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Brian R. Morton
Title Assistant Professor
Affiliation/Department Department of Biological Sciences, Barnard College
Telephone: (212) 854-5454
e-mail: bmorton@barnard.columbia.edu
Professional degree Ph.D., Genetics, University of California, Riverside, 1993
Research Keywords Codon bias, context dependency, molecular evolution
Research Description Our work focuses on two main aspects of the evolution of plastid DNA. The first is the selective constraints on codon usage across a wide variety of phyla of the plant kingdom. We are attempting to determine how and why selection intensity varies among lineages as well as over time, including tests of models concerning the evolution of codon bias following a proposedrecent relaxation within the flowering plant lineage. In addition, we are interested in how selective constraints on codon usage interact with other structural features, including amino acid composition of proteins and genome organization. The second major line of research involves an investigation of the nucleotide substitution dynamics of plastid DNA. Specifically, we are interested in how rate heterogeneity among sites is affected by variation in context, or the composition of nucleotides flanking those sites. This line of research also involves analyses of how context dependency affects various simplified models of molecular evolution and methods of phylogenetic reconstruction.
Representative Publications: Morton BR 1998 Selection on the codon bias of chloroplast and cyanelle genes in different plant and algal lineages. J. Mol. Evol. 46:449-459.

Morton BR, VM Oberholzer and MT Clegg 1997 The influence of specific neighboring bases on substitution bias in noncoding regions of the plant chloroplast genome. J. Mol. Evol. 45:227-231.

Morton BR and JA Levin 1997 The atypical codon usage of the plant psbA gene may be the remnant of an ancestral bias. Proc. Natl. Acad. Sci. USA 94:11434-11438.

Morton BR, BS Gaut and MT Clegg 1996 Evolution of alcohol dehydrogenase genes in the Palm and Grass families. Proc. Natl. Acad. Sci. USA 93:11735-11739.

Morton BR 1995 Neighboring base composition and transversion/transition bias in a comparison of rice and maize chloroplast noncoding regions. Proc. Natl. Acad. Sci. USA 92:9717-9721.
Current Research