David Hearn | Towson University


My research focuses on understanding the evolutionary, developmental, and ecological
processes responsible for land plant diversity. The analysis of character evolution
using tools from molecular phylogenetics and molecular genetics forms the core of
this research. In particular, fascination with plant form, plant morphogenesis, and
plant development fuel these interests. Currently, I am examining the evolutionary
and developmental mechanisms responsible for water storage tissue in stems and roots
(i.e., plant succulence). Stem succulence provides a classic example of convergent
evolution, as over thirty lineages have evolved stem succulence. I predicted that
shared (homologous) developmental modules are switched on and off during evolution
to account for multiple origins of succulent growth habits. My lab is undertaking
phylogenetic, bioinformatic, anatomical, and molecular genetic analyses in Brassica,
Arabidopsis, Vitaceae, and Passifloraceae to understand what aspects of succulence
evolution and development are shared and which aspects differ among distantly related
lineages. Such an understanding will contribute to a richer picture of mechanisms
of anatomical patterning, and, in the process, gene regulatory mechanisms may be discovered
that can generate storage-rooted and succulent-stemmed crops. Additional projects
include the analysis of biological shape, biodiversity informatics, and computational
approaches to characterize plants in an automated fashion. At its most general, my
lab focuses on the patterns and processes of biological pattern formation and employs
computational/bioinformatic, mathematical, field and lab experimental approaches.

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Recent Publications

Allen, R. J.*, Brenner, E. P. *, VanOrsdel, C. E. *, Hobson, J. J. *, Hearn, D. J.+, and M. R. Hemm+. 2014. Conservation analysis of the CydX protein yields insights into small protein
identification and evolution. BMC Genomics 15: 946 doi:10.1186/1471-2164-15-946. +=joint anchor authors.

Evans, M.+, Aubriot, X.+, Hearn, D. J., Lanciaux, M., Lavergne, S., Cruaud, C., Lowry, P. P. 2nd, and T. Haevermans.
2014. Insights on the evolution of plant succulence from a remarkable radiation in
Madagascar (Euphorbia). Systematic Biology 63: 697-711. Cover photo. +=Joint first author.

 Estes, A. M., Hearn, D. J., Snell-Rood, E. C., Feindler, M., Feeser, K.*, Abebe, T.*,
Dunning Hotopp, J. C., and A. P. Moczek. 2013. Vertical transmission of a unique gut
microbiome in the dung beetle Onthophagus taurus (Coleoptera: Scarabaeidae). PLoS ONE: DOI: 10.1371/journal.pone.0079061.

Hearn, D. J., Poulsen, T.*, and R. Spicer. 2013. The evolution of growth forms with
expanded root and shoot parenchymatous storage is correlated across the eudicots.
International Journal of Plant Sciences 174: 1049-1061.

Hearn, D. J. 2013. Dissection of evolutionary networks to assess their role in the
evolution of robustness, function, and diversification. Evolution 67: 2273-2283.

Pignal, M., Yockteng, R., Hearn, D., and J.-N. Labat. 2013. Adenia barthelatii (Passifloraceae), a new endemic species of Mayotte and its phylogenetic status within
the genus Adenia. Phytotaxa 99: DOI: http://dx.doi.org/10.11646/phytotaxa.99.1.3.

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Estes, A. M., Hearn, D. J., Burrack, H. J., Rempoulakis, P., and E. A. Pierson. 2012.
Prevalence of ‘Candidatus Erwinia dacicola’ in wild and laboratory olive fly populations and across developmental stages. Environmental Entomology 41: 265-274.

Evans, M. E., Hearn, D. J., K., Theiss, Cranston, K., Holsinger, K., and M. Donoghue.
2011. Extreme environments select for reproductive assurance: evidence from evening
primroses (Oenothera). New Phytologist 191: 555-563.

Wang, D., Zhang, C., Hearn, D. J., Kang, I.-H., Punwani, J. A., Skaggs, M. I., Drews,
G. N., Schumaker, K. S., and R. Yadegari. 2010. Identification of transcription-factor
genes expressed in the Arabidopsis female gametophyte. BMC Plant Biology 10: 110. doi:10.1186/1471-2229-10-110

Estes, A. M., Hearn, D. J., Bronstein, J., and E. Pierson. 2009. The olive fly endosymbiont,
Candidatus Erwinia dacicola”, switches from an intracellular to an extracellular existence during
host insect development. Applied Environmental Microbiology 75: 7097-7106.

Hearn, D. J. 2009. Developmental patterns in anatomy are shared among separate evolutionary
origins of stem succulent and storage root-bearing growth habits in Adenia (Passifloraceae). American Journal of Botany 51: 209-215.

Pryer, K. M., and D. J. Hearn. 2009. Evolution of leaf form in marsileaceous ferns:
evidence for heterochrony. Evolution 63: 498-513.

Hearn, D. J. 2009. Shape analysis for the automated identification of plants from
images of leaves. Taxon 58: 934-954.

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Hearn, D. J. 2009. Descriptive anatomy and evolutionary patterns of anatomical diversification
in Adenia (Passifloraceae). Aliso 27: 13-38.

Courses Taught

  • Spring: BIOL 202  Intro to Ecology and Evolution

View more information: https://www.towson.edu/fcsm/departments/biology/facultystaff/dhearn.html

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