研究领域

My research program focuses on the biology of avian blood parasites. The work encompasses many aspects of biology including molecular parasitology, ecology, evolution, and conservation genetics. In collaboration with researchers at the Center for Tropical Research at UCLA, and the Institute of Ecology at Vilnius University, Lithuania, my group studies the effects of deforestation on the spread of infectious diseases in African rainforest birds. Since 1990, a unique set of blood samples has been collected from over 200 rainforest bird species in a variety of habitats across Cameroon, Ghana, Côte d’Ivoire, Equatorial Guinea and Uganda. Significantly, the samples were collected from sites both before and after habitat degradation, permitting a unique examination into the direct effects of human induced habitat alterations. Using complementary techniques of blood smear analysis, and molecular biology, samples are assayed for the pathogens that cause malaria, trypanosomiasis, filiariasis and viruses. We have found that some parasites are entirely host specific and others are host generalists. We are examining the molecular basis for these patterns of host specificity. In addition, we use satellite imagery data to predict how changes in forest composition may affect the spread of diseases in the future. Through collaborations with UC Davis and the Golden Gate Raptor Observatory, we are studying the ecology of infectious avian blood parasites in California passerines and birds of prey. More recently, we have initiated a project to determine how global climate change can affect the prevalence and diversity of haemosporidian parasites in Alaska. Researchers in our Laboratory of Avian Parasitology utilize DNA sequencing, genomics, transcriptomics, microscopy and fieldwork to address these questions regarding the host specificity, pathogenicity and transmission of avian blood parasites

My research program focuses on the biology of avian blood parasites. The work encompasses many aspects  including molecular parasitology, ecology, evolution, and conservation genetics.   We have ongoing research projects in Africa, California, and Central America and significant collaborations with the Center for Tropical Research at UCLA, the Institute of Ecology at Vilnius University, and the Golden Gate Raptor Observatory.  There are projects amenable to both graduate and undergraduate research.  I teach General Parasitology, Parasitology Lab, and Emerging Infectious Diseases at San Francisco State University. 

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1.D. Freund, S. S. Wheeler, A. K. Townsend, W. M. Boyce, H. B. Ernest, C. Cicero, R. Sehgal. 2016. Genetic sequence data reveals widespread sharing of Leucocytozoon lineages in corvids. Parasitology Research. 1-9. (PDF) 2.E. Walther, G. Valkiūnas, E. A. Wommack, R. C. Bowie, T. A. Iezhova, R. Sehgal. 2016. Description and molecular characterization of a new Leucocytozoon parasite (Haemosporida: Leucocytozoidae), Leucocytozoon californicus sp. nov., found in American kestrels (Falco sparverius sparverius). Parasitology Research. 115: 1853-1862. (PDF) 3.A. R. Nelson, R. L. Cormier, D. L. Humple, J. C. Scullen, R. Sehgal, N. E. Seavy. 2016. Migration patterns of San Francisco Bay Area Hermit Thrushes differ across a fine spatial scale. Animal Migration 3:1. (PDF) 4.L. C. Wilkinson, C. M. Handel, C. Van Hemert, C. Loiseau, R. Sehgal. 2016. Avian malaria in a boreal resident species: long-term temporal variability, and increased prevalence in birds with avian keratin disorder.International Journal for Parasitology. 46: 281-290. (PDF) 5.R. Sehgal. 2015. Manifold habitat effects on the prevalence and diversity of avian blood parasites. International Journal for Parasitology: Parasites and Wildlife. (PDF) 6.R. Sehgal, T. A. Iezhova, T. Marzec, G. Valkiūnas. 2015. Trypanosoma naviformis sp. nov.(Kinetoplastidae: Trypanosomatidae) from widespread African songbirds, the Olive sunbird (Cyanomitra olivacea) and Yellow-whiskered greenbul (Andropadus latirostris). Zootaxa. 4034: 342-350. (PDF) 7.E. L. Walther, J. S. Carlson, A. Cornel, B. K. Morris, R. Sehgal. 2015. First molecular study of prevalence and diversity of avian haemosporidia in a Central California songbird community. Journal of Ornithology: 1-16. (PDF) 8.E. J. Lauron, H. X. Aw Yeang, S. M. Taffner, R. Sehgal. 2015. De novo assembly and transcriptome analysis of Plasmodium gallinaceum identifies the Rh5 interacting protein (ripr), and reveals a lack of EBL and RH gene family diversification. Malaria Journal. 14: 296. (PDF) 9.J.S. Carlson, E. Walther, R. Trout Fryxell, S. Staley, L. A. Tell, R. Sehgal, C. M. Barker and A. J. Cornel. 2015. Identifying avian malaria vectors: sampling methods influence outcomes. Parasites and Vectors. 8: 365. (PDF) 10.J. E. Martínez-Gómez, N. Matías-Ferrer, R. Sehgal and P. Escalante. 2015. Phylogenetic placement of the critically endangered Townsend’s Shearwater (Puffinus auricularis auricularis): evidence for its conspecific status with Newell’s Shearwater (Puffinus a. newelli) and a mismatch between genetic and phenotypic differentiation. Journal of Ornithology. DOI 10.1007/s10336-015-1189-2. (PDF) 11.E. J. Lauron, C. Loiseau, R. C. Bowie, G. S. Spicer, T. B. Smith, M. Melo and R. Sehgal. 2015. Coevolutionary patterns and diversification of avian malaria parasites in African sunbirds (Family Nectariniidae). Parasitology. 142: 635-647. (PDF) 12.O. Hellgren, C. T. Atkinson, S. Bensch, T. Albayrak, D. Dimitrov, J. G. Ewen, K. S. Kim, M. R. Lima, L. Martin, V. Palinauskas, R. Ricklefs, R. Sehgal, G. Valkiūnas, Y. Tsuda and A. Marzal. 2015. Global phylogeography of the avian malaria pathogen Plasmodium relictum based on MSP1 allelic diversity. Ecography. 38: 842-850. (PDF) 13.E. L. Evans, J. E. Martinez-Gomez and R. Sehgal. 2015. Phylogenetic relationships and taxonomic status of the endemic Socorro Warbler (Setophaga pitiayumi graysoni). Journal of Ornithology. 156: 363-370. (PDF) 14.E. J. Lauron, K. S. Oakgrove, L. A. Tell, K. Biskar, S. W. Roy and R. Sehgal. 2014. Transcriptome sequencing and analysis of Plasmodium gallinaceum reveals polymorphisms and selection on the apical membrane antigen-1. Malaria Journal. 13: 282. (PDF) 15.K. S. Oakgrove, R. J. Harrigan, C. Loiseau, S. Guers, B. Seppi and R. Sehgal. 2014. Distribution, diversity and drivers of blood-borne parasite co-infections in Alaskan bird populations. International Journal for Parasitology. 44: 717-727. (PDF) 16.E. L. Walther, G. Valkiūnas, A. D. González, N. E. Matta, R. E. Ricklefs, A. Cornel and R. Sehgal. 2014. Description, molecular characterization, and patterns of distribution of a widespread New World avian malaria parasite (Haemosporida: Plasmodiidae), Plasmodium (Novyella) homopolare sp. nov. Parasitology Research. 113: 3319-3332. (PDF) 17.A. Marzal, L. García-Longoria, J. M. C. Callirgos and R. Sehgal. 2014. Invasive avian malaria as an emerging parasitic disease in native birds of Peru. Biological Invasions. DOI 10.1007/s10530-014-0718-x. 1-7. (PDF) 18.M. A. Jasper, J. M. Hull, A. C. Hull, and R. Sehgal. 2014. Widespread lineage diversity of Leucocytozoon blood parasites in distinct populations of western Red-tailed Hawks. Journal of Ornithology. 155: 767–775. (PDF) 19.C. D. Mendenhall, H. M. Archer, F. O. Brenes, C. H. Sekercioglu and R. Sehgal. 2013. Balancing biodiversity with agriculture: Land sharing mitigates avian malaria prevalence. Conservation Letters. 6: 125-131. (PDF) 20.C. Martinez, T. Marzec, C. D. Smith, L. A. Tell, and R. Sehgal. 2013. Identification and expression of maebl, an erythrocyte binding gene in Plasmodium gallinaceum. Parasitology Research. 112: 945-954. (PDF) 21.A. Križanauskienė, T. A. Iezhova, R. Sehgal, J. S Carlson, V. Palinauskas, S. Bensch, and G. Valkiūnas. 2013. Molecular characterization of Haemoproteus sacharovi (Haemosporida, Haemoproteidae), a common parasite of columbiform birds, with remarks on classification of haemoproteids of doves and pigeons. Zootaxa. 3613: 085-094. (PDF) 22.G. Valkiūnas, T. A. Iezhova, E. Evans, J. S. Carlson, J. E. Martinez-Gomez, R. Sehgal. 2013. Two new Haemoproteus (Haemosporida: Haemoproteidae) species from Columbiform birds. Journal of Parasitology. 99(3): 513-521. (PDF) 23.J. S. Carlson, J. E. Martinez-Gomez, G. Valkiūnas, C. Loiseau, D. A. Bell and R. Sehgal. 2013. Diversity and phylogenetic relationships of hemosporidian parasites in birds of Socorro Island, Mexico, and their role in the re-introduction of the Socorro Dove (Zenaida graysoni). Journal of Parasitology. 99: 270-276. (PDF) 24.M. Dodge, S. L. Guers, C. H. Sekercioglu and R. Sehgal. 2013. North American transmission of hemosporidian parasites in the Swainson’s thrush (Catharus ustulatus), a migratory songbird. Journal of Parasitology. 99: 548-553. (PDF) 25.C. Loiseau, R. J. Harrigan, A. J. Cornel, S. L. Guers, M. Dodge, T. Marzec, J. S. Carlson, B. Seppi and R. Sehgal. 2012. First evidence and predictions of Plasmodium transmission in Alaskan bird populations. PloS One. 7:e44729. (PDF)