Phylogenetic Trees: Outgroup Analysis

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Phylogenetic trees allow us to organize all of life onto a single tree based on a common feature that all of life shares, to understand how things are related. We can also create specialized trees that map the evolutionary history of a specific species, such as mammals or reptiles. There are three features of a phylogenetic tree that must be understood: first, a phylogenetic tree depicts the common ancestry of the species that we are studying, whether it be all of life or just mammals. Second, there are the splitting of lineages within a tree which show the branching of the species that we are studying. Lastly, there are changes in inherited characteristics along a lineage (1). All of this shows the order in which all of life has evolved overtime. In addition, phylogenetic trees use an outgroup analysis method that allows us to compare the closest relative of our species of interest, called the ingroup, to a group that is closely related to the ingroup, but not as close as the ingroup are related to each other. For example, all vertebrates can be compared to the cephalochordates, a group of species that are closely related to the vertebrates.

Our study looked at cytochrome B, the gene that is …show more content…

Though the two marsupials are very similar, their size generally tells them apart. Wallaby’s are much smaller than kangaroos. Average male wallaby’s weigh about 20 kilograms whereas an average male kangaroo weight about 90 kilograms (3). Because kangaroos are much larger, their legs are much stronger and therefore built for speed in open terrain whereas a wallaby’s legs are built for quickness in forested areas. This may have resulted in their adaptation toward different environments where their physical characteristics can take advantage of the environment. Furthermore, wallaby’s tails lay on the ground whereas a kangaroo’s tail is bent to provide stabilization during motion

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