Revue internationale d'écologie méditerranéenne International ...
Revue internationale d'écologie méditerranéenne International ...
Revue internationale d'écologie méditerranéenne International ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Phylogenetic relationships and infrageneric classification of Astragalus tragacantha L. (Fabaceae), inferred from nuclear ribosomal<br />
DNA Internal transcribed spacers data (nrDNA ITS)<br />
nial herb widely spread in Eurasia, takes an<br />
obvious basal place, while Astragalus depressus,<br />
an astragal confined on mountains around<br />
Mediterranean Basin, is located between<br />
clade 2 and the base of the MP tree, supported<br />
by a poor bootstrap value.<br />
Homoplasy of thorny cushion-form<br />
in Mediterranean Astragals<br />
The NJ phylogeny positions the West Mediterranean<br />
Astragalus tragacantha in clade C<br />
(Figure 1), clearly separated from clade D<br />
which includes most of the thorny astragals<br />
(such as all sampled astragals of subgenus Tragacantha<br />
and some species of other subgenera).<br />
In fact, recently, morphological (Zarre &<br />
Podlech 1997) and then molecular analyses<br />
(Kazempour Osaloo et al. 2003) have allowed<br />
gathering many spiny astragals, previously<br />
separated in different subgenera. But the<br />
absence of A. tragacantha in clade D is an evidence<br />
of homoplasy for this character. The<br />
thorny cushion-forming is an adapted structure<br />
to aridity and strong winds of North-West<br />
Mediterranean coasts but also of Mediterranean<br />
mountains. This form exists in other<br />
astragals of the same section (Tragacantha DC<br />
of subgenus Cercidothrix Bunge) as A. genargenteus,<br />
A. gennarii, A. greuteri and A. sirinicus<br />
which are West Mediterranean orophytes<br />
and A. angustifolius, a South-East European<br />
orophyte (Baccheta & Brullo 2006), but none<br />
of these orophytes have been sequenced for<br />
nrDNA ITS. Their geographic proximity, their<br />
morphological similarities and their belonging<br />
to section Tragacantha are serious points<br />
underlining their probable close phylogenetic<br />
relationship with A. tragacantha. Knowing<br />
that South-Western and Sino-Himalayan<br />
regions of Asia are supposed to be the geographic<br />
origin of Astragalus genus, a scenario<br />
of differentiation from Eastern to Western<br />
Europe can be assumed (Nimis 1981).<br />
Based on these observations, no decisive conclusions<br />
can be proposed on Astragalus tragacantha<br />
history or homology with its closest<br />
relatives. In order to set robust hypothesis<br />
about evolution and history of Astragalus tragacantha,<br />
more taxa from clade C (Figure 1)<br />
must be sampled. Further steps of sampling<br />
should focus on other species of section Tragacantha<br />
as A. balearicus, A. genargenteus,<br />
A. sirinicus, A. gennarii, A. greuteri and A.<br />
angustifolius.<br />
ecologia mediterranea – Vol. 36 (1) – 2010<br />
Acknowledgments<br />
The authors thank Martin Wojciechowski for<br />
answering to our questions on a genus widely<br />
studied by his works, Pr Akhani to have provided<br />
us study elements about Astragalus, the<br />
Corsican Environment Office to have allowed<br />
us to sample in Corsica, and the Marseille<br />
municipality which grant funds to this study.<br />
Lastly, the authors would like to acknowledge<br />
the anonymous reviewer of this publication<br />
and Dr Ong’amo for helpful comments on the<br />
manuscript.<br />
References<br />
Bacchetta G. & Brullo S., 2006. Taxonomic revision of<br />
the Astragalus genargenteus complex (Fabaceae).<br />
Willdenowia, 36: 157-167.<br />
Barneby R., 1964. Atlas of North American Astragalus.<br />
Memoirs of The New York Botanical Garden, 13: 1-<br />
1188.<br />
Britton T., Anderson C.L., Jacquet D., Lundqvist S. &<br />
Bremer K., 2007. Estimating divergence times in<br />
large phylogenetic trees. Systematic Biology, 56:<br />
741-752.<br />
Bunge A., 1868. Generis Astragali species Gerontogeae.<br />
Pars prior. Claves diagnosticae. Mémoires de l’Académie<br />
Impériale des Sciences de St. Pétersbourg 11<br />
(16): 1-140.<br />
Davis P.H., 1970. Flora of Turkey and the East Aegean<br />
Islands. Vol. 3, University Press, Edinburgh, 628 p.<br />
Kazempour Osaloo S., Maassoumi A.A. & Murakami<br />
N., 2003. Molecular systematics of the genus Astragalus<br />
L. (Fabaceae): phylogenetic analyses of<br />
nuclear ribosomal DNA internal transcribed spacers<br />
and chloroplast gene ndhF sequences. Plant Systematics<br />
and Evolution 242: 1-32.<br />
Kazempour Osaloo S., Maassoumi A.A. & Murakami<br />
N., 2005. Molecular systematic of the Old World<br />
Astragalus (Fabaceae) as inferred from nrDNA ITS<br />
sequence data. Brittonia 57: 367-381.<br />
Kimura M., 1980. A simple method for estimating evolutionary<br />
rate of base substitutions through comparative<br />
studies of nucleotide sequences. Journal of<br />
Molecular Evolution 16: 11-120.<br />
Maassoumi A.A., 1998. Astragalus in the Old World,<br />
Check-List. Research Institute of Forests and<br />
Rangeland, Tehran.<br />
Nimis P.L., 1981. The thorny-cushions vegetation in<br />
Mediterranean Italy. Phytogeographical problems.<br />
Actas III optima. Anales del Jardín Botánico de<br />
Madrid 37 (2): 339-351.<br />
Podlech D., 1982. Neue Aspekte zur Evolution und<br />
Gliederung der Gattung Astragalus L. Mitteilungen<br />
der Botanischen Staatssammlung München 18: 359-<br />
378.<br />
Podlech D., 1986. Taxonomic and phytogeographical<br />
problems in Astragalus of the Old World and South-<br />
West Asia. Proceedings of the Royal Society of<br />
Edinburgh 89B: 37-43.<br />
Podlech D., 1991. The systematics of the annual species<br />
of the genus Astragalus L. (Leguminosae). Flora et<br />
Vegetatio Mundi 9: 1-8.<br />
105