Guillermo Orti

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Guillermo Orti

Louis Weintraub Professor of Biology


Office Phone: (202) 994-7065
Lisner Hall 411


Molecular systematics and phylogeography.

I am an evolutionary biologist with a primary interest in molecular systematics, phylogeography, and ecological genetics and genomics. My research has focused on a diversity of biological systems and questions conceptually unified by a phylogenetic perspective.

Most of my work has been empirical, based on comparative DNA sequence analysis, predominantly focusing on the evolution of fishes. I have been actively leading NSF-funded projects to assemble the tree of life for all fishes, such as the DeepFin Research Coordination Network (, the Euteleost Tree of Life Project (EToL), and the FishLife Project ( My lab is now applying a set of genome-wide exon markers to infer fish phylogenies, based on target capture approaches and next-gen sequencing.

The molecular phylogenies of fishes produced by these efforts are the basis of a new phylogenetic classification for bony fishes. I have done fieldwork and fish collections in Patagonia, the Amazon, the Caribbean, and Galápagos.

Licenciado en Biología, Universidad de Buenos Aires, Argentina (1981)

Ph.D., Department of Ecology and Evolution, Stony Brook University, New York  (1995)


For a complete list of publications see my Google Scholar Page at

Atta, Calder J., H. Yuan, C. Li, D. Arcila, R. Betancur-R, L.C. Hughes, G. Ortí, L. Tornabene. Exon-capture data and locus screening provide new insights into the phylogeny of flatfishes (Pleuronectoidei). Molecular Phylogenetics and Evolution Volume 166, January 2022, 107315 (first published 16 Sep 2021,

Santaquiteria, Aintzane, A.C. Siqueira, E. Duarte-Ribeiro, G. Carnevale, W. White, J. Pogonoski, C.C. Baldwin, G. Ortí, D. Arcila, and R. Betancur-R. Phylogenomics and Historical Biogeography of Seahorses, Dragonets, Goatfishes, and Allies (Teleostei: Syngnatharia): Assessing the Factors Driving Uncertainty in Biogeographic Inferences. Systematic Biology, syab028 (first published 23 April 2021,

Arcila, Dahiana, L.C. Hughes, F. Meléndez-Vazquez, C.C. Baldwin, W. White, K. Carpenter, J.T. Williams, M.D. Santos, J.Pogonoski, M. Miya, G. Ortí, R. Betancur-R. Testing the utility of alternative metrics of branch support to address the ancient evolutionary radiation of tunas, stromateoids, and allies (Teleostei: Pelagiaria). Systematic Biology, syab018 (first published 30 March 2021,

Rincon-Sandoval, M., E. Duarte-Ribeiro, A.M. Davis, A. Santaquiteria, L.C. Hughes, C.C. Baldwin, L. Soto-Torres, H.J. Walker, K.E. Carpenter, M. Sheaves, G. Ortí, D. Arcila, R. Betancur-R. 2020. Evolutionary determinism and convergence associated with water- column transitions in marine fishes. Proc. Nat. Acad. Sci. (USA) 117 (52): 33396-33403. first published December 16, 2020;

Hughes, L.C., G. Ortí, H. Saad, C. Li, W. T. White, C.C. Baldwin, K. A. Crandall, D.K. Arcila, R. Betancur-R. 2021. Exon probe sets and bioinformatics pipelines for all levels of fish phylogenomics. Molecular Ecology Resources 21 (3): 816-833; first published online 21 October 2020;

Kolmann, M.A., Hughes, L.C., Hernandez, L.P., Arcila, D., Betancur-R, R., Sabaj, M.H., López- Fernández, H., & Ortí, G. 2020. Phylogenomics of piranhas and pacus (Serrasalmidae) uncovers how dietary convergence and parallelism obfuscate traditional morphological taxonomy. Systematic Biology, syaa065 (published online August 4, 2020,

Arcila, D. and G. Ortí. Phylogenetic Systematics of Fishes. In S. Midway, C. Hasler, and P. Chakrabarty, editors. Methods for Fish Biology, 2nd edition. American Fisheries Society,
Bethesda, Maryland. Hughes, L.C., Y.P. Cardoso, J.A. Sommer, R. Cifuentes, M.Cuello, G.M. Somoza, M. González- Castro, L.R. Malabarba, V. Cussac, E.M. Habit, R. Betancur-R., and G. Ortí. 2020. Biogeography, habitat transitions and hybridization in a radiation of South American silverside fishes revealed by mitochondrial and genomic RAD data. Molecular Ecology 29:738–751. First published: 09 January 2020

Betancur-R, R., D. Arcila, R. Vari, L. Hughes, M. H. Sabaj, C. Oliveira, G. Ortí. 2019. Phylogenomic incongruence, hypothesis testing, and taxon sampling: the monophyly of characiform fishes, Evolution 73 (2): 329-345 (doi:10.1111/evo.13649).

Ribeiro, E., A. Davis; R. Rivero-Vega, G. Ortí, R. Betancur-R. 2018. Post-Cretaceous bursts of evolution along the benthic-pelagic axis in a major marine fish radiation. Proc. Roy. Soc. B 285: 20182010;

Hughes, L.C., G. Ortí, Y. Huang, Y. Sun, C. C. Baldwin, A. W. Thompson, D. K. Arcila, R. Betancur-R, C. Li, L. Becker, N. Bellora, X. Zhao, X. Li, M. Wang, C. Fang, B. Xie, Z. Zhou, H. Huang, S. Chen, B. Venkatesh, Q. Shi. 2018. Comprehensive phylogeny of ray-finned fishes (Actinopterygii) based on transcriptomic and genomic data. Proc. Nat. Acad. Sci. (USA), 115 (24) 6249-6254;

Arcila, D., P. Petry, G. Ortí. 2018. Phylogenetic position of the family Tarumanidae (Characiformes) based on nuclear and mitochondrial data. Neotropical Ichthyology 16(3): e180016; DOI: 10.1590/1982-0224-20180016

Thompson, A.W., A. Hayes, J.E. Podrabsky, G. Ortí. 2017. Gene expression during delayed hatching in fish-out-of-water. Ecological Genetics and Genomics 3-5 (2017) 52-59.

Betancur-R., R., G. Ortí, E.O. Wiley, G. Arratia, A. Acero, M. Miya, G, Lecointre. Phylogenetic classification of bony fishes. BMC Evolutionary Biology (2017) 17:162

Arcila, D., G. Ortí, R. Vari, L.J. Revell, J.W. Armbruster, M.L.J. Stiassny, K. Ko, M.H. Sabaj, J. Lundberg, R. Betancur-R. 2017. Gene genealogy interrogation advances resolution of recalcitrant phylogenies. Nature Ecology and Evolution 1, Article 0020 (published online 13 Jan 2017). doi:10.1038/s41559-016-0020.

Rueda, E.C., K.A. Mullaney, C. Conte-Grand, E.M. Habit, V. Cussac, G. Ortí. 2016. Displacement of native Patagonian freshwater silverside populations (Odontesthes hatcheri, Atherinopsidae) by introgressive hybridization with introduced O. bonariensis. Biological Invasions 19(3), 971-988. DOI: 10.1007/s10530-016-1295-y

Thompson, A.W. and G. Ortí. 2016. Annual killifish transcriptomics and candidate genes for metazoan diapause. Molecular Biology and Evolution 33(9): 2391-5. doi: 10.1093/molbev/msw110. Epub 2016 Jun 13.

Sun, Y., Y. Huang, X. Li, C.C. Baldwin, Z. Zhou, Z. Yan, K.A. Crandall, Y. Zhang, X. Zhao, M. Wang, A. Wong, C. Fang, X. Zhang, H. Huang, J.V. Lopez, K. Kilfoyle, Y. Zhang, G. Ortí, B. Venkatesh, Q. Shi. 2016. The Value of Fish Transcriptome Sequences and Their Construction by the Fish-T1K Project. GigaScience (2016) 5:18, DOI: 10.1186/s13742-016-0124-7

Willis, S.C., K.O. Winemiller, C.G. Montaña, P. Reiss, J. Macrander, I.P. Farias, G. Ortí. 2015. Population genetics of the speckled peacock bass (Cichla temensis): implications for management of South America’s most important inland sport fishery. Conservation Genetics 16 (6): 1345-1357, doi: 10.1007/s10592-015-0744-y

Thomaz, A., D. Arcila, G. Ortí, L.R. Malabarba. Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits. BMC Evolutionary Biology 15:146, doi: 10.1186/s12862-015-0403-4

Tonini, J.F.R., A. Moore, D. Stern, M. Shcheglovitova, G. Ortí.  Concatenation and species tree methods exhibit statistically indistinguishable accuracy under a range of simulated conditions. PLoS Currents Tree of Life, 2015 Mar 9. Edition 1.

Betancur-R, R. G. Ortí, R.A. Pyron. 2015. Fossil-based comparative analyses reveal ancient marine ancestry erased by extinction in ray-finned fishes. Ecology Letters 18 (5): 441-450.

Campanella, D., L.C. Hughes, P.J. Unmack, D.D. Bloom, K.R. Piller, G. Ortí. 2015. Multi-locus fossil-calibrated phylogeny of Atheriniformes (Teleostei, Ovalentaria). Molecular Phylogenetics and Evolution 86: 8–23

Arcila, D., A. Pyron, J.C. Tyler, G. Ortí, R. Betancur-R. 2015.  An evaluation of fossil tip-dating versus node-age calibrations in tetraodontiform fishes (Teleostei: Percomorphaceae). Molecular Phylogenetics and Evolution 82 (part A): 131–145.

Thompson, A.W., R. Betancur-R, H. López-Fernández and G. Ortí. 2014. A Time-Calibrated, Multi-locus Phylogeny of Piranhas and Pacus (Characiformes: Serrasalmidae) and a Comparison of Species Tree Methods. Molecular Phylogenetics and Evolution 81: 242–257.

Willis S.C., I. P. Farias,  G.  Ortí. 2014. Testing mitochondrial capture and deep coalescence in Amazonian cichlid fishes (Cichlidae: Cichla). Evolution 68-1: 256–268.

Betancur-R, R, G. Naylor, G. Ortí. 2014. Conserved genes, sampling error, and phylogenomic inference. Systematic Biology 63 (2): 257-262.

Rueda, E.C., P. Carriquiriborde, A. M. Monzon, G.M. Somoza, G. Ortí. 2013. Seasonal variation in genetic population structure of sábalo (Prochilodus lineatus) in the Lower Uruguay River. Genetica DOI 10.1007/s 10709-013-9739-0.

Willis S.C., I. P. Farias, G. Ortí. 2013. Testing mitochondrial capture and deep coalescence in Amazonian cichlid fishes (Cichlidae: Cichla). Evolution doi: 10.1111/evo. 12230 (in press).

Willis S.C., I. P. Farias, G. Ortí. 2013. Multi-Locus species Tree for the Amazonian Peacock Basses (Cichlidae: Cichla): Emergent phylogenetic signal despite limited nuclear variation. Molecular Phylogenetics and Evolution 69(3): 479-490, doi. 10.1016/j.ympev.2013.07.031

Betancur-R., R., C. Li, T. A. Munroe, J. A. Ballesteros, G. Ortí. 2013. Addressing the gene-tree discordance and non-stationarity to resolve a multi-locus phylogeny of the flatfishes (Teleostei: Pleuronectiformes). Systematic Biology, 62(5): 763-785 doi.

Betancu-R., R., R.E. Broughton, E.O. Wiley, K. Carpenter, J.A. Lopez, C. Li, G. Arratia, N.I. Holcroft, D. Arcila, M. Sanciango, J. Cureton, F. Zhang, T. Buser, M. Campbell, T. Rawley, J.A. Ballesteros, G. Lu, T. Grande, & G. Ortí. 2013. The tree of life and a new classification of bony fishes. PLoS Currents Tree of Life, Apr 18 [last modified: 2013 Apr 23]. Edition 1. doi: 10.1371/currents.tol.53ba26640df0ccaee75bb165c8c26288.

Broughton, R.E., R. Betancur-R, C. Li, G Arratia, G. Ortí. 2013. Multi-locus phylogenetic analysis reveals the pattern and tempo of bony fish evolution. PL0S Currents Tree of Life, 2013 Apr 16 [last modified: 2013 May 9]. Edition 1. doi: 10.1371/currents.tol.2ca8041495ffafd0c92756e75247483e.

Mariguela, T.C., G. Ortí, K.T. Abe, G.S. Avelino, C. Oliveira. 2013. Composition and interrelationships of a large Neotropical freshwater fish group, the subfamily Cheirodontinae (Characiformes: Characidae): a case study based on mitochondrial and nuclear DNA sequences. Molecular Phylogenetics and Evolution 68 (2013) 23-34.

Grubich J.R., S. Huskey, S.Crofts, G. Ortí, and J. Porto. 2012. MEGA-BITES: Extreme jaw forces of living and extinct piranhas (Serrasalmidae). Scientific Reports, in press.

Willis, S.C., J. Macrander, I. P. Farias and G. Ortí. 2012. Simultaneous delimitation of species and quantification of interspecific hybridization in Amazonian peacock cichlids (genus Cichla) using multi-locus data. BMC Evolutionary Biology, 12: 96 (22 June 2012).

Betancur, R., G. Ortí, A.M. Stein, A.P. Marceniuk, and A. Pyron. 2012. Apparent signal of competition limiting diversification after ecological transitions from marine to freshwater habitats. Ecology Letters, 15(8): 822–830.

Bernardi, G., E.O. Wiley, H., Mansour, M.R. Miller, G. Ortí, D. Haussler, S.J. O'Brien, O.A. Ryder, B. Venkatesh. 2012. The Fishes of Genome 10K. Marine Genomics 7 (2012): 3–6.

Willis, S.C., H. López-Fernández, C.G. Montaña, I.P. Farias, G. Ortí. 2012. Species-level phylogeny of ‘Satan’s perches’ based on discordant gene trees (Teleostei: Cichlidae: Satanoperca Günther 1862). Molecular Phylogenetics and Evolution 63(3): 798-808.

Oliveira, C., G.S. Avelino, K.T. Abe, T.C. Mariguela, R.C. Benine, G. Ortí, R.P. Vari, R.M. Corrêa e Castro. 2011. Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling. BMC Evolutionary Biology 11: 275.

Rueda, EC, P. Amavet, F. Brancolini, J. Sommer, and G. Ortí. 2011b. Isolation and characterization of eight polymorphic microsatellite markers for the migratory characiform fish, Salminus brasiliensis, Journal of Fish Biology, 79: 1370-1375.

Li, C., R. Betancur-R.; W. L. Smith, and G. Ortí. 2011. Monophyly and interrelationships of Snook and Barramundi (Centropomidae sensu Greenwood) and five new markers for fish phylogenetics. Molecular Phylogenetics and Evolution, 60: 463-471.

Carvalho-Costa, L.F., N.M. Piorski, S.C. Willis, P.M. Galetti Jr., and G. Ortí. 2011. Molecular systematics of the neotropical shovelnose catfish genus Pseudoplatystoma Bleeker 1862 based on nuclear and mtDNA markers. Molecular Phylogenetics and Evolution 59: 177-194.

Willis, SC, M Nunes, CG Montana, IP Farias, G Ortí, and NR Lovejoy. 2010. The Casiquiare River as a dispersal corridor between the Amazonas and Orinoco River basins: Biogeographic analysis of the genus Cichla. Molecular Ecology 19(5): 1014-1030.

Roa-Varón, A. and G. Ortí. 2009. Phylogenetic relationships among families of Gadiformes (Teleostei, Paracanthopterygii) based on nuclear and mitochondrial data. Molecular Phylogenetics and Evolution, 52(3): 688-704. doi:10.1016/j.ympev.2009.03.020.

Ortí, G. and  Li, C. 2009. Phylogeny and Classification (Chapter 1). Pp 1-24 in Reproductive Biology and Phylogeny of Fish (Agnatha and Bony Fishes), Series Editor B.M.G. Jamieson, Science Publishers, Enfield, New Hampshire, 788 pp.

Li, C., G. Lu, and G. Ortí. 2008. Optimal Data Partitioning and a Test Case for Ray-finned Fishes (Actinopterygii) Based on Ten Nuclear Loci. Systematic Biology 57(4): 519–539.

Ortí, G., A. Sivasundar, K. Dietz, and M. Jégu. 2008. Phylogeny of the Serrasalmidae (Characiformes) based on mitochondrial DNA sequences. Genetics and Molecular Biology 31, 1 (suppl): 343-351.

Li, C., G. Ortí, G. Zhang, and G. Lu. 2007. A practical approach to phylogenomics: the phylogeny of ray-finned fish (Actinopterygii) as a case study. BMC Evolutionary Biology 7: 44.

Ross, C., J. French, and G. Ortí. 2007. Germ Line Chimerism and Paternal Care in Marmosets (Callithrix kuhlii). Proc. Natl. Acad. Sci. USA 104(15): 6278–6282.

Guilgur, L.G., G. Ortí, P,H. Strobl-Mazzulla, J.I. Fernandino, L.A. Miranda & G. Somoza. 2007. Characterization of the cDNAs encoding three GnRH forms in the pejerrey fish Odontesthes bonariensis (Atheriniformes) and the evolution of GnRH precursors. Journal of Molecular Evolution 64: 614–627.

Steinauer, M.L., B.B. Nickol, R. Broughton, G. Ortí. 2005. First Sequenced Mitochondrial Genome from the Phylum Acanthocephala (Leptorhynchoides thecatus) and its Phylogenetic Position Within Metazoa. Journal of Molecular Evolution 60: 706-715.

Chen, W.-J., G. Ortí, A. Meyer. 2004. Novel evolutionary relationship among four fish model systems. Trends in Genetics 20(9): 424-431. Lopez, A. W.-J. Chen, G. Ortí. 2004. Esociform phylogeny. Copeia 2004(3): 449-464.

Sivasundar, A., E. Bermingham, and G. Ortí. 2001. Population structure and biogeography of migratory freshwater fishes (Prochilodus: Characiformes) in major South American rivers. Molecular Ecology 10(2): 407-418.


National Geographic TV documentary “Megapiranha”  (Explorer series), Air date 17 May 2011. Expedition to the Xingu River featured in the show took place in August 2010.