DOWNIE, STEPHEN R. Department of Plant Biology, University of Illinois, Urbana, IL 61801. - Tribes and clades within Apiaceae subfamily Apioideae: the contribution of molecular data.
This paper synthesizes the results of some 25 molecular systematic
investigations carried out by numerous researchers over the past six
years as they pertain to elucidating the higher level relationships
within Apiaceae (Umbelliferae) subfamily Apioideae. Here a variety of
molecular characters has been considered, including the comparative
sequencing of chloroplast genes (rbcL and matK) and
introns (rpl16, rpoC1, and rps16) and the nuclear
ribosomal DNA ITS region. Restriction site mapping of the chloroplast
genome has also been performed, with these data revealing
unprecedented variation in size and position of the inverted repeat.
On the basis of these phylogenetic studies and consistent with all
available molecular evidence, ten major lineages within the subfamily
are erected or confirmed as monophyletic. These are referred to as
tribes Aciphylleae, Bupleureae, Careae, Echinophoreae, Heteromorpheae,
Oenantheae, Pleurospermeae, Pyramidoptereae, Scandiceae, and
Smyrnieae. Tribe Scandiceae includes subtribes Daucinae, Scandicinae,
and Torilidinae. Caucalideae sensu Heywood is not monophyletic,
containing elements of subtribes Daucinae and Torilidinae. Seven
additional groups, such as the Angelica, Apium, Arracacia,
Heracleum, and Pimpinella clades, and the apioid
superclade, are also recognized but have yet to be treated formally.
Relationships among the major clades comprising the apioid superclade
are equivocal; moreover, within this superclade several genera are of
uncertain phylogenetic placement. Tribe Heteromorpheae is sister to
all other apioid taxa investigated, with Bupleureae, Pleurospermeae,
the Komarovia clade, and Oenantheae comprising successively
more distantly branching lineages. Apioideae, upon the inclusion of
the saniculoid genus Lagoecia and the exclusion of the
subsaharan African endemic genera Polemanniopsis and
Steganotaenia, are monophyletic and sister to subfamily
Saniculoideae. Subfamily Hydrocotyloideae, however, are polyphyletic,
with the Azorella clade (Azorella, Bolax, and
Eremocharis, and possibly Bowlesia and
Klotzschia) sister to Apioideae plus Saniculoideae. These
molecular data provide the framework from which future revisionary and
evolutionary studies within subfamily Apioideae can proceed.
Key words: Apiaceae subfamily Apioideae, chloroplast introns, molecular systematics, phylogeny, Umbelliferae