Assignment Title: Molecular Clock Analysis
2. Analyse the significance of genetic variation to the process of natural selection
For the past 40 years, evolutionary biologists have been investigating the possibility that some evolutionary changes occur in a clock-like fashion. Over the course of millions of years, mutations may build up in any given stretch of DNA at a reliable rate. For example, the gene that codes for the protein alpha-globin (a component of haemoglobin) experiences base changes at a rate of 0.56 changes per base pair per billion years. If this rate is reliable, the gene could be used as a molecular clock and can be used as a tool for estimating the dates of lineage-splitting events. As part of the preparation for this assignment you will complete the ‘Phylogenetic Tree Puzzle worksheets, working in groups with real data from real populations of lizards of various islands in the Canary Island Archipelago http://www.ucmp.berkeley.edu/fosrec/Filson.html . The data will include observations of lizard morphology (body form), geological age estimates of the various islands, geographic distances, and genetic distances based on nucleotide base differences in DNA.
This written assignment has two tasks:
1. Discuss the significance of genetic variation in the process of natural selection and evolution.
2. Discuss and evaluate the use of molecular clocks in phylogenetic analysis using relevant examples