Benjamin Normark

Photograph of First Last


Contact Info

Phone: 413-577-3780
Office: Fernald Hall 204B


B.A., Yale University, 1985

Ph.D., Cornell University, 1994,


Harvard University, 1997-2000

N.S.F. International Research Fellow, Natural History Museum, London 1996-1997

A. P. Sloan Postdoctoral Fellow, University of Arizona, 1994-1996

Research Interests

Evolution of Unusual Genetic Systems

The laws of genetics are not universal. While many species have classical Mendelian genetics, in which both parents contribute equally to the genomes of all offspring, several other genetic systems exist. In thousands of insect species, females monopolize parentage of sons. In others, males are completely absent. This variation and its evolutionary significance remain poorly understood, illustrating the incompleteness of the synthesis of genetics with evolutionary biology that constitutes the theoretical underpinning of modern biology. My laboratory studies the evolution of unusual genetic systems -- especially paternal genome elimination and parthenogenesis -- in armored scale insects.

Niche explosion: evolution of extreme generalists
Parthenogenesis (asexual reproduction) in insects is frequently correlated with an extremely broad range of host plants. Other correlates include: flightless females, invasiveness, status as economic pests. To account for these correlations, I have proposed the niche explosion hypothesis, postulating a positive feedback loop between host range and population size that resulted in extreme polyphagy and abundance in several insect groups having flightless females, including scale insects, broad-nosed weevils, and several families of moths. We are working to test several of the genomic and ecological predictions of this hypothesis. Consistent with the hypothesis, we find that several cosmopolitan pest species of armored scales are abundant and truly polyphagous in a tropical rainforest canopy in Panama.

Systematics and molecular identification of armored scale insects
Identifying armored scale insects to species is a non-trivial problem. In part this is simply due to the fact that that only skillfully microscope-slide-mounted adult females can be identified, but in part it is due to interesting biological phenomena such as very large population sizes and cryptic species complexes. My lab is assembling a collection and database consisting of thousands of genomic DNA samples linked to individual well-mounted, well-identified specimens. This collection will enable us to test evolutionary hypotheses, reconstruct evolutionary history, and improve the classification of these insects. It will also make possible a reliable system of molecular identification.

Representative Publications

Normark, B. B., and N. A. Johnson. In press. Niche explosion.Genetica.

Andersen, J. C., Wu, J., Gruwell, M. E. Gwiazdowski, R., Santana, S., Feliciano, N. M., Morse, G. E., and B. B. Normark. 2010. Phylogenetic analysis of armored scale insects (Hemiptera: Diaspididae) based on nuclear, mitochondrial, and endosymbiont DNA sequences. Molecular Phylogenetics and Evolution, 57: 992-1003.

Andersen, J. C., Gruwell, M. E. Morse, G. E., and B. B. Normark. 2010. Cryptic diversity in the Aspidiotus nerii complex in Australia. Annals of the Entomological Society of America, 103: 844-854.

Rugman-Jones, P., J. C. Andersen, J. Morse, B. B. Normark and R. Stouthamer. 2010. Molecular phylogenetics of the recently described armored scale insect Abgrallaspis aguacatae and several congeners. Annals of the Entomological Society of America, 103: 30-38.

Gruwell, M. E., J. Wu, and B. B. Normark. 2009. Diversity and phylogeny of Cardinium bacteria associated with armored scale insects (Hemiptera: Diaspididae). Annals of the Entomological Society of America, 102: 1050-1061.

Burke, G. R., B. B. Normark, C. Favret, and N. A. Moran. 2009.
Evolution and diversity of facultative symbionts from the aphid subfamily Lachninae. Applied and Environmental Microbiology, 75: 5328-5335.

Buckley, T. R., D. Attanayake, D.-C. Park, and S. Ravindran, T. R. Jewell, and B. B. Normark. 2008. Evolution of parthenogenesis in the New Zealand stick insect genus Acanthoxyla Uvarov (Phasmatodea: Phasmatidae): evidence from multiple loci. Molecular Phylogenetics and Evolution, 48: 335-349.

Gruwell, M. E., G. E. Morse, and B. B. Normark. 2007. Phylogenetic congruence of armored scale insects (Hemiptera: Diaspididae) and their primary endosymbionts from the phylum Bacteroidetes. Molecular Phylogenetics and Evolution, 44: 267-280.

Úbeda, F., and B. B. Normark. 2006. Sibling competition, male killers and the origins of paternal genome elimination. Theoretical Population Biology 70: 511-526.

Gwiazdowski, R. A., R. G. Van Driesche, A. Desnoyers, S. Lyon, S. Wu, N. Kamata, and B. B. Normark. 2006. Possible geographic origin of beech scale, Cryptococcus fagisuga (Hemiptera: Eriococcidae), an invasive pest in North America. Biological Control, 39: 9-18.

Normark, B. B. 2006. Perspective: maternal kin groups and the evolution of asymmetric genetic systems -- genomic imprinting, haplodiploidy, and parthenogenesis. Evolution, 60: 631-642.

Morse, G. E., and B. B. Normark. 2006. A molecular phylogenetic study of armoured scale insects (Diaspididae). Systematic Entomology, 31: 338-349.

Provencher. L. M., G. E. Morse, A. R. Weeks, and B. B. Normark. 2005. Parthenogenesis in the Aspidiotus nerii complex (Hemiptera: Diaspididae): a single origin of a worldwide, polyphagous lineage associated with Cardinium bacteria. Annals of the Entomological Society of America, 98: 629-635.

Normark, B. B. 2004. Haplodiploidy as an outcome of coevolution between male-killing cytoplasmic elements and their hosts. Evolution, 58: 790-798.

Normark, B. B. 2003. Evolution of alternative genetic systems in insects. Annual Review of Entomology, 48: 397-423.