The Hox genes are a set of related genes that code for transcription factors involved in determining the general body plan of an organism along the anterior to posterior axis. One unique feature of the hox gene is that its function and presence is highly conserved in a wide range of species, including the model organism Drosophila, amphibians, and mammals. Because of such a high level of homology amongst species where this gene cluster exists, conducting research using model organisms containing the hox gene cluster can lead to relevant discoveries in higher organisms and help to better understand evolutionary diversity. Another notable conserved feature of the hox genes is that they display colinearity, meaning that are they expressed along …show more content…
One major difference in expression of hox genes is whether they are expressed in invertebrates or vertebrates. Here we will look at some of the distinct differences that exist in vertebrates, beginning with amphibians. Oftentimes, amphibians are used to study the function of the hox genes in limb development, specifically Hox9 to Hox13. One area of particular interest in amphibians is the absence of the fifth finger in some organisms. It is believed that there is a difference in the set of genes expressed between amphibians and other vertebrates, which resulted from a transition to terrestrial lifestyle in their early evolutionary history. This has been shown to be due to the absence of the Hoxd-12 gene, which is important in autopodial development. Through the use of PCR to amplify the sequences responsible for the hox genes responsible for limb development (9-13), it has been shown that there is very little evidence of the Hox12-d being present where it would be expected to exist. This estimate was based on sequence lengths from other organisms and overlapping of multiple sequence amplifications. This ultimately showed a distinct mechanism that makes amphibians differ from other vertebrates, such as …show more content…
The larger number of sets of the gene cluster in vertebrates, compared to flies, demonstrates the reason for vertebrates being higher organisms. And although they work in similar ways, it is the signaling of somites in vertebrates, rather than merely signaling the segments of the fly body that makes them stand apart. It is also interesting to see how evolutionary adaptions have resulted from, or have been the cause of the loss of specific sequences for genes that code for the development of body parts no longer required for specific organisms, such as the loss of certain digits in amphibians. Understanding the conservation of these genes allows for more significant uses of certain organisms in research and can ultimately help understand the evolutionary history of these organism, relative to each
Fox, R. 2001. Invertebrate Anatomy OnLine: Artemia Franciscana. Lander University. http://webs.lander.edu/rsfox/invertebrates/artemia.html, retrieved February 13, 2011.
The objective of this experiment is to determine what genes are responsible for the white-eye color in two strains of Drosophila melanogaster, known as the common fruit fly. Drosophila is used as the experimental organism for many reasons which include its small size, easy maintenance, short 10 day generation time, and a fully sequenced genome. The characteristics of the wild type, which is the most common phenotype found in nature, include brick red eyes, long wings, gray/tan body, and smooth bristles. Of course, there are mutations that occur that cause specific traits to deviate from the wild-type phenotype. These traits include wing length, bristle shape, body color, and eye color.
There is common plan for all limbs: one bone, followed by two bones, then a bunch of little bones, and finally digits. This array of bones is seen in many species including, but not restricted to bats, whales, and lizards. But how do these limbs develop and why do they all look similar? Shubin explains it by conveying that there are certain genetic switches that help assemble who we are. When scientists went looking for this genetic switch in limbs, they found a couple tissue areas in the limbs that allow this body plan to occur. “A strip of tissue at the extreme end of the limb bud is essential for all limb development…This patch of tissue was named the zone of polarizing activity (ZPA).” ZPA allows humans to have opposable thumbs and pinkies. In other organisms, it differentiates the “thumb” side from the “pinky” side. Scientists then wanted to discover the molecule that allowed this changen in the ZPA, the answer is Sonic hedgehog. Shubin points out that every limbed animal h...
Cain, M. L., Urry, L. A., & Reece, J. B. (2010). Campbell Biology. Benjamin Cummings.
Hyla versicolor, commonly know as the Gray Tree Frog or the Eastern Gray Tree Frog, is an amphibian that is referred to as the “Chameleon of the Frog world” (Craighead, 2004, p.1) because of its ability to change colors. “This frog was once thought to be the same species as the Cope’s Gray Tree Frog”. They can only be distinguished by their calls and the fact that the Cope Gray Tree Frog is diploid while the Gray Tree Frog is tetraploid (NPWRC, 2004). The Gray Tree Frog is classified as follows:
The F2 punnett square shows that there should not be a female fly that has apterous wing mutation. Our observed experiment showed that female flies are capable of forming in the F2 Generation. Therefore, the mutation is located on autosomal chromosomes. In trial 1, the p value is not significant. This could be due to the fact that the male to female ratio in the F1 generation was unequal. In trial 2, the p value is significant and likely due to chance. The probability error is between 1 % and 5%.
Hall, Linley Erin. “Understanding Genetics DNA and RNA.” New York: The Rosen Publishing Group, Inc., 2011. Print. 01 Apr. 2014.
Tomkins, Jeffrey, Ph.D. "Duons: Parallel Gene Code Defies Evolution." Duons: Parallel Gene Code Defies Evolution. Institute Creation Research, n.d. Web. 23 Apr. 2014.
The eye is an extremely diverse organ, ranging in complexity across and within animal phyla. Here, a comparative approach is taken to outlining the diversity of the eye forms within vertebrates and invertebrates. The eye morphology of a variety of organisms was examined. Eye function, and placement on the body was also considered. Here, variation in eye form is discussed in relation to the environment the organism is adapted to. It is shown that an organisms eye morphology functions optimally for the ecological niche it occupies. Evolutionary analysis is used to account for the emergence of the different eyes. Convergent evolution is used to justify the similarities in eye types seen in organisms of different species. This analysis begins with the simplest of eye forms composes of single cells, present in the zooplankton larvae. Such primitive forms are identified in mollucs, annelids, cnidarians, and are then compared to more advanced eye forms contain lenses. This comparative approach provides a breadth of examples of vertebrates and invertebrates, making visible, the diversity of eye morphology within the animal kingdom.
Gould, Edwin, George McKay, and David Kirshner. Encyclopedia of Mammals. San Francisco, CA: Fog City, 2003. Print.
Web. The Web. The Web. 11 February 2014 “Biology: Evolution”. The New York Public Library Science Desk Reference.
www.newton.dep.anl.gov/askasci/bio99/bio99395.htm. www.bmb.leeds.ac.uk/tpdg/hglobin.htm. Books: Title: Biology, Author: Indge/Rowland/Baker, Publisher: Hodder & Co. Stoughton Title: Human Biology, Author: G.D. Chalk/G.P.J. Baster, Publisher: E.
It also allows species to survive. It produces new and different species through ancestral populations of organisms and moves them to new populations. Both natural selection and genetic drift decrease genetic variation. If they were the only mechanisms of evolution, populations would eventually become homogeneous and further evolution would be impossible. There are, however, mechanisms that replace variation depleted by selection and drift (Colby).
After Bonnet’s aphids gave birth to ninety-five offspring through parthenogenesis, Bonnet wrote to Réaumur of his success. Réaumur then read Bonnet’s letter to the French Academy of Sciences leading to Bonnet being officially named a correspondent in the experiment (Lawrence). Bonnet’s experiments were then repeated and refined by multiple biologists throughout the rest of the eighteenth century. However, progress came slowly. The first significant discovery of parthenogenesis in vertebrates did not occur until the 1950’s when scientists observed the process in certain strains of turkeys. Later, in the 1990’s, scientists observed parthenogenic tendencies in crustaceans such as brine shrimp. Unfortunately, neither of these species were able to reproduce by parthenogenesis in labs (Booth). After this monumental observation, biologists began to investigate the natural process of parthenogenesis in vertebrates living in the wild. The scientists specifically searched for a species that primarily reproduced by parthenogenesis, in an attempt to successfully replicate the process in labs. Through this research, it is now known that snakes,
The development of niche construction as an evolutionary process, was studied over an extended period of time, as it includes the construction of everything that a living organism does from conception to death. However, the theory of niche construction, over time, has developed the idea that it “can change the direction, rate, and dynamics of the evolutionary process. Niche construction is a potent evolutionary agent because it introduces feedback into the evolutionary dynamic” (Niche Construction, 2). To put this theory into context, take for example leaf-cutter ants from Odling-Smee, Laland, and Feldman’s reading regarding niche construction. Here they present a case where leaf-cutter ants construct their nests in areas of high fungi growth potential, to supply an abundant amount of food for their population.