BIO 367- Lab Report 3 revised

BIO 367- Lab Report 3 revised - Introduction The purpose of...

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Introduction The purpose of understanding history is to link the present to the past in order to gain further understanding. Knowledge of the past allows one to address issues and concerns of the present as well as prevent future conflicts. In biology, phylogenetics is the study of the evolutionary history of taxa (Aguirre 2007). One of the most obvious reasons of studying phylogenetics is to further our understanding of an organism. Knowing how an organism evolved gives us greater insight to resolve current problems. For instance, determining that malaria of the Apicomplexa has a plastid indicates the occurrence of an endosymbiotic event (Collier, J., 2007). This information has given clues to creating new drugs to combat malaria. Until the late 20 th century, much of phylogeny heavily relied on morphology (Aguirre, 2007). While morphological and behavioral observations are important measures of data, they can produce misleading results regarding an organism’s evolutionary past. In fact, one of the principles of phylogenic analysis is maximum parsimony , which states that the least number of character states or evolutionary changes to explain a taxa’s phylogeny is best (Avise, 2004). Using DNA or mtDNA utilizes the maximum parsimony principle, by not solely relying on observable character states, but instead incorporating more biologically functional aspects. The introduction of Polymerase Chain Reaction greatly facilitated the methods for collecting DNA sequence data. Using DNA sequence data or mitochondrial (mtDNA) data allows us to understand how different species are related to each other. In addition, DNA sequences are easy to generate and produces many characters. This is a novel approach that is relying more on quantitative information than on just morphological or behavioral traits, which were the common measures of studying evolution in the past. Much of present evolutionary biology utilizes and concentrates on molecular data- specifically, genetics. 2
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What makes G. aculeatus (threespine stickleback) suitable for generating molecular phylogenies is its model behavior. The threespine stickleback fish is a model system in evolutionary biology, particularly for analyzing genetic, morphological, and behavioral traits. Reasons for establishing this species as a model system are attributed to its large progeny, ease in its maintaining the species in a laboratory, and its great number of phenotypes. The latter characteristic was particularly studied in Bell and Foster’s review which indicated that the threespine stickleback species are highly prone to adaptive evolution (1994). Gasterosteidae is an ancient family containing a long evolutionary history with great amounts of genetic information. Using the cytochrome b locus on its mitochondrial DNA, researchers- Johnson and Taylor organized the populations by two major haplotypes, which were also two geographical clades- ENAC and TNPC. According to Johnson and Taylor, “ The Euro- North American clade (ENAC) is found in coastal lakes and marine waters throughout Europe
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BIO 367- Lab Report 3 revised - Introduction The purpose of...

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