Juan Carlos Villarreal

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Doctoral Student
Office: BioPharm 312
Voice: (860) 486-6306
Fax: (860) 486-6364
E-mail: juan.villarreal@uconn.edu, jcarlos.villarreal@gmail.com
Mailing address:
75 N. Eagleville Road, U-3043
Storrs, CT 06269

Jc fuego.jpg
Nothoceros aenigmaticus, collected in North Carolina. Note the elongated eggs inside of the thallus, probably from a damselfly (K. Tennessen, pers. com.). More studies are needed to verify the identity of the insect. See Chinquapin. 2009. 17 (1).


I am interested in the diversification and biogeographical distribution patterns of hornworts especially the Nothoceros alliance (including the Megaceros from the American Continent). My dissertation research is focusing on the major evolutionary events leading to the lack of sexual reproduction in the Southern Appalachian (SA) endemic and asexual hornwort Nothoceros aenigmaticus . The species is the only member of the genus in North America and there are no reported observations of sporophyte production. In the SA region male and female plants live ~ 30 miles apart and male plants produce depauperate antheridia (for unknown reasons sperm cells are unable to develop functional flagella). The proposed research has three main objectives:

1) Reconstruct the phylogenetic origin and timeframe of the loss of sexuality in N. aenigmaticus. 2) Assess the population genetic structure of clonal populations of N. aenigmaticus using microsatellites. 3) Estimate the molecular signature in the transition to asexuality using nuclear coding regions. 4) Transcriptomic and genomic data of N. aenigmaticus.

The first aspect of my research is unraveling the phylogenetic origin of N. aenigmaticus and its closest Neotropical relative using a multi-locus approach. I am also testing for any cryptic sexual recombination using microsatellites and exploring the genetic consequences of the lack of sex in the population dynamics of the SA populations. In addition I will be comparing patterns of genotypic diversity between SA populations and putative conspecific and sexually reproducing populations from tropical alpine regions. Given the potential extinction threat due to the Muller's ratchet effect (accumulation of deleterious mutations), this study will have conservation and evolutionary implications. The haploid nature of Nothoceros aenigmaticus makes the hornwort more vulnerable to deleterious mutations since no other allele is present in the gametophyte. (more details soon).

Using next generation technology (454 Roche) I will be exploring genomic and transcriptomic data from the gametophyte of this species (more details soon).

Lagunas de Zempoala, Morelos, Mexico. A Pleistocene sleeping volcano


This research has beeen funded by the the National Science Foundation (DDIG) [1]; Ronald Bamford Fund, EEB Department, UCONN; International Association of Bryologists; International Association of Plant Taxonomists; Aaron J. Sharp Fund (University of Tennessee); Southern Appalachian Botanical Society.


Systematics, anatomy, ultrastructure, molecular evolution and biogeography of hornworts (Anthocerotophyta), especially American taxa. Dating, population genetics, genomic evolution and genetic implications of the loss of sex in bryophytes.

Other interests are the evolution of carbon concentration mechanisms in the hornwort chloroplast, especially the ultrastructural and physiological implications of the presence of an algal-like pyrenoid. Chloroplast genomes in bryophytes and effect of level of RNA editing in hornworts. An increasing interest is the evolution of transcriptomes in hornworts.

Páramo near Cerro Chirripó, Costa Rica. Photo courtesy of Dr. N. Wickett


University of Connecticut, Ecology and Evolutionary Biology, USA. Spring 2006- Doctorate degree

Workshop on Molecular Evolution, Woods Hole, MA. July-August 2009 - http://workshop.molecularevolution.org/mbl/

Southern Illinois University, Department of Plant Biology, Carbondale, USA. Fall 2003- Dec. 2005- Master’s degree: Ultrastructure and evolution of hornworts with emphasis on symbiotic interactions with cyanobacteria and character evolution.

Universidad de Costa Rica & Organization for Tropical Studies (OTS), Costa Rica. Jan.-Feb. Graduate course in Tropical Ecology and Conservation

University of Panamá, Bachelor’s degree in Plant Biology with Major in Bryology. Humboldt Field Research Institute & University of Maine, USA. June 2001 Field undergraduate course on biosystematics of temperate bryophytes

PAPERS AND BOOK CHAPTERS (all peer-reviewed)

Collage of hornwort morphological diversity. Legends for this plate in Villarreal et al. (2010), the paper is free access

14. Villarreal, J.C.; L.V. Campos and B. Goffinet. (In press). Parallel evolutions of endospory in hornworts: the case of Nothoceros renzagliensis, sp. nov. Systematic Botany.

13. Garcia, C., C. Sergio, J.C. Villarreal and F. Lara (In press). The genera Dendroceros Nees and Megaceros Campb. in São Tomé e Príncipe (Africa, Gulf of Guinea) and description of a new species, Dendroceros paivae . Cryptogamie, Bryologie et Lichenologie.

12. Sérusiaux, E., J.C. Villarreal A., T. Wheeler & B. Goffinet. (Accepted) Recent origin, active speciation and dispersal for the lichen genus Nephroma (Peltigerales) in Macaronesia. Journal of Biogeography

11. Villarreal, J.C.; B. Goffinet; R.J. Duff & D.C. Cargill &. 2010. Phaeomegaceros squamuliger subspecies hasselii (Dendrocerotaceae, Anthocerotophyta), a new taxon from the Southern Hemisphere. Nova Hedwigia 91 (3–4):000–000.

10. Villarreal, J.C., D.C. Cargill, L. Söderström, A. Hagborg & K.S. Renzaglia. 2010. Synthesis of hornwort biodiversity: Patterns, causes and future work. Phytotaxa 9:150-166. [2]

9. Villarreal, JC., B. Goffinet et al. 2010. Phylogenetic delineation of the genera Nothoceros and Megaceros (Dendrocerotaceae). The Bryologist 113 (1): 106-113.

8. Renzaglia, K.S., J.C. Villarreal & R.J. Duff. 2009 . New insights into morphology, anatomy and systematics of hornworts. In Bryophyte Biology II, B. Goffinet & J. Shaw (eds). (Book chapter) [3]

7. Villarreal, J.C., G. Hässel de Menéndez & N. Salazar Allen. 2007 Nothoceros superbus (Dendrocerotaceae), a new species of hornwort from the Neotropics. The Bryologist 110: 279-285. [4]

6. Duff, R.J., J.C. Villarreal, D.C. Cargill & K.S. Renzaglia. 2007. Progress and challenges toward developing a phylogeny and classification of the hornworts. The Bryologist, 110: 214-243.

5. Villarreal, J.C. & K.S. Renzaglia. 2006. Structure and development of Nostoc strands in Leiosporoceros dussii (Anthocerotophyta): a novel symbiosis in land plants. American Journal of Botany 93(5): 693-705. (Link to Cover [5]

4. Villarreal, J.C. & K.S. Renzaglia. 2006. Sporophyte structure in the neotropical hornwort Phaeomegaceros fimbriatus: implications for phylogeny, taxonomy and character evolution. International Journal of Plant Sciences 167: 413-427.

3. Dauphin, G.; T. Pócs; J. C. Villarreal & N. Salazar Allen. 2006. Nuevos Registros de Hepáticas y Anthocerotófitas para Panamá. Tropical Bryology 27: 73-85.

2. Cargill, D.C.; R.J. Duff, J.C. Villarreal & K.S. Renzaglia. 2005. Generic concepts in hornworts: historical review, contemporary insights and future directions. Australian Systematic Botany 18: 7-16.

1. Duff, R.J.; D.C. Cargill, J.C. Villarreal & K.S. Renzaglia. 2004. Phylogenetic relationships of the hornworts based on rbcL sequence data: novel relationships and new insights. Monographs in Systematic Botany from the Missouri Botanical Garden 98: 41-58. (Book chapter)


J.C. Villarreal; W. Frey & D.C. Cargill. 2010. Bryophyte Biology, Phylogeography and Evolution in the Southern Hemisphere: In honour of Gabriela Hassel de Menendez. Nova Hedwigia 91(3-4): 1–250 pp. (A list of contributed and peer-reviewed papers on biogeography, niche modeling, cryo-microscopy, floristics and evolution of Southern Hemisphere bryophytes). [6]


- Villarreal, J.C. 2010. Before the Vascular plants. Book review of “Syllabus of Plant Families A. Engler’s Syllabus der Pflanzenfamilien. 3. Bryophytes and seedless vascular plants. 2009. Eds: Wolfgang Frey, Michael Stech & Eberhard Fischer. The Bryologist 113: 431–434.

- Villarreal, JC. 2009. Evolutionary implications of the lack of sexual reproduction in the Southern Appalachian endemic hornwort Megaceros aenigmaticus. Chinquapin 17 (1): 1. (A bulletin of the Southern Appalachian Botanical Society).


- A.J. Sharp Award (American Bryological and Lichenological Society) Best student paper at the annual meeting of the American Bryological and Lichenological Society, Providence, RI. $500.

- Sullivant Award from the American Bryological and Lichenological Society for the best paper published in the Bryologist during the year 2007 for the paper " Progress and challenges toward developing a phylogeny and classification of the hornworts" . The Bryologist, 110: 214-243 by Duff, R.J., J.C. Villarreal, D.C. Cargill & K.S. Renzaglia.

- Michael J. Hogan (Current UCONN President) Summer Research Award-2009 (A nomination-based award given to 5 out of over 60 graduate nominees across UCONN). $5000

- Doctoral Dissertation Fellowship-UCONN- 2009.$2000

TEACHING EXPERIENCE (Teaching assistant for the following courses, mostly at UCONN otherwise specified)

- Evolution of Green plants (graduate and upper undergrad level class)

- Bryophyte and lichen biology (graduate and upper undergrad level class)

- Introduction to Botany

- Introduction to Biology

- Neotropical Environments (with McGill University, Panama Field Semester)


Panama, Costa Rica, Venezuela (Merida), Dominican Republic, Southern Appalachians, Mexico, Colombia (Pasto, Nariño)

Pasto, Nariño, Colombia, 2009. Photo courtesy of Prof. Laura Victoria Campos
Looking for hornworts in the Smoky Mountains, Southern Appalachians. Photo courtesy of Dr. K. McFarland


Journal of Experimental Botany; The Bryologist; Cryptogamie, Bryologie-Lichénologie, Fieldiana, Cambridge University Press; Nova Hedwigia; Tropical Bryology, Phytotaxa, Arctoa


Early Land Plants Today/Encyclopedia of Life (World Meeting of Liverwort-Hornwort Taxonomy), The Field Museum, Chicago (2009);Congreso Colombiano de Botánica, Nariño, Colombia (2009); Department of Botany, The Field Museum, Chicago (2008); Department of Biology, University of New Mexico (2007); Congreso Latinoamericano de Botánica, Dominican Republic (2006); Department of Biology, University of Panamá (2006); World Congress of Bryology, Venezuela (2004).