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Bioinformatics approaches in Molecular
Systematics: the case of
Silene
section
Siphonomorpha
Otth (
Caryophyllaceae
)
Helena COTRIM
1
, M. Salomé PAIS
1
, Michael F. FAY
2
and Mark W. CHASE
2
1
Plant Molecular Biology and Biotechnology Laboratory, ICAT, Ed. ICAT, Faculty of
Sciences, University of Lisbon, Campo Grande P-1749-016 Lisbon, Portugal, email:
hcotrim@icat.fc.ul.pt/hmcotrim@fc.ul.pt.
2
Jodrell Laboratory, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, UK.
Abstract.
The primary goal of computational molecular biology, like molecular
biology itself, is to understand the meaning of the genomic information and how this
information is expressed. Molecular systematics makes phylogenetic inferences
from molecular data using computacional methods. The systematics of
Silene
section
Siphonomorpha
Otth was approached from three different perspectives, the
first analysing global relationships within the section, the second studying two pairs
of taxa with problematic species boundaries, and the third using one of the species to
study rarity at ecological and genetic level.
1. Introduction
Silene
(Caryophyllaceae) is a large plant genus with more than seven hundred
species found in the Northern Hemisphere. The genus includes many rare species, and 80%
of those referred to as rare or endangered [1, 2] belong to section
Siphonomorpha
Otth. The
section includes circa twenty-five taxa, two of which are a widely distributed in Europe
(
Silene nutans
and
S. italica
) and several regional or local endemics occurring mainly in the
Iberian Peninsula. Their taxonomy has undergone several modifications since Otth.
Morphological separation is difficult, especially in the
S. italica
complex. Breeding barriers
are essentially absent in the group, which makes species boundaries a crucial subject.
Moreover the extreme morphological similarity of some of the taxa hinders their
conservation.
2. Material and Methods
Molecular and morphological methods were applied to trace evolutionary
relationships within section
Siphonomorpha
. Nuclear ITS and plastid
trn
L-F DNA were
sequenced for eighteen taxa [3]. Plastid
trn
L-F microsatellites and nuclear AFLPs were also
used. The micromorphology of
Silene longicilia
ssp.
cintrana
and
S. rothmaleri
was studied
using scanning electron microscopy. Karyological characterisation of both species was
made with silver staining and in situ hybridisation techniques [4]. The relationships
between
S. longicilia
ssp.
longicilia
and
S. longicilia
ssp.
cintrana
were analysed with
AFLPs.
Silene rothmaleri
, one of the numerous rare taxa of this section, previously
considered extinct [5], was used as a case study of rarity. Ecological traits of this taxon
were studied and populations characterised. The within and between population genetic
variability was assessed by RAPD across the entire range of the taxon [6].
