Alejandra Vasco

Postdoctoral Research Associate, Genomics Program and Institute of Systematic Botany, The New York Botanical Garden

Ph.D., City University of New York (2010)
"Systematics of Elaphoglossum section Lepidoglossa"
Expertise: Neotropical Pteridophytes

Profile

My main research interests are the diversity and evolution of ferns and lycophytes. I work primarily in the systematics of the tropical fern genus Elaphoglossum and in leaf development and evolution of ferns. I use molecular, anatomical and morphological data, both to understand the evolutionary relationships of ferns, and the molecular genetic basis of fern leaf development. My work includes fieldwork and herbarium work, as well as investigations of the development of morphology using scanning electron microscopy and histological sections, and investigations of gene function in development.

Fern leaf development and Evolution

The evolution and development of leaves in land plants has been a major question in systematic botany, one that has engendered debate among botanists for decades. Questions about the origin of microphylls and megaphylls, and the homology of all megaphylls, remain unanswered. These questions are beginning to be assessed by molecular genetic studies that have elucidated aspects of leaf development in flowering plants and lycophytes. Comparable studies, however, are largely lacking for ferns, yet ferns occupy a key phylogenetic position in the land plants. Thus the data generated for ferns will be important for understanding larger questions of how leaves evolved.

To address this gap in our understanding of ferns, we are carrying out a synergistic project that combines a taxonomic revision and phylogenetic analysis of Elaphoglossum section Squamipedia and an evolutionary developmental study of its leaf diversity. This section is remarkable for having 3 species with dissected leaves in an otherwise simple-leaved genus. Our phylogenetic analyses show that the 3 species with dissected leaves are not monophyletic, thus the presence of 3 independent reversions to dissected leaves, presents an ideal situation for addressing questions about homology and convergence within a phylogenetic framework. The comparative molecular genetic data we are generating is allowing us to test two hypotheses about ferns: first, that leaf developmental genes are conserved among ferns, lycophytes, and angiosperms; second, that differences in the temporal and spatial pattern of expression of leaf development genes correlate with different fern leaf morphologies.

Systematics of Elaphoglossum

Elaphoglossum is one of the most species-rich genera of ferns with ca. 600 species. At the taxonomic level it poses some interesting challenges because its species are similar and the characters that distinguish them are typically few and subtle. This morphological similarity has made the recognition of natural groups difficult. As a consequence, taxonomic revision within the genus has been hindered.

The main goals of my systematic work are (1) to explore the evolutionary relationships within Elaphoglossum main clades, using molecular systematics and morphology; and (2) to identify smaller and morphologically well circumscribed monophyletic groups within the genus to facilitate their taxonomic revision.

For my PhD I worked in Elaphoglossum section Lepidoglossa. I generated a molecular phylogenetic hypothesis of the relationships of the species in the section and wrote two taxonomic revisions of monophyletic groups recovered in the phylogeny: The Elaphoglossum ciliatum group and the Elaphoglossum subsection muscosa group. As a result of this monographic work three species new science were described.

Currently I am working on a taxonomic revision and phylogenetic analysis of Elaphoglossum section Squamipedia. This study is intended to provide a framework for my postdoctoral project on the molecular genetics of fern leaf development in Elaphoglossum sect. Squamipedia.

Webpage

Complementing my systematics and evolutionary developmental work, I am developing, along with some collaborators at The New York Botanical Garden, the Elaphoglossum pages (http://sweetgum.nybg.org/elaphoglossum/index.php). This is a long-term project in which we hope to generate an electronic monograph of the whole genus. Currently we are making available through the site all the information compiled in our published and ongoing taxonomic revisions, as well as images of Elaphoglossum with the hope that this will facilitate collaboration and stimulate research.

 

Selected Publications

Vasco, A. 2011. Taxonomic revision of Elaphoglossum subsection Muscosa (Dryopteridaceae). Blumea 56: 165-202

Sundue, M., Vasco, A., Moran, RC. 2011. Cryptochlorophyllous spores in ferns: Nongreen spores that contain chlorophyll. International Journal of Plant Sciences 172 (9): 1110-1119

Vasco, A., Moran, R.C., Rouhan, G. 2009. Monograph of the Elaphoglossum ciliatum group (Dryopteridaceae). Brittonia 61 (3):241-272.

Vasco, A., Moran, R.C., Rouhan, G. 2009. Circumscription and phylogeny of the Elaphoglossum ciliatum group (E. sect. Lepidoglossa, Dryopteridaceae) based on cpDNA sequences. Taxon 58 (3): 825-834.

Vasco, A. 2006. Elaphoglossum gemmatum (Elaphoglossaceae), a new proliferous species from Colombia. Brittonia 58: 1-3.


Benavides, A., Duque, A., Duivenvoorden, J., Vasco, A. & Callejas, R. 2005. A first quantitative census of vascular epiphytes in rain forests of Colombian Amazonia. Biodiversity and Conservation 14: 739-758