Solo Blogpost for Research Project 1

Solo Blogpost for Research Project 1

By Marisa Kemper

The goal of this experiment is to use molecular data drawn from protein gel electrophoresis to reconstruct a phylogeny tree and compare the accuracy of this tree with that of a well-evidenced version.

Many types of evidence are used to reconstruct a phylogenetic tree. In this experiment, the goal is to test the efficacy of reconstructing a tree based on molecular data alone (Bio-rad 2006). In order to do this, muscle tissue was selected to make comparison's between six different species' amounts of actin, myosin, and other common muscle proteins. The six species chosen were (common names are given) octopus, squid, wild-caught shrimp, scallop, mussel, and oyster. This arrangement was chosen because squid and octopus are sister taxa within the class Cephalopoda; mussel, oyster, and scallop are sister taxa in the class Bivalvia; and with all aforementioned species part of the same phylum Mollusca, shrimp serves as an outgroup member from the phylum Arthropoda (Tree of Life Web Project 1995). The relationship between these species is well documented and so the results of this experiment can easily be compared with known ideas.

In order to keep the comparison consistent, muscle was selected from each species that was postulated to be similar in molecular structure due to a similarity in function. This was particularly important in the case of squid and octopus. Octopus have eight arms that are structurally similar to the eight arms of squid but very different from the two unique prey-catching tentacles that also belong to squid (Kier and Schachat 2008). These tentacles are fast-acting and have a different sarcomere arrangement, potentially causing what would appear as a difference between the species and resulting in an incorrect tree arrangement (Kier and Schachat 2008). By denaturing the muscle tissue of these species and separating the proteins within them by size, bands were compared on the resulting protein gel electrophoresis and an experimental evidence based phylogenetic tree was reconstructed. This tree was then compared to the one formed in the hypothesis and a determination on the efficacy of molecular evidence was made.


Reference List

Kier W, Schachat F. 2008. Muscle specialization in the squid motor system. J Exp Biol [Internet]. [cited 10 Feb 2017]; 211(2):164-169. Available from: http://jeb.biologists.org/content/211/2/164.article-info

Bio-Rad Laboratories. 2006. Comparative Proteomics Kit I: ProteinProfiler Module (Catalog #166-2700EDU) Biotechnology Explorer student manual.

Tree of Life Web Project. 1995. Mollusca. Snails, clams, mussels, squids, octopi, chitons, and tusk shells. Version 01 January 1995 (temporary). Available from http://tolweb.org/Mollusca/2488/1995.01.01 in The Tree of Life Web Project, http://tolweb.org/