query: what do you call that type of asexual reproduction yeast

pos: Asexual reproduction by mitosis, producing several nuclei. The cytoplasm then separates, creating multiple daughter cells. In apicomplexans, multiple fission, or schizogony appears either as merogony, sporogony or gametogony. Merogony results in merozoites, which are multiple daughter cells, that originate within the same cell membrane, sporogony results in sporozoites, and gametogony results in microgametes. Some cells split via budding (for example baker's yeast), resulting in a "mother" and "daughter" cell. The offspring organism is smaller than the parent. Budding is also known on a multi-cellular level; an animal example is the hydra, which reproduces by budding. The buds grow into fully matured individuals

pos: Budding Budding Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. The small bulb like projection coming out from the yeast cell is called a bud. The new organism remains attached as it grows, separating from the parent organism only when it is mature, leaving behind scar tissue. Since the reproduction is asexual, the newly created organism is a clone and is genetically identical to the parent organism. Organisms such as hydra use regenerative cells for reproduction in the process of budding. In hydra,

pos: Yeast pharmaceutical, cosmetic and chemical industries as well as for marine culture and environmental protection . Marine yeast was successfully used to produce bioethanol using seawater-based media which will potentially reduce the WF of bioethanol . Yeasts, like all fungi, may have asexual and sexual reproductive cycles. The most common mode of vegetative growth in yeast is asexual reproduction by budding. Here, a small bud (also known as a bleb), or daughter cell, is formed on the parent cell. The nucleus of the parent cell splits into a daughter nucleus and migrates into the daughter cell. The bud continues to grow

pos: Plant reproduction female gametes do not fuse, as they do in sexual reproduction. Asexual reproduction may occur through budding, fragmentation, fission, spore formation and vegetative propagation. Plants have two main types of asexual reproduction in which new plants are produced that are genetically identical clones of the parent individual. Vegetative reproduction invoves a vegetative piece of the original plant (budding, tillering, etc.) and is distinguished from "apomixis", which is a replacement for sexual reproduction, and in some cases involves seeds. Apomixis occurs in many plant species and also in some non-plant organisms. For apomixis and similar processes in non-plant organisms, see parthenogenesis.

pos: Reproduction or identical copies of themselves without the contribution of genetic material from another organism. Bacteria divide asexually via binary fission; viruses take control of host cells to produce more viruses; Hydras (invertebrates of the order "Hydroidea") and yeasts are able to reproduce by budding. These organisms often do not possess different sexes, and they are capable of "splitting" themselves into two or more copies of themselves. Most plants have the ability to reproduce asexually and the ant species Mycocepurus smithii is thought to reproduce entirely by asexual means. Some species that are capable of reproducing asexually, like hydra, yeast (See

pos: Budding new nest usually near the natal one. In virology, "budding" is a form of viral shedding by which enveloped viruses acquire their external envelope from the host cell membrane, which bulges outwards and encloses the virion. In agriculture and horticulture, budding refers to grafting the bud of one plant onto another. Budding Budding is a type of asexual reproduction in which a new organism develops from an outgrowth or bud due to cell division at one particular site. The small bulb like projection coming out from the yeast cell is called a bud. The new organism remains attached as it

pos: Asexual reproduction which eventually break away from the parent organism. Internal budding is a process of asexual reproduction, favoured by parasites such as "Toxoplasma gondii". It involves an unusual process in which two ("endodyogeny") or more ("endopolygeny") daughter cells are produced inside a mother cell, which is then consumed by the offspring prior to their separation. Also, budding (external or internal) is present in some worm like Taenia or Echinococci; these worm produce cyst and then produce (invaginated or evaginated) protoscolex with budding. Vegetative propagation is a type of asexual reproduction found in plants where new individuals are formed without the production

pos: Paul Lindner Released in 1893, in the tenth volume of the German brewery weekly "Wochenschrift für Brauerei", the article described Lindner's lab's methods, results, and observations. It focused on the work of one of Lindner's employees, Ziedler, and how he purified a pure form of the yeast by using acidified beer wort. Lindner described "S. pombe" as "thoroughly peculiar" and called it a "fission yeast" due to its lack of asexual reproduction through budding. Lindner's report also included a drawing of their observations with a microscope. The text of the original article was later translated from German into English by translator Ted

pos: Ascomycota produce microscopic spores inside special, elongated cells or sacs, known as 'asci', which give the group its name. Asexual reproduction: Asexual reproduction is the dominant form of propagation in the Ascomycota, and is responsible for the rapid spread of these fungi into new areas. Asexual reproduction of ascomycetes is very diverse from both structural and functional points of view. The most important and general is production of conidia, but chlamydospores are also frequently produced. Furthermore, Ascomycota also reproduce asexually through budding. 1) Conidia formation: Asexual reproduction may occur through vegetative reproductive spores, the conidia. The asexual, non-motile haploid spores of

pos: Zoanthus sociatus asexual although sexual reproduction may happen as well. There is extratentacular budding, which is the creation of a new polyp from an old polyp, and fission, a new fragment in formed.The size of a fragment is also controlled by the increasing rate of mortality with decreasing fragment size. A colony is generally genetically the same. Even when a colony is sexually reproductive, a large proportion of polyps remain infertile, which demonstrates the greater importance of asexual reproduction and growth. "Z. sociatus" colonies do not become reproductive until they reach a certain size. They use external fertilization, and are mostly hermaphroditic,

pos: Ascomycota bed of conidiophores produced under a plant cuticle, which eventually erupt through the cuticle for dispersal. 2) Budding: Asexual reproduction process in ascomycetes also involves the budding which we clearly observe in yeast. This is termed a “blastic process”. It involves the blowing out or blebbing of the hyphal tip wall. The blastic process can involve all wall layers, or there can be a new cell wall synthesized which is extruded from within the old wall. The initial events of budding can be seen as the development of a ring of chitin around the point where the bud is about

pos: Tremella mesenterica Y-shaped basidia with two spores, unlike the longitudinally split basidia characteristic of "Tremella"; additionally, "D. chrysospermus" is smaller, has a whitish attachment point to its substrate, and grows on conifer wood. "Tremella mesenterica" has a yeastlike phase in its life cycle that arises as a result of budding of basidiospores. The alternation between asexual and sexual propagation is achieved by mating of yeast-form haploid cells of two compatible mating types. Each mating type secretes a mating pheromone that elicits sexual differentiation of the target cell having the opposite mating type to the pheromone-producing cell. The sexual differentiation is characterized by

pos: Polycyathus muellerae in caves and under overhangs at depths of or less. "P. muellerae" is a non-zooxanthellate coral; it does not have a symbiotic relationship with microscopic dinoflagellates as do most corals, instead obtaining all its nutrition from the planktonic organisms caught by the polyps. Asexual reproduction by budding increases the size of the colony. Sexual reproduction has not been observed in this species, but the fact that the coral has a widespread distribution suggests that it is likely to occur. This coral is sometimes parasitized by the barnacle "Megatrema anglicum". A study of the assemblages of organisms living in caves in

neg: Mucor racemosus nitrogen also converted to yeast. Conversely, increasing oxygen concentration will cause conversion of the yeast form to the mould form. Like many zygomycetes, "M. racemosus" reproduces both sexually and asexually depending on environmental conditions. During sexual reproduction, hyphae of compatible mating types touch and fuse, ultimately giving rise to a thick-walled zygosporangium containing a single zygospore. Germination from the zygospore leads to growth of new hyphae that give rise to asexual spores of both + and - mating type. Germination of these spores produces new haploid hyphae of the same mating type. "M. racemosus" possesses the ability to exhibit multiple

neg: Asexual reproduction Asexual reproduction Asexual reproduction is a type of reproduction by which offspring arise from a single organism, and inherit the genes of that parent only; it does not involve the fusion of gametes, and almost never changes the number of chromosomes. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many plants and fungi sometimes reproduce asexually. While all prokaryotes reproduce without the formation and fusion of gametes, mechanisms for lateral gene transfer such as conjugation, transformation and transduction can be likened to sexual reproduction in the sense of genetic recombination in meiosis.

neg: Asexual reproduction (parthenogenetic) reproduction for millions of years, the longest period known for any insect. In the grass thrips genus "Aptinothrips" there have been several transitions to asexuality, likely due to different causes. Asexual reproduction Asexual reproduction is a type of reproduction by which offspring arise from a single organism, and inherit the genes of that parent only; it does not involve the fusion of gametes, and almost never changes the number of chromosomes. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many plants and fungi sometimes reproduce asexually. While all prokaryotes reproduce without

neg: WHI3 yeast is capable of both sexual and asexual reproduction. During sexual reproduction, two yeast cells signal their presence by diffusing pheromones, and it has been shown that when a cell is exposed to mating pheromones but does not perform mating, it "remembers" the event and is less likely to undergo mating afterwards. When exposed to pheromones, yeast will undergo cell-cycle arrest and attempt to mate, however, within the first three hours it will escape the arrest, and the previously inhibited CLN3 will resume activity. The WHI3 protein then aggregate and form a super-assembly, which is inactive and partially insoluble. This

neg: Reproduction opposite of what it predicts. Reproduction 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

neg: Coevolution race is known as the Red Queen hypothesis. The Red Queen hypothesis predicts that sexual reproduction allows a host to stay just ahead of its parasite, similar to the Red Queen's race in "Through the Looking-Glass": "it takes all the running "you" can do, to keep in the same place". The host reproduces sexually, producing some offspring with immunity over its parasite, which then evolves in response. The parasite/host relationship probably drove the prevalence of sexual reproduction over the more efficient asexual reproduction. It seems that when a parasite infects a host, sexual reproduction affords a better chance of developing

neg: Gemma (botany) Gemma (botany) A gemma (plural "gemmae") is a single cell, or a mass of cells, or a modified bud of tissue, that detaches from the parent and develops into a new individual. This type of asexual reproduction is referred to as fragmentation. It is a means of asexual propagation in plants. These structures are commonly found in fungi, algae, liverworts and mosses, but also in some flowering plants such as pygmy sundews and some species of butterworts. Vascular plants have many other methods of asexual reproduction including bulbils and turions. The production of gemmae is a widespread means of asexual

neg: Christianity and sexual orientation Bible does not clearly state a view on it. However, some Christians have recently made statements on the subject. In the Christian magazine "Vision", David Nantais, S.J. and Scott Opperman, S.J. wrote in 2002, "Question: What do you call a person who is asexual? Answer: Not a person. Asexual people do not exist. Sexuality is a gift from God and thus a fundamental part of our human identity. Those who repress their sexuality are not living as God created them to be: fully alive and well. As such, they're most likely unhappy people with which to live.” Christianity and sexual

neg: Karenia (dinoflagellate) life cycle of a dinoflagellate with a motile, haploid, asexual cell with regular mitotic divisions. This binary fission reproduction occurs once about every 2–10 days, and division occurs primarily at night (Brand et al., 2012). They occasionally produce diploid planozygotes (mobile zygotes) implying they are capable of sexual reproduction. They have been observed to be in what appears to be the process of conjugation, a type of unicellular sexual reproduction. They can enter a hypnozygote cyst stage, which is an often thick walled, resting cyst that results from sexual fusion. This occurs when environmental conditions are adverse and allows it

neg: Chilodonella uncinata type. "Paramecium" can only mate with individual of opposite mating type. Unlike "Tetrahymena" or "Paramecium", it has been observed that "C. uncinata" has a larger number of IES sequences within a single protein-coding gene than in other ciliates . Also there exists populations of "C. uncinata" that contain an IES sequence that other populations do not carry. "Chilodonella uncinata" has sexual conjugation for recombination, and replication of the cell occurs by asexual division Sex and reproduction are separate in ciliates. "C. uncinata" is capable of mating with other "C. uncinata" cells that have the same mating type. After mating type

neg: Plant reproduction transmission of pathogens from parent to offspring; it is uncommon for pathogens to be transmitted from the plant to its seeds (in sexual reproduction or in apomixis), though there are occasions when it occurs. Seeds generated by apomixis are a means of asexual reproduction, involving the formation and dispersal of seeds that do not originate from the fertilization of the embryos. Hawkweed ("Hieracium"), dandelion ("Taraxacum"), some Citrus ("Citrus") and Kentucky blue grass ("Poa pratensis") all use this form of asexual reproduction. Pseudogamy occurs in some plants that have apomictic seeds, where pollination is often needed to initiate embryo growth, though

neg: Ulocladium botrytis "Ulocladium botrytis" is an anamorphic fungus, thus it undergoes asexual reproduction. Although it is an asexual fungus, "U. botrytis" possesses the mating type locus, which consists of two dissimilar DNA sequences termed MAT1-1-1 and MAT1-2-1. These "U. botrytis" MAT genes are essential for controlling colony size and asexual traits such as conidial size and number in "U.botrytis". The "U. botrytis" MAT genes have lost the ability to regulate sexual reproduction in "U. botrytis"; however, they have the ability to partially induce sexual reproduction in "Cochliobolus heterostrophus", a heterothallic species, upon heterologous complementation. "Ulocladium botrytis" has cellulolytic ability and contains a

neg: Zygosaccharomyces bailii bud is separated to form a daughter cell of unequal size. "Z. bailii" cell size varies within a range of (3.5 - 6.5) x (4.5 - 11.5) µm and the cells exist singly or in pair, rarely in short chain. It has been observed that the doubling time of this yeast is approximately 3 hours at 23 °C in yeast nitrogen base broth containing 20% (w/v) fructose (pH 4.0). In more stressful conditions, this generation time is significantly extended. Besides the asexual reproduction mode, under certain conditions (e.g. nutritional stress) "Z. bailii" produces sexual spores (ascospores) in a sac called

neg: Propagule infectious propagules are carried in droplets of host saliva or mucus that are expelled during coughing or sneezing. In horticulture, a propagule is any plant material used for the purpose of plant propagation. In asexual reproduction, a propagule is often a stem cutting. In some plants, a leaf section or a portion of root can be used. In sexual reproduction, a propagule is a seed or spore. In micropropagation, a type of asexual reproduction, any part of the plant may be used, though it is usually a highly meristematic part such as root and stem ends or buds. Propagule In

neg: Female male, and vice versa. Some organisms can also reproduce by themselves in a process known as asexual reproduction. An example of asexual reproduction that some female species can perform is parthenogenesis. There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. Patterns of sexual reproduction include Other than the defining difference in the type of gamete produced, differences between males and females in one lineage cannot always be predicted by differences in another. The concept is not limited to animals; egg

neg: Bryobia per year, while others have several. The eggs are laid singly or in clutches, and some mites may cover the eggs with dust or other matter. Unlike some other spider mites, bryobia mites do not spin webs. The great majority of "Bryobia" mites are asexual (although certain species do reproduce sexually). Their populations are all female, and individuals reproduce by thelytoky, a form of parthenogenesis. They emerge from unfertilized eggs. Phylogenetic analysis shows that the asexual species in the genus are not a monophyletic group; indicating that asexual reproduction evolved several times or that sexuality re-evolved. The asexual species have

neg: Chlorophyceae different species. Most of the members have one or more storage bodies called pyrenoids located in the chloroplast. Pyrenoids contain protein besides starch. Some algae may store food in the form of oil droplets. Green algae usually have a rigid cell wall made up of an inner layer of cellulose and outer layer of pectose. Vegetative reproduction usually takes place by fragmentation. Asexual reproduction is by flagellated zoospores. And haplospore, perrination (akinate and palmellastage). Asexual reproduction by mytospore absent in spyrogyra. Sexual reproduction shows considerable variation in the type and formation of sex cells and it may be isogamous e.g.

neg: Asexual reproduction as well as meiotic spores. Many algae similarly switch between sexual and asexual reproduction. A number of plants use both sexual and asexual means to produce new plants, some species alter their primary modes of reproduction from sexual to asexual under varying environmental conditions. For example, in the rotifer "Brachionus calyciflorus" asexual reproduction (obligate parthenogenesis) can be inherited by a recessive allele, which leads to loss of sexual reproduction in homozygous offspring. Inheritance of asexual reproduction by a single recessive locus has also been found in the parasitoid wasp "Lysiphlebus fabarum". Asexual reproduction is found in nearly half of the

neg: Pseudogamy Pseudogamy Pseudogamy refers to aspects of reproduction. It has different (but related) meanings in zoology and in botany. In zoology it means a type of parthenogenesis in which the sperm stimulates the egg cell to develop into an embryo, but no genes from the male are inherited. Gynogenesis is a synonym. In botany, "pseudogamy" is also related to asexual reproduction. Wilhelm Olbers Focke (1881) is usually cited for the definition of the term. What he actually said was (page 525, translated) Thus in botany, "pseudogamy" means any reproductive process that requires pollination but does not involve male inheritance. It is

neg: Reproduction Reproduction 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

neg: Reproductive biology reproduction. In asexual reproduction the generation of new organisms does not require the fusion sperm with an egg. However, in sexual reproduction new organisms are formed by the fusion of haploid sperm and eggs resulting in what is known as the zygote. Although animals exhibit both sexual and asexual reproduction the vast majority of animals reproduce by sexual reproduction. Gametogenesis is the formation of gametes, or reproductive cells. Spermatogenesis is the production of sperm cells in the testis. In mature testes primordial germ cells divide mitotically to form the spermatogonia, which in turn generate spermatocytes by mitosis. Then each spermatocyte

neg: Conidiobolus coronatus since discharge, rather than on the external environmental factors, however these external factors do still play a role. The spores formed by "C. coronatus" during asexual reproduction are globose, villose and multiplicative in some isolates, and have at least seven nuclei per spore. This presence of villose and multiplicative spores is what differentiates "C. coronatus" from the genus "Entomophthora". Though "C.coronatus" is classified under Zygomycota, it does not produce zygospores and therefore does not undergo sexual reproduction. It has been demonstrated that "C. coronatus" produces lipolytic, chitinolytic and proteolytic enzymes, especially extracellular proteinases, namely serine proteases which are optimally active

neg: Shark well understood, but genetic fingerprinting showed that the pups had no paternal genetic contribution, ruling out sperm storage. The extent of this behavior in the wild is unknown. Mammals are now the only major vertebrate group in which asexual reproduction has not been observed. Scientists say that asexual reproduction in the wild is rare, and probably a last-ditch effort to reproduce when a mate is not present. Asexual reproduction diminishes genetic diversity, which helps build defenses against threats to the species. Species that rely solely on it risk extinction. Asexual reproduction may have contributed to the blue shark's decline off

neg: Fission (biology) protozoans reproduce by yet another mechanism of fission called as plasmotomy. In this type of fission, a multinucleate adult parent undergoes cytokinesis to form two multinucleate (or coenocytic) daughter cells. The daughter cells so produced undergo karyokinesis, further. Such a type of reproduction is shown by opalina and pelomyxa. Fragmentation in multicellular or colonial organisms is a form of asexual reproduction or cloning where an organism is split into fragments. Each of these fragments develop into mature, fully grown individuals that are clones of the original organism. In echinoderms, this method of reproduction is usually known as fissiparity. Any splitting

neg: Muller's ratchet Muller's ratchet In evolutionary genetics, Muller's 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 (harmful 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 that do not undergo recombination. Although

neg: Biological life cycle a life cycle like this, and some eukaryotes apparently do too (e.g., Cryptophyta, Choanoflagellata, many Euglenozoa, many Amoebozoa, some red algae, some green algae, the imperfect fungi, some rotifers and many other groups, not necessarily haploid). However, these eukaryotes probably are not primitively asexual, but have lost their sexual reproduction, or it just was not observed yet. Many eukaryotes (including animals and plants) exhibit asexual reproduction, which may be facultative or obligate in the life cycle, with sexual reproduction occurring more or less frequently. Biological life cycle In biology, a biological life cycle (or just life cycle when the biological

neg: Aiptasia female offspring through asexual reproduction. Some clones even develop into hermaphrodites. Sexual reproduction in the well-studied "Aiptasia pallida" and "Aiptasia pulchella", is dioecious, meaning that individual "Aiptasia" are of separate sexes. During spawning, anemones release their gametes into the water where fertilization occurs. The resulting zygote becomes a free swimming planula larva which eventually settles onto a suitable substrate where it undergoes metamorphosis to become a small polyp. Newly produced larvae are aposymbiotic meaning they do not contain symbionts. The larvae or newly settled polyps can acquire symbiotic algae from the environment. External factors affect the method of reproductions. Asexual

neg: Asexual reproduction A complete lack of sexual reproduction is relatively rare among multi-cellular organisms, particularly animals. It is not entirely understood why the ability to reproduce sexually is so common among them. Current hypotheses suggest that asexual reproduction may have short term benefits when rapid population growth is important or in stable environments, while sexual reproduction offers a net advantage by allowing more rapid generation of genetic diversity, allowing adaptation to changing environments. Developmental constraints may underlie why few animals have relinquished sexual reproduction completely in their life-cycles. Another constraint on switching from sexual to asexual reproduction would be the concomitant loss

neg: Reproductive isolation in animals. Although the hybrid may be sterile, it can continue to multiply in the wild by asexual reproduction, whether vegetative propagation or apomixis or the production of seeds. Indeed, interspecific hybridization can be associated with polyploidia and, in this way, the origin of new species that are called allopolyploids. "Rosa canina", for example, is the result of multiple hybridizations. or there is a type of wheat that is an allohexaploid that contains the genomes of three different species. In general, the barriers that separate species do not consist of just one mechanism. The twin species of "Drosophila", "D. pseudoobscura"

neg: Genetic purging in homozygosis, natural selection begins purging them. The figure to the right gives the expected decline of fitness against the number of generations, taking into account just the increase in inbreeding (red line), or both inbreeding and purging (blue line, computed using the purged inbreeding coefficient ). This example shows that purging can be very efficient preventing inbreeding depression. However, for non-lethal deleterious alleles, the efficiency of purging would be smaller, and it can require larger populations to overcome genetic drift. The yeast Saccharomyces cerevisiae and Saccharomyces paradoxus have a life cycle that alternates between long periods of asexual reproduction

neg: Planarian Eggs develop inside the body and are shed in capsules. Weeks later, the eggs hatch and grow into adults. In asexual reproduction, the planarian detaches its tail end and each half regrows the lost parts by regeneration, allowing neoblasts (adult stem cells) to divide and differentiate, thus resulting in two worms. Some researchers claim that the products derived from bisecting planaria are similar to the products of planarian asexual reproduction; however, debates about the nature of asexual reproduction in planaria and its effect on the population are ongoing. Some species of planaria are exclusively asexual, whereas some can reproduce both

neg: Sporidiobolus salmonicolor Sporidiobolus salmonicolor Sporoidiobolus salmonicolor is a yeast-like fungus in the Basidiomycota more commonly known by the name of its asexual yeast-like state, "Sporobolomyces salmonicolor". It is generally considered a Biosafety Risk Group 1 fungus; however isolates of "S. salmonicolor" have been recovered from cerebrospinal fluid, infected skin, a nasal polyp, lymphadenitis and a case of endophthalmitis. It has also been reported in AIDS-related infections. The fungus exists predominantly in the asexual state as a unicellular, haploid yeast yet this species can sometimes produce a sexual state when conjugation of compatible yeast cells occurs. The asexual form consists of a characteristic,

neg: Apomixis Apomixis In botany, apomixis was defined by Hans Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization. Its etymology is Greek for "away from" + "mixing". This definition notably does not mention meiosis. Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis. Apomictically produced offspring are genetically identical to the parent plant. Some authors included all forms of asexual reproduction within apomixis, but that

neg: Asexual reproduction might be considered a form of asexual reproduction (agamogenesis) despite being the result of meiosis and undergoing a reduction in ploidy. However, both events (spore formation and fertilization) are necessary to complete sexual reproduction in the plant life cycle. Fungi and some algae can also utilize true asexual spore formation, which involves mitosis giving rise to reproductive cells called mitospores that develop into a new organism after dispersal. This method of reproduction is found for example in conidial fungi and the red algae "Polysiphonia", and involves sporogenesis without meiosis. Thus the chromosome number of the spore cell is the same

neg: Evolutionary history of life Sexual reproduction in eukaryotes may have evolved from bacterial transformation. (Also see Evolution of sexual reproduction#Origin of sexual reproduction.) The disadvantages of sexual reproduction are well-known: the genetic reshuffle of recombination may break up favorable combinations of genes; and since males do not directly increase the number of offspring in the next generation, an asexual population can out-breed and displace in as little as 50 generations a sexual population that is equal in every other respect. Nevertheless, the great majority of animals, plants, fungi and protists reproduce sexually. There is strong evidence that sexual reproduction arose early in the history

neg: Asexual reproduction in starfish Asexual reproduction in starfish Asexual reproduction in starfish takes place by fission or through autotomy of arms. In fission, the central disc breaks into two pieces and each portion then regenerates the missing parts. In autotomy, an arm is shed which continues to live independently as a "comet", eventually growing a new disc and further arms. Only certain genera of starfish are able to reproduce in these ways. Fissiparity in the starfish family Asteriidae is confined to the genera "Coscinasterias", "Stephanasterias" and "Sclerasterias". Another family in which asexual reproduction by fission has independently arisen is the Asterinidae. The life span

neg: Fucus vesiculosus released when water velocities are low. Individuals of "F. vesiculosus" from the North Sea colonized the Baltic Sea less than 8 000 years ago. The event is paralleled by a switch from what seems to be obligate sexual recruitment to facultative asexual recruitment. Asexual reproduction in Baltic Sea populations is accomplished by the production of adventitious branches that come loose and reattach to the bottom by the formation of rhizoids. Adventitious branches are present in thalli of "F. vesiculosus" also in other areas, but asexual formation of new thalli has never been reported outside the Baltic Sea. Primary chemical constituents

neg: Genetics and Y chromosomes form a strongly heterogeneous pair. When cells divide, their full genome is copied and each daughter cell inherits one copy. This process, called mitosis, is the simplest form of reproduction and is the basis for asexual reproduction. Asexual reproduction can also occur in multicellular organisms, producing offspring that inherit their genome from a single parent. Offspring that are genetically identical to their parents are called clones. Eukaryotic organisms often use sexual reproduction to generate offspring that contain a mixture of genetic material inherited from two different parents. The process of sexual reproduction alternates between forms that contain

neg: Green-beard effect by multiple loci across the genome. A more recent example, found in 2008, is a gene that makes brewer's yeast clump together in response to a toxin such as alcohol. By investigating flocculation, a type of self-adherence generally present in asexual aggregations, Smukalla "et al." showed that "S. cerevisiae" is a model for cooperative behavior evolution. When this yeast expresses FLO1 in the laboratory, flocculation is restored. Flocculation is apparently protective for the FLO1+ cells, which are shielded from certain stresses (ethanol, for example). In addition FLO1+ cells preferentially adhere to each other. The authors therefore conclude that flocculation is

neg: Microsporum canis forms that can coexist in time and space. "Microsporum canis" exemplifies a common situation in ascomycetous fungi in which, over time, one mating type strain has undergone habitat divergence from the other and established a self-sustaining reproductive population that consists only of the asexual form. It is hypothesized that asexual lineage of "Microsporum canis" evolved as a result of host-specific interactions, changes in ecological niche, as well as, geographic isolation of + and – mating types of "Arthroderma otae", hence making it difficult to sustain sexual reproduction. Early domestication of animals, such as cats and dogs, in Africa led to

neg: Cloning clones such as Dolly that are born from SCNT are not perfect copies of the donor of the nucleus. Organism cloning (also called reproductive cloning) refers to the procedure of creating a new multicellular organism, genetically identical to another. In essence this form of cloning is an asexual method of reproduction, where fertilization or inter-gamete contact does not take place. Asexual reproduction is a naturally occurring phenomenon in many species, including most plants and some insects. Scientists have made some major achievements with cloning, including the asexual reproduction of sheep and cows. There is a lot of ethical debate over

neg: Daphnia magna can offer a competitive advantage to this species over strictly pelagic filter feeders in some environments where suspended food sources might be temporally limited. As most of the other species of the genus "Daphnia", "D. magna" reproduces by cyclical parthenogenesis. This form of reproduction is characterised by the alternating production of asexual offspring (clonal reproduction) and at certain time sexual reproduction through haploid eggs that need to be fertilised. The asexual eggs (up to few dozens per clutch) are diploid and usually develop into females or, in response to adverse environmental stimuli, into males. Asexual eggs hatch in the female

neg: Fungus uses ionizing radiation as a source of energy. Fungal reproduction is complex, reflecting the differences in lifestyles and genetic makeup within this diverse kingdom of organisms. It is estimated that a third of all fungi reproduce using more than one method of propagation; for example, reproduction may occur in two well-differentiated stages within the life cycle of a species, the teleomorph and the anamorph. Environmental conditions trigger genetically determined developmental states that lead to the creation of specialized structures for sexual or asexual reproduction. These structures aid reproduction by efficiently dispersing spores or spore-containing propagules. Asexual reproduction occurs via vegetative

neg: Reproduction machines until the two overlap to yield "truly programmable organisms". Researchers involved stated that the creation of "true synthetic biochemical life" is relatively close in reach with current technology and cheap compared to the effort needed to place man on the Moon. Sexual reproduction has many drawbacks, since it requires far more energy than asexual reproduction and diverts the organisms from other pursuits, and there is some argument about why so many species use it. George C. Williams used lottery tickets as an analogy in one explanation for the widespread use of sexual reproduction. He argued that asexual reproduction, which

neg: Sexual reproduction additional or transformed genetic material, reproduce through asexual reproduction but may, in lateral gene transfer, display processes such as bacterial conjugation, transformation and transduction, which are similar to sexual reproduction although they do not lead to reproduction. The first fossilized evidence of sexual reproduction in eukaryotes is from the Stenian period, about 1 to 1.2 billion years ago. Biologists studying evolution propose several explanations for why sexual reproduction developed and why it is maintained. These reasons include reducing the likelihood of the accumulation of deleterious mutations, increasing rate of adaptation to changing environments, dealing with competition, and masking deleterious mutations.

neg: Yeast in winemaking the neck of the bottle, frozen, and expelled via pressure of the carbonated wine. Yeast taxonomy includes classification of yeast species depending on the presence or absence of a sexual phase. Therefore, some winemaking yeasts are classified by their asexual anamorph (or "imperfect" form) while others may be classified by their sexual teleomorph (or "perfect" form). A common example of this is "Brettanomyces" (or "Brett") that is usually referenced in wine and viticulture text under its asexual classification though some scientific and winemaking texts may describe specific species (such as "Dekkera bruxellensis") under its sporulating sexual classification of "Dekkera". Unless

neg: Reproduction produces little or no genetic variety in offspring, was like buying many tickets that all have the same number, limiting the chance of "winning" - that is, producing surviving offspring. Sexual reproduction, he argued, was like purchasing fewer tickets but with a greater variety of numbers and therefore a greater chance of success. The point of this analogy is that since asexual reproduction does not produce genetic variations, there is little ability to quickly adapt to a changing environment. The lottery principle is less accepted these days because of evidence that asexual reproduction is more prevalent in unstable environments, the

neg: Plant reproduction the pollen contributes no genetic material to the developing offspring. Other forms of apomixis occur in plants also, including the generation of a plantlet in replacement of a seed or the generation of bulbils instead of flowers, where new cloned individuals are produced. Asexual reproduction is a type of reproduction where the offspring comes from one parent only, thus, inheriting the characteristics of the parent. A rhizome is a modified underground stem serving as an organ of vegetative reproduction; the growing tips of the rhizome can separate as new plants, e.g., polypody, iris, couch grass and nettles. Prostrate aerial stems,

neg: Basidiobolus ranarum asexual reproduction is favored by glucose and sexual reproduction is favored by acid amines. Primary asexual spores are singly formed on the apices of unbranched hyphae and will then be discharged to form ballistic spores. Secondary asexual spores are singly developed from a hypha that was generated from a geminated ballistic spore. Also, sporangiospores can be generated by internal cleave of the cytoplasm and can then be dispersed when the sporangial wall is dissolved. As a result, the ejected asexual spores can form satellite colonies in a distance. After around 10 days of growth, sexual spores, zygospores with 20–50 μm

neg: Type Directors Club ‘Call yourselves anything you like, but give us what we want.’ By the same token, if type directors keep calling themselves just that, they will, in time, be recognized for what they actually do contribute.” Education has always been an important part of the Type Directors Club’s mission. The TDC began offering lectures in 1947, the second year of the Club’s existence. Called Ten Talks on Type, the lectures were given by James Secrest, Arnold Bank, Gene Ettenberg, Charles Felton, Milton Zudeck, O. Alfred Dickman, Joseph Weiler, Frank Powers, and Hal Zamboni. The series’ success led to it becoming an

neg: Vegetative reproduction Vegetative reproduction Vegetative reproduction (also known as vegetative propagation, vegetative multiplication or vegetative cloning) is any form of asexual reproduction occurring in plants in which a new plant grows from a fragment of the parent plant or a specialized reproductive structure. Many plants naturally reproduce this way, but it can also be induced artificially. Horticulturalists have developed asexual propagation techniques that use vegetative plant parts to replicate plants. Success rates and difficulty of propagation vary greatly. Monocotyledons typically lack a vascular cambium and therefore are harder to propagate. Plant propagation is the process of plant reproduction of a species or

neg: Gemma (botany) of the soil gives out many rhizoids. This surface eventually becomes the lower(ventral) surface of the thallus. Meanwhile, the apical cells present in the two lateral notches become active and form two thalli in opposite directions. Gemma (botany) A gemma (plural "gemmae") is a single cell, or a mass of cells, or a modified bud of tissue, that detaches from the parent and develops into a new individual. This type of asexual reproduction is referred to as fragmentation. It is a means of asexual propagation in plants. These structures are commonly found in fungi, algae, liverworts and mosses, but also

neg: Volvox interior, which produce new colonies through repeated division. In sexual reproduction two types of gametes are produced. "Volvox" species can be monoecious or dioecious. Male colonies release numerous sperm packets, while in female colonies single cells enlarge to become oogametes, or eggs. "Volvox" is facultatively sexual and can reproduce both sexually and asexually. In the lab, asexual reproduction is most commonly observed; the relative frequencies of sexual and asexual reproduction in the wild is unknown. The switch from asexual to sexual reproduction can be triggered by environmental conditions and by the production of a sex-inducing pheromone. Desiccation-resistant diploid zygotes are

neg: Saccharomyces cerevisiae fungus. Under optimal conditions, yeast cells can double their population every 100 minutes. However, growth rates vary enormously both between strains and between environments. Mean replicative lifespan is about 26 cell divisions. In the wild, recessive deleterious mutations accumulate during long periods of asexual reproduction of diploids, and are purged during selfing: this purging has been termed "genome renewal". All strains of "S. cerevisiae" can grow aerobically on glucose, maltose, and trehalose and fail to grow on lactose and cellobiose. However, growth on other sugars is variable. Galactose and fructose are shown to be two of the best fermenting sugars.

neg: Karyogamy cell, called a zygote or zygospore can then enter meiosis (a process of chromosome duplication, recombination, and division, to produce four new haploid cells), or continue to divide by mitosis. Mammalian fertilization uses a comparable process to combine haploid sperm and egg cells (gametes) to create a diploid fertilized egg. The term karyogamy comes from the Greek "karyo-" (from κάρυον "karyon") meaning "nut" and γάμος "gamos", meaning "marriage". Haploid organisms such as fungi, yeast, and algae can have complex cell cycles, in which the choice between sexual or asexual reproduction is fluid, and often influenced by the environment. Some organisms,

neg: The Aristocrats (film) often impressed, asking "And what do you call the act?" The punchline of the joke is then given: "'The Aristocrats'". The joke, as first delivered in the film, contains the set-up line "What the heck do you call an act like that?" followed by the punchline "I call it 'The Aristocrats'." In subsequent renditions of the joke, the agent asks, "What do you call your act?" The film itself consists of interviews with various comedians and actors, usually in candid settings. The interviewees engage both in telling their own versions of the joke, and in reminiscing about their experiences with

neg: Evolution of sexual reproduction This section will briefly focus on the ostensible disadvantages of sexual reproduction as compared to relative advantages in asexual reproduction. Given that sexual reproduction abounds in multicellular organisms, this section is followed by a lengthy overview of theories aiming to elucidate the advantages of sex and sexual reproduction. An asexual population can grow much more rapidly with each generation. Assume the entire population of some theoretical species has 100 total organisms consisting of two sexes (i.e. males and females) with 50:50 male-to-female representation, and only the females of this species can bear offspring. If all capable members of this population

neg: Plant reproduction Plant reproduction Reproduction means producing offspring for the survival of the species. Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur. In seed plants, the offspring can be packaged in a protective seed, which is used as an agent of dispersal. Reproduction in which male and

neg: Asexual reproduction has no apparent genetic basis, though its occurrence is common. There are at least 10 million identical human twins and triplets in the world today. Bdelloid rotifers reproduce exclusively asexually, and all individuals in the class Bdelloidea are females. Asexuality evolved in these animals millions of years ago and has persisted since. There is evidence to suggest that asexual reproduction has allowed the animals to evolve new proteins through the Meselson effect that have allowed them to survive better in periods of dehydration. Molecular evidence strongly suggests that several species of the stick insect genus "Timema" have used only asexual

neg: Agkistrodon contortrix longer tongue tine lengths than females during the breeding season, which may aid in chemoreception of males searching for females. Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. "A. contortrix" can reproduce by facultative parthenogenesis, that is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome-wide homozygosity, expression of deleterious recessive

neg: Snake entwined. Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. "Agkistrodon contortrix" (copperhead) and "Agkistrodon piscivorus" (cotton mouth) can reproduce by facultative parthenogenesis. That is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome wide homozygosity, expression of deleterious recessive alleles and often to developmental abnormalities. Both captive-born and wild-born "A. contortrix"

neg: Squamata to mate with includes topping, a behavior exhibited by most viperids, in which one male will twist around the vertically elevated fore body of its opponent and forcing it downward. It is common for neck biting to occur while the snakes are entwined. Parthenogenesis is a natural form of reproduction in which the growth and development of embryos occur without fertilization. "Agkistrodon contortrix" (copperhead snake) and "Agkistrodon piscivorus" (cotton mouth snake) can reproduce by facultative parthenogenesis. That is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs

neg: Holoplankton Holoplankton Holoplankton are organisms that are planktic (they live in the water column and cannot swim against a current) for their entire life cycle. Examples of holoplankton include some diatoms, radiolarians, some dinoflagellates, foraminifera, amphipods, krill, copepods, and salps, as well as some gastropod mollusk species. Holoplankton dwell in the pelagic zone as opposed to the benthic zone. Holoplankton include both phytoplankton and zooplankton and vary in size. The most common plankton are protists. Holoplankton have unique traits that make reproduction in the water column possible. Both sexual and asexual reproduction are used depending on the type of plankton. Some

neg: Monolingualism joke: "What do you call a person who speaks three languages? A trilingual. What do you call a person who speaks two languages? A bilingual. What do you call a person who speaks one language? An American." There is also increasing pressure on bilingual immigrants to renounce their mother tongue and to adopt their host country's language. As a result, even though there may be immigrants from a wide variety of nationalities and cultures, the main language spoken in the country does not reflect them. Snow and Hakuta write that in a cost-benefit analysis, the choosing of English as the

neg: Sexual reproduction to form a fertilized egg, the resulting child will have 23 chromosomes from each parent genetically recombined into 23 chromosome pairs or 46 total. Cell division mitosis then initiates the development of a new individual organism in multicellular organisms, including animals and plants, for the vast majority of whom this is the primary method of reproduction. The evolution of sexual reproduction is a major puzzle because asexual reproduction should be able to outcompete it as every young organism created can bear its own young. This implies that an asexual population has an intrinsic capacity to grow more rapidly with each

neg: Evolution of sexual reproduction from the genome. While DNA is able to recombine to modify alleles, DNA is also susceptible to mutations within the sequence that can affect an organism in a negative manner. Asexual organisms do not have the ability to recombine their genetic information to form new and differing alleles. Once a mutation occurs in the DNA or other genetic carrying sequence, there is no way for the mutation to be removed from the population until another mutation occurs that ultimately deletes the primary mutation. This is rare among organisms. Hermann Joseph Muller introduced the idea that mutations build up in asexual

neg: Plant reproduction archegonia on the same gametophyte which is thus hermaphrodite. Plant reproduction Reproduction means producing offspring for the survival of the species. Plant reproduction is the production of new individuals or offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur. In seed plants, the offspring can be packaged in a protective seed, which is used as

neg: Parthenogenesis in squamata species of snakes. "True" parthenogenesis is a form of asexual reproduction in all-female species that produce offspring without any male involvement. There are at least eight parthenogenetic species of Caucasian rock lizard in the genus "Lacerta". This genus is unique in containing the only known monoclonal parthenogenetic species, "Lacerta rostombekovi," where the entire species originates from a single hybridization event. In all other cases of unisexual reptilian species that have been examined, multiple separate asexual lineages are present. As true parthenotes, Lacerta do not require stimulation from sperm to reproduce. The best-known and perhaps most evolutionarily derived example of parthenogenesis

neg: Agkistrodon piscivorus is a natural form of reproduction in which growth and development of embryos occur without fertilization. "A. piscivorus" can reproduce by facultative parthenogenesis, that is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote (see Figure). This process leads to genome wide homozygosity, expression of deleterious recessive alleles and often to developmental failure (inbreeding depression). Both captive-born and wild-born "A. piscivorus" specimens appear to be

neg: Penicillium as a starter for blue cheese production. This finding was based, in part, on evidence for functional mating type (MAT) genes that are involved in fungal sexual compatibility, and the presence in the sequenced genome of most of the important genes known to be involved in meiosis. "Penicillium chrysogenum" is of major medical and historical importance as the original and present-day industrial source of the antibiotic penicillin. The species was considered asexual for more than 100 years despite concerted efforts to induce sexual reproduction. However, in 2013, Bohm et al. finally demonstrated sexual reproduction in "P. chrysogenum". "Penicillium marneffei", an

neg: Jakoba appears they have retained the ancestral eubacterial RNA polymerase, which has been replaced by viral type polymerase in all other mitochondriate eukaryotes. Overall, jakobid mitochondrial genomes are primitively complex in that they resemble their proteobacterial ancestors more than any other mitochondria. "Jakoba" use asexual reproduction by binary fission. The sexual reproduction or the formation of cysts have not been observed. “The circular mitochondrial genome of "Jakoba libera" strain ATCC 50422 is 96.6 kbp in size. Sequencing is nearly completed. At present, 77 genes have been identified, none of them including an intron. Intergenic regions account for ~ 30% of the

neg: Fungi imperfecti Fungi imperfecti The fungi imperfecti or imperfect fungi, also known as Deuteromycota, are fungi which do not fit into the commonly established taxonomic classifications of fungi that are based on biological species concepts or morphological characteristics of sexual structures because their sexual form of reproduction has never been observed. Only their asexual form of reproduction is known, meaning that these fungi produce their spores asexually, in the process called sporogenesis. There are about 25,000 species that have been classified in the deuteromycota and many are basidiomycota or ascomycota anamorphs. Fungi producing the antibiotic penicillin and those that cause athlete's foot

neg: Vegetative reproduction Kentucky bluegrass ("Poa pratensis") all use this form of asexual reproduction. Bulbils are sometimes formed instead of the flowers of garlic. Meristem tissue makes the process of asexual reproduction possible. It is normally found in stems, leaves, and tips of stems and roots and consists of undifferentiated cells that are constantly dividing allowing for plant growth and give rise to plant tissue systems. The meristem tissue's ability to continuously divide allows for vegetative propagation to occur. Another important ability that allows for vegetative propagation is the ability to develop adventitious roots which arise from other vegetative parts of the plants

neg: Digenea adaptation to low abundance within hosts, allowing the life cycle to continue when only one individual successfully infects the final host. Fertilisation is internal, with sperm being transferred via the cirrus to the Laurer's Canal or genital aperture. A key group of digeneans which are dioecious are the schistosomes. Asexual reproduction in the first larval stage is ubiquitous. While the sexual formation of the digenean eggs and asexual reproduction in the first larval stage (miracidium) is widely reported, the developmental biology of the asexual stages remains a problem. Electron microscopic studies have shown that the light microscopically visible germ balls

neg: Asexual reproduction as that of the parent producing the spores. However, mitotic sporogenesis is an exception and most spores, such as those of plants, most Basidiomycota, and many algae, are produced by meiosis. Fragmentation is a form of asexual reproduction where a new organism grows from a fragment of the parent. Each fragment develops into a mature, fully grown individual. Fragmentation is seen in many organisms. Animals that reproduce asexually include planarians, many annelid worms including polychaetes and some oligochaetes, turbellarians and sea stars. Many fungi and plants reproduce asexually. Some plants have specialized structures for reproduction via fragmentation, such as "gemma"

neg: Parthenogenesis can lead to parthenogenetic reproduction is unknown. Recently, a hybrid parthenogenetic whiptail lizard was bred in the laboratory from a cross between an asexual and a sexual whiptail. Because multiple hybridization events can occur, individual parthenogenetic whiptail species can consist of multiple independent asexual lineages. Within lineages, there is very little genetic diversity, but different lineages may have quite different genotypes. An interesting aspect to reproduction in these asexual lizards is that mating behaviors are still seen, although the populations are all female. One female plays the role played by the male in closely related species, and mounts the female

neg: Asexual reproduction in liverworts. Most lichens, which are a symbiotic union of a fungus and photosynthetic algae or bacteria, reproduce through fragmentation to ensure that new individuals contain both symbiont. These fragments can take the form of "soredia", dust-like particles consisting of fungal hyphen wrapped around photobiont cells. Clonal Fragmentation in multi-cellular or colonial organisms is a form of asexual reproduction or cloning where an organism is split into fragments. Each of these fragments develop into mature, fully grown individuals that are clones of the original organism. In echinoderms, this method of reproduction is usually known as fissiparity. Researchers claim today that

neg: Asexual reproduction in starfish the disc begins to develop and eventually a madreporite appears. This process lasts for some time, and about 10 months after separation, the comet has a half disc and 4 arms about 1 cm (0.4 in) long. Asexual reproduction in starfish Asexual reproduction in starfish takes place by fission or through autotomy of arms. In fission, the central disc breaks into two pieces and each portion then regenerates the missing parts. In autotomy, an arm is shed which continues to live independently as a "comet", eventually growing a new disc and further arms. Only certain genera of starfish are able

neg: Biological immortality asexually reproducing types. Studies on genus Schmidtea mediterranea suggest these planarians appear to regenerate (i.e. heal) indefinitely, and asexual individuals have an "apparently limitless [telomere] regenerative capacity fueled by a population of highly proliferative adult stem cells". "Both asexual and sexual animals display age-related decline in telomere length; however, asexual animals are able to maintain telomere lengths somatically (i.e. during reproduction by fission or when regeneration is induced by amputation), whereas sexual animals restore telomeres by extension during sexual reproduction or during embryogenesis like other sexual species. Homeostatic telomerase activity observed in both asexual and sexual animals is not sufficient

neg: Yeast aerially dispersed, asexual ballistoconidia. The useful physiological properties of yeast have led to their use in the field of biotechnology. Fermentation of sugars by yeast is the oldest and largest application of this technology. Many types of yeasts are used for making many foods: baker's yeast in bread production, brewer's yeast in beer fermentation, and yeast in wine fermentation and for xylitol production. So-called red rice yeast is actually a mold, "Monascus purpureus". Yeasts include some of the most widely used model organisms for genetics and cell biology. Alcoholic beverages are defined as beverages that contain ethanol (CHOH). This ethanol

neg: Lichenology nature of these organisms still classified as plants. A controversial issue surrounding lichens since the early 19th century is their reproduction. In these years a group of researchers faithful to the tenets of Linnaeus considered that lichens reproduced sexually and had sexual reproductive organs, as in other plants, independent of whether asexual reproduction also occurred. Other researchers only considered asexual reproduction by means of Propagules. Against this background appeared the Swedish botanist Erik Acharius disciple of Linnaeus, who is today considered the father of lichenology, starting the taxonomy of lichens with his pioneering study of Swedish lichens in Lichenographiae Suecicae

neg: Evolution of sexual reproduction least half of the diversity. So, the main question is to explain the advantages given by sexual differentiation, i.e. the benefits of two separate sexes compared to hermaphrodites rather than to explain benefits of sexual forms (hermaphrodite + dioecious) over asexual ones. It has already been understood that since sexual reproduction is not associated with any clear reproductive advantages, as compared with asexual, there should be some important advantages in evolution. For the advantage due to genetic variation, there are three possible reasons this might happen. First, sexual reproduction can combine the effects of two beneficial mutations in the same

neg: Reproduction through asexual reproduction tend to grow in number exponentially. However, because they rely on mutation for variations in their DNA, all members of the species have similar vulnerabilities. Organisms that reproduce sexually yield a smaller number of offspring, but the large amount of variation in their genes makes them less susceptible to disease. Many organisms can reproduce sexually as well as asexually. Aphids, slime molds, sea anemones, some species of starfish (by fragmentation), and many plants are examples. When environmental factors are favorable, asexual reproduction is employed to exploit suitable conditions for survival such as an abundant food supply, adequate

neg: Parthenogenesis are cyclical parthenogenesis, heterogamy or heterogony). The switch between sexuality and parthenogenesis in such species may be triggered by the season (aphid, some gall wasps), or by a lack of males or by conditions that favour rapid population growth (rotifers and cladocerans like daphnia). In these species asexual reproduction occurs either in summer (aphids) or as long as conditions are favourable. This is because in asexual reproduction a successful genotype can spread quickly without being modified by sex or wasting resources on male offspring who won't give birth. In times of stress, offspring produced by sexual reproduction may be fitter

neg: Ornamental bulbous plant through seeds is that the resulting plants have a greater variability in a wide range of characteristics, such as flower colour and height and flowering period. This means that asexual or vegetative reproduction is normally used commercially to propagate this type of plant. This means that the characteristics of a determined cultivar remain unaltered. Bulbs can reproduce vegetatively in a number of ways depending of the type of storage organ the plant has. Bulbs can be evergreen, such as "Clivia," "Agapanthus" and some species and varieties of "Iris" and "Hemerocallis". However, the majority are deciduous, dying down to the storage

neg: Santana 22 would be faster than a Cal 20?' That was the real yardstick boat at that time. We were sketching on the backs of napkins, as we do. "Right after that lunch, I had to fly to New York, and when I came back, there were all these messages on the desk, 'Call Bill Schock; Call Bill Schock,' so I called and said 'What do you need?' And he said 'Where the hell are the drawings?' I said, 'What drawings?' He said, 'You said you were going to design a boat for me.' I said, 'No, you said you were going

neg: Calamites to have a clonal habit. This type of asexual reproduction would allow them to spread quickly into new territory, and help to anchor them firmly in the unstable ground along rivers and in newly deposited delta sediments. The rhizomes of "Calamites" look quite similar to the stems in most cases, but have nodes that get progressively closer together as they approach the apical area (the growth tip that spreads outward through the soil). "Calamites" come in a variety of different "form genera". One type, "Calamites suckowi", is distinguishable from other "Calamites" forms by its prominent, swollen nodes and relatively wide-spaced