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artículos
Título:
PHYLOGENETIC IMPLICATIONS OF COROLLA MORPHOLOGY IN SUBFAMILY BARNADESIOIDEAE (ASTERACEAE)
Autor/es:
T. F. STUESSY; E. URTUBEY
Revista:
FLORA
Editorial:
Elsevier
Referencias:
Lugar: -; Año: 2006 vol. 201 p. 340 - 352
ISSN:
0367-2530
Resumen:
Phylogenetic implications of corolla morphology in subfamily Barnadesioideae
(Asteraceae)
Dedicated to Prof. Dr. Stefan Vogel on the occasion of his 80th birthday.
Tod F. Stuessya, and Estrella Urtubeyb
aDepartment of Higher Plant Systematics
and Evolution, Institute of Botany, University of Vienna, Rennweg 14, A-1030
Vienna, AustriabDivisión Plantas Vasculares,
Museo de La Plata, Universidad Nacional de La Plata, Paseo del Bosque s.n., La
Plata, Argentina Received 8 March 2005; accepted 25 July 2005. Available
online 22 June 2006.
Abstract
The previously insignificant and small South American subtribe Barnadesiinae
of tribe Mutisieae has been shown recently to be ancient within Asteraceae. Due
to absence of a 22 kb diagnostic chloroplast inversion, plus other features,
this subtribe has been elevated to subfamilial status as Barnadesioideae, now
containing 90 species in nine genera. Recent cladistic analyses at the generic
and specific levels based on morphology and DNA sequences (ITS and trnL
intron) have revealed different relationships among taxa of the subfamily. To
better understand these conflicts, we analyze specific morphological features of
corollas (shape and vascularization) to develop trends (trees) in these features
based on minimal structural change (i.e., morphological parsimony), and to
compare these with relationships among genera derived from the two recent
cladistic analyses. We define six principal types of corollas in Barnadesioideae
(tubular, split, double split, ligulate, subbilabiate and bilabiate) and six
principal types of corolla vascularization patterns (combinations of presence or
absence of central bundles, fusion of adjacent bundles and fusion of bundles at
the apex of corolla lobes). In all features we assume character states in
Calyceraceae to be ancestral. In corolla shape, from tubular ancestry, we
hypothesize two general evolutionary trends within the subfamily: (1) splitting
of the tube, and (2) flattening of the tube. In vascularization of corollas,
from an ancestral condition of one central and one lateral bundle in each
corolla lobe and all traces fused at the apex, we hypothesize four basic trends:
(1) gain or (2) loss of lateral vascular traces in each lobe, (3) loss of the
central vein, and (4) loss of fusion of traces in lobe apices. These
morphological trends allow tests of the two previous phylogenetic hypotheses by
(1) counting step changes (following steps in the morphological network) in the
two characters on the two competing phylogenetic trees and (2) constructing an
index of morphological advancement for each genus (based on morphological trees
of the two characters) and correlating these with cladistic distances within the
two phylogenies. Results of both tests reveal the molecular phylogeny to be more
compatible with evolutionary inferences from the two morphological features.
With Fulcaldea excluded, a highly significant correlation is seen between
morphological advancement and cladistic distance in the molecular phylogeny.
Keywords: Asteraceae; Barnadesioideae