Dr. Greg Spicer
My interest in molecular, genetic, and systematic studies comes from a desire to understand the basic mechanisms involved in evolution. The focus of my research program is concerned with the integration of these studies, so that I can test evolutionary and adaptational hypotheses. These studies have two primary goals: one concerned with the genetic analysis of morphological differentiation and isolating mechanisms, and the other with the elucidation of molecular evolution and its application to phylogenetic reconstruction.

The best way to reconstruct phylogenetic relationships is through molecular evolutionary studies. Consequently, a major part of my research effort has been the collection of molecular data to generate phylogenies and molecular clocks, which are fundamental for the comparative method. However, to adequately use molecular probes for these purposes it is necessary to understand the evolutionary dynamics of the substitution process. My students have attempted to accomplish this by sequencing a large number of haplotypes from a wide variety of populations and species, ranging from very closely to very distantly related (up to 60 million years), in the fruitfly genus Drosophila. By examining the kinds of substitutions (e.g., transitions vs transversions) and how they are affected by such factors as codon bias, codon position, base composition bias, replication position of the gene, and amino acid composition, allow me to ascertain the molecular evolutionary processes that are occurring. The sequences have been collected by the direct sequencing of mitochondrial and nuclear DNA fragments by using the polymerase chain reaction (PCR) technique. In particular, we have sequenced parts of the 12S and 16S rRNA, cytochrome oxidase subunits (I, II, and III), alcohol dehydrogenase, engrailed , and period genes in over 70 species of Drosophila. These DNA sequence data sets better enable us to resolve some of the phylogenetic relationships within the genus Drosophila, generate an improved molecular clock for dating divergence times, and importantly, permit a better understanding of the molecular evolution of these genes. Students are continuing this line of research in my laboratory.



Last modified July 10, 2002