of the parents genetic information ...
Some organisms reproduce sexually while others reproduce asexually. Define both types of reproduction. What are the advantages and disadvantages of reproducing each way? Name two organisms that reproduce sexually and two that.
What is asexual reproduction. Asexual reproduction is reproduction without sex. In this form of reproduction, a single organism or cell makes a copy of itself. The genes of the original and its.
The genetics of bacteria is the study of the reproductive capabilities of bacteria and the mechanisms which they utilize to diversify their genetic composition. Similar to eukaryotic cells, bacterial cells are capable of retaining function and variation, which gets passed on through generations. Despite the fact that the development of bacteria resistant strains is a major issue, bacteria actually do not have a high mutation rate. Rather, bacteria are capable of proliferating rapidly which allows them to increase genetic diversity, along with the effects of genetic recombination. Furthermore, bacteria do not reproduce by meiosis. Instead they use binary fission to replicate themselves, which is a form of asexual reproduction. Asexual reproduction is common of prokaryotic organisms.. Bacteria can alter their genetic information through transformation, transduction and conjugation.. ...
Theoretical arguments are presented which suggest that each advance of Mullers ratchet in a haploid asexual population causes the fixation of a deleterious mutation at a single locus. A similar process operates in a diploid, fully asexual population under a wide range of parameter values, with resp …
Southeastern Australian populations of the dioecious, subtidal sea anemone Anthothoe albocincta display considerable spatial variation in the colour patterns of the constituent polyps, and the most visually striking feature of local populations are sets of dense aggregations each comprised of polyps with a single colour pattern. We used a combination of genetic data, observations and manipulative experiments to infer that A. albocincta generates these monomorphic aggregations via asexual reproduction and that asexual reproduction plays the major role in the maintenance of established populations. Allozyme electrophoresis of 2 to 5 polyps from each of 20 mapped aggregations (in 2 populations) revealed that in 18 cases (90%) all polyps were electrophoretically identical and always distinct from differently coloured polyps taken from each of 26 adjacent aggregations. Furthermore, the genetic structure of each of 13 populations separated by up to 930 km was consistent with the predicted effects of ...
In discussing the advantages of sex, one must keep in mind the host of disadvantages that comes with it. For one, large amounts of energy are required to maintain the sex organs. Studies have shown that Drosophila with sex organs removed tend to live significantly longer than their sexually active counterparters (controlled for STDs, I assume!). Of course, the actual practice of sexual intercourse itself tends to be quite dangerous. Just think of the diseases that can be passed around this way! Also, remember that sex isnt confined to humans alone. Flies and lizards have sex too! Many animals have elaborate mating rituals that require great input of energy and often make these animals easy pickings for predators. When you say that diversity is main benefit conveyed by sex, you should keep in mind that the first sexual organisms were single celled organisms with evolutionary time scales multitudes faster than our own. The rate of mutation in bacterial colonies comes from the fact that they can ...
The Genetics Society of America (GSA), founded in 1931, is the professional membership organization for scientific researchers and educators in the field of genetics. Our members work to advance knowledge in the basic mechanisms of inheritance, from the molecular to the population level.. Online ISSN: 1943-2631. ...
Many organisms that reproduce through asexual reproduction are single-celled organisms like, paramecium, amoeba, and bacteria. The picture on the right shows a amoeba reproducing through a type of asexual reproduction called binary fission. Binary Fission is when the organism splits into TWO equal parts. Then each part becomes a separate organism. ...
Some organisms, such as plant and fungi reproduce asexually by mitosis. For example yeast, a single-celled micro-organisms, reproduce asexually by budding which uses mitosis:. 1. A bud forms on the cells surface.. 2. The D,N,A and organelles replicate. 3. The cell undergoes mitosis.. 4. Nuclear division is complete, the budding cell has identical D,N,A.. …. ...
Runners are a form of asexual reproduction and so require mitosis which produces two identical daughter cells, which are known as clones. This means that the plants will not adapt to the changing conditions and so are more likely to die. This is why asexual reproduction is good in stable environments ...
Daily News How Gaining and Losing Weight Affects the Body Millions of measurements from 23 people who consumed extra calories every day for a month reveal changes in proteins, metabolites, and gut microbiota that accompany shifts in body mass.. ...
Daily News How Gaining and Losing Weight Affects the Body Millions of measurements from 23 people who consumed extra calories every day for a month reveal changes in proteins, metabolites, and gut microbiota that accompany shifts in body mass.. ...
Reproductive cloning doesnt require the use of egg cells, just normal somatic skin cells will suffice. This is somewhat amazing in itself; but what is also amazing, and may be taken for granted by many, is the technology behind the equipment used to perform the delicate transfer of cells to oocytes. It is common to show the transfer on screens, where the glass equipment used can clearly be seen. Reference ASME ...
Bdelloid rotifers are microscopic animals that have apparently survived without sex for millions of years and are able to survive desiccation at all life stages through a process called anhydrobiosis. Both of these characteristics are believed to have played a role in shaping several unusual features of bdelloid genomes discovered in recent years. Studies into the impact of asexuality and anhydrobiosis on bdelloid genomes have focused on understanding gene copy number. Here we investigate copy number and sequence divergence in alpha tubulin. Alpha tubulin is conserved and normally present in low copy numbers in animals, but multiplication of alpha tubulin copies has occurred in animals adapted to extreme environments, such as cold-adapted Antarctic fish. Using cloning and sequencing we compared alpha tubulin copy variation in four species of bdelloid rotifers and four species of monogonont rotifers, which are facultatively sexual and cannot survive desiccation as adults. Results were verified using
Penelope-like elements (PLEs) are an enigmatic group of retroelements sharing a common ancestor with telomerase reverse transcriptases. In our previous studies, we identified endonuclease-deficient PLEs that are associated with telomeres in bdelloid rotifers, small freshwater invertebrates best known for their long-term asexuality and high foreign DNA content. Completion of the high-quality draft genome sequence of the bdelloid rotifer Adineta vaga provides us with the opportunity to examine its genomic transposable element (TE) content, as well as TE impact on genome function and evolution. We performed an exhaustive search of the A. vaga genome assembly, aimed at identification of canonical PLEs combining both the reverse transcriptase (RT) and the GIY-YIG endonuclease (EN) domains. We find that the RT/EN-containing Penelope families co-exist in the A. vaga genome with the EN-deficient RT-containing Athena retroelements. Canonical PLEs are present at very low copy numbers, often as a ...
Looking for online definition of asexuality in the Medical Dictionary? asexuality explanation free. What is asexuality? Meaning of asexuality medical term. What does asexuality mean?
Medical definition of asexual reproduction: reproduction (as cell division, spore formation, fission, or budding) without union of individuals or gametes.
Krisko, A., M. Leroy, M. Radman, M. Meselson. (2012). Extreme anti-oxidant protection against ionizing radiation in bdelloid rotifers. PNAS. (published online before print). Hur, J., K. Van Doninck, M. Mandigo, M. Meselson. (2009). Degenerate Tetraploidy Was Established Before Bdelloid Rotifer Families Diverged. Molecular Biology and Evolution 26:375-383.. Gladyshev, E., M. Meselson (2008). Extraordinary resistance of Bdelloid rotifers to ionizing radiation. PNAS, 105: 5139-5144.. Gladyshev, E., M. Meselson, I. Arkhipova. (2008). Massive horizontal gene transfer in Bdelloid rotifers. Science 320: 1210-1213.. Mark Welch, D.B., J. Mark Welch, M. Meselson (2008). Evidence for degenerate triplody in Bdelloid rotifers. PNAS, 105: 5145-5149.. Meselson, M., D. Mark Welch (2007). Evolution. Stable heterozygosity? Science, 318: 202-203.. Hegreness, M., M. Meselson (2007). What did Sutton See? Thirty years of confusion over the chromosomal basis of Mendelism. Genetics 176: 1939-1944.. Gladyshev, E.A., M. ...
The dual role of recombination in TE proliferation has generated great interest in the effects of sexual versus asexual reproduction on TE loads in the genome over time (Arkhipova & Meselson 2000; Wright & Finnegan 2001; Dolgin & Charlesworth 2006). Sex can facilitate the spread of a new TE throughout a population, but it also provides a mechanism through which new copies can be lost. Thus, sex can lead to an accelerated rate of increase and decrease in TEs over time relative to asexuals, and also impact the distribution of TEs among individuals within a population where sex has been lost (Schaack et al. in press). We surveyed six families of transposable elements in populations of D. pulex, which reproduce either with or without sex and find that both the number and distribution of TEs differ between cyclical parthenogens and obligate asexuals, despite the fact that obligately asexual populations in this species are thought to be relatively young (Lynch et al. 2008). Even though purging ...
THE efficacy of natural selection may be severely reduced in asexual compared to sexual organisms due to the absence of recombination and segregation (Fisher 1930; Barton and Charlesworth 1998; Otto and Lenormand 2002; Agrawal 2006). Consequently, asexual populations may adapt more slowly to changing environments (Peck 1994; Orr 2000; Roze and Barton 2006) and suffer from an increased genetic load (Muller 1964; Crow and Kimura 1970; Pamilo et al. 1987; Kondrashov 1988; Charlesworth 1994). Both of these factors may contribute to the rarity of obligate asexuality in eukaryotes (Bell 1982), despite its immediate advantages over sexual reproduction (Maynard Smith 1978). The main reason for the decreased efficiency of selection in asexual organisms is that due to the complete linkage of their genomes, selection cannot operate on different mutations independently (the Hill-Robertson effect, Hill and Robertson 1966). Thus, deleterious mutations anywhere in the genome reduce the effective population ...
The non-LTR retrotransposon Hebe from the bdelloid rotifer A. vaga was found to undergo frequent microhomology-associated deletions, rather than 5-terminal truncations characteristic of this class of retrotransposons, and to exhibit preference for telomeric localization. These findings represent th …
Tunicates are the unique chordates to possess species reproducing sexually and asexually. Among them, the colonial ascidian Botryllus schlosseri is a reference model for the study of similarities and differences in these two developmental pathways. We here illustrate the characterization and expression pattern during both pathways of a transcript for a gene orthologous to Dazap1. Dazap1 genes encode for RNA-binding proteins and fall into the Musashi-like (Msi-like) group. Our phylogenetic analysis shows that these are related to other RNA-binding proteins (Tardbp and several heterogeneous nuclear ribonucleoproteins types) that share the same modular domain structure of conserved tandem RNA Recognition Motifs (RRMs). We also classify the whole group as derived from a single ancient duplication of the RRM. Our results also show that Dazap1 is expressed with discrete spatiotemporal pattern during embryogenesis and blastogenesis of B. schlosseri. It is never expressed in wholly differentiated tissues, but
Gonad differentiation is an essential function for all sexually reproducing species, and many aspects of these developmental processes are highly conserved among the metazoa. The colonial ascidian, Botryllus schlosseri is a chordate model organism which offers two unique traits that can be utilized to characterize the genes underlying germline development: a colonial life history and variable fertility. These properties allow individual genotypes to be isolated at different stages of fertility and gene expression can be characterized comprehensively. Here we characterized the transcriptome of both fertile and infertile colonies throughout blastogenesis (asexual development) using differential expression analysis. We identified genes (as few as 7 and as many as 647) regulating fertility in Botryllus at each stage of blastogenesis. Several of these genes appear to drive gonad maturation, as they are expressed by follicle cells surrounding both testis and oocyte precursors. Spatial and temporal expression
Its known that for humans, the primary cause of pregnancy loss is chromosomal abnormalities arising from meiosis, says Anne Pringle, a professor of botany at UW-Madison and another author of the research. But what wasnt at all clear was whether meiosis is a leading cause of inviability not just in humans, but wherever it occurs.. To answer this question, Levitis compared the viability of offspring produced by three different kinds of reproduction. Sexual reproduction, where two players make a genetic contribution, always requires meiosis. On the other hand, asexual reproduction - where the offspring are clones of their parents - usually uses the much simpler mitosis, a comparatively easy cloning of cells, no genetic reshuffling required. When asexual reproduction does use meiosis, it is even more complicated than sex.. In this three-way comparison, Levitis found that more complex reproduction resulted in lower offspring survival. For example, asexual lizards that use meiosis had lower ...
To Injaz, a female dromedary camel, one female calf (as yet unnamed), weight 38 kilograms, born on November 2nd, 2015. After recent reports about the drawbacks and disadvantages of cloning, especially the unnecessary health risks; comes a happier story of the first cloned camel to produce a normally conceived calf. Injaz, the mother, was cloned in 2009 by somatic cell nuclear transfer (SCNT). She was created from an animal slaughtered for meat. The most difficult part of the SCNT was to electrically fuse the parts of the newly created egg cell, and provide a mixture of chemicals to act as a catalyst to initiate the normal cellular reproduction processes. This was duly achieved and the viable egg cell was then introduced into Injaz. The skilled procedures were performed at the Reproductive Biotechnology Centre in Nad Al Sheba, Dubai by a team led by Dr Nisar Wani, scientific director of the centre. The work was performed under the patronage of Sheikh Hamdan bin Mohammed Al Maktoum, Crown Prince ...
Porifera includes very primitive multi-cellular animals having only the cellular level of body organization with no tissues and organs. In Porifera (sponges), only cells show division of labor for the purpose of performing specialized functions. All Poriferans, animals of the phylum Porifera, are aquatic with most of them being marine. Sponges are sessile (not mobile) organisms including both solitary and colony-forming types ...
Dear All: Hybrid vigor, while evident in plants raised from seed, does not last for ever if continued asexual reproduction of a plant is continued over many years. The classic example perhaps is to be found in the strawberry Royal Sovereign, which just failed after many years. At one time it was far ahead of other cultivars, but then lost many of the qualities for which it was renowned. To my knowledge such loss of desired qualities were simply lost due to the continued asexual propagation. Just what happens when such does take place I do not know, but such has been refereed to as Clonal Breakdown. Possibly the desired arrangement and composition of the cells in the plant(s) was changed. John Lonsdale asked how TC fix this. Again a definitive answer, to my knowledge, as not been determined, but it does work. Perhaps this method of propagation is taking advantage of cells that are, for want of a better explanation, stronger and closer to the original cells of the first crosses and better replicas ...
The objective was to perform a brief reflection on asexuality and its relationship with medical (pathologizing) and social (sexual diversity) practices. Asexuality is s..
Answer (1 of 1): Basically in eukaryotic reproduction cycle , the asexual reproduction involves mitosis only while the sexual reproduction involves meiosis and syngamy. Both of these processes are the counterparts of each other thats why both of them are required in the sexual reproduction. Meiosis and Syngamy, together make the reproduction process a cycle|. In the meiosis phase, the cells are gone through the cell division and get haploid number of chromosomes. The process of reproduction is completed when the two gametes are fused in the syngamy phase. In this way both of these processes are must in the completion of the reproduction cycle.
Parthenogenesis is the asexual reproduction of a creature without the benefit of a male of the species. There are both benefits and problems with sexless reproduction.
or ω in population genetics models) is the quantitative representation of natural and sexual selection within evolutionary biology. It can be defined either with respect to a genotype or to a phenotype in a given environment. In either case, it describes individual reproductive success and is equal to the average contribution to the gene pool of the next generation that is made by individuals of the specified genotype or phenotype. The fitness of a genotype is manifested through its phenotype, which is also affected by the developmental environment. The fitness of a given phenotype can also be different in different selective environments. With asexual reproduction, it is sufficient to assign fitnesses to genotypes. With sexual reproduction, genotypes are scrambled every generation. In this case, fitness values can be assigned to alleles by averaging over possible genetic backgrounds. Natural selection tends to make alleles with higher fitness more common over time, resulting in Darwinian ...
Family name: Aphididae. Size: 1/8 inch. Color(s): Green, white, yellow, brown, black. Life Cycle: You probably dont want to know this part! For the most part, they reproduce through asexual reproduction. The female aphids give birth to female (daughter) aphids throughout the year, producing several dozen generations. Ugh. Those daughters are born through live birth, rather than hatching from eggs. When sexual reproduction does take place, thats for the purpose of laying eggs that will overwinter - to start the cycle all over again the following spring. The eggs are laid on winter host plants, rather than the host plants you typically see aphids on during the growing season.. ...
Citation: De Jong, R., Bolton, M.D., Kombrink, A., Yadeta, K.A., Van Den Berg, G.C., Thomma, B.P. 2013. Extensive chromosomal reshuffling drives evolution of virulence in an asexual pathogen. Genome Research. 23:1271-1282. Interpretive Summary: Plant pathogens that utilize sexual reproduction tend to have populations that are genetically more diverse. This diversity tends to help the population overcome environmental pressures, such as those faced when a crop has genetic resistance to the pathogen. However, many plant pathogens rely on asexual reproduction, which is thought to be more limited in its ability to provide genetic diversity in populations. In this paper, we investigated genetic variation in the asexual pathogen Verticillium dahliae, a pathogen that causes disease in many crops including sugarbeet, potato, and tomato. We discovered that mitotic chromosomal recombination is occurring in this fungus in regions of the genome that harbor effectors, genes that are important for causing ...
Mitosis is the process by cell division by which two identical cells are produced. Before the process occurs, the cell must replicate it DNA so that its information can be passed on to the next generation of cells. This process of mitosis is also refered to as asexual reproduction. Why? Well, in mitosis two identical cells are made from one parent and this is the same as in asexual reproduction ...
García-Verdugo C, Calleja JA, Vargas P, Silva L, Moreira O, Pulido F. Molecular Ecology 2013 (in press, doi: 10.1111/mec.12194). Refugia are expected to preserve genetic variation of relict taxa, especially in polyploids, because high gene dosages could prevent genetic erosion in small isolated populations. However, other attributes linked to polyploidy, such as asexual reproduction, may strongly limit the levels of genetic variability in relict populations. Here, ploidy levels and patterns of genetic variation at nuclear microsatellite loci were analysed in Prunus lusitanica, a polyploid species with clonal reproduction that is considered a paradigmatic example of a Tertiary relict. Sampling in this study considered a total of 20 populations of three subspecies: mainland lusitanica (Iberian Peninsula and Morocco), and island azorica (Azores) and hixa (Canary Islands and Madeira).. [Leer más...]. ...
In 1915, at the height of the American Womans Suffrage Movement, Charlotte Gilman Perkins published Herland, a future-set utopian novel in which women, perhaps through divine intervention, acquire the ability to reproduce without men. For one hundred generations they bear only daughters who, in turn, bear yet more daughters.. This vision, an ideal world based on generations of motherhood, became an underlying theme of feminist and lesbian literature throughout the 20th century. Peaking during the 1970s Womens Lib Movement, the feminist library filled with similar utopian worlds where womens severance from male culture was symbolically finalized when they achieved reproduction without men.. Parthenogenesis is the term coined by esteemed English biologist, Richard Owen in 1849, from the Greek parthenos meaning virgin and genesis meaning birth; It refers to asexual reproduction through the development of an unfertilized egg.. Among animals there are a number of creatures that reproduce, at ...
Introduction. TITLE An investigation into how the activity of a population of yeast is affected with respect to temperature. INTRODUCTION Yeast cells also known as Saccharomyces Cerevisiae are unicellular organisms, which reproduce asexually requiring only one parent. The are seven major forms of asexual reproduction: binary fission, budding, fragmentation, sporulation, vegetative propagation, cloning and parthenogenesis. Yeast cells reproduce by budding. This is a very simple mechanism similar to binary fission, except that the two resultant cells are not of equal size but comprise a smaller bud cell, becoming detached from a larger parent cell. Yeast use oxygen to build membranes components that are essential to replication. These cell-wall building blocks (unsaturated fatty acids and sterols) can sustain yeast growth even when present at very low levels. In anaerobic respiration, when free oxygen is not present, hydrogen cannot be disposed of by combination with oxygen. The electron transfer ...
All else being equal, an asexually reproducing population will grow at twice the rate as a sexually reproducing population. The reason for this is simple: members of a sexually reproducing population must produce both sexes, but effectively only half of them can give birth to offspring ot their own. In contrast, all offspring of an individual from an asexually reproducing population can potentially give birth. This is the two-fold cost of sexual reproduction.. Despite this cost, sexual reproduction is a prevalent mode of reproduction. Therefore, there must be some advantage to reproducing sexually, or else the sexually reproducing populations would soon become replaced by the much larger sexual populations. One advantage of sexual reproduction is that sexual reproduciton maintains more genetic variation than asexual reproduciton. ...
If you think of futuristic discoveries, the idea of cloning yourself must come to mind. What if I had another person exactly like me roaming around on the earth? Although many people might think this, few people actually know what genetic cloning is. Genetic cloning is the creation of an organism that is an exact genetic copy of another, meaning that they have the same genetic makeup. Cloning is also an asexual form of reproduction, meaning that the offspring comes from one parent rather than the normal (for humans) two. In humans, and mammals in general, this idea of asexual reproduction is unnatural, so it must be done forcefully and unnaturally. There are many ways to go about this, but the most known is Somatic Cell Nuclear Transfer (SCNC). This procedure creates an exact clone or genetic copy of an individual. A somatic cell is any cell in the body other than reproductive cells. The difference between reproductive cells and somatic cells is that somatic cells have two complete sets of ...
This program explores the remarkable world of plants - without them, no other life form would exist. It looks at characteristics of all living things, including cellular respiration, growing and repairing, responding to stimuli, taking nutrients from the environment, and reproduction - and emphasises how these occur in plants. Both sexual and asexual reproduction are covered and the role of chlorophyll, chloroplasts and sunlight is highlighted. The program also explores the form and vital functions of roots, stems and leaves. The junior program covers the material at a general, simpler level, which is suitable for lower/middle secondary levels. The senior program covers the material in more complex terms, and is pitched at students of senior biology ...
If you think of futuristic discoveries, the idea of cloning yourself must come to mind. What if I had another person exactly like me roaming around on the earth? Although many people might think this, few people actually know what genetic cloning is. Genetic cloning is the creation of an organism that is an exact genetic copy of another, meaning that they have the same genetic makeup. Cloning is also an asexual form of reproduction, meaning that the offspring comes from one parent rather than the normal (for humans) two. In humans, and mammals in general, this idea of asexual reproduction is unnatural, so it must be done forcefully and unnaturally. There are many ways to go about this, but the most known is Somatic Cell Nuclear Transfer (SCNC). This procedure creates an exact clone or genetic copy of an individual. A somatic cell is any cell in the body other than reproductive cells. The difference between reproductive cells and somatic cells is that somatic cells have two complete sets of ...
S: Amanda Nguyen. BC: mADE BY AMANDA NGUYEN PICTURES FROM GOOGLE. FC: A-Z Review! Amanda Nguyen , STOP THIS BOOK MAY CONTAIN A LOT OF LETTERS. 1: Reproduction in which a cell doubles its contents and the divides into two identical cells. , A Asexual Reproduction. 2: B is Bilateral Symmetry , Bi means two. A line drawn down the center both sides look the same!. 3: C is Cnidarian , Carnivores with stinging tentacles that captures prey and help defense.. 4: D is Digestive System , Breaks down food into molecules the the body can use!. 5: System in the body that collects wastes made by the cells and removes the waste from the body , E is Excretory System. 6: Can cause athletes foot. It can be spread around! EWWW!! , F is Fungi. 7: G is Gluteus Maximus , A muscle where your butt is!. 8: H is Half-Life , The amount of time it takes a radio active element to lose half its mass.. 9: I is Invertebrate , Animals that dont have a backbone. 10: J is Jawless Fish Has no jaw.( Skeleton made out of ...
This seems tough to answer on definitional grounds: if you mean that the tissue should live as in independently continue to carry out the totality of processes necessary for ongoing biological function-- well, cutting off a piece of you that goes on to become a fully-functional organism is just asexual reproduction, isnt it? Plenty of that going on. And conversely, for it not to be a case of reproduction, the detached tissue would have to not be a fully-functioning organism-- i.e., missing some major processes necessary for life-- which means that its pretty much moribund in any case. The distinction between a human head that blinks for a second or so after decapitation, and a human gamete that swims for a couple of days, is really just time, isnt it ...
The reproduction of seaweed can occur in sexual and asexual ways. Certain types of seaweed create the male and female cells to grow new seaweed. The asexual reproduction occurs on the simple seaweed. The small spores will be produced by the parent seaweed. Then it will be go away from the parent and settle in a certain location and grow into seaweed.. ...
Introduction. Cloning A clone is an organism or a group of organism that has come from another organism through asexual reproduction; this can be applied to cells as well as organisms. Most of the time the members of a clone are genetically identical, however sometimes mutations may occur when replicating the DNA. Clones dont always have to be artificially produced, an example of naturally occurring clones are identical twins, they have been produced from the division of a fertilised egg. Also prokaryotic cells reproduce asexually as well as other simple organisms such as algae and some yeasts and some larger, more complex organisms such as dandelions and aspen trees. Currently scientists are able to isolate a single gene from one organism and grow it in another organism from a different species. Most of the time the species used as the recipient is able to produce asexually (for example bacterium). This mean that it is possible to produce large numbers of cloned cells that all contain the ...
Pennatula phosphorea, annual spawning occurred in autumn or winter (between October and January). Also the mature oocytes were very large (>800µm), which suggested a lecithotrophic larval development (Edwards & Moore, 2009). The lecithotrophic larval stage of Funiculina quadrangularis may result in a relatively long period of time in the water column and high potential dispersal ability, and may explain the high gene flow observed between colonies of Funiculina quadrangularis in two Scotish sea lochs (Wright et al., 2015). Wright et al. (2015) found limited genetic population subdivision within and between populations of Funiculina quadrangularis in Loch linnhe and Loch Duich. However, the high genetic diversity and unique genotypes supported the absence of asexual reproduction in this species (Wright et al., 2015). No similar studies were available for Virgularia mirabilis, but Edwards & Moore (2009) noted that many sea pens exhibited similar characteristics. In a study of the intertidal ...
Following the initial operational description of a virus as a filterable agent, struggles were made to identify properties of viruses that isolated them from other microorganisms. The single defining characteristic of all viruses is that they are obligate intracellular molecular parasites.. A second inviolate characteristic of viruses is that they do not reproduce by binary fission - a method of asexual propagation where pre-existing cells split into two equal daughter cells. For viruses, the method of reproduction is akin to an assembly line in which different parts come together to create new viral particles.. In general, viruses contain only one variety of nucleic acid (either DNA or RNA) that carries the information required for viral replication. Nevertheless, it is obvious now that some viruses contain other nucleic acid molecules; for example, in retroviruses, cellular transfer RNAs are fundamental for the action of the enzyme reverse transcriptase.. The chemical composition of viruses ...
Parent: I learned that there are good and bad things that go along with asexual reproduction. Good things: whole genome is preserved, you dont need a mate, takes less energy, fast and efficient. Bad things: decrease in genetic diversity and these organisms cant handle change as well. Bacteria, yeast and dandelions are all examples of organisms that do this. Madison also taught me that a polyphyletic group comes from many common ancestors, a paraphyletic group is missing some descendants from a common ancestor and a monophyletic group has a common ancestor and all descendants. Student: I explained to my mom that the phyletic groups can be thought of like legos. A common ancestor is the box that the legos come in and the legos are the descendants. A mono group is one complete box of legos. A para group is a lego box that has lost some of the pieces (descendants). A poly group is when there are legos from many different boxes. ...
On Fri, 17 Feb 1995, Brian E. Keas wrote: , What I was trying to do in my definition of a parasite was have a , definition that clearly and without exception included organisms that , almost all people would agree to be parasites. Clearly, cows dont fit , most peoples definition of a parasite and thus my definition was made to , exclude cows and other classic herbivores. It is somewhat a matter of , scale, but it would be very difficult to imagine an adult tapeworm, for , example, infecting two (hosts) intestines simultaneously, regardless of , its size. What about two tapeworms that are genetically identical? Asexual reproduction may provide a way for scaled down consumers to feed on two hosts simultaneously. Derek Devils Advocate Zelmer ...
Plants 1.0--3 cm, caespitose, unbranched or dichotomously branched 1 to 4 times; shoot apex circinate. Axis elliptic, 0.2--0.8 mm diam. Dorsal wing 1.5--5 mm wide, margin entire, lacerate or erose with age, with wing cells near the axis 70--100 ´ 30--50 µm, with the marginal cells 30--50 ´ 22--40 µm. Oil cells 21--23 ´ 17--25 µm; oil bodies 15--17 µm diam. Lateral leaf scales remote, oriented obliquely, 1-stratose with a multistratose base, ovate to oblong (obovate to lingulate), 355--800 ´ 125--400 µm. Ventral leaf scales 1-stratose, irregular, often panduriform with a broad isthmus and equal or unequal lobes or oblong (obovate-ovate), 165--540 ´ 100--350 µm. Specialized asexual reproduction by gemmae, ventral from the youngest axis portions, intermixed apically with the scales, panduriform with two rounded lobes, 730--1050 ´ 450--775 µm, multicellular. Sexual condition dioicous. Antheridia up to 75 in a single series; antheridial body ca. 210--235 ´ 160--185 µm. Archegonial ...
Protantheae: Actiniaria without basilar muscles or ciliated tracts. Column with longitudinal muscles and spirocysts. Gonactiniidae: Protantheae with flattened, disc-like proximal end. Column of the same structure as the tentacles with spirocysts and a more or less strongly developed longitudinal muscle layer, not capable of involution. No distinct sphincter. Tentacles not retractile. Longitudinal muscles of tentacles and radial muscles of oral disc ectodermal. Actinopharynx with longitudinal muscles and often with spirocysts, with weak siphonoglyphs. Mesenteries typically arranged in cycles, each pair, except the directives, with the longitudinal muscles facing each other. 8 mesenteries, the two pairs of directives and on each side 2 single mesenteries whose retractors face the ventral directives, perfect. Owing to asexual reproduction some more mesenteries may be perfect. Gonads usually on all perfect mesenteries. Ciliated tracts of the filaments absent. Cnidom: spirocysts, atrichs, basitrichs, ...
Female sharks can fertilize their own eggs and give birth without sperm from males, according to a new study of the asexual reproduction of a hammerhead in a U.S. zoo.
Quote: Originally Posted by thiru The disadvantages far outweigh the advantages. Asexual reproduction is energetically favorable (in the...
Garlic ( Allium sativumL.) has a long history of cultivation by asexual propagation. Due to its asexual nature, improvement of garlic has been limited as compared to onion. With the impending...
Dieckmann U & Doebeli M (2004). Adaptive dynamics of speciation: Sexual populations. In: Adaptive Speciation. Eds. Dieckmann, U., Doebeli, M., Metz, J.A.J. & Tautz, D., Cambridge: Cambridge University Press. ISBN 0-521-82842-2 DOI:10.2277/0521828422. Full text not available from this repository ...
Overview== By Kiersten Bell ,br>,br> Eukaryotic microbes do not simply reproduce through binary fission as bacteria do; rather, a large number of eukaryotic microbes undergo some form of sexual reproduction. Sex appears to be ubiquitous among larger eukaryotes, but its presence among the smaller, unicellular organisms is yet to be determined. Discovering sexual reproduction in eukaryotic microbes presents its own host of problems due to the fact that microbial sex is often rare, furtive, or cryptic [1]. Rare because many microbes reproduce in a sexual manner rarely and asexually commonly, furtive because many times sexual reproduction occurs under conditions which cannot be seen, or cryptic meaning that it can be observed but difficult to recognize what is going on [1]. Sexual reproduction is defined as any process in which chromosomes from two different cells, or two nuclei from the same cell, combine into a single nucleus and undergo homologous recombination to create a new genome [1, 2]. ...
Social justice activists like myself have a tendency to construct a lot of rules about which words to use or avoid. For example, gay is preferred to homosexual because the latter is too formal, clinical, and distant. On the other hand, homosexual may be acceptable when its used in parallel with heterosexual, or if its contrasted with homoromantic. These rules can be frustrating to learn, but they have some rationale behind them.. And then there are other rules which just dont have any clear rationale. For instance, gay is to be used only as an adjective, never as a noun, and certainly never as a plural noun (i.e. the gays). Why? We dont have a problem with using plural nouns for other identities, such as Americans, liberals or atheists. Even other sexual orientations are usually acceptable, as in the case of lesbians, bisexuals, or asexuals.. On an individual level, the only rationale is that the gays just sounds wrong, and conjures negative associations. It makes ...