- B.S., Ecology and Evolutionary Studies, University of Rochester, 1993
- Ph.D., Indiana University Bloomington, 2004
We seek to understand the genetic factors contributing to genomic variation and phenotypic diversity. To this end, we employ molecular and bioinformatic tools to study evolutionary processes at the level of populations, both experimental and natural, and genomes. Our research interests encompass a wide range of topics, including the evolution of organellar and nuclear genomes, gene duplication and the origin of novel function, and the fitness and phenotypic consequences of mutation in evolution. Our ongoing research is largely focused on the topics listed below.
Do diverse classes of mutations accumulate differentially in genomes subjected to varying intensities of natural selection?
The fitness effect of a mutation can range continuously from the lethal to deleterious to neutral to beneficial. Loss or fixation of mutations and their consequences for population fitness depend upon the selection coefficients (s) associated with individual mutations and the effective population size. Our primary innovation and contribution has been the development of spontaneous spontaneous MA lines of Caenorhabditis elegans at differing population sizes under highly controlled conditions over a period of close to five years. Our goal is to employ a modern genomic approach to determine for the very first time how different classes of spontaneous mutations accumulate in mitochondrial and nuclear genomes under varying intensities of natural selection and infer their average fitness effects.
Determine the rate of fitness decay in experimental lines as a function of the effective population size.
We aim to provide the first and most comprehensive time-series analysis of fitness decline in populations of varying effective population size (Ne) under a regime of spontaneous mutation accumulation. Fitness assays will be conducted under both benign and competitive environmental conditions, to directly quantify the extent to which the former underestimates fitness decline and key mutational parameters. A comparison of the rates of fitness decline across the varying Ne treatments will elucidate how smaller populations are compromised by mutation accumulation via drift, with important implications for conservation biology and captive breeding programs.
Role of selection versus drift in the evolutionary dynamics of copy-number variants (CNVs).
The role of selection versus drift in dictating the evolutionary fate of gene duplicates is still obscure. Are CNVs more likely to reach fixation at small or large Ne? We are employing modern genomic technologies to screen experimental C. elegans lines for CNVs to determine the evolutionary force (positive selection, genetic drift or purifying selection) paramount in dictating their evolutionary fate.
Bu, L., and V. Katju. 2015. Early evolutionary history and genomic features of gene duplicates in the human genome. BMC Genomics 16(1): 621.
Katju, V., L. B. Packard, L. Bu, P. D. Keightley, and U. Bergthorsson. 2015. Fitness decline in spontaneous mutation accumulation lines of Caenorhabditis elegans with varying effective population sizes. Evolution 69(1): 104-116.
Katju, V., and U. Bergthorsson. 2013. Copy-number changes in evolution: rates, fitness effects and adaptive significance. Frontiers in Genetics 4: 273.
Katju, V. 2013. To the beat of a different drum: determinants implicated in the asymmetric sequence divergence of Caenorhabditis elegans paralogs. BMC Evolutionary Biology 13:73.
Katju, V. 2012. In with the old, in with the new: the promiscuity of the duplication process engenders diverse pathways for novel gene creation. International Journal of Evolutionary Biology 2012:Article ID 341932, 24 pages.
Bu, L. U. Bergthorsson and V. Katju. 2011. Local synteny and codon usage contribute to asymmetric sequence divergence of Saccharomyces cerevisiae gene duplicates. BMC Evolutionary Biology 11:279.
Lipinski, K. J., J. C. Farslow, K. A. Fitzpatrick, M. Lynch, V. Katju and U. Bergthorsson. 2011. High spontaneous rate of gene duplication in Caenorhabditis elegans. Current Biology 21(4):306-310.
Rane, H. S., J. M. Smith, U. Bergthorsson and V. Katju. 2010. Gene conversion and
DNA sequence polymorphism in the sex-determination gene fog-2 and its paralog ftr-1 in Caenorhabditis elegans. Molecular Biology and Evolution 27(7):1561-1569.
Katju, V., J. C. Farslow and U. Bergthorsson. 2009. Variation in gene duplicates with low synonymous divergence in Saccharomyces cerevisiae relative to Caenorhabditis elegans. Genome Biology 10(7):R75.
Katju, V., E. M. LaBeau, K. J. Lipinski, and U. Bergthorsson. 2008. Sex-change by gene conversion in a Caenorhabditis elegans fog-2 mutant. Genetics 180(1):669-672.