1. Phylogenetics and taxonomy
phylogeny of the sandalwood order (Santalales)
was published over 20 years ago (Nickrent and Franchina 1990) and
since those humble beginnings my lab and collaborators have generated
much information about the evolution of this fascinating order of
plants. Some of the questions that our group has addressed include 1)
how many times has parasitism evolved? 2) how many times has the
mistletoe habit evolved? 3) are the polymorphic families Santalaceae
and Olacaceae monophyletic? and 4) what are the relationships among the
genera in the large family Loranthaceae?
Every group traditionally recognized as a family has been examined
using molecular techniques. This work was possible only through
the collaborative efforts of these individuals: Olaceae (Dr.
Valéry Malécot), Loranthaceae (Drs. Romina Vidal-Russell
and Guillermo Amico), Misodendraceae (Dr. Vidal-Russell) and
Santalaceae (Drs. Joshua Der and Miguel A. García). The
Taxon publication (Nickrent et al. 2010) provided a complete synopsis
of current understanding of relationships in the order, and gave a
revised classification based mainly on the molecular evidence.
During the course of this work, three new genera were named (Hondurodendron, Pilgerina, and Staufferia).
The reclassification of the order based on the concept of
monophyly resulted in some new (or recycled) family names.
Olacaceae was split into Aptandraceae,
Coulaceae, Erythropalaceae, Octoknemaceae, Olacaceae s.
s., Schoepfiaceae, Strombosiaceae, and Ximeniaceae.
Santalaceae was split into Amphorogynaceae, Cervantesiaceae,
Comandraceae, Nanodeaceae, Santalaceae s. st., and
Thesiaceae. Three genera formerly classified in Santalaceae
were moved to Schoepfiaceae (Arjona,
Excluding Balanophoraceae, the order now consists of 18 families,
148 genera and nearly 2300 species. Our classification of
Olacaceae was adopted by the Angiosperm Phylogeny Group (APG III 2009)
but unfortunately they did not follow our recommendations for
"Santalaceae s. lat." and chose to lump Viscaceae into it. My viewpoint
on this was expressed in the Haustorium newsletter found on pp. 4-6 HERE.
Answers to some of the questions raised above can now be given. It
appears that parasitism evolved just once in the order, although more
recent multigene analyses draw this conclusion into question (stay
tuned!). It seems clear, however, that the mistletoe habit
evolved five times independently. "Santalaceae" and "Olacaceae", as
traditionally defined, were polyphyletic. In our new
classification all families are monophyletic. Thanks to the
efforts of Romina Vidal-Russell, we now have a phylogeny for
Loranthaceae. These results allowed us to proposed the first
infrafamilial classification of the family based on phylogenetic
evidence. Nuytsia is sister to all other genera in the family and
base chromosome number shows a progressive aneuploid reduction from
X=12 in basal genera to X=9 in more derived clades (e.g. the African
members). These data literally turned a previous biogeographic
concept on its head, highlighting dispersal, not vicariance, for the
origin of the African and Asian loranths.
In review. Nickrent,
Flora North America. Treatments of the order Santalales,
including the following families: Ximeniaceae,
Comandraceae, Thesiaceae, Cervantesiaceae, Santalaceae,
Viscaceae. Oxford University Press.
101. Nickrent, D. L.
V. Malécot, R. Vidal-Russell, and J. P. Der. 2010. A revised
classification of Santalales. Taxon 59: 538-558. For
a PDF file of this article
click HERE. Supplemental
data file on chromosome numbers HERE.
106. Nickrent, D. L.
2011. Santalales (Including Mistletoes). Encyclopedia of Life Science.
John Wiley & Sons, Ltd.: Chichester [DOI:
10.1002/9780470015902.a0003714.pub2]. Wiley website (search for
article) HERE. For
a PDF file of this article
C. U, D. L. Nickrent , C.
Whitefoord, and D. L. Kelly. Hondurodendron,
a new monotypic
genus of Aptandraceae from Honduras. Annals of the Missouri Botanical
Garden 97: 457-467.
a PDF file of this article
95. Vidal-Russell, R. and D.
2008. Evolutionary relationships in the showy mistletoe family
(Loranthaceae). American Journal of Botany 95: 1015-1029. For a PDF file of this article click HERE.
93. Rogers, Z. S.,
Nickrent, and V. Malécot. 2008. Staufferia and Pilgerina: two new arborescent
genera of Santalaceae from Madagascar. Annals of the Missouri Botanical
Garden 95: 391-404. For
file of this article click HERE.
92. Vidal-Russell, R. and D. L. Nickrent.
2008. The first mistletoes: origins of aerial parasitism in Santalales.
Molecular Phylogenetics and Evolution 47 (2): 523-537. For a PDF file of this article (constructed from original files,
not MPE pdf that is
restricted by Elsevier), click HERE.
J. P. and Nickrent, D. L. 2008.
A molecular phylogeny of Santalaceae (Santalales). Systematic Botany
33: 107-116. For
a PDF file
of this article, click HERE.
V. and Nickrent, D. L. 2008.
phylogenetic relationships of Olacaceae and related Santalales.
Systematic Botany 33: 97-106. For a PDF file of this article, click HERE.
75. Malécot, V., D. L. Nickrent, P. Baas, L.
van den Oever, D. Lobreau-Callen. 2004. Phylogeny of Olacaceae based on
a morphological cladistic analysis. Systematic Botany. 29:569-586. For a PDF file of this article, click HERE
60. Nickrent, D. L., and V. Malécot. 2001. A
molecular phylogeny of Santalales. Pages 69-74 in A. Fer, P. Thalouarn,
D. M. Joel, L. J. Musselman, C. Parker, and J. A. C. Verkleij, eds.
Proceedings of the 7th. International Parasitic Weed Symposium.
Faculté des Sciences, Université de Nantes, Nantes,
France. For a
PDF file of this
article, click HERE. An updated web version of this work
39. Nickrent, D. L. and R. J. Duff. 1996. Molecular studies of
parasitic plants using ribosomal RNA. Pp. 28-52. In: M. T. Moreno, J.
I. Cubero, D. Berner, D. Joel, L. J. Musselman, C. Parker (eds.),
Advances in Parasitic Plant Research, Junta de Andalucia, Dirección
General de Investigación Agraria, Cordoba, Spain. For PDF file of this
article, click HERE.
Nickrent, D. L. and C. R.
Franchina. 1990. Phylogenetic
relationships of the Santalales and relatives. Journal of Molecular
Evolution 31: 294-301. For
PDF file of the article, click HERE.