The Role Of Hybridization In Speciation Biology Essay

The Role Of Hybridization In Speciation Biology Essay Charles Darwin had published, The origin of species by natural selection, using his lifes discoveries and analysis to define what a species is and how species originate follow through as a contentious debate especially in the study of evolutionary biology. The study of evolution helps us to understand what species are by loosely idealizing it as alien till one feeds on their hunger to gain knowledge about what has created the world and the extant and extinct varieties that have claimed it, including man. Many different species are discussed and debated continuously, with each one being weighed by pros and cons which can also be seen as the strong point to either validate the concept or a short -fall to nullify it. The most accepted definition of current is Mayrs biological species concept, according to Coyne Orr (2004) who have accepted nine species concepts (Claridge et al, 1997). Mayrss biological species concept places the evolution of complete reproductive isolation as the focal point of the process and nature of speciation (Mayr, 2002), the biological species concept was the solid basis of which he based his belief in gene flow being absent in some species, a decreased fitness level to certain hybrids. It is believed that the emergent species would infrequently form from the process in question according to Mayr (2002). Hybrid speciation implies that hybridization has had a principal role in the origin of a new species, hybrid species that have doubled their chromosome number (Mallet, 2007), the definition applies: 50% contributions from each derived species initially contain exactly one genome from each parent, although, in older polyploids, recombination and gene conversion may eventually lead to unequal contributions (Mallet, 2007). The factor which is critical in hybrid speciation is due to being reproductively isolated with a decreased fitness-level; therefore these progeny formed are of transitional then it is more likely to be more weakly reproductively isolated. Speciation can also be influenced by hybridization by the factor of reinforcement, this means that obstacles in reference to mating because of unfit hybrids being chosen, even-though progeny from this relationship does not form from the courtship, the scenario is questionable as to whether reinforcement can be looked at as hybrid spe ciation. An example of this that can be discussed is the diploid or triploid frog Rana esculenta which is complete heterozygous for Rana lessonae and Rana ridibunda genomes (Mallet, 2007; TunnerNopp, 1979). Poly-, Allopoly- and Homoploidy, is it all just about how you do It? Plants use the means of polyploid evolution; these species are reproductively isolated due to the process of mating with diploid mates which give rise to uneven ploidies of progeny like triploids. These progeny may be able to reproduce but these progeny would cease to exist due aneuploidy (Stebbins, 1971; Grant, 1981; Ramsey Schemske, 2002) polyploidy is a simple way of creating speciation. Bisexually polypoid speciation is highly prevalent in plants as compared to animals due to: plants usually have indeterminate growth and somatic chromosome doubling can lead to germline polyploidy, germline refers to the sex cells that an organism contains which is sperm, egg and pollen in plants. Plants are often perennial or temporarily clonal which allow multigenerational persistence of hybrid cells within which polyploid mutations occur; plants are more often hermaphrodites, in rare polyploids self-fertilization allows a means of sexual reproduction (Mallet, 2007). Gene flow is weaker in pla nts as compared to animals with local populations which have unusual ploidy ( Bullini, 1994; OttoWhitton, 2000; Astaurov, 1969). Speciation can occur by the process of duplication of chromosomes within a species or duplication of hybrids (Mallet, 2005) between an autopolyploidy and allopolyploidy, respectively. Allopolyploid speciation follows self-fertilization and gives rise to a tetraploid; this can be seen from studies on Primula kewensis which was a result of Primula verticillata and Primula floribunda which had cultivated diploid hybrids. Speculation had lead to the belief that fusion of unreduced gametes had caused this due to the failure in reduction divisions during meiosis. A triploid species, known to be sterile, may add to the production of tetraploids by progeny being back-crossing triploid gametes; this was used to produce the first bisexual self-sustaining animal in a laboratory which was a polypoid strain hybrid between silk moths: Bombyx mori and Bombyx mandarina (Astaurov.B.L, 1969; Mallet.J, 2005). Homoploid hybrid speciation is well known to angiosperms, also known as flowering plants. Speciation occurs by mean of sympatry, a hybridization which requires gene flow. This is hybrids need to overcome challenges such as chromosome and gene incompatabilies with the lack of reproductive isolation, this often renders the process unlikely. There are approximately twenty plant species which are known for being a good example of homoploids however, this plant is hardly detected due to prevalence. Helianthus anomalus, Helianthus deserticola and Helianthis paradoxus are the best documented desert sunflowers which come from hybrids between mesic-adapted Helianthus annuus and Helianthus petiolaris (Buerkle et al, 2000; Gross Rieseberg, 2005; Mallet, 2007). Synthetic hybrid populations are re-created; being similar to those of wild species due to selection continuously favors combinations of compatible chromosomal rearrangements. In Helianthus recombinant genotypes and spatial separation hav e enabled the hybrids to flourish where their parents are absent (Mallet, 2005). In animals, bisexual polyploids are often excluded, the homoploid hybrids are less prominent in animals yet there is no given reason. The number in animals is growing rapidly (Dowling Secor, 1997; Gross Rieseberg, 2005). A recent example is the invasive sculpin, a hybrid fish derived from the Scheldt River (compare Cottus perifretum) and upper tributaries of the Rhine (compare Cottus rhenanum) (Mallet, 2007). Upper river tributaries of Europe have normal conditions of clear, cold waters, which make them oxygen-rich, for Sculpins. Earlier canal building became connected and these are a result of The Rhine and Scheldt rivers, but invasive sculpins appeared in the warmer water and muddier lower Rhine only in the past fifteen years. Morphologically the invasive sculpin is intermediate and its mitochondrial DNA, as well as nuclear single nucleotide polymorphisms and microsatellites, are characteristic of b oth Scheldt and Rhine forms (Mallet, 2007; Nolte et al., 2005). This provides evidence of adaptive hybrid origin hence communicating that hybrids are displaying positive selective pressure. Hybrid speciation in the animal kingdom results thus far by data based on the respective genome. The disadvantages is that many homoploid hybrids fail to be present in the parent, secondly a decreased level of being reproductively isolated, however, contributing to maintaining or expanding ecologically with latest forms (Mallet, 2007). Importance of a future Innumerable discussions and journals of speciation have stressed the importance of reproductive compatabilities and isolation that occur due to physical and geological barriers; from this essay one can see that polyploidy is more dominant in plants but found to be rare in animals. Furthermore, at the root of many animal and plant groups ancient polyploidy has been found. Genome duplications probably facilitated the evolution of complex organisms (although this is debated) (Mallet, 2007; Otto Whitton, 2000), and we can infer that successful genome duplications were mostly allopolyploid, provided that limited plant community data are reliable (Grant, 1981; Brochman et al., 2004; Mallet, 2007). In my opinion, hybridization can be viewed as an effective catalyst for speciation to occur as it creates variation as in the case of the liger, apart from mutations, which according to the Molecular Clock hypothesis, occurs at a constant rate over time. The process of natural selection includes the need for gene variety which can then be complemented with hybridization also, the compatibility of species more suitably in more noticeably growing groups; suggesting that enough suspected animal homoploid hybrid species exist. A need for in depth genomic analyses is required, it is already possible for hybrid species, like the Helianthus, which can be developed and made accessible via the laboratory or grown naturally, making it hard to find another speciation mode documented historically and can be used experimentally easily. If hybrid species can adapt to survive, showing positive selection pressure, regardless of the challenges which are faced and to survive in competition with the parent organisms by completely new adaptations then will hybridization truly demonstrate the power of evolution through the years, starting a completely new train of thought which will spark more questions hence more research into this wide unknown. The ability of hybrid species to invade hitherto unoccupied niches also means that hybridization can contribute to adaptive radiations such as African cichlid fish and Darwins finches (Mallet, 2007). Humans have come up with uses of genetically modified crops and other ways in which to manipulate the gene and species of not only plants but animals too, therefore it can be said that Homo sapiens are in fact the invaders of Earth, not hybridization of species.

Use of Dramatic Techniques in Cartwrights Road and Kanes Blasted Essa

Use of Dramatic Techniques in Cartwright's Road and Kane's Blasted      Ã‚   In this essay I shall concentrate on the plays 'Road' by Jim Cartwright and 'Blasted' by Sarah Kane with specific reference to use of language and structure of dialogue as examples of dramatic techniques.    My explanation of dramatic techniques is perhaps akin to Brecht's opinion regarding this theme:    '...The strong centralisation of the story, a momentum that draws the separate parts into a common relationship.   A particular passion of utterance, a certain emphasis on the class of forces are hallmarks of the dramatic.' (Brecht:p70)    Here we can perhaps see the way in which Brecht explains the aim of techniques such as use of language and structure of dialogue.   They in essence are attempting to draw together a common theme.   Perhaps in 'Road' language and dialogue is attempting to prove a sense of futility in individuals' lives, whereas in 'Blasted' the theme could be the atrocities of war are on both a personal and national level. How is the drama portrayed through the playwrights techniques?    In road, Cartwright uses definite techniques of language to create dramatic tension and in some instances irony.   Firstly his use of rhyming worlds within the dialogue creates a number of aspects.   Within Valerie's monologue the phrase:    'pissing and missing the bog'    has sibilance from the repetition of the 's' sound.   Dramatically this creates a harsh consonant sound almost as if they actor playing Valerie is aggressively spitting out the anger that she feels about her husband.   Within class this line was delivered with the dictated Northern accent which furthered the sibilant qualit... ...ife up North.   It is perhaps my own error that I feel more comfortable with 'Road' there is love shown through the moments of Joey and Clare, and there is friendship, Carol and Louise.   'Blasted' on the other hand holds nothing hopeful and in my opinion little which is insightful.   Kane's use of dramatic techniques is rooted in the interaction of characters and their dialogue whereas Cartwright reveals characters in a more insular fashion through the use of dramatic monologues, and the descriptions they use.   In short I weep when Joey dies, I laugh when Carol and Brenda provide humour, but 'Blasted' I am just shocked.    Works Cited: Banks, R.A. 'Drama & Theatre Arts', Hodder Headline Plc, London, 1991. Brecht, B. 'Brecht on Theatre', Metheun Publishing Ltd, London, 1957. Boal, A. 'Theatre of the Oppressed', Pluto Press, London, 1979.    Use of Dramatic Techniques in Cartwright's Road and Kane's Blasted Essa Use of Dramatic Techniques in Cartwright's Road and Kane's Blasted      Ã‚   In this essay I shall concentrate on the plays 'Road' by Jim Cartwright and 'Blasted' by Sarah Kane with specific reference to use of language and structure of dialogue as examples of dramatic techniques.    My explanation of dramatic techniques is perhaps akin to Brecht's opinion regarding this theme:    '...The strong centralisation of the story, a momentum that draws the separate parts into a common relationship.   A particular passion of utterance, a certain emphasis on the class of forces are hallmarks of the dramatic.' (Brecht:p70)    Here we can perhaps see the way in which Brecht explains the aim of techniques such as use of language and structure of dialogue.   They in essence are attempting to draw together a common theme.   Perhaps in 'Road' language and dialogue is attempting to prove a sense of futility in individuals' lives, whereas in 'Blasted' the theme could be the atrocities of war are on both a personal and national level. How is the drama portrayed through the playwrights techniques?    In road, Cartwright uses definite techniques of language to create dramatic tension and in some instances irony.   Firstly his use of rhyming worlds within the dialogue creates a number of aspects.   Within Valerie's monologue the phrase:    'pissing and missing the bog'    has sibilance from the repetition of the 's' sound.   Dramatically this creates a harsh consonant sound almost as if they actor playing Valerie is aggressively spitting out the anger that she feels about her husband.   Within class this line was delivered with the dictated Northern accent which furthered the sibilant qualit... ...ife up North.   It is perhaps my own error that I feel more comfortable with 'Road' there is love shown through the moments of Joey and Clare, and there is friendship, Carol and Louise.   'Blasted' on the other hand holds nothing hopeful and in my opinion little which is insightful.   Kane's use of dramatic techniques is rooted in the interaction of characters and their dialogue whereas Cartwright reveals characters in a more insular fashion through the use of dramatic monologues, and the descriptions they use.   In short I weep when Joey dies, I laugh when Carol and Brenda provide humour, but 'Blasted' I am just shocked.    Works Cited: Banks, R.A. 'Drama & Theatre Arts', Hodder Headline Plc, London, 1991. Brecht, B. 'Brecht on Theatre', Metheun Publishing Ltd, London, 1957. Boal, A. 'Theatre of the Oppressed', Pluto Press, London, 1979.   

Establish and adjust the marketing mix Essay

Promotions are not just aimed at increasing usage of the products. Followings are five other specific promotional aims. Sales Growth There have two term of campaigns, long term and short term campaigns. In a short-term, the main aim would be to drive revenues or cash flow, it also trigger the buyer actions. In the long-term campaign, the main aim would be intended to lead optimized profit margins. Especially for a new business they might aim to build a customer base in order to cover new start-up business costs and maintain a sustainable business. For the established companies, their aim would be to generate more business during slow or off season periods, and to expand the business into the newer markets. Brand Recognition One of the most popular promotional objectives would be building or maintaining brand recognition. The objective is to let customers or people know and well recognized your brand logo, other symbols or characters. Customers identify it with your company and hopefully associated with good impression to it, this might lead to customers will advertise our brand to his/her friends. It also gives people something to remember you by , that helps the business stand out even more. Understanding and connecting with the image of your brand is critical to long-term customer’s loyalty and profits. Purchase Intent As customers become more familiar with your brand, the next stage is to motivate purchase intent. The goal is to eliminate, neutralize or blocks the efforts of competitors to grab market share. You need to lure customers away from aggressive competitors. Promotional activities can be used such as refreshing trial use, encouraging existing customers to consume more quantity it occurs when customers are satisfied and can see no reason to buy  form another company and more frequency and getting customers to switch from competing options. Some customers are so satisfied with your services they cannot imagine shopping somewhere else A variety of promotional tools are used in this endeavor, including free trial offers or first-time buyer discounts Create Awareness Increased market awareness is a primary promotional objective. A mature product that is providing something new such as a product improvement or enhancement can also turn to promotion. A product that’s new to the marketplace will need promotion to be introduced to consumers. In all these cases, the objective is to make noise in the market that results in sales. Goodwill One ongoing objective of companies is to promote goodwill with the public and also public relation campaign. Staying active in community activities and giving to charities are common promotional tools with public relationship. Coinciding with building and maintaining goodwill, public relationship and other promotional campaigns are sometimes used to combat negative publicity already festering. Wal-Mart often uses advertising to promote positive attributes of the company in the face of criticism for some of its business practices.

Fight Club and society today essays

Fight Club and society today essays Our society, today, has fallen victim to the belief that we cannot survive without materials and possessions. Motivation for life has become the push to possess worldly goods, things of worthless value, which, for some reason, seemingly complete the human beings whom we compose. Fight Club is an outline of what, we, as a society have become. Through Tyler Durdens beliefs, ideas, and the stand in which he takes on them, it is immensely apparent that we are a society formed on a foundation built from consumerism. Consumerism is the theory that a progressively greater consumption of goods is economically beneficial. Consumerists possess the attachment to materialistic values or possessions. Materialism is a theory, which appropriately goes hand in hand with the theory of consumerism. It is the theory or doctrine that physical well-being and worldly possessions constitute the greatest good and highest value in life. Society, today, has adapted these theories as the way of life, the only way to be successful. We start children out young, sending them off to receive the best education possible, which, in other words means, the most expensive education available for the parents of the child. The child does not care or hold one feeling higher than another about which education he receives. Guaranteed that the only things on that childs mind are if there are companions for him and if there are toys for him to play with. Life from this point on becomes nothing but a downhill battle. Children will attend college because their parents want them to. They will strive to be the best that they can be. What does this mean? The child is supposed to be a good person on the inside and exhibit love and respect for others. Wrong. To be successful means to obtain a career in which one will make the most money, to drive the nicest car possible, to wear the flashiest clothes possible, and, the list goes on. This is what we, as a ...

The Regeneration of Roaring Camp essays

The Regeneration of Roaring Camp essays And so the work of regeneration began in Roaring Camp(4). The regeneration referred to takes place in a California mining camp in 1850. It takes the birth of Tommy Luck, son of Cherokee Sal, the camps prostitute, who died giving birth, to start this transformation of the town. Sometimes one doesnt realize how much he needs to change until he gets a small push from fate. Just a little addition to the world can cause a regeneration of an entire town. Bret Harte demonstrates this idea in the story The Luck of Roaring Camp. In this story, Harte shows that even the roughest men can change into kind, gentle, wholesome people, through the love of a child. America is an early, crude and lawless place where regeneration can occur. The men of Roaring Camp were all unruly and all it takes is the love a child to change the rude into responsible. To the burly men of Roaring Camp, deaths were an ordinary event, but the birth of a child was a very special event that never took place because there were not any women. A commotion started as a result of the baby being born, but the men did not take it that serious and even made bets on whether or not the baby and Cherokee Sal would survive. They had no respect for the fact that Sal was in pain and in need of some type of assistance in the beginning, but as the screams worsened and the knew that Sal had passed on then, The camp rose to its feet as one man! (2). People were lined up single file and orderly because they had wanted to see the baby. This was the first sign of regeneration in the story. The first encounter with the baby was the start of a whole new lifestyle for the men. As they walked past the newborn, the men would give items that they had. A variety of things were given such as a diamond ring, a gun, a Bible, and around 200 dollars. As man named Kentuck walked by, the baby grabbed his finger in a cute way that awed K...

The Future of Cybersecurity Essay Example | Topics and Well Written Essays - 1750 words

The Future of Cybersecurity - Essay Example As we have seen $14 billion has been invested by the U.S federal government to empower its security sector (Amoroso & Amoroso, 2007). This research aims to answer some of the important questions that are associated with cyber security. In this scenario, this paper attempts to answer the questions such as what changes need to occur in the cyber security industry of the future and why. And is cyber security becoming more important to national security than the security of kinetic weaponry? The outburst of Cyber Assault The countries which are currently attacking United States include China and Russia. In fact, the chances of cyber security attacks have increased to a huge extent from these two nations because of their original revival in the global economy. The United States has been accusing both China and Russia of current attacks that the United States has been experiencing. The current technological advancement has greatly influenced several nations which have mainly exposed China, United States, UK and Bangladesh. It is quite expected that physical defense associated with countries particularly talking about USA will be affected which mainly with cyber terrors. Threats for controlling systems can be associated from various resources especially antagonistic governments, terrorist associations (staysafeonline.org, 2013). Additionally, for ensuring confidentiality and privacy in the informatics, it is exceedingly recommended that there should be a national level association to demeanor the in vogue studies and prepare reports on issues in the works at the crossroads of cyber attacks and privacy, society level suggested boards that would help speak to these issues from local or community perspectives. In addition, there is also a risk that even the restricted public cyber attacks that have been modeled after the ethics committees to take in hand the explicit situations concerning health data and privacy should be working in order to preserve the restrictions rel ated to the field of cyber security. In this scenario, some of the major suggestions regarding implementation of security measures to deal with these cyber attacks include adopting the restricted, well defined, well practiced and fruitful public security requirements, including a focused assessment of security attentiveness for all public systems, and contemplation for split funding of the work compulsory to achieve ample security. It is an admitted fact that securing the rights of the people and retaining their due confidence is the responsibility taken up by the government and this has been very intensely regulated by institutions (govtrack.us, 2012). President Obama perception on Cyber Attacks A Cyber security executive orders were issued by the president of the U.S.A, Barack Obama, drew the attention by proposing policies that could defend the country from the current torment of cyber attacks

Three Positions on Abortion Essay Example | Topics and Well Written Essays - 1000 words

Three Positions on Abortion - Essay Example The conservative stand rejects abortion at any cost. This position is largely based on religious beliefs regarding the sanctity of life. Conservatives also cite the ‘slippery slope’ argument, where the right to end life could be extended to other situations, such as euthanasia. The liberal position permits abortion unconditionally. Liberals accept various justifications for abortion, including the woman’s right to make decisions over her own body, the quality of life of fetus and mother, and monetary and career considerations. The conservative and liberal positions are both reflections of the uncompromising rigidity which often characterizes any debate on the issue of abortion. On the other hand, the moderate position on abortion recognizes the moral implications it entails, and acknowledges that the rights of the mother and the fetus are in conflict in this situation. Moderates accept the need for abortion, but limit their acceptance to situations entailing defor mity in the fetus, health risks to the mother, and cases of rape and incest. I agree with the moderate position on abortion because of its attempt to reconcile two extreme stands. The moderate position appeals to me as it represents a genuine attempt to reconcile two opposing viewpoints: the conservative and the liberal. ... From the liberal perspective, the moderate position accepts that several mitigating factors, largely concerned with the well-being of the mother, can justify the overruling of the right-to-life of the fetus. However, it rejects a casual attitude towards the suffering of the fetus. This middle-of-the-road position ensures that the issue of abortion can be taken on a case-by-case basis. After all, each case has its own unique circumstances, and the conservative stand of unilaterally ruling out abortion is unacceptable. For example, if the pregnancy poses a risk to the health of the mother, abortion can be justified. Similarly, moderates do not condone abortion out-of-hand. This sets curbs on the overly permissive liberal position, which could generate a laissez-faire attitude towards casual sex and pregnancy. Abortion without any restrictions would lead to sexual permissiveness and lack of responsibility. The moderate position approaches the issue of abortion without any preconceived i deas of morality, and adopts a non-judgmental stand which particularly appeals to me. Just as the moderate position on abortion is a calculated compromise between two extreme viewpoints, it incorporates several ethical approaches into its deliberately balanced stand, and rejects any rigidity. The moderate position, by nature of its flexibility, and willingness to accept compromise, rejects the Deontological Ethical Approach, because the latter emphasizes rigid moral obligation. Moral obligation, without any consideration of the resulting consequences, is foreign to moderates. Similarly, moderates reject the Intuitive Approach, based on the perception that this approach is often individual morality, or personal prejudices, painted in stubborn