It is a common misperception that evolution is something that has only occurred in the long past of the Earth, and is not quintessential to today’s changing world. Evolution can and is occurring at different rates for different organisms, and understanding this could help solve scientific problems that need solutions. Phylogeny is a major component of understanding a species evolution, technological methods help scientists better understand how evolution has occurred in certain organisms at the molecular level, and specific genetic tools have been found that help develop human success in the world. Whether it is agriculture development, medical advancements, or conservation biology resolutions, evolution can influence how we change the world for the better with both humans and nature.
Part 1:
The Asian Elephant, or Elephas maximus, is the last living species of the genus “Elephas,” as the rest were mammoths. Asian Elephants are distributed all throughout the Asian continent; they are present in isolated pockets of India and Southeast Asia, including a small group in Borneo. Asian Elephants used to be widely distributed from south of the Himalayas, to as far north as the Yangtze River located in China. Habitat destruction, human development, and poaching have caused this species to be listed as endangered (National Zoo 2018). Learning the taxonomy and evolutionary history of this species could allow scientists to better understand their role in an ecosystem and how to conserve them.
Asian Elephants are members of the kingdom Animalia. They are under the Chordate phylum. There are some distinct characteristics of chordates that separate them from their ancestors. All chordates have a notochord, or a sort of “rod” of special cells, encased and surrounded by a tight sleeve that is located ventral to a neural tube in the embryos and some adults. Chordates also have a hollow nerve cord that lies upper to the notochord previously described. A third characteristic of chordates is Pharyngeal slits, which are openings between the pharynx, and the outside of the body. These slits have been modified extensively throughout the course of evolution. In “older” species of chordates, these slits are used to filter food particles from the water. In some amphibians and fishes, the slits have gills which are used for exchanging gas. In most land- dwelling chordate species, the “gill slits” are found only during growing embryonic stages (SHSU).
Asian Elephants are members of the Mammalia class, with sister taxa being sauropsida. This class is characterized by a placenta to allow an exchange of nutrients. The Asian Elephant species is in the order Proboscidea. These are eutherian mammals that contain living elephants along with extinct mammoths, mastodons and gomphotheres. They are categorized by having a proboscis or trunk that they use for grabbing food and water. They also have specialized molars to eat special vegetation, as well as tusks (which are a set of second upper incisors ) that help scrape bark off trees, dig for food, and fight (Speer 1997).
Asian Elephants belong to the Elephantidae family. A sister clade for this species within the Elephantidae family is mammuthus primigenius, also called wooly mammoths which differ from Asian Elephants by having had different sized and shaped tusks, and a body completely covered in shaggy hair (University of California Berkeley 1987). Lastly, the genus for Asian Elephants is Elephas. This classification is categorized by different sized backs, smaller ears, and no tusks in females. Their very sloped backs help them climb the mountains in Southeast Asia; elephants in Africa do not need to climb steep hills. Their smaller ears take up less room in overgrown jungles. Finally, only the males use their tusks for fighting, so females do not need them, and both sexes of African elephants have tusks (National Zoo 2018).
Part 2:
One important aspect of appreciating and understanding life on Earth is through phylogeny, as one can examine how organisms could be related and branched from each other. While there are many ways to categorize and group organisms in clades and trees, there are certain technological methods used to examine these phylogenetic relationships. Four cluster analysis, protein-likelihood method, and Felsenstein’s Bootstrap test are techniques that have proven useful for using molecular genetics to categorize organisms.
One example of a method used in phylogeny analysis is the four cluster analysis. This method helps find relationships between four groups of organisms. Because each group of organisms can contain so many specific species, it can be very hard to differentiate between groupings (Nei 1996). The four cluster analysis is an extension of the Minimum Evolution method, and it can be applied to large groups of organisms as long as they are monophyletic (Khan 2017). Using ribosomal DNA scientists can compute a simple algorithm to examine the specific differences between the organisms, which in turn can show where branches on the tree of life could be added or changed. This specific method allowed scientists to discover that fungi and animals are more closely related than plants and fungi or plants and animals (Rokas 2011).
The protein-likelihood method can be useful for organisms that appear to be closely related to each other. Transition matrices are used for examining nuclear proteins and their respective mitochondrial proteins. This method has shown that protein sequencing can be more reliable than DNA sequencing when trying to form phylogenetic trees for species and groups. A small variation of this method helped show that ocean dwelling whales are closely related to land living hippopotamus (Ursing and Arnason 1998).
Felsenstein’s Bootstrap test is a very commonly used method for determining phylogenetic trees. This test requires a tree that’s already been roughly formed to be examined using a bootstrap resampling technique. Randomly sampled nucleotide sites are given replacements to see how the phylogeny changes. This step is repeated multiple times and the given proportion where clustered sequences replications appear is then measured. If the proportion measure is high, then statistically significant evidence has been found (Nei 1996). Felsenstein’s Bootstrap test was used with mitochondrial protein-coding genes in order to evaluate two different phylogenies of tetrapods and specific mammals (Zardoya and Meyer 1996).
While simply watching organisms externally for defining features to group phylogeny can sometimes be useful, often times deeper examination is needed to categorize where animals, plants, fungi, or protists belong on the tree of life.
Part 3:
Two major contributors to human population growth and survival over the last century are agricultural advancements and medical breakthroughs. The foundations for these attributors rely on evolutionary studies that allow scientists to extract, manipulate, or simply utilize the DNA of organisms that harness important and possibly useful adaptations. Three scientific skills that have proven useful are DNA shuffling, bioprospecting, and DNA synthesis; these methods have enabled major agriculture and medical advancements to boost human life success.
The shuffling of DNA is a technique that has been utilized by humans for many years, but there is recent activity with this method that has created major advances in agriculture. There was a finding of restriction endonucleases; certain enzymes which can cut DNA in areas comprising nucleotide sequences ( Crameri et., al 1998) . This emergence of recombinant DNA gave scientists the means to make high precision tools to remove or insert genes into genomes (Patten, Howard, and Stemmer 1997). This method of shuffling genes has mainly affected agriculture crops in such a way that allows production to increase. Creating new DNA sequences has allowed people to build agriculture production, to support a growing world population.
Bioprospecting is a technique that has revolutionized drug creation. This method searches for natural based solutions to modern diseases, using biological compounds found in animals, plants, or fungi. Proteins, genetic blueprints, or complex compounds can provide scientists with solutions and cures for diseases. In fact, roughly 60 percent of modern medicine is derived through bioprospecting, and produced by natural origins ( Globalization, biosecurity, and the future of the life sciences 2006). One example for successful use of this technique is with aspirin: the well known drug is created from salicin, which is a naturally occurring glycoside in plants, specifically salix willow trees (Rausser and Small 2000).
In the 1970’s, scientists discovered they could use de novo generation with specific genetic sequences which program certain cells for protein expression. This method became known as DNA synthesis. It was previously thought unlikely that scientists could reproduce large strands of genomes, but this method has put this goal within reach; a goal that could result in major medical breakthroughs. This DNA synthesis method has enabled studies to examine synthesis and creation for large segments of the hepatitis C virus genome. Replication competent RNA molecules were able to be rescued through this process (Caruthers 1987).
Often times humans can become wary of scientific progress that surrounds DNA examination. However, these advancements in genome studies have continuously proven useful in assisting human success. DNA synthesis helps produce and examine large strands of genomes for viral and bacterial studies, bioprospecting yields natural compounds that assist in disease curing, and DNA shuffling helps produce hardy and strong crops. These methods have aided in societal progress using basic genetic principles, and will certainly continue to produce successful solutions.
Conclusion:
Organizing species into different clades using the phylogeny classification system helps scientists understand how organisms are related and developed over time; it can even help with conservation biology. Furthermore, molecular techniques for classification can show even more precise organismal taxonomies. Finally, genomic studies that use evolutionary techniques and ideas have continuously helped with societal and environmental progress, and will continue to help solve problems humans face.
References:
- Asian elephant. (2018, June 12). Retrieved from https://nationalzoo.si.edu/animals/asian-elephant
- Caruthers, M. (1985). Gene synthesis machines: DNA chemistry and its uses. Science,230( 4723),
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- Chordata: More on Morphology. (1987). Retrieved from http://www.ucmp.berkeley.edu/chordata/chordatamm.html
- Crameri, A., Raillard, S., Bermudez, E., & Stemmer, W. P. (1998). DNA shuffling of a family of genes from diverse species accelerates directed evolution. Nature,391(6664), 288-291.
- Globalization, biosecurity, and the future of the life sciences . (2006). Washington, D.C.: National Academies Press.
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- Small, A. A. (2000). Valuing Research Leads: Bioprospecting and the Conservation of Genetic Resources. SSRN Electronic Journal.
- Rokas, A. (2011). Phylogenetic Analysis of Protein Sequence Data Using the Randomized Axelerated Maximum Likelihood (RAXML) Program. Current Protocols in Molecular Biology,96( 1).
- Speer, B. (1997). The Proboscidea. Retrieved from http://www.ucmp.berkeley.edu/mammal/mesaxonia/proboscidea.php
- Ursing, B. M., & Arnason, U. (1998). Analyses of mitochondrial genomes strongly support a hippopotamus-whale clade. Proceedings of the Royal Society B: Biological Sciences, 265(1412).
- Zardoya, R., & Meyer, A. (1996). Phylogenetic performance of mitochondrial protein-coding genes in resolving relationships among vertebrates. Molecular Biology and Evolution,13( 7).