H. Allen Orr (born 1960) is an American evolutionary biologist specializing in the genetics of speciation and adaptation. He is the Shirley Cox Kearns Professor of Biology at the University of Rochester.

Education and career Orr earned his bachelor's degree in biology and philosophy from the College of William and Mary and his Ph.D. in biology from the University of Chicago. At Chicago, Orr studied under Jerry Coyne. He performed postdoctoral research at the University of California, Davis.Orr's CV from his lab page

Work Orr is an evolutionary geneticist whose research focuses on the genetics of speciation and the genetics of adaptation, in particular on the genetic basis of hybrid sterility and inviability. How many genes cause reproductive isolation between species? What are the normal functions of these genes and what evolutionary forces drove their divergence? He studies these problems through genetic analysis of reproductive isolation between species of Drosophila.

In his adaptation work, Orr is interested in theoretical rules or patterns that might characterize the population genetics of adaptation. He studies these patterns using both population genetic theory and experiment. His early work on Drosophila set the terms of much of the current research on speciation.Coyne, Jerry A. and Orr, H. Allen, Evolution, Vol. 43, No. 2 (Mar., 1989), pp. 362-381 Orr is said to be one of the few evolutionary biologists ever to have made fundamental contributions about how changes occur within lineages over time, and about how lineages split to result in new species.U of Rochester announcement

Speciation His book Speciation,Jerry A. Coyne and H. A. Orr (2004). Speciation. Sinauer Associates, Sunderland, MA, USA, co-authored with Jerry Coyne, was hailed in Science as "exceedingly well-written and persuasive".EVOLUTION:How Species Arise A review by Benjamin K. Blackman and Loren H. Rieseberg Science 305 no. 5684, pp. 612-613 They consider that studying speciation is largely synonymous with studying reproductive isolation, and explore what we know about where, when, and how isolating barriers evolve. Following Ernst Mayr they argue that speciation usually occurs where populations are geographically isolated or allopatric. They present evidence for the primacy of natural and sexual selection over genetic drift in driving speciation. Signatures of positive selection on genes involved in postzygotic isolation and reproductive proteins as well as experimental evidence from both the lab and field connect adaptation and sexual selection to reproductive isolation. They also present evidence for the congruence of the Dobzhansky-Muller model for the evolution of postzygotic isolation with the genetics of hybrid incompatibilities in many natural systems. Results that support their conclusions in the book continue to be published.see e.g. D. A. Barbash, D. F. Siino, A. M. Tarone, J. Roote, Proc. Natl. Acad. Sci. U.S.A. 100, 5302 (2003) and the paper in Nature 423, 715 cited below

Fisher's theory of dominance According to R. A. Fisher's theory of dominance, genes in diploid organisms may be recessive as an effect of hypothetical regulator genes. In 1981 Kacser and Burns gave convincing theoretical arguments why the explanation for dominance lay in simple biochemistry rather than in Fisher's more complicated genetic theory. Orr put this on an experimental basis with studies of Chlamydomonas reinhardtii, an alga that exists almost exclusively as a haploid organism, but which passes through occasional diploid generations. He found that the great majority of genes in diploid cells were recessive, contradicting Fisher's theory.

Awards and recognition Orr has been the recipient of a Guggenheim Fellowship, a David and Lucile Packard Fellowship, an Alfred P. Sloan Foundation Postdoctoral Fellowship, and a Rockefeller Foundation Scholar in Residence Fellowship at Bellagio Study Center, Italy. He was awarded the Dobzhansky Prize by the Society for the Study of Evolution and the Young Investigator Prize by the American Society of Naturalists. He was also named Professor of the Year in Natural Sciences by the Student Association at University of Rochester in 2002. In 2008 he was one of thirteen recipients of the Darwin-Wallace Medal, which is bestowed every 50 years by the Linnean Society of London.

Publications Orr is widely published in some of the leading scientific journals including Nature, Science and PNAS.

Books Speciation. 2004. .

Scientific publications Orr's papers include:

"A test of Fisher’s theory of dominance", PNASOrr, H. A. 1991. A test of Fisher’s theory of dominance. Proc. Natl. Acad. Sci. USA 88: 11413-11415. "Haldane's rule has multiple genetic causes", NatureOrr, H. A. 1993. Haldane’s rule has multiple genetic causes. Nature 361 532-533. [See “News and Views” by J. Brookfield: Nature 361: 496-497.] "A mathematical model of Haldane's rule", EvolutionOrr, H. A. 1993. A mathematical model of Haldane’s rule. Evolution 47: 1606-1611. [See “News and Views” by Jerry Coyne: Nature 363: 298.] "The evolutionary genetics of speciation", Phil. Trans. Roy. Soc. Lond. BCoyne, Jerry A. and Orr, H. Allen. 1998. The evolutionary genetics of speciation. Phil. Trans. R. Soc. Lond. B 353: 287-305. [reprinted in Evolution of Biological Diversity, Ed. by A. E. Magurran and R. M. May. pp. 1-36. Oxford University Press, Oxford, 1999. Also reprinted in Evolutionary Genetics: from Molecules to Morphology, Ed. by R. S. Singh and C. B. Krimbas, Cambridge University Press, Cambridge, 2000. Also reprinted in Evolution, Second Edition, ed. by M. Ridley, Oxford University Press, Oxford, 2003] "The population genetics of adaptation: the distribution of factors fixed during adaptive evolution", EvolutionOrr, H. A. 1998. The population genetics of adaptation: the distribution of factors fixed during adaptive evolution. Evolution 52: 935-949. [See “News and Views” by N. Barton: Nature 395: 751-752. See also Science 284: 2106-2107.] "Haldane's rule is obeyed in taxa lacking a hemizygous X", SciencePresgraves, D. C. and Orr, H. A. 1998. Haldane’s rule is obeyed in taxa lacking a hemizygous X. Science 282: 952-954. [See “Perspectives” by M. Turelli: Science 282: 889-891.] "Morphological innovation and developmental genetics", PNASMarshall, C. R. H. A. Orr, and N. H. Patel. 1999. Morphological innovation and developmental genetics. Proc. Natl. Acad. Sci. USA 96: 9995-9996. "Adaptive evolution drives divergence of a hybrid inviability gene in Drosophila", NaturePresgraves, D. C., L. Balagopalan, S. M. Abmayr, and H. A. Orr. 2003. Adaptive evolution drives divergence of a hybrid inviability gene in Drosophila. Nature 423: 715-719. [See “News and Comment” by M. Noor: Nature 423: 699-700; see also news item in Nature Reviews Genetics 4: 580; “Faculty of 1000” listed paper]

Notes and references

External links Orr lab website H. Allen Orr at The New York Review of Books