Frank H. Hellwig

Centaureinae (Asteraceae) in the Mediterranean – history of ecogeographical radiation

Abstract.The ecogeographical history of Cardueae-Centaureinae (Asteraceae) in the Mediterranean is discussed on the background of the geological history of the region. Two main phases of radiation are postulated. The first one separated the basal groups of the subtribe (Klasea group, Rhaponticoides/Cheirolophus group, Rhaponticum group, Amberboa group, Psephellus, and Plectocephalus). This happened during late Oligocene and Miocene. The major modern or derived clades (Centaurea, Colymbada group, Cyanus and Carthamus/Carduncellus group) may have differentiated around the transition from Pliocene to Pleistocene. Aridisation favoured the development of biennial and annual species independently in different groups. Different modes of evolution are observed in annual and perennial species, reflected by morphology as well as DNA sequences. The myrmekochory syndrome, adaptation to man-made habitats, chromosome and genome evolution, and modes of reproduction receive special attention.

Genetic diversity of Ranunculus acris L. (Ranunculaceae) populations in relation to species diversity and habitat type in grassland communities

Correlates between genetic diversity at intra‐ and interpopulation levels and the species diversity in plant communities are rarely investigated. Such correlates may give insights into the effect of local selective forces across different communities on the genetic diversity of local plant populations. This study has employed amplified fragment length polymorphism to assess the genetic diversity within and between 10 populations of Ranunculus acris in relation to the species diversity (richness and evenness) of grassland communities of two different habitat types, ‘seminatural’ and ‘agriculturally improved’, located in central Germany. Within‐population genetic diversity estimated by Neis unbiased gene diversity (HE) was high (0.258–0.334), and was not correlated with species richness (Pearsons r = −0.17; P = 0.64) or species evenness (Pearsons r = 0.15; P = 0.68) of the plant communities. However, the genetic differentiation between R. acris populations was significantly correlated with the difference in species evenness (Mantels r = 0.62, P = 0.02), but not with difference in species richness of plant communities (r = −0.17, P = 0.22). Moreover, we also found that populations of R. acris from the ‘seminatural’ habitat were genetically different (amova, P < 0.05) from those in ‘agriculturally improved’ habitats, suggesting that gene flow between these habitat types is limited. The results reported in this study may indicate that habitat characteristics influence the genetic diversity of plant species.

The chloroplast genome of the “basal” angiosperm Calycanthus fertilis – structural and phylogenetic analyses

Abstract.The nucleotide sequence of the complete chloroplast genome of a basal angiosperm, Calycanthusfertilis, has been determined. The circular 153337 bp long cpDNA is colinear with those of tobacco, Arabidopsis and spinach. A total of 133 predicted genes (115 individual gene species, 18 genes duplicated in the inverted repeats) including 88 potential protein-coding genes (81 gene species), 8 ribosomal RNA genes (4 gene species) and 37 tRNA genes (30 gene species) representing 20 amino acids were identified based on similarity to their homologs from other chloroplast genomes. This is the highest gene number ever registered in an angiosperm plastome. Calycanthus fertilis cpDNA also contains a homolog of the recently discovered mitochondrial ACRS gene. Since no gene transfer from mitochondria to the chloroplast has ever been documented, we investigated the evolutionary affinity of this gene in detail. Phylogenetic analysis of the protein-coding subset of the plastome suggests that the ancient line of Laurales emerged after the split of the angiosperms into monocots and dicots.

The genus Psephellus Cass. (Compositae, Cardueae) revisited with a broadened concept

Abstract Wagenitz, G. & Hellwig, F. H.: The genus Psephellus Cass. (Compositae, Cardueae) revisited with a broadened concept. — Willdenowia 30: 29-44. 2000. — ISSN 0511-9618. A new concept of the genus Psephellus is presented on the basis of morphological, anatomical, palynological and caryological evidence. The few molecular data seem to confirm the monophyly of the genus. The following former sections of Centaurea are included: C. sect. Psephelloideae, Psephellus, Hyalinella, Aetheopappus, Amblyopogon, Heterolophus, Czerniakovskya, Odontolophoideae, Odontolophus, Xanthopsis, Uralepis and Sosnovskya. New combinations under Psephellus are provided for these sections and for 35 species, especially from Turkey and Iran. Psephellus in this broadened sense has 75–80 species and a distribution with a centre in E Anatolia, Caucasia and NW Iran; only few species occur outside this area. Close relationships exist between different sections despite considerable differences especially in the characters of the pappus.

A phylogenetic analysis of Primulaceae s.l. based on internal transcribed spacer (ITS) DNA sequence data

Abstract. Phylogenetic relationships in Primulaceae were investigated by analysis of nuclear rDNA ITS sequences. Thirty-four species of Primulaceae, two of Myrsinaceae and four outgroup taxa were analyzed. In accordance to the results of recently published papers on the phylogeny of Primulaceae we found the family to be paraphyletic and resolved the positions of some genera. Our results show (a) the rather basal position of Centunculus within Lysimachieae, the genus thus being rather distantly related to Anagallis, (b) the close relationship between Lysimachia sect. Lerouxia, Anagallis, Asterolinon, and Pelletiera, (c) the well-supported monophyly of a group consisting of the four genera Hottonia, Omphalogramma, Bryocarpum, and Soldanella, and (d) the affinity of Stimpsonia to the Myrsinaceae-Lysimachieae-Ardisiandra clade. The ITS sequence data do not provide sufficient information to resolve basal relationships within the Primulaceae s.l. There is evidence against the monophyly of the large genera Primula, Androsace, and Lysimachia. In contrast to the phylogenetic reconstructions based on plastid gene sequences, Cyclamen does not appear as a member of the Myrsinaceae-Lysimachieae clade, but its position remains unclear.

Further support for the phylogenetic relationships within Euphorbia L. (Euphorbiaceae) from nrITS and trnL–trnF IGS sequence data

The cosmopolitan genus Euphorbia is one of the largest plant genera with an extreme phenotypic plasticity ranging from globose succulents to large shrubs and trees adapted to very divergent habitats like forests or deserts. We compiled the current knowledge about the evolution of Euphorbia by reconstructing a molecular phylogeny based on nearly all available internal transcribed spacer (nrITS) sequence data from previous investigations and sequences of newly sampled species. We compared the results with phylogenetic analyses based on a combined data set of nrITS and trnL–trnF intergenic spacer sequences of a subset of taxa. Apart from a few exceptions, the results correspond well to recently published studies based on different molecular markers. The genus Euphorbia is divided into four major clades, of which the clade comprising subgen. Rhizanthium is restricted to Africa and Madagascar, whereas the remaining three clades are distributed over several continents. Our results support the hypothesis that Euphorbia evolved in Africa from progenitors of subgen. Esula.

Evidence for the most basal split in land plants dividing bryophyte and tracheophyte lineages

The problem of relationships among the major basal living groups of land plants is long standing, yet the uncertainty as to the phylogenetic affinity of these lines persists in the literature. Molecular and modern cladistic studies of the phylogenetic relationships of the above groups resulted in a large number of conflicting topologies. However, with the exception of the cladistic analyses of spermatogenesis, suggesting monophyly of extant bryophytes, these studies agree the paraphyletic bryophyte grade is basal within the embryophyte tree. Here we would like to present analyses on the basis of the concatenated datasets of nucleotide and amino-acid sequences of 57 protein-coding genes common to 17 chloroplast genomes of land plants and a charophyte alga Chaetosphaeridium globosum. Character-wise, these are the largest datasets currently available to address the problem of basal relationships within embryophytes. Main lineages of bryophytes, i.e liverworts, hornworts and mosses are represented in our alignments with a single taxon, whereas 14 taxa represent the tracheophytes. With our data, phylogeny with liverwort basal appears to be and artifact related to high and unequal A+T contents among the sequences analysed. Reducing this compositional bias and applying methods developed to counter it, we recovered an alternative, strongly supported topology wherein both bryophytes and tracheophytes are monophyletic. Within bryophytes, hornworts are basal and liverworts are sister to mosses.

Genetic diversity in natural and anthropogenic inland populations of salt-tolerant plants: random amplified polymorphic DNA analyses of Aster tripolium L. (Compositae) and Salicornia ramosissima Woods (Chenopodiaceae)

Eight populations of Aster tripolium (Compositae) and six of Salicornia ramosissima (Chenopodiaceae) from inland, naturally salt‐contaminated habitats and anthropogenic salt‐polluted sites in central Germany (Thuringia, Anhalt‐Saxony) were analysed using random amplified polymorphic DNA (RAPD) markers to investigate the patterns of genetic variation. In both species, the genetic diversity observed in the younger, anthropogenic sites caused by potash mines during the last century was found to be not significantly lower than in the older, naturally salt‐contaminated habitats. Therefore, it is speculated that the loss of genetic diversity caused by founder effects on the anthropogenic habitats was balanced by successive colonization events, actual gene flow between populations, or the rapid growth of populations on the secondary habitats after colonization. Analyses of molecular variance (amova) of the RAPD markers, neighbour‐joining clustering of populations based on Reynolds’ co‐ancestry distances, and Mantel tests indicate that: (i) anthropogenic habitats were colonized independently; (ii) genetic differentiation among populations of S. ramosissima is more pronounced than in A. tripolium, which is considered to be mainly due to biological differences between the two species; and (iii) the geographical pattern of genetic diversity was considerably modulated by historical events and/or population genetic effects.

Genetic structure of the genus Lemna L. (Lemnaceae) as revealed by amplified fragment length polymorphism

Duckweeds (Lemnaceae) are extremely reduced in morphology, which made their taxonomy a challenge for a long time. The amplified fragment length polymorphism (AFLP) marker technique was applied to solve this problem. 84 clones of the genus Lemna were investigated representing all 13 accepted Lemna species. By neighbour-joining (NJ) analysis, 10 out of these 13 species were clearly recognized: L. minor, L. obscura, L. turionifera, L. japonica, L. disperma, L. aequinoctialis, L. perpusilla, L. trisulca, L. tenera, and L. minuta. However, L. valdiviana and L. yungensis could be distinguished neither by NJ cluster analysis nor by structure analysis. Moreover, the 16 analysed clones of L. gibba were assembled into four genetically differentiated groups. Only one of these groups, which includes the standard clones 7107 (G1) and 7741 (G3), represents obviously the “true” L. gibba. At least four of the clones investigated, so far considered as L. gibba (clones 8655a, 9481, 9436b, and Tra05-L), represent evidently close relatives to L. turionifera but do not form turions under any of the conditions tested. Another group of clones (6745, 6751, and 7922) corresponds to putative hybrids and may be identical with L. parodiana, a species not accepted until now because of the difficulties of delineation on morphology alone. In conclusion, AFLP analysis offers a solid base for the identification of Lemna clones, which is particularly important in view of Lemnaceae application in biomonitoring.

Two new species of Centaurea (Compositae, Cardueae) from Turkey

Abstract Wagenitz, G., Hellwig, F. H., Parolly, G. & Martins, L.: Two new species of Centaurea (Compositae, Cardueae) from Turkey. — Willdenowia 36 (Special Issue): 423–435. — ISSN 0511-9618;