Jan McDowell

Associate Professor

Email: [[mcdowell]]
Phone: (804) 684-7263
Office: Chesapeake Bay Hall N209
Section: Natural Resources

Curriculum Vitae
  • B.S. University of Iowa
  • Ph.D. College of William and Mary
Research Interests
  • Our research interests are in the areas of population genetics, conservation genetics, systematics, molecular ecology and evolutionary biology. We use molecular markers study the forces that shape and maintain population structure in the marine realm.  Many of our research questions ultimately focus on the effects of genetic structure on the management and conservation of marine species.
Current Projects
  • Genetic investigation into the distinctiveness of tautog, Tautoga onitis, off the coast of Virginia.
  • Stock structure and connectivity of speckled trout (Cynoscion nebulosus) in Virginia and North Carolina.
  • Estimation of the levels of genetic diversity and genetic connectivity among populations of the blue shark Prionace glauca at a global scale.
  • Genetic tagging of bluefin tuna (Thunnus thynnus).
  • De novo marker discovery in the eastern oyster, Crassostrea virginica.
  • Genetic tracking of an oyster restoration project in the Lafayette River, Virginia
  • Population Genetic Analyses of Atlantic Istiophorid Billfishes.
  • Discrimination of cownose ray, Rhinoptera bonasus, stocks based on microsatellite DNA markers.
  • Genetic investigation of Gymnura micrura in US Gulf of Mexico and western North Atlantic waters.

In Preparation

  • Mamoozadeh, N.R., J.R. McDowell, J.E. Graves. Submitted. Population structure of striped marlin (Kajikia audax) in the Pacific and Indian oceans based on genome-wide single nucleotide polymorphisms
  • McDowell, J.R., P. Grewe, M. Lauretta, J. F. Walter, K. Shulzitski, J. Lamkin, W. Ingram, E. Malca, M. Bravington. In preparation The relatedness of Atlantic bluefin tuna larvae in the Gulf of Mexico.
  • Roman, S.A., D.B. Rudders, R.A., J.R. McDowell. In preparation. Observations on a re-emerging epizootic of the sea scallop, Placopecten magellanicus, resource
  • Chak, S.T.C., K.M. Hultgren, J.R. McDowell, B.K. Song, J.E. Duffy. In preparation. Host partitioning and competitive superiority of eusocial snapping shrimps
  • Ellis, TA, H. Brightman, J., S. Musick, J.A. Buckel, J.R. McDowell. In preparation Population structure of spotted seatrout in its northern range.
  • Small, H. and McDowell, J.R. In preparation. Genetic structure of the tautog (Tautoga onitis) along the U.S. East Coast.
  • Marcek, B.J., M.C. Fabrizio, J.R. McDowell, R.S. McBride. In preparation. Effects of Hypoxia on the Reproductive Capacity of Atlantic Croaker in Chesapeake Bay.
  • McDowell, J.R., R.A. Fisher, R.D. Grubbs. In preparation. Genetic population structure of the cownose ray, Rhinoptera bonasus.


  • Song, J., Brill, R. W., J.R. McDowell. (2019). Plasticity in Standard and Maximum Aerobic Metabolic Rates in Two Populations of an Estuarine Dependent Teleost, Spotted Seatrout (Cynoscion nebulosus). Biology, 8(2), 46. doi:10.3390/biology8020046.
  • Turley, B., K. Reece, J. Shen, J-H. Lee, X. Guo, J.McDowell. (2019) Multiple drivers of interannual oyster settlement and recruitment in the lower Chesapeake Bay. Conservation Genetics. 10.1007/s10592-019-01194-0.
  • McDowell, J.R. and H. Brightman (2018). High level of genetic connectivity in a deepwater reef fish, the blueline tilefish (Caulolatilus microps). Journal of Fish Biology. 93:766-777.
  • McDowell, J.R., N.R. Mamoozadeh, H.B. Brightman, J.E. Graves (2018). Use of rapidly evolving molecular markers to distinguish species and clarify range uncertainties in the spearfishes (Istiophoridae, Tetrapturus). Bulletin of Marine Science. Volume 94, Number 4, October 2018, pp. 1355-1378(24). doi:
  • Veríssimo, A. I. Sampaio, J.R. McDowell, P. Alexandrino, G. Mucientes, N. Queiroz, C. da Silva, C.S. Jones, L.R. Noble (2017). World without borders – genetic population structure of a highly migratory marine predator, the blue shark (Prionace glauca). Ecology and Evolution 7:4768-4781.
  • Mamoozadeh, N. J.R. McDowell, J.E. Graves (2017). Genetic evaluation of population structure in white marlin (Kajikia albida): the importance of statistical power. ICES Journal of Marine Science. doi:10.1093/icesjms/fsx047.
  • Williams, S.M., J.R. McDowell, M. Bennett, J.E. Graves, J.R. Ovenden (2017). Analysis of whole mitochondrial genome sequences increases phylogenetic resolution of Istiophorid billfishes. Bulletin of Marine Science. doi: 10.5343/bms.2017.1078
  • Hill-Spanik, K, J.R. McDowell, N.A. Stokes, K.S. Reece, E.M. Burreson, R.B. Carnegie (2015). Phylogeographic perspective on the distribution and dispersal of a marine pathogen, oyster parasite Bonamia exitiosa. Marine Ecological Progress Series 536:65-76.
  • Graves, J.E., J.R. McDowell (2015). Population structure of Istiophorid billfishes. Fisheries Research 166: 21-28.
  • Fisher, R.A, J.R. McDowell, and G.C. Call (2014). Reproductive variations in the cownose ray (Rhinoptera bonasus) from Chesapeake Bay. Environmental Biology of Fishes 97:1031-1038.
  • Pagenkopp Lohan, K., J.R. McDowell, J.D. Shields, K.S. Reece (2014). Genotypic variation in the parasitic dinoflagellate Hematodinium perezi along the Delmarva Peninsula, Virginia Marine Biology 161: 261-273.
  • Sorenson, L. J.R. McDowell, T. Knott, J.E Graves (2013). Assignment test method using hypervariable markers for blue marlin (Makaira nigricans) stock identification. Conservation Genetic Resources 5: 293-297.
  • Veríssimo, A., J.R. McDowell, and J.E. Graves (2012). Genetic population structure and connectivity in a commercially exploited and wide-ranging deepwater shark, the leafscale gulper Centrophorus squamosus. Marine and Freshwater Research 63: 505-512.
  • O'Meara D., C. Edwards, P. Sleeman, T. Cross, M. Statham, J.R. McDowell, E. Dillane, J. Coughlan, D. O'Leary, C. O'Reilly, D. Bradley, J. Carlsson (2012). Genetic structure of Eurasian badgers Meles meles (Carnivora: Mustelidae) and the colonisation history of Ireland. Biological Journal of the Linnean Society. 893-909.
  • Pagenkopp-Lohan, K.M., J.R McDowell, J. Shields, J. Xiao, T. Miller, K.S. Reece (2012). Isolation and characterization of microsatellite loci for the parasitic dinoflagellate, Hematodinium perezi, a parasite of Callinectes sapidus. Molecular Ecology Resources.12: 570-572.
  • Sorenson L. L., J.R. McDowell, J.E. Graves (2011) Isolation and characterization of microsatellite markers for blue marlin, Makaira nigricans. Conservation Genetics Resources, 3 (4): 721.
  • Veríssimo A., J.R. McDowell, J.E. Graves(2011). Population structure of a deepwater squaloid shark, the Portuguese dogfish Centroscymnus coelolepis. ICES Journal of Marine Science. 68:555-563.
  • Veríssimo, A, D. Grubbs, J.R. McDowell, J. Musick, D. Portnoy (2011). Frequency of multiple paternity in the Spiny dogfish, Squalus acanthius, in the western Atlantic. Journal of Heredity 102:88-93.
  • Veríssimo A, T. Moura T, J.R. McDowell, J.E. Graves, L Gordo, R. Hoelzel (2011). Isolation and characterization of ten nuclear microsatellite loci for the Portuguese dogfish Centroscymnus coelolepis. Conservation Genetic Resources. 3:299-301
  • Portnoy, D.S., J. R. McDowell, E. J. Heist, J. A. Musick, J. E. Graves (2010). World phylogeography and male mediated gene flow in the sandbar shark, Carcharhinus plumbeus. Molecular Ecology 19:1994-2010.
  • Veríssimo, A, J.R. McDowell, and J. E. Graves (2010). Global population structure of the spiny dogfish, Squalus acanthias, a temperate shark with an antitropical distribution. Molecular Ecology 19:1651-1662.
  • Lynch, A., J.R. McDowell and J.E. Graves (2010). A molecular genetic investigation of the population structure of Atlantic menhaden (Brevoortia tyrannus). Fishery Bulletin 108:87–97.
  • Gray, K.N., J.R. McDowell, B.B. Collette, J.E. Graves (2009). A molecular phylogeny of the remoras and their relatives. Bulletin of Marine Science. 84: 183-198.
  • Gray, K.N., J.R. McDowell, B.B. Collette, J.E. Graves (2009). An investigation of the global population structure of the marlinsucker (Remora osteochir) inferred from mitochondrial control region DNA sequences. Bulletin of Marine Science. 84: 25-42.
  • Portnoy, D.S., J.R. McDowell, C.T. McCandless, J.A. Musick, J.E. Graves (2008). Effective size closely approximates the census size in the heavily exploited western Atlantic population of sandbar shark, Carcharhinus plumbeus. Conservation Genetics. 10: 1697-1705.
  • Chandler, E.A., J.R. McDowell, J.E. Graves (2008). Genetically monomorphic invasive populations of the rapa whelk, Rapana venosa. Molecular Ecology. 17: 4079-4091.
  • McDowell, J.R., J.E. Graves (2008). Microsatellite and mitochondrial DNA analyses of striped marlin (Tetrapturus audax) population structure in the Pacific Ocean. Canadian Journal of Fisheries and Aquatic Sciences. 65: 1307-1320.
  • Brendtro, K.S., J.R McDowell, J.E. Graves (2008). Population genetic structure of escolar (Lepidocybium flavobrunneum). Marine Biology. 155: 11-22.
  • Paine, M.A., J.R. McDowell, J.E. Graves (2008). Specific identification using COI analysis of scombrid larvae collected off the Kona coast of Hawaii. Ichthyological Research. 55(1): 7.
  • McDowell, J.R., J.E.L. Carlsson, J.E. Graves (2007). Genetic analysis of blue marlin (Makaira nigricans) stock structure in the Atlantic Ocean. Gulf and Caribbean Research. 19: 75-82.
  • Paine, M.A., J.R. McDowell, J.R., J.E. Graves (2007). Specific identification of Atlantic Ocean Scombrids using mitochondrial DNA cytochrome c oxidase subunit I (COI) gene region sequences. Bulletin of Marince Science. 80: 353-367.
  • Carlsson, J.C., J.R. McDowell, J.E.L. Carlsson, J.E. Graves (2007). Microsatellite and mitochondrial DNA analyses of young-of-the-year Atlantic bluefin tuna reveal population structure in the Atlantic and Mediterranean Sea. Journal of Heredity. 98: 23-28.
  • Collette B.B., J.R. McDowell, J.E. Graves (2006). Phylogeny of recent billfishes (Xiphiodei). Bulletin of Marine Science. Bulletin of Marine Science. 79: 455-468.
  • Graves, J.E., J.R. McDowell (2006). Genetic Analysis of White Marlin (Tetrapturus albidus) Stock Structure. Bulletin of Marine Science. 79: 469-482.
  • Portnoy, D.S., J.R. McDowell, K. Thompson, J. A. Musick, J.E. Graves (2006). Isolation and characterization of six dinucleotide microsatellite loci in the sandbar shark, Carcharhinus plumbeus. Molecular Ecology Notes. 6: 431-433.
  • Carlsson, J.C., J.R. McDowell, J.E.L. Carlsson, D. Olafsdottir, J.E. Graves (2006). Genetic heterogeneity of Atlantic bluefin tuna caught in the eastern North Atlantic Ocean south of Iceland. ICES Journal of Marine Science. 63: 1111-1117.
  • Luthy, S.A., R. K. Cowen, J.E. Serafy, J.R. McDowell (2005). Towards distinguishing larval sailfish, white marlin, and blue marlin in the western North Atlantic Ocean. Fishery Bulletin, 103: 588-600.
  • Carlsson, J., J.R. McDowell, P. Diaz-Jaimes, ,J.E.L. Carlsson, S.B. Boles, J.R. Gold, J.E. Graves (2004). Microsatellite and mitochondrial DNA analyses of Atlantic bluefin tuna (Thunnus thynnus thynnus) population structure in the Mediterranean Sea. Molecular Ecology, Molecular Ecology. 13: 3345-3356.
  • Graves, J.E., and J.R. McDowell (2003). Population structure of the world's billfishes: a genetic perspective. Marine and Freshwater Research. 54: 1-11.
  • McDowell, J.R., P. Diaz-Jaimes, and J.E. Graves (2002). Isolation and characterization of seven tetra-nucleotide microsatellite loci from Atlantic northern bluefin tuna Thunnus thynnus thynnus. Molecular Ecology Notes. 2: 214-216.
  • McDowell, J.R., J.E. Graves (2002). Nuclear and mitochondrial DNA markers for the specific identification of istiophorid and xiphiid billfishes. Fishery Bulletin. 100: 537-544.
  • Buonaccorsi, V.P., J.R. McDowell, J.E. Graves (2001). Reconciling patterns of inter-ocean molecular variance from four classes of molecular markers in blue marlin (Makaira nigricans). Molecular Ecology. 10: 1179-1196.
  • Graves, J.E., J.R. McDowell (1995). Inter-Ocean genetic divergence of istiophorid billfishes. Marine Biology 122: 193-204.
  • Graves, J.E., J.R. McDowell (1994). Genetic analysis of striped marlin Tetrapturus audax population structure in the Pacific Ocean. Canadian Journal of Fisheries and Aquatic Sciences. 51: 1762-1768.
  • Graves, J.E., A.M. Beardsley, J.R. McDowell, D.R. Scoles (1992). Stock structure of the bluefish Pomatomus saltatrix along the mid-Atlantic coast. Fishery Bulletin. 90: 703-710.
  • Graves, J.E., J.R. McDowell, M.L. Jones (1992). A genetic analysis of weakfish Cynoscion regalis stock structure along the mid-Atlantic coast. Fishery Bulletin. 90: 469-475.
  • Soll, D.L., C.S. Langtimm, J.R. McDowell, J. Hicks, R. Galask (1987). High-frequency switching in Candida strains isolated from vaginitis patients. Journal of Clinical Microbiology. 25: 1611-1622.
Lab Members

Ellen Biesack

I am the manager of the Fisheries Genetics and Pelagic Fishes laboratory at VIMS. My current projects, among many others, include loss of genetic diversity due to carryover effects in the eastern oyster, Crassostrea virginica, and the population structure of cobia, Rachycentron canadum, in the southeast United States. I’m interested in the use of population-level genetics for conservation and stock delineation. In my free time I enjoy crafting and maintaining my potted succulent and vegetable garden.




Hamish Small

I’m an Associate Research Scientist here at VIMS. I do a little bit of everything (ecology, aquatic infectious disease, molecular biology, microscopy) that mainly spans the Aquatic Health Sciences and Fisheries Sciences Departments. Recent collaborative efforts with Dr. Jan McDowell have focused on using molecular techniques to elucidate the population structure of tautog (Tautoga onitis) and cobia (Rachycentron canadum), both of which are recreationally important sport fish. As an avid saltwater angler this allows me combine my love of being on the water and providing sound science to management agencies.

Current Students

Sam Askin

I am a Master's student in the McDowell lab at VIMS. My current research topics include population genetics and fisheries management for channeled whelk, Busycotypus canaliculatus, a marine snail native to the east coast of the United States. My project is using genetic tools to help provide information to fisheries management agencies, so that channeled whelk can be properly managed for sustainable fishing. This will allow for continued economic success of this commercially important species. I am also part of an education assistantship at VIMS that provides me with the opportunity to do marine science outreach to various groups in the community. In my free time I like to go birding and search for herpetofauna at Newport News Park.


Jackson Martinez

I am from Houston, Texas and completed my undergrad at Texas A&M University at Galveston. There, I worked in the Shark Biology and Fisheries Science Lab, investigating the trophic ecology of the Sargassum Frogfish. Prior to VIMS, I worked as a Platform Removal Observer for NOAA/NMFS in the Gulf of Mexico. I am broadly interested in employing genetic techniques to answer questions regarding fish population genetics, stock structure, and movement. My research aims to characterize the temporal stock composition of the striped marlin, Kajikia audax, in the central North Pacific. In contrast to other billfishes, striped marlin exhibit a relatively high degree of genetic population structuring. Effective stock delineation may lead to improved assessments and management decisions for this highly migratory species.


Lindsey Nelson

I graduated with a B.S. of Biology from the University of Washington in 2012. Following that, I worked as a North Pacific Fisheries Observer in Alaska for nearly 5 years collecting fishing effort, catch data, and biological specimens. My research focus at VIMS is on Clearnose skates. Specifically, I am examining population genetics, morphology, and distribution in order to look for evidence of population structure. This information can be used by fisheries management councils to delineate stocks and effectively manage of our marine resources. I am very involved in campus organizations and events. I represent VIMS on the William & Mary Graduate Council; I am a member of the VIMS GSA Green Team and Professional Development Committee; I participate in volunteer and outreach events. I also enjoy anything outdoors, especially kayaking, birding, and camping.

Twitter: @indseynoel


Ann Ropp

I am a Master’s students in the McDowell and Reece Labs with interests in population and conservation genetics. My research focuses on the hard clam, Mercenaria mercenaria. It is an economically important wild harvest and aquaculture species in its native range along the East and Gulf coasts of North America. For my thesis I am first investigating the population structure and genetic diversity of wild hard clams along their range using high throughput molecular markers. I am then creating targeted assay panels from those markers that are able to address aquaculture based questions such as parentage and stock discrimination.




Jingwei Song

I am a PhD student in the McDowell lab. My research interests lie in the areas of population genetics, molecular ecology and evolutionary biology. Molecular markers are powerful tools for studying the forces that shape and maintain genetic diversity in the marine realm. Ultimately understanding the genetic structure and the distribution of adaptive genetic diversity of a species can lead to better management and conservation. My dissertation focuses on spotted seatrout, Cynoscion nebulosus, as a model system to understand how adaptation to water temperatures evolve at the genomic, transcriptomic and the physiology level. This research can help us better predict population-specific responses to climate change.

Former Students
Courses Taught/Teaching
  • MSCI 583       Bioinformatics
  • MSCI 673       Marine Molecular Genetics
  • MSCI 674       Marine Molecular Genetics Laboratory