Chris Organ

Adjunct Professor, Brown University

Postdoctoral Fellow, Harvard University

Department of Organismic and Evolutionary Biology
Harvard University,
26 Oxford Street,
Cambridge, MA 02138

MCZ Room 500C
Tel: 617-496-9389
Fax: 617-495-5667

organchris(at)gmail.com

Download a PDF version of my CV.

Research Interests:

We are only now, in the post-genome era, able to ask comprehensive questions about how genes and genomes evolved among groups and populations over long periods of geologic time.  My current research takes advantage of these developments to address fundamental questions that span broad levels of biological organization, from genes and morphology to paleobiology. Below are the primary questions currently driving my research.

Evolutionary  Genetics/Genomics: How has evolution shaped reptile and bird genes and what does this tell us about amniote genomes in general?Except for a handful of model organisms, the genomes of vertebrates are poorly known. Given their vital phylogenetic position as a hub connecting amphibians to birds and mammals, reptiles are especially neglected. My ongoing research on bird and reptile genetics and genomics is aimed at helping to fill this gap. I use Bayesian and likelihood comparative phylogenetic methods to understand how genomes and sex chromosomes evolve. For example, at the whole-genome and chromosomal level, we found that reptilian genome size distribution is consistent with a model of continuous gradual evolution while genomic compartmentalization, as manifested by the number of microchromosomes and macrochromosomes, appears to have undergone early rapid change. At the sequence level, we found that exon size in Alligator is distributed in a pattern matching that of exons in Gallus (chicken), especially in the 101-200bp size class, and that introns are smaller in reptiles than introns in mammals.

Paleogenomics: What characterizes genome architecture in extinct animals compared with living relatives and what does this reveal about genome macroevolution and the biology of extinct organisms?Ninety-nine percent of all animal species to have ever lived are now extinct, leaving us with a preciously small sample from which to understand biological phenomena. Recovering some part of that biological information is vital for understanding biology broadly and deeply.  I combine genomic and paleontological data with Bayesian phylogenetic comparative methods to characterize the genomes of extinct organisms.  For example, I have shown that the small, gene-dense genomes of birds evolved in saurischian dinosaurs between 230 and 250 million years ago and that Mesozoic marine reptiles had genotypic sex determination.  I am also evaluating neutral theories of genome evolution that incorporate ideas from population genetics. This research is on the cutting edge of genome biology because it combines paleogenomics with laboratory and computational approaches to test evolutionary hypotheses infeasible when looking at living species alone.

Comparative Methods: How can we use the advances in comparative phylogenetic methods and bioinformatics to make evolutionarily informed predictions? Prediction is a basic and necessary aspect of science that allows hypotheses to interconnect and makes the results of science explicitly testable. Moreover, as a historical discipline, it is essential to make quantitative predictions in evolutionary biology that can be tested by comparative approaches, such as with the aid of traits that undergo correlated evolution. Examples include reconstructing character states, such as the presence of a certain behavior, muscular connections, physiological and developmental traits, and even genomic characteristics for which direct measurements are intractable. Species under study may be extinct, in which aspects of the species' biology can be predicted using correlate data (binary or continuous), or species may lie in the future, in which phylogeny and correlate data provide a framework for hypothesizing about how species will respond to current or future pressures. This work flows directly into my other areas of interest and is pursued with colleagues Mark Pagel and Andrew Meade.

Publications

1. Janes, D. E., C. L. Organ, and S. V. Edwards. (in review). Variability in sex-determining mechanisms influences genome complexity in Reptiles.

2. Organ, C. L. and S. V. Edwards (in press). Major Events in the Evolution of the Avian Genome. In The Evolution of Modern Birds. (Eds.) G. Dyke and G. Kaiser. University of California Press.

3. Organ, C. L., M. Rasmussen, M. W. Baldwin, M. Kellis, and S. V. Edwards (in press). A phylogenomic approach to the evolutionary dynamics of gene duplication in birds. In Evolution After Gene Duplication. Eds. K. Dittmar and D. Liberles. Wiley & Sons.

4. Organ, C. L., D. E. Janes, A. Meade, M. Pagel. (2009). Genotypic sex determination enabled adaptive radiations of extinct marine reptiles. Nature. 461: 389-392.

5. Organ, C. L., S. Brusatte, and K. Stein (2009). Sauropod dinosaurs evolved moderately sized genomes unrelated to body size. Proceedings of the Royal Society, B.

6. Schweitzer, M. H., W. Zheng, C. L. Organ, R. Avci, Z. Suo,  L. M. Freimark,  V. S. Lebleu, M. B. Duncan, M. G. Vander Heiden, J. M. Neveu, W. S. Lane, J. S. Cottrell, J. R. Horner, L. C. Cantley,  R. Kalluri, and J. M. Asara (2009). Biomolecular characterization and protein sequences of the Campanian hadrosaur B. canadensis. Science. 324: 626-361.

7. Organ, C. L. and A. M. Shedlock (2009). Paleogenomics of pterosaurs and the evolution of small genome size in flying vertebrates. Biology Letters. 5: 47–50.

8. Organ, C. L., R. Godinez Moreno, and S. V. Edwards (2008). Three tiers of genome evolution in reptiles. Integrative and Comparative Biology. 48(4): 494-504.

9. Organ, C. L. and D. Janes (2008). Sex chromosome evolution in reptiles. Integrative and Comparative Biology. 48(4): 512-519.

10. Janes, D. E., C. L. Organ and N. Valenzuela (2008). New resources inform study of genome size, content and organization in non-avian reptiles. Integrative and Comparative Biology. 48(4): 447-453.

11. Organ, C. L., M. H. Schweitzer, W. Zheng, L. M. Freimark, L. C. Cantley, J. M. Asara. (2008). Molecular phylogenetics of mastodon and Tyrannosaurus rex. Science. 320 (5875): 499.

12. Organ, C. L. (2008). Paleogenomics. Pp. 249-251. In McGraw Hill 2008 Yearbook of Science & Technology. McGraw-Hill Publishers, New York, NY.

13. Organ, C. L., A. M. Shedlock, A. Meade, M. Pagel, S. V. Edwards. (2007). Origin of avian genome size and structure in nonavian dinosaurs. Nature. 446: 180-184.

14. Holmes, R. and C. L. Organ. (2007). An ossified tendon trellis in Chasmosaurus (Ornithischia: Ceratopsidae). Journal of Paleontology. 81(2): 411–414.

15. Organ, C. L. (2006). Biomechanics of ossified tendons in ornithopod dinosaurs. Paleobiology. 32 (4): 652-665.

16. Organ, C. L. (2006). Thoracic epaxial muscles in living archosaurs and ornithopod dinosaurs. The Anatomical
    Record Part A: Discoveries in Molecular, Cellular, and Evolutionary Biology. 288A: 782-793.

17. Organ, C. L. and J. Adams. (2005). The histology of ossified tendon in dinosaurs. Journal of Vertebrate Paleontology. 25 (3): 602-613.

18. Adams, J. and C. L. Organ. (2005). Histologic determination of ontogenetic patterns and processes in hadrosaurian ossified tendons. Journal of Vertebrate Paleontology. 25 (3): 614-622.

19. Organ, C. L., J. B. Cooley, and T. L. Hieronymus. (2003). A non-invasive quarry mapping system. Palaios. 18(1): 74-77.

Published Abstracts and Presentations (last few years only)

1. Organ, C. L., D. E. Janes, A. Meade, M. Pagel. (2009). Genotypic sex determination enabled adaptive radiations of extinct marine reptiles. Evolution Meeting (SSE).

2. Organ, C. L. (2008). Phylogenetics and reconstructing ancient biomolecular characters. Molecular Paleontology Working Group, North Carolina State University, Raleigh.

3. Organ, C. L., M. Andrew, and M. Pagel (2009). Bayesian inference of discrete character states. SICB 2009 Annual Meeting. Boston, MA.

4. Schweitzer, M. H., W. Zheng, T. Cleland, R. Kalluri, J. M. Asara,  C. L. Organ, and J. R. Horner (2008). Exceptional preservation in Brachylophosaurus Canadensis (Campanian, Judith River Formation, Montana, USA). Journal of Vertebrate Paleontology.

5. Organ, C. L., R. G. Moreno and S. V. Edwards (2008). Genome Architecture & Diversity in Reptiles. SICB 2008 Annual Meeting. San Antonio, Texas.

Grants and Fellowships

1. NSF, Science and Technology Centers: Center for Analytical Paleontology – Investigator (in review; proposed $150,000)

2. Harvard Postdoctoral Travel Grant Program (2009; $1000)

3. Society for Integrative and Comparative Biology Symposium Grant, Reptile Genomics and Evolutionary Genetics Symposium (2008), San Antonio, TX ($5,000).

4. OEB Departmental Travel Grant (2007; $1,500)

5. National Science Foundation: Symposium - Reptile Genomics and Evolutionary Genetics (2007; $6,749) 

6. NIH NSRF Postdoctoral Fellowship (2005-2008): Evolution of Bmp Genes 2 and 4 in Archosaurs ($142,200)

7. International Society of Biomechanics Dissertation Grant (2001): The Evolution of Tail Deflection and Erect
   Posture Synapsida and Diapsida ($4,000)