LEVIN, RACHEL A.1,2* and LUCINDA A. MCDADE3. 1Department of Ecology & Evolutionary Biology, University of Arizona, Tucson, AZ 85721; 2Laboratory of Molecular Systematics, Smithsonian, 4210 Silver Hill Rd.,Suitland, MD 20746; 3Academy of Natural Sciences, 1900 Ben Franklin Parkway, Philadelphia, PA 19103. - The utility of floral and vegetative fragrance for phylogenetic inference in three genera of Nyctaginaceae.
The use of chemical information in phylogenetic studies is an
under-used resource for studying evolutionary relationships. The
absence of chemical data in phylogenetic inference is likely due in
part to difficulties associated with coding chemical data as
characters. Using floral and vegetative fragrance data from twenty
species in three southwestern genera of Nyctaginaceae, we have
explored several methods for handling fragrance data. Chemical data
collected from several individuals within species were summarized to
yield a single value per species and optimized onto a phylogeny
inferred independently using molecular sequence data. Fragrance data
were also coded in a variety of ways including (a) presence/absence of
each compound, (b) presence/absence characters according to the
biosynthetic pathway by which each compound was synthesized, and (c)
multistate characters coded according to amount of floral compounds
from each biosynthetic pathway. Phylogenies were inferred using these
data sets, and the resultant topologies were compared to the molecular
phylogeny. In addition to using fragrance data in phylogeny
reconstruction, we also experimented with optimizing these fragrance
data sets onto the molecular phylogeny. It appears that there is no
one clear approach to handling fragrance data that retains the most
phylogenetic information. Rather, the "best" coding method
may differ among characters; treating biosynthetic pathways as
characters may sometimes be most phylogenetically informative, whereas
for other fragrance components coding specific compounds as characters
might be most appropriate. Further, despite much homoplasy, results
suggest that fragrance data do contain phylogenetic information.
Key words: Acleisanthes, Mirabilis, Nyctaginaceae, phylogenetics, scent, Selinocarpus