Based on experimental evidence from the Astyanax mexicanus investigation, it can be argued that eye regeneration in the dark cave environment is due to adaptive evolution. Experiments that have been carried out on Astyanax cavefish do not seem to favor the neutral mutation theory. The results from these experiments have shown that several eye genes are pleiotropic and regulatory since they have many functions in development in addition to their eye forming roles. This means that the genes do not experience the neutral decay process. Even critical eye structural genes such as retinal opsin, which functions at the base of gene cascades, are still expressed during the eye development of cavefish. This is why the adaptation hypothesis based on pleiotropy is the most credible explanation behind the loss of eyes in cave-adapted animals.
It is now a fact that most animal species that live in caves tend to lose their vision. This trait has been observed for several centuries. For instance, in 1768, Laurenti found the first described cave-adapted animal, Proteus anguinus, which is a salamander species (Juan, Guzik, Jaume, & Cooper, 2010). It was blind and according to most tales, it was thought to be the larval phase of a dragon. This amphibian’s preliminary eye development is normal. However, development of its eyes slows down with time; the lens undergoes rigorous lytic processes and the cornea involutes, making the eye to be strongly sunken and reduced.
Amblyopsis spelaea, the first cavefish species to be described in 1842, was also found to be blind (Juan, Guzik, Jaume, & Cooper, 2010). Today, biologists are carrying out numerous investigations on the Astyanax cavefish species, which have eye degenerative traits. The degree of functi...
... middle of paper ...
...’s ‘wrecks of ancient life’ in the molecular era. Molecular Ecology, 19, 3865-3880.
Meng, F., Braasch, I., Phillips, J. B., Lin, X., Titus, T., Zhang, C., & Postlethwait, J. H. (2013). Evolution of the eye transcriptome under constant darkness in Sinocyclocheilus cavefish. Molecular Biology and Evolution, 10. Retrieved from http://mbe.oxfordjournals.org/content/early/2013/05/21/molbev.mst079.full
Rétaux, S., & Casane, D. (2013). Evolution of eye development in the darkness of caves: adaptation, drift, or both. Evo Devo. Retrieved from http://www.biomedcentral.com/content/pdf/2041-9139-4-26.pdf
Yoshizawa, M., Yamamoto, Y., O'Quin, K. E., & Jeffery, W. R. (2012). Evolution of an adaptive behavior and its sensory receptors promotes eye regression in blind cavefish. BMC Biology, 10. Retrieved from http://www.biomedcentral.com/1741-7007/10/108
It is the most popular sport in the world today. There are at least 240 million people that play soccer in the world according to FIFA (Federation de Football Association). FIFA is the main source of soccer. When people talk about soccer they reference FIFA a lot. There are several American soccer teams. One of the more famous one are the Portland Timbers. In the year of 2015 they won the championships. There are a bunch of cool things about soccer. Here are some cool things that might interest you. The exact size of an average soccer ball is 27’’ in circumference; the goals are 2.44 meters tall and 7.32 meters wide. The USA women’s team was the first team to win the championships in 1991. They won it for a second time in 1999; they have never been less than the top 3 places. Brazilian Ronaldo hold the record for the most goals scored in the world cup games with a high of fifteen goals in three games. The United States has the most soccer players in the world with eighteen million, with 78% of the eighteen million are under the age of eighteen. Arthur Wharton was the first professional African American
Tadić, A., Wagner, S., Hoch, J., Başkaya, Ö., von Cube, R., Skaletz, C., ... & Dahmen, N. (2009).
This sport was first played in China by military forces during the 2nd century. Soccer is one of the most popular sports in the world. Want to know why? Soccer is an easy sport to understand, it is a fun sport to play, and you meet a lot of friends through playing!
Soccer is much more competitive than other sport.Where you have a time limit.The time limit makes things so much more competitive because you’re trying to beat the other in this time limit.Many sports have time limits in them,but soccer if the 90 minutes are up they will give 2-3 minutes for a chance to score a goal.these 2-3 minutes are more competitive than anything in the world.In that time a lot stuff start getting intense.people will be waiting for the other team to score a point.
The impact that soccer has had on the United States has drastically changed the American society and it will continue to mold the culture for years to come. Soccer, in one or more ways, has had some part in the lives every American citizen, whether it be the money spent by the government on stadiums and professional teams, or the time spent watching and playing the game. Although the sport did not have a strong early presence in American lives it has substantially grown in recent years, thus effectively popularizing soccer in every corner of the globe. The sport plays an important role in modern American society and has a bright future ahead of it.
In the story Allegory of the Cave written by Plato, it looks into human perception, showing that what we see isn’t always the truth. In the story it begins by describing the lives of three men living inside a cave. In this cave they are chained, with their backs toward the entrance of the cave unable to see anything behind them. The three men have been living in this cave their entire lives, only being able to see shadows of any objects that pass by. The shadows, have became a game to the three men, each guessing what shadow would appear next. The three men had no idea what they were seeing was only shadows of actual objects; the shadows were all they knew, so to them the shadows were what was real. One of the three men, after years of living this way, was finally able to break free from his chains. After freeing himself from the chains, he then ventured away from the cave. After stepping out, the sun quickly burned his eyes as he walked outside.”Eventually, he is able to look at the stars and moon at night until finally he can look upon the sun itself. “ only after he can look straight at the sun "is he able to reason about it" and what it is.. The Republic Book VII. Penguin Group Inc. pp. 365–401. After
Soccer is known to be one of the most popular sports in Europe and the America’s. It carries a very clear history in the world of sports. Some say soccer was being played in China during the 2nd and 3rd centuries BC. Facts also support that Romans and Greeks used to play for fun!
Over the past several decades, soccer has seen an incredible growth in the United States. More teams, players, and fans are sprouting up in a new era of the world’s most popular sport. The Men’s and Women’s U.S. National Team have both performed well in recent World Cups, showing their skill on the big stage. MLS (Major League Soccer) has explosively expanded as well, reaching many big cities and entertaining thousands of fans. Soccer is also becoming a popular sport among the nation’s youth, attracting hordes of young players. American soccer is finally finding its rightful place in the world.
England remained upset that they couldn’t play soccer, which they called football in 1605 and still today. It resulted with the sport becoming legal and pleased the Englishmen once again. The englishmen were also pleased “that the United States football was played among the Northeastern universities and colleges of Harvard, Princeton, Amherst and Brown.” (Wood n.p.) This big step for soccer happened in 1820; soccer became much more popular in America, it is now the seventh most popular sport in our country that holds many people passionate for the game. (Zac n.p.).
Schreuder, Jolanda A. H.; Roelen, Corné A. M.; van Zweeden, Nely F.; Jongsma, Dianne; van der Klink, Jac J. L.; Groothoff, Johan W.
In the Cave the people are trained to see only the shadows with the little light that is given from behind them. They see the shadowed objects in the same order every time. It is like us students,
In an environment that changes often or a species moves to a different environment a genotype has the ability to produce various phenotypes to sustain the environment. The ability for the genotype to process different phenotypes based on the pressures in the environment is called phenotypic plasticity. Phenotypic can be rapid or gradual depending on the environment and the features need for adaptation. An adaptive phenotype will be able to change morphology, behavior, and development alterations (Futuyma, 2013). Developmental may not be able to be reversed, but the changes can happen rapidly. An adaptive phenotype will be able to alter its phenotype when the environment changes, resulting in different phenotypes to adapt. Adaptive will increase the fitness of a species, because they will be able to adapt quickly to different environments increasing their chances of survival. A non-adaptive phenotype will decrease the fitness of a species. This phenotype may change the species to go against or resist the changes in the environment or not adapt at all. If the species does not change...
Convergent evolution is the process in which organisms which are not closely related derive akin traits separately due to the need for adaptation to similar environments or ecological niches. According to the neo-Darwinian view, species with similar environmental living settings experience similar selection pressures. Natural selection then acts on the arbitrary changes or current genetic variability leading to identical phenotypic solutions. There may be resemblances at a phylogenetic level, but the basic DNA sequences are different. Convergent evolution gives rise to characteristics which are referred to as “analogous structures”. They are often contradicted with “homologous structures” which have the same ancestors. Convergent evolution
Soccer is the most popular sport in the world. Soccer is played in every country on earth, and for many of them, it's their number one sport. The sport's beast leagues are traditionally in European countries such as England, Spain, Italy and Germany. Some are even considered to be in Latin American countries such as Mexico, Brazil, and Argentina. The United States and Canada are not traditionally known for their high level leagues, however, Major League Soccer is quickly changing that.
Barker, V., Giles, H., Hajek, C., Ota, H., Noels, K., Lim, T-S., & Somera, L. (2008).