Rama Shankar Singh, Ph.D.

Rama Singh

Tel: (905) 525-9140
Office: LS - 531 Ext 24378
Lab: LS - 523 Ext 27413
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  • Interests & Activities
  • Publications
  • Research


Evolutionary genetics: molecular genetics of speciation in Drosophila; evolution of sex- and reproduction-related genes; evolution of human diversity and social systems (e.g., the Indian Caste System).


  • Singh, R.S. 2011. Darwin’s legacy: why biology is not physics: or why evolution has not become a common sense. Genome. 54:868-73.
  • Jagadeeshan, S., Haerty, W., and R.S. Singh. 2011. Is speciation accompanied by rapid evolution? Insights from comparing reproductive and nonreproductive transcriptomes in Drosophila. International Journal of Evolutionary Biology. 2011:595121.
  • Ahuja, A., De Vito, S., and R.S. Singh. 2011. Condition dependence and the nature of genetic variation for male sex comb bristle number in Drosophila melanogaster. Genetica. 139:505-510.
  • Artieri, C.G., and R.S. Singh. 2010. Molecular evidence for increased regulatory conservation during metamorphosis, and against deleterious cascading effects of hybrid breakdown in Drosophila. BMC Biology. 8:26.
  • Singh, R.S., and Artieri, C.G. 2010. Male sex drive and the maintenance of sex: evidence from Drosophila. Journal of Heredity. Suppl 1:S100-6.
  • Artieri, C.G., and R.S. Singh. 2010. Demystifying phenotypes: The comparative genomics of evo-devo. Fly (Austin). 4:18-20.
  • Artieri, C. G., W.Haerty and R.S. Singh. 2009. Ontogeny and phylogeny: molecular signatures of selection, constraint, and temporal pleiotropy in the development of Drosophila.    BMC Biology 7:42
  • Kulathinal, R.J., and R.S. Singh. 2008. The molecular basis of speciation: from patterns to processes, rules to mechanisms (Invited Perspective to mark Darwins Centennial). Journal of Genetics 87:327-338.
  • Singh, R.S. 2008. Women and Social Change: A New Gandhian Social Movement - Mahila Shanti Sena. Intl. Encyclopedia of Peace (in press)
  • Haerty W, Artieri C, Khezri N, Singh RS, Gupta BP. 2008. Comparative analysis of function and interaction of transcription factors in nematodes: extensive conservation of orthology coupled to rapid sequence evolution. BMC Genomics 9:399.
  • Ahuja, A., and R.S. Singh. 2008. Variation and evolution of sex combs in Drosophila: Nature os selection response and theories of genetic variation for sexual traits. Genetics 179: 503-509.
  • Artieri, C., W. Haerty, B. Gupta, and R.S. Singh. 2008. Sexual selection and maintenance of of sex: Evidence from comparisons of genomic accumulation of mutations and divergence of sex-related genes in sexual and hermaphroditic species od Caenorhabditis. Mol Biol Evol 25:972-979.
  • Artieri, C.G., Haerty, W., Singh, R.S. 2007. Association Between Levels of Coding Sequence Divergence and Gene Misregulation in Drosophila Male Hybrids. Journal of Molecular Evolution 65: 697-704.
  • Haerty, W., Jagadeeshan, S., Kulathinal, R.J., Wong, A., Ravi Ram, K., Sirot, L.K., Levesque, L., Artieri , C.G., Wolfner, M.F., Civetta, A., Singh, R.S. 2007.  Evolution in the fast lane: Rapidly evolving sex-related genes in Drosophila. Genetics 177: 1321-1335.
  • Drosophila 12 Genome Consortium (including W. Haerty, C. Artieri, S. Jagadeeshan and R. Singh). 2007. Evplution of genes and genomes on the Drosophila phylogeny. Nature 450: 203-218.
  • Jagadeeshan S. and Singh R.S. 2007. Rapid evolution of outer egg membrane proteins in the Drosophila melanogaster subgroup: a case of ecologically driven evolution of female reproductive traits. Mol Biol Evol 24: 929-938.
  • Haerty W. and Singh R.S. 2006. Gene Regulation Divergence Is a Major Contributor to the Evolution of Dobzhansky-Muller Incompatibilities between Species of Drosophila. Mol Biol Evol 23: 1707-1714
  • Jagadeeshan S. and Singh R.S. 2006. A time-sequence functional analysis of mating behaviour and genital coupling in Drosophila: role of cryptic female choice and male sex-drive in the evolution of male genitalia. J Evol Biol 19:             1058-1070
  • Torgerson, D.G., and Singh, R.S. 2006. Enhanced adaptive evolution of sperm-expressed genes on the mammalian X chromosome. Heredity 96(1): 39-44.
  • Musters, H., Huntley, M.A., and Singh.R.S. 2006. A Genomic Comparison of Faster-Sex, Faster-X, and Faster-Male Evolution between Drosophila melanogaster and Drosophila pseudoobscura. J. Mol. Evol. 61(5): 650-658
  • Torgerson, D.G., Whitty, B.R., and Singh, R.S. 2005. Sex-specific functional specialization and the evolutionary rates of essential fertility genes. J. Mol. Evol. 61(5): 650-658.
  • Jagadeeshan, S., and Singh, R.S. 2005. Rapidly Evolving Genes ofDrosophila: Differing levels of Selective Pressure in Testis, Ovary and Head Tissues Between Sibling Species. Mol Biol Evol. 22: 1793 1801.
  • Singh, R.S., and Kulathinal, R.J. 2005. Male sex-drive and masculinization of the genome. BioEssays 27: 518-25.
  • Singh, R.S. 2001. The Indian Caste System, human diversity and genetic determinism. In Thinking about evolution: Historical, philosophical and political perspectives. R.S. Singh et al. (eds.), Cambridge University Press.
  • Singh, R.S. 2001. Polymorphisms. Encyclopedia of Genetics. Academic Press, New York.
  • Singh, R.S. and R.J. Kulathinal. 2000. Sex gene pool evolution and speciation: A new paradigm. Genes Genet. Syst. 75: 119-130.
  • Kulathinal, R.J. and R.S. Singh. 2000. Gene flow between D. pseudoobscura and D. persimilis?: A reply to Noor, Johnson and Hey.Evolution 54: 2176-2177.
  • Kulathinal, RJ. and R.S. Singh. 2000. A biogeographic genetic approach for testing the role of reinforcement: The case of Drosophila pseudoobscura and D. persimilis. Evolution 54(1): 210-217.
  • Singh, R.S. 2000. Toward a unified theory of speciation. In Evolutionary genetics: From molecules to morphology. R.S. Singh and C.B. Krimbas (eds.), Cambridge University Press.
  • Singh, R.S., W.F. Eanes, D.A. Hickey, L.M. King and M.A. Riley. 2000. The molecular foundations of population genetics. In Evolutionary genetics: From molecules to morphology. R.S. Singh and C.B. Krimbas (eds.), Cambridge University Press.
  • Singh, R.S., S.M. Singh and R.S. Pandeya. 1999. Genetic Resources, Biotechnology, and World Food Supply: A Special Symposium. Genome42: 551-655.
  • Civetta, A. and R.S. Singh. 1999. Broad-sense of sexual selection, sex gene pool evolution and speciation. Genome 42: 1033-1042.
  • Kulathinal, R. and R.S. Singh. 1998. Cytological characterization of premeiotic versus postmeiotic defects producing hybrid male sterility among sibling species of the Drosophila melanogaster complex. Evolution52: 1067-1079.
  • Civetta, A. and R.S. Singh. 1998. Sex and speciation: Genetic architecture and evolutionary potential of sexual versus nonsexual traits in the sibling species of the Drosophila melanogaster complex. Evolution 52: 1080-1092.
  • Civetta, A. and R.S. Singh. 1998. Sex-related genes, directional sexual selection and speication. Mol. Biol. Evol. 15: 901-909.
  • Bromfield, E.S.P., A.M.P. Behara, R.S. Singh and L.R. Barran. 1998. Genetic variation in local populations of Rhizobium meliloti. Soil Biol. and Biochem. 30: 1707-1716.
  • Joly, D. and R.S. Singh. 1997. Genetic basis of sperm and testis length differences and epistatic effect on hybrid inviability and sperm motility between Drosophila simulans and D. sechellia. Heredity 78: 354-362.
  • Civetta, A. and R.S. Singh. 1995. High divergence of reproductive tract proteins and their association with postzygotic reproductive isolation in Drosophila melanogaster and Drosophila virilis group species. J. Mol. Evol. 41: 1085-1095.
  • Long, A.D. and R.S. Singh. 1995. Molecules versus morphology: The detection of selection acting on morphological characters along a cline in Drosophila melanogaster. Heredity 74: 569-581.
  • Zeng, L.-W. and R.S. Singh. 1995. A general method for identifying major hybrid male sterility genes in Drosophila. Heredity 75: 331-341.
  • Singh, R.S. and L.-W. Zeng. 1994. Genetic divergence, reproductive isolation and speciation. In: Non-Neutral Evolution Theories and Data. G.B. Golding (ed.), pp. 217-232, Chapman and Hall, N.Y.
  • Zeng, L.-W. and R.S. Singh. 1993. A combined classical genetic and high resolution two-dimensional electrophoretic approach to the assessment of the number of genes affecting hybrid male sterility in Drosophila simulans and Drosophila sechellia. Genetics 135: 135-147.
  • Stoehr, M.U. and R.S. Singh. 1993. Restriction map and polymophisms of nuclear ribosomal genes of Populus balsamifera. Tree Physiology 12: 419-425.
  • Zeng, L.-W. and R.S. Singh. 1993. The genetic basis of Haldane's Rule and the nature of asymmetric hybrid male sterility between Drosophila simulans, D. mauritiana and D. sechellia. Genetics 134: 251-260.
  • Singh, R.S. and A.D. Long. 1992. Geographic variation in Drosophila: From molecules to morphology and back. Trends in Ecology and Evolution7: 340-345.
  • Choudhary, M., M.B. Coulthart and R.S. Singh. 1992. A comprehensive study of genic variation in natural populations of Drosophila melanogaster. VI. Patterns and processes of genic divergence between D. melanogaster and its siblings species D. simulans. Genetics 130: 843-853.



  • Singh, R.S., C.B. Krimbas, D. Paul and J. Beatty (editors). 2001. Thinking about evolution: Historical, philosophical and political perspectives. Cambridge University Press, Cambridge.
  • Singh, R.S. and C. Krimbas (editors). 2000. Evolutionary genetics: From molecules to morphology. Cambridge University Press, Cambridge.


Rapidly evolving sexual systems and the genomics of speciation
An important goal in evolutionary biology has been to elucidate the molecular basis of species formation. Patterns of divergence between closely related species suggest that there may be a particular functional class of genes that is preferentially involved in speciation. For example, the pronounced effects of reproductive traits manifested in hybrid incompatibilities are well-known. In addition, reproductive characters have been shown to exhibit rapid divergence within species through sexual selection. Over the last twenty years, our laboratory has adopted a functional genomic approach to resolve the problem of speciation. Current projects that are being conducted in our laboratory in order to better understand this process include:

  • Rapid divergence of sex and reproduction-related (SRR) genes
  • Identification and characterization of genes affecting hybrid male sterility between sibling species
  • Microarray analysis of gene expression in hybrids of Drosophila
  • Sexual selection and rapidly evolving genes in Drosophila

Origin and Evolution of Sex Differences
Sex and Sexual dimorphism constitute the two most spectacular aspects of organismic diversity. Darwin invented his theory of sexual selection through female choice to explain certain secondary sexual traits in the male that on the surface looked maladaptive and hence could not be explained by natural selection.  Sexual selection has gained considerable interest, especially of behavioral biologists, but it has always remained as an aside in evolutionary biology. The arrival of functional and evolutionary genomics has opened the field of the origin and evolution of sexual dimorphism to molecular evolutionary analysis -from origin of sex to sexual dimorphism, sexual selection to speciation.
Evolution of the male sex comb in Drosophila:
The male sex comb of Drosophila, an array of specialized bristles on the foreleg, exhibits high intra- and interspecific variation in morphology. Bristle number has been shown previously to have varying effects on female preferences in different species, making these a model trait for studies of sexual trait diversification and their role in reproductive isolation. Two replicates of D. melanogaster lines divergent for sex comb bristle number have been developed through long term artificial selection (Figure 1). These lines are now being introgressed into ubi – DE cad