1022-7954/01/3709- $25.00 © 2001
Russian Journal of Genetics, Vol. 37, No. 9, 2001, pp. 1068–1073. Translated from Genetika, Vol. 37, No. 9, 2001, pp. 1274–1280.
Original Russian Text Copyright © 2001 by Yatsentyuk, Valiejo-Roman, Samigullin, Wilkström, Troitsky.
Lycopods is an ancient taxon of vascular plants
known from the early Devon, i.e. approximately
390 Ma [1–4]. In their long evolution, they preserved
many traits unchanged, which makes possible to com-
pare the general organization of the fossils with modern
Typically, lycopods are assigned the rank of division
(Lycopodiophyta) with classes Lycopodiopsida or
Lycopsida (including order Lycopodiales) and Isoetop-
sida (including orders Selaginellales and Isoetales) .
In other systems, lycopods are regarded as a class, and
modern forms are classiﬁed into orders Lycopodiales,
Isoerales, and Selaginellales [1, 3].
According to paleobotanical data, Lycopsida devel-
oped as a completely isolated evolution lineage of vas-
cular plants. This lineage is thought to originate from
Zosterophyllopsida. However, the strictly monophyl-
etic origin of Lycopsida has not been conclusively
proven. For instance, some authors argue that the
Rhyniopsida–Zosterophyllopsida line led to Lycopodi-
ales, whereas Selaginellales and Isoetales continue the
Rhyniopsida–Protolepidodendrales line .
In the Carboniferous period, Lycopsida constituted
an appreciable part of land ﬂora and included almost
half of all known fossil plants of that time.
At present, Lycopsida comprise only a small frac-
tion in the biological diversity of vascular plants and are
represented by a relatively small number of species
(700 to 1250), approximately 400 of which are
included in Lycopodiaceae, the central family of mod-
ern Lycopsida [2, 3].
In phylogenetic studies of Lycopsida, the main dif-
ﬁculty is a relatively simple organization of these
plants. Morphological distinctions of representatives of
modern taxa that are the closest to Lycopodiaceae (Iso-
etaceae and Selaginellaceae) and the lack of clearly dis-
tinguishable taxonomic characteristics in the putative
fossil relatives of Lycopsida hamper the determination
of taxonomic status of the family.
In recent years, gene-taxonomy methods have been
successfully applied to solve the problems of plant phy-
logeny . We used this approach for the study of
Lycopodiaceae. For this purpose, we determined nucle-
otide sequences of spacer regions of chloroplast rRNA
in 27 species of Lycopsida and constructed phyloge-
netic trees based on these data. The results are com-
pared with earlier evidence on chloroplast sequences of
, and intergenic spacer
MATERIALS AND METHODS
DNA was isolated from plant samples which were
either used in previously published works [6–8] (
) or collected in
Moscow oblast (
). DNA was isolated using the
method based on the use of cetyltrimethylammonium
bromide for DNA puriﬁcation from the admixed
polysaccharides (with modiﬁcations) .
The list of species studied and their geographical
distribution and taxonomic state (according to Ølgaard’s
system ) are presented in Table 1. This table also
includes the GenBank accession numbers of sequences
and the size of spacers.
Evolution of Lycopodiaceae Inferred
from Spacer Sequencing of Chloroplast rRNA Genes
S. P. Yatsentyuk
, K. M. Valiejo-Roman
, T. H. Samigullin
, N. Wilkström
, and A. V. Troitsky
Belozerskii Institute of Molecular Biology and Bioorganic Chemistry, Moscow State University, Moscow, 119899 Russia
fax: (095) 939-31-81; e-mail: email@example.com
Department of Botany, The Natural History Museum,
Cromwell Road, London, SW7 5BD United Kingdom; fax: (44-0207) 942-53-83; e-mail: N. Wilstrom@nhm.ac.uk
Received February 12, 2001
—Nucleotide sequences of a chloroplast rDNA region including 8 bp from the 3' end of 23S rDNA–
ITS2–4.5S rDNA–ITS3–5S rDNA–ITS4 (approximately 800 bp) were determined in 25 species of Lycopodi-
aceae and two species of the genus
. The rate of molecular evolution of spacers signiﬁcantly varied in
different Lycopsida taxa. A phylogenetic analysis by the neighbor-joining (NJ) method revealed that the family
Lycopodiaceae is monophyletic. The topology of phylogenetic trees suggests the isolation of four or probably
ﬁve genera in family Lycopodiaceae. For these genera, synapomorphic indels were detected. The obtained data
were compared with the results of phylogenetic analysis of Lycopsida with regard to other sequences. The rela-
tionships of taxa within the family Lycopodiaceae is discussed.