G. F. Shields Research with Undergraduate Students at Carroll College
My research investigates the molecular and chromosomal changes that promote speciation in
black flies (Diptera: Simuliidae). Our major observations are that taxa of black flies classified as
single morphological species are actually any number of reproductively isolated sibling species
based on the presence of unique Y chromosomes associated with paracentric inversions. Within
the Simulium arcticum complex alone we have described a minimum of six sibling species and
an additional 20 cytotypes that could be siblings if more detailed study were done. Moreover,
we believe that Y chromosome inversions occur early in the diversification process since
comparative DNA sequencing (mitochondrial, nuclear, and microsatellites) does not separate
taxa defined by chromosomes alone. Thus, our observations run counter to “accepted dogma”
that chromosome changes have no role in the speciation process (Coyne and Orr, 2004). My
research is holistic, inexpensive, and appropriate for undergraduate students (15 have worked
with me at Carroll) since it involves field collection, morphological study of larvae, polytene
chromosome analysis, and analysis of well-understood DNA markers.
Recent peer-reviewed Publications:
Shields, G. F., G. Clausen, Cristina S. Marchion, Tracy L. Michel, Kathryn C. Styren, Callie N.
Riggin and Tonya D. Santoro and L. M. Strizich. 2007a. The Effect of Elevation on the
Distribution of Sibling Species in the Black Fly, Simulium arcticum Complex (Diptera: Simuliidae).
The Western North American Naturalist. 67, 39-45.
Shields, G. F., G. Clausen, J. Pickens, and L. M. Strizich. 2007b. Reproductive Status of
Cytospecies and Cytotypes of the Simulium arcticum Complex (Diptera: Simuliidae) in Montana.
Intermountain Journal of Sciences. Vol. 13, No. 1, 32-43.
Shields, G. F., B. A. Christiaens, M. L. Van Leuven and A. L. Hartman. 2009. Reproductive Status
and Continuity of Taxa of the Simulium arcticum Complex (Diptera: Simuliidae) at the
Clearwater River, Montana (2007, 2008, and 2009). Western North American Naturalist. 69,
511-520.
Conflitti, I. M., M. J. Kratochvil, M. Spironello, G. F. Shields and D. C. Currie. 2010. Good Species
Behaving Badly: Non-monophyly of Black Fly Sibling Species in the Simulium arcticum Complex
(Diptera: Simuliidae). Molecular Phylogenetics and Evolution. 57: 245-257.
Conflitti, I.M., G.F. Shields, and D.C. Currie. 2012. A 'Complex' problem: delimiting sibling
species boundaries in black flies (Diptera: Simuliidae). The Canadian Entomologist !44: 323-336.
Shields, G. F. and M. J. Kratochvil. 2012. A Remnant of an Incipient Speciation Event in the
Simulium arcticum complex: (Diptera: Simuliidae) at the Coeur d’Alene River, Idaho. American
Midland Naturalist . 166- 239-251.
Shields, G. F. 2012. The significance of chromosome change in black fly speciation. Western
North American Naturalist Monographs. 6: 63-86.
Shields, G. F. 2014. Incipient Speciation and Additional Evidence of Diversity in the Simulium
arcticum Complex (Diptera: Simuliidae). In Press: American Midland Naturalist.
Conflitti, I. M., G. F. Shields, R. W. Murphy, and D. C. Currie. 2014. Untangling the speciation
continuum: assessing population structure, gene flow and monophyly among members of the
Simulium arcticum complex (Diptera: Simuliidae). In Review: Molecular Phylogenetics and
Evolution.
Conflitti, I. M., G. F. Shields, R. W. Murphy, and D. C. Currie. 2014. Molecular population
genetics of a contact zone between Simulium saxosum and S. arcticum sensu. stricto. In Review.
Heredity.