Chris Organ

Ph.D. Montana State 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

corgan (at) oeb.harvard.edu

Download a PDF version of my CV.

Research Interests:

As an evolutionary and organismal biologist, my research is interdisciplinary and addresses questions that span several levels of organization, from genomics and developmental genes to morphology andpaleobiology. My research is rooted in comparative methods and evaluates hypotheses with bioinformatic, anatomical, histological, and genomic data. My recent work falls into the following categories:

Karyotypic evolution in reptiles

Comparative Genomics: How has evolution shaped reptile and bird genes and what does this tell us about amniote genomes and development 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 into the genomics of birds and reptiles is aimed at helping to fill this gap. I am researching the evolution of genome size and karyotype in reptiles, in addition to specific genes.  For example, I am investigating bone morphogenetic proteins (BMPs), which are conserved in vertebrates and act as regulators of bone formation, maintenance, and repair. Because BMPs directly influence bone development, which is the primary component of vertebrate fossils, they have been a critical linchpin integrating paleontology, development, and genetics to address various evodevo questions, including digit identity in birds and feather evolution. My research suggests that the second exon in bmp2 has undergone positive selection during the evolution of Aves from other reptiles, coincident with the trend of skeletal co-ossification on the line to birds.

Relationship between bone cell size and genome size

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 the scope of biological phenomena. Recovering some part of that biological information is vital for understanding biology broadly and deeply. Moreover, the evolution of genome architecture in vertebrates, or any other lineage, is difficult to study because genomic information is often absent for long extinct relatives. I use an approach that combines genomics and paleohistology with bayesian comparative statistics 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, long before this lineage gave rise to the first birds. Yet, a subsequent analysis I performed on pterosaurs suggests that there may be a preadaptive relationship between the evolution of genome architecture and the physiology needed for volant flight in vertebrates. Moreover, because active and extinct interspersed mobile genetic elements are the primary determinant of genome size in animals, we were able translate raw genome size into estimates of mobile element abundance for extinct animals.

My research has been featured in many popular outlets, including the New York Times, Science Magazine, Heredity, the Boston Globe, Science News, Cosmos Magazine, Discover Magazine, Science and Vie, Arstechnica.com, ScienceDaily.com, NBC, ABC, the Discovery Channel, the BBC, and dozens of U.S. and international newspapers.

Paleobiology & Organismal Biology: How do organismal innovations arise and evolve within animals? The biology and evolution of birds, and their utility as a comparative model with mammals to understand the evolution of biologic innovations, must be considered within the light of dinosaur biology. I am therefore interested in elucidating dinosaur biology and evolution using various approaches. For instance, using comparative morphology, I studied the enigmatic three-layered trellis of ossified tendons in duck-billed dinosaurs, homologizing them to spinal muscles in crocodilians and birds, many of which also experience intratendinous ossification. Using comparative osteohistology I also determined that intratendinous ossification began developmentally much earlier in ornithischian dinosaurs than in birds. Functionally, ossified tendons have always been a mystery. My biomechanical research suggests that ossified tendons passively supported the spines of ornithischian dinosaurs, aiding in holding their tails off the ground and possibly returning elastic energy during locomotion.

Recent Publications

1. Organ, C. L. and A. M. Shedlock (in submission). Evolution of genome contraction in bats, birds, and pterosaurs.

2. Janes, D. E., C. L. Organ and N. Valenzuela (in press).  New resources inform study of genome size, content and organization in non-avian reptiles. Integrative and Comparative Biology.

3. Organ, C. L., R. Godinez Moreno, and S. V. Edwards (in press). Three tiers of genome evolution in reptiles. Integrative and Comparative Biology.

4. Organ, C. L. and D. Janes (in press). Sex chromosome evolution in reptiles. Integrative and Comparative Biology.

5. 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.

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

7. 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.

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

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

10. 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. [pdf]

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

12. 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. [pdf]

13. 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 2 years only)

1. Organ, C. L. and S. V. Edwards. (2006). Paleogenomics of pterosaurs and the evolution of vertebrate flight. Journal of Vertebrate Paleontology. 26(Supplement to 3): 107A.

2. Organ, C. L., M. Pagel, and S. V. Edwards. (2006). Dinogenomics: The genomes of dinosaurs and the origin of avian genome architecture. Evolution Meeting (SSE).

3. Organ, C. L. and S. V. Edwards. (2006). Paleogenomics—The dinosaurian origins of avian genome structure. Workshop on Chicken Genomics & Development. Cold Spring Harbor Laboratory.

Grants and Fellowships

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

2. National Science Foundation: Symposium - Reptile Genomics and Evolutionary Genetics ($6,749) Co-author: Nicole Valenzuela and Dan Janes

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

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

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