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When I first thought of what a writing class for the biological sciences entailed I was not too thrilled about the idea. I thought I knew what I needed to know to write a good scientific paper. Now at the end of the semester I realize that I was wrong in assuming that I had the skills to produce a biological paper in the correct and acceptable way to present to the scientific community.
This class gave me the opportunity to come up with my own scientific experiments and research ideas. For the first time I had to think on my own for things that I was interested in and wanted to look deeper into. This was not only a class for the improvement of writing; this was a class that expanded our minds as biologists and what it means to be a scientist.
This class has not only given me the concept and practice of how to produce research in a comprehensive way but how to do so more efficiently. The skills that we have been taught in this class about using different programs on a computer have greatly impacted the way I will go about scientific writing and presentations in the future. Looking back now on all of the things our class undertook I am grateful for the experience and the skill I have learned.
Growth hormone (GH), also called somatotropin, is synthesized and released from the epithelial cells in the anterior pituitary gland. When GH is released it acts in the liver and other target organs to produce insulin-like-growth factors (IGF-I,II) , also called somatomedins. These are produced by the liver and act on the growing cartilage to induce bone growth. They act on the Osteoblasts in bone in cartilage, also on protein synthesis in bone and cartilage, glucose uptake in muscle, neuronal survival, and myelin formation.
Some diseases that are associated with improper levels of these hormones are dwarfism and giantism. Giantism is caused by hypersecretion of GH during childhood, and sometimes into adulthood. This is an abnormal disease that acts to increase the length of all the bones in the body. Dwarfism is the hyposecretion of GH during the years of growth in children. The low levels of GH cause a slow rate of bone growth and a closure of the epiphyseal plates (growth plates) before normal height is reached.
Aldosterone acts on epithelial cells of the distal convoluted tubule and collecting duct in a nephron (a functional unit of the kidney) to increase reabsorption of sodium from the glomerular filtrate to the blood. The increased amounts of sodium are exchanged for potassium and hydrogen ions in the distal convoluted tubule and collecting duct. This leads to a potassium ion loss and an increase in the acidity of urine. The pH of glomerular filtrate is about 7.4, which is the same as blood, but the pH of urine is around 6.0 and can go as low as 4.0 due to the hydrogen ions.
The giant African snail was introduced to Hawaii as a proposed food source. However, it soon became apparent that snails were not very palatable to the masses, and the industry soon failed. Snails, unlike cows and sheep, are much more difficult to manage, and some got out of their enclosures. They began breeding and eating the agricultural crops that other farmers were trying to grow. People again turned to a biological solution. They brought in the cannibal snail, also from Africa, to control the populations of giant African snails. Hawaii was also home to other kinds of snails. There were over 1,000 species of native Hawaiian snails, found only in Hawaii. They had vibrant shells that people would collect after the animal had died. Some species had small holes in their shells that would "sing" when the wind would blow through the trees. When the cannibal snail was brought over to Hawaii, it chose to eat the native species instead. Now, most of the native snail species are extinct, and the rest are endangered.
I think that there should be a law passed governing how many golf courses can be established in an area. Golf courses are horrible for the environment. They require tens of thousands of gallons of water to maintain the grass every year. They also require pesticides and herbicides to keep just the "golf course" grass growing in the golf course. These chemicals don't stay on the golf course, however. They can run off into nearby forests or streams and contaminate the ecology there. I don't see why a state needs to establish more than 2 golf courses.
Nor can I understand why people think off-shore drilling is a good idea. When problems occur at an off-shore drilling site, the oil goes everywhere, and because it's off-shore, it makes it extremely difficult to maintain. It damages the local environment, and it also spreads much more quickly because of the liquid medium that it is on.
The vast majority of people are under the impression that our primary mode of communication is through the usage of words, whether they are in the form of audible speech, or in text. The truth of the matter is that we relay just as much, if not more information about ourselves with our clothing, accessories, gestures, and body language. Although the assumptions people may infer from these signals may not be a true reflection of who you are as a person, the signals are still being passed between you and others. Every aspect of the way in which we carry and present ourselves is reflective of the combination of our personality, social status, and fitness. Each one of these factors can be linked to ways in which animals communicate with members of their own species as well as others.
If you were to ask the question, â€œHow do people communicate?â€ Chances are that about ninety percent of people would answer that we communicate through speech. Although this is the most obvious form of communication, we also communicate with our body language and gestures. Amphibians and reptiles are not any different; they use four main methods: visual, acoustic, chemical, and tactile communication. Each species uses each method in a different way, but the combination of all four allows them to relay mass amounts of information to other members of their own species as well as members of other species around them.
With amphibians and reptiles, visual communication usually consists of specific body movements or the flashing of a body part with a distinctive shape or color. In confrontational situations they will often open their mouth widely to warn either predators or another male. These visual displays can be directed at a particular individual or they may be presented for all to see. Although at first it may be hard to draw parallels to human activity, when you factor in the purpose of each one of these actions the similarities become obvious. When a male anole flashes a brightly colored dewlap to draw the attention of a potential female mate it is a lot like a guy wearing flashy clothing or accessories to draw the attention of a woman. You could also draw parallels between a lizardâ€™s open mouth threats and a manâ€™s clenched fist or rigid posture.
Frogs are the most vocal of all amphibians and reptiles. They are most prominent users of acoustic communication. Many frogs have vocal sacs that allow them to enhance the sound which is created by producing airflow over the vocal cords. They can be heard most frequently during their breeding season in which females select mates based on their calls. Female frogs are able to distinguish between males that are of the same species and frogs of different species. This method of acoustic communication is the most obvious relation that humans have to the amphibians and reptiles. Males use a loud threatening yell to warn other males that may be attempting to occupy their territory and a softer form of speech in an attempt to find a female to mate with.
A third method of communication that is performed subconsciously is chemical communication. Both males and females use chemical signaling in different ways. Males often mark their territories with pheromones to either lead females to a nesting site or to warn other males to stay away. Females most commonly secrete sexual pheromones to let the males know that she is interested in mating. For every chemical signal that is emitted from an individual, there must also be a corresponding organ that allows other individuals to sense it. Many species have highly advanced methods for interpreting whether or not a specific pheromone is coming from a member of their own species and also where that individual is located. Humans do not use scent in quite the same way, but smells trigger various responses.
The last mode of communication is referred to as tactile communication. This refers to instances when individuals rub, press, or hit body parts against one another. The contact can take place during courtship of a mate and also in male-male competition. Male tuatara align themselves next to one another and thrash their tails and if neither one backs down; the two enter into a fight which involves biting until one of the retreats. This is very similar to male humans who often enter a pushing match that can escalate unless one of the two walks away from the confrontation. Males will also rub their bodies against females in an attempt to court them. Men perform many similar actions in attempts to copulate with females.
This type of action by action breakdown can be done for many different species and parallels can be drawn between many of them. The fact is that humans are animals as well and most of the signaling and communication discussed in science is for the purpose of mating or male-male competition which is essentially universal across all species. Aggressive, competitive males always try to protect what they value and also prove themselves as the best mate selection to conspecific females.
Vitt, Laurie J., and Janalee P. Caldwell. Herpetology An Introductory Biology of Amphibians and Reptiles. 3rd ed. San Diego, California: Elsevier, 2009. 239-255. Print.
Speciation is said to be the formation of a new race or subspecies as a result of geographic, physiological, or behavioral differences between two previously interbreeding species. There are three main types of speciation: allopatric, parapatric, and sympatric. Each one explains different ways in which a group of a certain species is isolated from the rest of that species population. After being isolated, the species evolves new traits which can eventually lead to the formation of a new species, subspecies, or race. Over an extended period of time, the isolated sector can become reproductively isolated from the original species. This includes both pre and post mating isolation.
The process of speciation includes both micro and macroevolution. Microevolution is evolution within a species which is what happens at the start of speciation. Macroevolution is the formation of a new species. As previously stated, speciation is the formation of a new species, subspecies, or race. Natural selection is a key component in the evolution of life, and is also part of what causes speciation. The new species that are formed have new traits that were favored by natural selection and therefore are a key component in evolution.
The most common form of speciation is allopatric speciation. The word â€œalloâ€ means other country while â€œpatricâ€ means â€œfather land.â€(Lahti, 3/25/09) If you combine the two meanings, you can infer that allopatric means other or new county which is different from the father land. This is usually caused by creating a geographic barrier between members of a species. This can be anything from a mountain range to a canyon, even a river. One of the more well known examples of this can be found in the case of wrasse fish. The fish used to be able to swim freely from the Atlantic to the Pacific Ocean until a section of terrain rose at the Isthmus of Panama 3 million years ago. The most important effect of this barrier and others like it is that it prevented and continues to prevent gene flow between the populations that have been separated. When there is gene flow, the species maintains a singular phenotypic identity. (Lande, pg. 464) In the case of the wrasse fish, some have developed differences in genes for certain enzymes. It is thought that if two populations are separated long enough they will become reproductively incompatible. If a true speciation event has taken place, the two populations could be reintroduced to each other and would no longer be able to interbreed and produce viable offspring. Although it is almost unanimously accepted that the separated species evolve and become reproductively isolated, it is said that this is only a by-product of other genetic mutations happening for other reasons. (Lande, pg.463) When a species is separated into different environments as is the case in allopatric speciation, they are likely going to adapt to their habitat. Natural selection favors the traits that increase the fitness of the individual or the genes of that individual, but in different environments, different traits would serve the individual best. This is why when geographically isolated; it is easiest for species to diverge from their original traits. The wrasse fish are a classic case used to describe the effects of allopatric speciation, but more modern research has implied that the rules applied on land cannot be carried over into a marine environment. The extreme case of the wrasse fish still stands, but more common cases involving coral reefs are being called into question. There have been cases of speciation previously attributed to allopatry that have been found to violate a fundamental â€œlawâ€ of allopatric speciation. Certain species of fish have diverged even with fairly frequent gene flow.(Rocha, Robertson, Roman, Bowen) This is a singular example of a flaw in the vast field of allopatry but there are many more examples of allopatry creating new diverged species.
There is also another form of allopatric speciation in which a small group of a certain species moves away from the larger populations and starts their own. This process is commonly known as the founder effect. (Bush, pg.346) There are very select species that can successfully start up a lasting colony and make it prosper to the point of forming a new species. One such species is the Hawaiian Drosophila studied by Carson. He found that it was possible for a single fertile female to spark a colony itself. He also hypothesized that these particular populations were already adapted to some degree of inbreeding and could have potentially been the result of lax natural selection. Certain differences in this new population that would have normally been â€œweeded outâ€ by natural selection were allowed to continue through new generations via the founder female. The fact that the separated species had these genetic differences almost immediately following the geographic separation also lead to a more rapid divergence from the original â€œmotherâ€ species. This species in particular also seemed to exhibited selection for homozygosity which would have further separated the species with recessive mutant traits. The founder effect allopatric speciation seems to me a more radical and rapid divergence. The founder(s) can have potential genetic differences that would become extremely prevalent within only a few generations.
Another rarer and more controversial form of speciation is known as parapatric speciation. Para meaning next to, or parallel to, and patric again meaning father land. (Lahti, 3/25/09) So you can gather that parapatric speciation would be the creation of a new species next to the original population. Unlike allopatric speciation, there is not an actual physical barrier separating the populations. Without a mountain range or canyon separating the species, there have to be other obstacles preventing gene flow between the populations of the species. Because of this factor, parapatric speciation is most commonly associated with animals that have limited mobility. The new adjacent population remains in contact with the original population and there is even limited gene flow between the two at the boarders. One example of parapatric speciation can be seen in the wingless grasshopper. With its limited mobility and emergence into a new adjacent environment, it was a prime candidate to undergo parapatric speciation. The grasshoppers in the new environment adapted as many of the animals did when going though allopatric speciation, but the difference is that some of the members of the two populations were able to interact. White hypothesized that the grasshoppers used a method similar to that of the Hawaiian Drosophila in that there were high levels of selection for homozygotes. The fact that the new niche inhabited by the grasshoppers was on the outskirts of the population aided in this process. If the diverging population had been integrated into the main population, the recessive traits would have been overtaken by the dominant ones. The semi remote positioning of the grasshoppers allows for this homozygote selection to be possible. Pre and post mating isolation also play a large role in many parapatric speciation events. These types of mutations occur more frequently in plants and prevent interbreeding at earlier stages in the speciation process. In a specific example, a species of plants moved onto an area of contaminated soil in which the plants built a resistance. This rapid evolution to allow the plants to survive in this environment also drastically changed their ability to reproduce with their former fellow species. The plants even developed different flowering time schedules. The most outstanding piece of information regarding this research is the proximity of the new and old plant species; many of the boarder plants were only separated by a few feet. (Bush, pg. 345-351)
The third major recognized form of speciation is known as sympatric speciation. Sym means symphony or together and â€œpatricâ€ means father land. So, sympatric speciation is speciation within a species population. This implies that there are not any physical barriers and also that the new population is not located on the outskirts of the original population. One of the requirements for sympatric speciation is polymorphism, meaning that the species must exist in several forms and or colors. (Lahti, 3/25/09) Maynard Smith hypothesized that the polymorphism could be elevated into sexual selection. If there were a case in which phenotypically different individuals were better off in a certain area within a population, then those individuals would mate. The habitat and mate selection would contribute to the evolution of two reproductively isolated populations. (Bush, pg. 352) Many evolutionary biologists have suggested that sympatric speciation is only a special case of parapatric speciation. The main difference is in the way pre and post mating isolation arise between members of the new and old species. In parapatric speciation, the reproductive isolation is established as the population moves into its new niche. In sympatric speciation, the pre mating reproductive isolation occurs before the new species population enters a new niche.
One of the major factors involved in all three types of speciation is reproductive isolation. One of the types of reproductive isolation is pre mating. A species can become reproductively isolated from one another because of their habitat. For example, in allopatric speciation there is a geographical barrier between the two populations which make it impossible to even socially interact never mind mate. There can also be seasonal differences meaning that the two populations may breed at different times. Behavior can also be a type of pre mating isolation. For example, grey tree frogs have a certain mating call that the females recognize and go to. If an individual was part of another species it would not know how to vocalize the correct call and therefore the female grey tree frog would not mate with it. The third type of pre mating isolation is mechanical; which just means that even if two individuals attempted mating, their sexual organs would not fit or lineup. There are also three types of post mating isolation. The first is known as gamete mortality, which just means that the sperm dies before it is able to fertilize the egg. The second type is zygote mortality which means that the egg is fertilized but the organism dies before it reaches sexual maturity. The third type is hybrid sterility which just means that the offspring is unable to reproduce even after reaching sexual maturity. Natural selection eventually turns post mating isolation into pre mating because it is a waste of energy for organisms to mate unsuccessfully.(Lahti, 3/25/09)
There has been extensive research into speciation of plants, animals, and other organism, but what I would be most interested in would be research into humans. There are some slight differences between human populations in different regions of the world such as language and culture, but I would be interested in more drastic changes. Although it would not be ethical and isnâ€™t even possible, I would want to see what would happen if we separated a group of people and placed them in an environment completely different from that on the earth. The ways animals are able to adapt and evolve into new species is incredible, so I would want to see how the most advanced animal, humans, would do. This type of experimentation could never be accomplished in the manner that I am talking about, but we can see smaller changes in people and cultures all the time. Full scale experimentation would allow us to see how rapidly humans can evolve in direct comparison to other species.
Bush, Guy L. "Modes of Animal Speciation." Annual Review of Ecology and Systematics 6 (1975): 339-64.
Hall, Brian K., and Benedikt Hallgrimsson. Strickberger's Evolution. Null: Not Avail, 2007.
Lahti, David. Lecture. Speciation. University of Massachusetts, Amherst. 25 Mar. 2009.
Lande, Russell. "Genetic Variation and Phenotypic Evolution During Allopatric Speciation." The American Naturalist 116 (1980): 463-79.
Palumbi, Stephen R. "Genetic Divergence, Reproductive Isolation, and Marine Speciation." Annual Review of Ecology and Systematics 25 (1994): 547-72.
Rocha, Luiz A., Ross D. Robertson, Joe Roman, and Brian W. Bowen. "Ecological speciation in tropical reef fishes." Proceedings of the Royal Society B: Biological Sciences 272 (2005): 573-79.
Smith, Maynard J. "Sympatric Speciation." The American Naturalist 100 (1966).