Definition of Postzygotic Isolation in Evolution

Speciation is the divergence of two or more lineages from a common ancestor. For speciation to occur, there must be some reproductive isolation that occurs between formerly reproducing members of the original ancestor species. While most of these reproductive isolations are prezygotic isolations, there are still some types of postzygotic isolation that leads to making sure the newly made species stay separate and do not converge back together. Before the postzygotic isolation can happen, there must be an offspring born from a male and female of two different species. This means there were no prezygotic isolations, like the fitting together of the sex organs or incompatibility of the gametes or differences in mating rituals or locations, that kept the species in reproductive isolation. Once the sperm and the egg fuse during fertilization in ​sexual reproduction, a diploid zygote is produced. The zygote then goes on to develop into the offspring that is born and hopefully will then become a viable adult. However, offspring of two different species (known as a hybrid) are not always viable. Sometimes they will self-abort before being born. Other times, they will be sickly or weak as they develop. Even if they make it to adulthood, a hybrid will most likely be unable to produce its offspring and therefore reinforce the concept that the two species are more suited to their environments as separate species as natural selection works on the hybrids. Below are the different types of postzygotic isolation mechanisms that reinforce the idea that the two species that created the hybrid are better off as separate species and should continue with evolution on their own paths. The Zygote Is Not Viable Even if the sperm and the egg from the two separate species can fuse during fertilization, that does not mean the zygote will survive. The incompatibilities of the gametes may be a product of the number of chromosomes each species has or how those gametes are formed during meiosis. A hybrid of two species that do not have compatible chromosomes in either shape, size, or number will often self-abort or not make it to full term. If the hybrid does manage to make it to birth, it often has at least one, and more likely multiple defects that keep it from becoming a healthy, functioning adult that can reproduce and pass down its genes to the next generation. Natural selection ensures that only the individuals with favorable adaptations survive long enough to reproduce. Therefore, if the hybrid form is not strong enough to survive long enough to reproduce, it reinforces the idea that the two species should stay separate. Adults of the Hybrid Species Are Not Viable If the hybrid can survive through the zygote and early life stages, it will become an adult. However, it does not mean that it will thrive once it reaches adulthood. Hybrids are often not suited for their environment the way a pure species would be. They may have trouble competing for resources such as food and shelter. Without the necessities of sustaining life, the adult would not be viable in its environment. Once again, this puts the hybrid at a distinct disadvantage evolution-wise, and natural selection steps in to correct the situation. Individuals that are not viable and not desirable will most likely not reproduce and pass down its genes to its offspring. This, again, reinforces the idea of speciation and keeping the lineages on the tree of life going in different directions. Adults of the Hybrid Species Are Not Fertile Even though hybrids are not prevalent for all species in nature, there are many hybrids out there that were viable zygotes and even viable adults. However, most animal hybrids are sterile at adulthood. Many of these hybrids have chromosome incompatibilities that make them sterile. So even though they survived development and are strong enough to make it to adulthood, they are not able to reproduce and pass down their genes to the next generation. Since, in nature, fitness is determined by the number of offspring an individual leaves behind and the genes are passed on, hybrids are usually considered unfit since they cannot pass down their genes. Most types of hybrids can only be made by the mating of two different species instead of two hybrids producing their own offspring of their species. For instance, a mule is a hybrid of a donkey and a horse. However, mules are sterile and cannot produce offspring, so the only way to make more mules is to mate more donkeys and horses.

Problems Faced by Students in Pakistan - 3448 Words

Problems faced by students in current educational setup amp; their possible solutions 17 About the Author: Zara Saleem is one of the most talented students of Hajvery University, Lahore, Pakistan. She is the student of Final Semester, Pharm. D. | As we know that education is the backbone in the development of any nation, it is a fact that the countries with an effective system of education lead the world, both socially and economically. The key to development is good education system. Pakistan is one of those very few countries where the system of education has constantly deteriorated. The situation at present is so bad that our system of education is almost near collapse. [hana-code-insert name=StumbleUpon /][hana-code-insert†¦show more content†¦They cannot afford even the negligible fees being charged in the government institutions, let alone the books and uniforms for which they are to pay from their own pockets. Majority of our young ones are child labor, they indulge in child labor not only to feed them selves but to support their families too. In Pakistan education is very expensive due to the shortage of public educational institutes. We have only 73 public universities and most of the population study in these universities. Similarly, there is short number of public colleges where students can get free education. Our most of the students belong to the middle class and they have very limited resources. Parents can’t afford easily the expenses of studying their children. Lots of students have to work part time to sponsor their studies themselves. In students life nearly every student usually face financial crisis. Students usually have to buy books, note books, notes of their course outline and meet transportation expenses. They have to bear some extra expenses for that they can’t ask to their parents as bunk classes and going out with fellows, buying gifts for their girl friends / boyfriends and many other activities. Solution: Students can cope with these crises very easily by a little effort. There are lots of home tuitions available for to teach students for 2 or 3 hours and earnShow MoreRelatedThe Release Of India From The British Grip Of Power Seemed1728 Words   |  7 PagesThe release of India from the British grip of power seemed to be a historic victory, but it soon posed problems for the inhabitants the subcontinent. Ever since the formation of Pakistan and India, the East Pakistani population saw a cultural divide between themselves and their Western counterpart. Although there were numerous other factors that had contributed to this difference, language was the one critical catalyst for Bengali self-determination. The formation of Bangladeshi nationalism beganRead MoreEthical Issues Faced By Coke And Pepsi1247 Words   |  5 PagesAnalysis: 2 The stake holders: 2 Top management: 2 Consumers: 2 Government: 2 My perspective: 2 Your recommendations. 3 Conclusion: 3 References: 4 Introduction: This case about Coke and Pepsi in India has been really interesting for me. I belong to Pakistan which is somewhat same kind of market as like India. This case focuses on ethical issue in host country and conflict management by multinational companies. Coca-Cola and PepsiCo have operations in all over the world and also expanding their marketRead MoreLoad Shedding Crisis in Pakistan1740 Words   |  7 PagesLoad Shedding Crisis in Pakistan Electricity is a basic need for sustaining human life. We cannot even imagine how our lives would have been if electricity was not discovered. Looking at it from an economic growth perspective of a country, the creation of energy is very essential. Pakistan however has been facing an acute shortage of electricity for many years now (since 2007). Electricity crisis and load shedding reaches to 10hours in Karachi. In commercial and residential areas of Karachi loadRead MoreList of Important Topics for Essays1583 Words   |  7 Pagesformatted. 01. Dilemma of the water and energy crisis in Pakistan (2003) 02. Art critics and reviewers (2003) 03. Alleviation of poverty (2005) 04. Persecuted poor women (2005) 05. Foreign direct investment (F.D.I) in Pakistan (2006) 06. Global warming (2006) 07. Personalization of Pakistani politics (2006) 08. Formal and casual dressing codes (2003) 09. Liberalism (2006) 10. Existentialism (2003) 11. Socio-economic challenges faced by Pakistan (2005) 12. Islam versus the west (2005) 13. InternationalRead MoreComparison of Ptv and Geo1457 Words   |  6 Pagesavoid losing their market share. A positioning strategy is concerned with maintaining long term relationships with the audience. In this regard, PTV has a distinct advantage since it has been the prime source of entertainment since the creation of Pakistan. PTV news is viewed as a ‘channel for oldies’. The prime reason being the kind of programs it airs on the channel. From the morning show to the hourly news bulletin, the channel is all about dull colors and quiet environment which is mostly preferredRead MoreChallenges Faced by Youth1980 Words   |  8 Pagesmost widely used rhetoric about our country’s future and this rhetoric is even more prevalent on our national days. Youth is a not biological age but rather a mindset. Pakistan is essentially a young country – almost half of the segment of Pakistani population belongs to youth with ages between the age 15-35 (66%). But, the problem with this assertion is quite simple, an army can have the best weapons in the world, but if it doesn’t use them properly and effectively it still loses the war. The sameRead MoreAnalysis And Evaluation Of The Business And Financial Performance Of An Organization1365 Words   |  6 Pagescomfortable dealing with number s, even during my studies as ACCA student I performed better in Areas that deal with numeric data as opposed to discussion and theories. I chose to write on Pharmaceuticals industry and Company I chose from this industry is Abbott Laboratories Limited (Pakistan). Reason for choosing target Company . Project Objective Objective that I set out for myself are: To do a financial analysis of Abbott Laboratories Pakistan. over the period of three years i.e. from 2013-2015. To conductRead MoreReflection Of I Am Malala1063 Words   |  5 Pages In â€Å"I am Malala†, Malala Yousafzai was born on July 12, 1997 in the province/state KPK in Pakistan (â€Å"I am Malala† chapter 3 pg.55). She belongs to a struggling but educated family, her father owns a school. Following two younger brothers, she is bright and talented student in her class, therefore, remain at top of the class. The entire world has been changed after 9/11 so does her life and Pakistan (I am Malala: chapter 6 pg. 85). There was also a great change in Pakistani government. She describesRead MoreLiteracy And Its Effects On Education1985 Words   |  8 Pageswas an issues in some countries. In past years, Illiteracy was a big issue to some countries like Pakistan, Ghana Ethiopia, South Africa and other places in Africa. Over the past years, the government of these countries focused on education. The levels of literacy in these countries was too high and there were causes of n egative impact toward education. For instance, literacy rate of girls in Pakistan and family were the negative impact. Literacy rates for both gender was too high in Ghana, EthiopiaRead MoreLiteracy Rate Of Low Enrollment1973 Words   |  8 PagesIn past years, Illiteracy was a big issue to some countries like Pakistan, Ghana Ethiopia, South Africa and other places in Africa. Over the past years, the government of these countries focused on education. The levels of literacy in these countries was too high and there were causes of negative impact toward education. For instance, literacy rate of girls in Pakistan and family were the negative impact. Literacy rates for both gender was too high in Ghana, Ethiopia and South Africa and the negative

Education and Economic Aspect English Free Essays

As we know in this modern era English has been an international language, English has been used by many country in the world, English also used in international events, such as seminar, public discussion, conference, and treaty, the importance of English language can be seen and felt in everywhere such as: economy aspect, social aspect and educational aspect. First is economic aspect English is the dominant business language and it has become almost a necessity for all people to speak English if they are want to enter a global workforce, research from all over the world shows that the business communication is the most often conducted in English. It is very importance in the global market place to learning English because to join our dream’s jobs in any country, especially in an English-speaking country, we must be fluent in this language. We will write a custom essay sample on Education and Economic Aspect English or any similar topic only for you Order Now Whether we are an aspiring doctor, engineer, academician, sportsperson, like students, businessmen, player’s, service holders Etc, we must learn English to progress in our field, So English language is really important for every occupation. And the second is social aspect; communication is the most important aspect to know our social, because with communication we will know the condition in our society, some countries use English as their mother tongue, English is language of communication between the people with different cultures, it is also the language of computers that help to communicate with the people around the world through Internet technology and e-mail. But we have to know that almost all computing operating systems, programs, software, etc are dominated by English language. So knowing English will help us to get information from other world. And the last is education aspect; education is one of the important aspects in our life because Education is the key to a person’s future. If we have a good education it will help us to achieve all types of goals and to reach our goals we have to study until high level and in this modern era if we want to continue our higher education we must learn English because most of the higher education books are in English. Language is the medium of expressing thought and feelings to others. English is the International language. People of the countries of the world speak English as a common language. As a result English has become the language of communication, higher studies science and technology. It is also the language of business and diplomacy. Without English no one can go to a foreign country. It is also necessary to get a good job. So all kinds of people like students, businessmen, player’s, service holders, doctor, engineer, academician, sportsperson and etc, must learn communicative English to make progress in their life. Without communicative English no one can shine in life, so, in my opinion we should give much stress in learning English from the very beginning, even thought there are many people said that English is difficult but I think it is not? We just need dedicate some time on regular basis to learning English. How to cite Education and Economic Aspect English, Papers

Corporation Business and Corporation Law

Question: Discuss about the case study Corporation for Business and Corporation Law. Answer: Introduction: According to law, a contract or agreement between individuals in which either of the parties can lawfully compel the performance of the other is known as enforceable agreement (Alan Robert, 2003; p. 25). This means that the agreement or contract carries the force of law behind it. The courts can also become involved in enforcing contracts, with the inclusion of having a portion declared void. In the situation presented, Jane has simply made Jack an offer without stating a price limit of how much it should sell for. Therefore, the contract is rather open and it is Jack who is to decide whether or not to accept the offer. Moreover, he is not obliged by law to fulfill the particulars of this contract or act upon it. Application/Analysis Jane has made an offer to give her Lotus Super 7 sports car to Jack. She has not stated any price in terms of how much the car should go for. However, Jane has only stated the market value of this type of car in good condition. Given these facts, this type of agreement or contract is an unenforceable one even though it is still considered valid. Therefore, a legal entity cannot compel one or both parties to act on it or fulfill its terms and conditions since there is a public policy or statute making it unenforceable (Leigh, 2001; p. 74). Jane may not succeed in selling her Lotus Super 7 sports car to Jack especially if Jack finds the offer unfavorable. Moreover, Jack is not legally liable to fulfill the terms and conditions of this particular agreement because it is only the market value which has been stated. On the other hand, Jack may counteroffer this offer by offering a lower price than the $25,000 for the sports car since he has already accepted it. Jane offers to sell Jack her Lotus Super 7 sports car for $25,000. The market value for this type of vehicle in good condition is around $25,000. Jack accepts. Issue The issue here is whether or not an enforceable agreement is present when Jack accepts the offer. Rules As already indicated, an enforceable agreement is that which either parties can lawfully induce the performance of the other. In this case, there is an enforceable agreement because Jane has not only offered a selling value for her Lotus Super 7 sports car, but has also indicated the market value for this type of vehicle in good condition. In addition, Jack has accepted to fulfill the terms of this agreement. This means that he has been legally obliged to act on the contract, lest he be held liable for breach of contract. Application/Analysis Jane made an offer for her Lotus Super 7 sports car at $25,000. Notably, this price is similar to the market value of the vehicle in good condition. Jack has accepted the offer. One may conclude that the vehicle was in good condition because of the similarity in prices. Therefore, Jane would get value for her sports car and would not go at a loss. Conclusion Given the fact that this particular contract is enforceable, Jack would be held liable for breach of contract if he fails to honor its terms. Jane is also offering the vehicle in good condition and this is perhaps the reason why Jack has accepted the offer. Jane offers to sell Jack her Lotus Super 7 sports car for $2,500. The market value for this type of vehicle in good condition is around $25,000. Jack accepts. Issue The issue here is whether or not an enforceable agreement is present when Jack accepts the offer. Rules In this case, the contract is enforceable. Jane has offered to sell her Lotus Super 7 sports car at a much lower value than its market price. This is an attractive price for any potential buyer. However, a contract or agreement, oral or written, may be difficult to enforce unless the terms therein can be evidenced or are admitted by the parties involved (Mather, 1999; p. 76). Once Jane has accepted payment or Jack has accepted delivery of the sports car covered by the oral contract, it makes the agreement valid even in a court of law. Application/Analysis Jane has offered to sell her vehicle to Jack at a lower price than that of its market value. Jack has accepted, making the contract valid. Looking at these facts, the parties involved are not only competent individuals who have the lawful capacity to contract, but have also agreed to the terms laid therein. There is also mutuality of obligation. Notably, Jack has apparently made a counteroffer and received a lower price than the vehicles market value. Jane has accepted the counteroffer and is willing to fulfill the terms of the contract. Conclusion If this was a court case, Jack would not prevail because he has already accepted the offer made particularly after making the counteroffer. It may be assumed that the vehicle is not in good condition and thus cannot be offered at its market value. This means that Jack has accepted to receive the Lotus Super 7 sports car at the value being offered by Jane, and will make the necessary repairs or alterations himself. Failure to pay for the vehicle may result in a legal suit. A shipbuilder had contracted to build a tanker for North Ocean Tankers. The contract was in US dollars and didnt contain any provisions for currency fluctuations. Approximately halfway through construction of the ship, the United States devalued its currency by 10%. As the shipbuilder stood to make a loss on the contract, it demanded that an extra US$3 million be paid or it would stop working. The buyer reluctantly agreed under protest to pay, as he already had a charter for the tanker and it was essential that it be delivered on time. The buyer didnt commence action to recover the excess payment until some nine months after deliver. Will the buyer succeed in recovering the excess? Issue The issue here is whether or not the buyer will succeed in recovering the excess. Rules In the case presented, the buyer will not succeed in recovering the excess payment because it is considered to be void. A contract made not more than nine months or 180 days before the judgment against the buyer became uncollectible between the buyer and shipbuilder in which the former had a financial interest. If the tanker has experienced normal wear and tear, then the buyer shall be liable to the shipbuilder for the full amount the former paid for the contract (Beaston, n.d.; p. 43). Otherwise, the buyer shall only be liable to the shipbuilder for the market value of the tanker. From what can be deduced in the case presented, the contract did not include any provisions regarding currency fluctuations. An unexpected incident which was the devaluing of the currency by 10% was observed. This meant that the shipbuilder would incur losses on the initial contract. A contract between the shipbuilder and the buyer pursuant to which the latter has paid or agreed to pay the money to the for mer, and where the shipbuilder has not yet carried out the obligations under the contract, makes this effort uncollectable. The buyer in this case reluctantly agreed to pay for the loss incurred by the buyer following the currency devaluation. However, he did not proceed to recover the excess payment until some one hundred and eighty days after delivery. Application/Analysis The facts of the case are that a shipbuilder had contracted to build a tanker. In the agreement, there were no provisions with respect to currency fluctuations. Nevertheless, a fluctuation did take place and the shipbuilder refused to continue working on the tanker until he was paid an extra amount of money. Legal contracts or agreements seeking to offer clarity and certainty for parties involved require that certain components be agreed upon before being lawfully enforceable. These elements include parties, property, and price. The additional payment for the loss incurred was not included in the original contract and therefore meant that it would be determined by the purchasers word-of-mouth or promise (Slawson, n.d.; p. 90). There was no wholly acceptable price or provisions for currency fluctuations in the contract. Moreover, there was no objective mechanism laid out in case of such incidents while the shipbuilder was building the tanker. The buyer was coerced into making the extr a payment because he/she had a deadline to beat. Notably, he pursued the recovery of the excess payment nine months after the tanker had been delivered to him. According to the law, despite the misunderstanding in between the fulfillment of the contract terms, the shipbuilder managed to complete the construction of the tanker and deliver it on time. He did not breach the contract. However, the buyer was late in pursuing this particular issue and thus rendered the recovery of the excess amount void. The buyer had an opportunity to cancel the contract with the shipbuilder when the currency fluctuated, but he did not. By law, when the shipbuilder communicated his disinterest in continuing to build the tanker for the buyer, he was indirectly breaching the contract. But since the buyer was willing to reluctantly cater for the loss incurred, the contract was not terminated (Bakan, 2004; p. 45). Notably, failure by the shipbuilder to carry out the obligation to provide the buyer with the necessary conditions within the time established by the contract and lack of proof of readiness of the tanker for shipment, constitute the shipbuilders failure to perform as per the contract. This condition is admitted as reasonable claim for the recovery of excess payment made by the buyer and the penalty founded on that payment. Conclusion Looking at the case presented, it has been established that the buyer will not succeed in recovering the excess payment. If this was a court case, it would be found that the shipbuilder has no case to answer and is not liable for anything. The fact of the matter is that the buyer made an effort to recover the excess nine months after delivery of the tanker. This means that the agreement of the contract had already been fulfilled despite the brief misunderstanding following the currency fluctuation. The shipbuilder did not breach the initial contract despite there being no knowledge of future occurrences. For recovery of excess payment in a contract to take place, there needs to be a number of conditions for instance the pursuance is made prior to the nine months deadline. Recovery can also be made if the contract was breached, and only partial fulfillment of the original contract was completed. The buyer can also be successful in recovery of payment if he/she had opted to terminate o r cancel the initial contract at the point when the shipbuilder requested for additional payment following the currency fluctuation (Muchlinski, 2007; p. 77). Recovery of excess payment would be made possible if this payment was made under fraudulent circumstances. However, the shipbuilder was quite clear about his condition despite the fact that the terms of the contract had not yet been fulfilled. The initial contract was binding and considered valid. Therefore, any payment that would be made in the course of the contract period would also be considered lawful. Moreover, the factors necessary for a contract to be considered valid or legal were present, for instance consent, acceptance, offer, consideration, contractual terms, and capacity (Seidl-Hohenveldern, n.d.; p. 97). When changes were made in the course of fulfilling the contract, the buyer did not refuse to pay the extra charges. There was no fraud, carelessness, favoritism, collusion, or misrepresentation in this particular case. That is why the buyer will not be able to recover the excess. References Alan, S., and Robert, S, E., 2003. Contract Theory and the Limits of Contract Law. The Yale Law Journal, 113(3). Alan, S., and Robert, S, E., 2010. Contract Interpretation Redux. The Yale Law Journal, 119(5). Andrew, R., 2005. The Limits of Voluntariness in Contract. Melbourne University Law Review, 29(1). Bakan, J., 2004. The corporation: The pathological pursuit of profit and power, New York: Free Press. Beaston, J. E. ., and Friedman, D. E., n.d. Good Faith and Fault in Contract Law. USA: Claredon Press. Buckley, F, H., 2005. Just Exchange: A Theory of Contracts. London: Routledge. DiMatteo, L, A., n.d. Contract Theory: The Evolution of Contractual Agreement. USA: Michigan State University Press. Kreither, R., 2007. Calculating Promises: The Emergence of Modern American Contract Doctrine. USA: Stanford University Press. Leigh, B., 2001. Freedom of or Freedom from? The Enforceability of Contracts and the Integrity of the LLC. Duke Law Journal, 50(4). Mather, H., 1999. Contract Law and Morality. Westport, C,T: Greenwood Press. Muchlinski, P., 2007. Multinational enterprises and the law. 2nd Edition, Oxford: Oxford University Press. Omri, B-S., and Bernstain, L., 2000. The Secrecy Interest in Contract Law. The Yale Law Journal, 109(8). Posner, E, A., 2003. Economic Analysis of Contract Law after Three Decades: Success or Failure? The Yale Law Journal, 112(4). Randin, M, J., 2012. Bipolerate: The Fine Print, Vanishing Rights, and the Rule of Law. Princeton: Princeton University Press. Seidl-Hohenveldern, I., n.d. Corporations in and under international law, Cambridge, UK: Grotius. Slawson, D., n.d. Binding Promises: The Late 20th Century Reformation of Contract Law. Princeton: Princeton University Press.