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Understanding the relative importance of different mechanisms of speciation in a given lineage requires fully resolved interspecific relationships. Using Facchinia, a genus of seven species centred in the European Alps, we explore whether the polytomy found by Sanger sequencing analyses of standard nuclear (ITS) and plastid markers (trnQ-rps16) is a hard or soft polytomy by substantially increasing the amount of DNA sequence data, generated by genotyping-by-sequencing. In comparison to 142 phylogenetically informative sites in the Sanger sequences the GBS sequences yielded 3363 phylogenetically informative sites after exclusion of apparently oversaturated SNPs. Maximum parsimony, maximum likelihood, NeighborNet, SVDquartets and Astral-II analyses all resulted in phylogenetic trees (and networks) in which interspecific relationships were largely unresolved. After excluding incomplete lineage sorting, hybridisation and oversaturation of characters as possible causes for lack of phylogenetic resolution, we conclude that the polytomy obtained most likely represents a hard polytomy. We hypothesize that diversification of Facchinia is best interpreted as the result of multiple simultaneous vicariance in response to climatic changes during the Early Quaternary.

Cherleria sedoides, a plant species widespread in alpine areas of the major European mountain ranges and in Scotland, contains two highly divergent chloroplast haplotype groups, one widespread (WH) and one present only in some populations in the Alps (AH). We investigated whether this haplotype diversity is the result of (1) intraspecific differentiation, (2) retention of an ancestral polymorphism or (3) hybridisation. For this purpose, 106 matK sequences from throughout the Caryophyllaceae and 80 trnQ-rps16 and psbD-trnT sequences of C. sedoides (51) and other species of Cherleria (29) were used for the construction of phylogenies and haplotype networks. As the two haplotype groups were never each other’s closest relatives, haplotype diversity as a result of intraspecific differentiation is unlikely. Patterns of genetic differentiation within the WH and AH groups are very different. Whereas WH shows a radial pattern typical of rapid expansion, AH is divided into two divergent subgroups each containing more variation than the WH group. This suggests that the two haplotype groups have dissimilar histories and are therefore unlikely to represent an ancestral polymorphism. Instead, we conclude that the polymorphism is best interpreted as the result of hybridisation. As the WH and AH haplotype groups fall into Cherleria, but do not group with any extant species, we conclude that the rare AH group represents the original C. sedoides, and that the WH group was captured from another, now extinct, species of Cherleria.

Summary The currently favoured model of the evolution of C4 photosynthesis relies heavily on the interpretation of the broad phenotypic range of naturally growing C3–C4 intermediates as proxies for evolutionary intermediate steps. On the other hand, C3–C4 intermediates had earlier been interpreted as hybrids or hybrid derivates. By first comparing experimentally generated with naturally growing C3–C4 intermediates, and second summarising either direct or circumstantial evidence for hybridisation in lineages comprising C3, C4 and C3–C4 intermediates, we conclude that a possible hybrid origin of C3–C4 intermediates deserves careful examination. While we acknowledge that the current model of C4 photosynthesis evolution is clearly the best available, C3–C4 intermediates of hybrid origin, if existing, should not be used for further analysis of this model. However, experimental C3 × C4 hybrids potentially are excellent systems to analyse the genetic differences between C3 and C4 species and, also using segregating progeny, to study the relationship between individual photosynthetic traits and environmental factors.

A species-level phylogeny is presented for Triglochin, the largest genus of Juncaginaceae (Alismatales) comprising about 30 species of annual and perennial herbs. Triglochin has an almost cosmopolitan distribution with Australia as centre of species diversity. Trans-Atlantic and trans-African disjunctions exist in the genus. Phylogenetic analyses were conducted based on molecular data obtained from nuclear (ITS, internal transcribed spacer) and chloroplast sequence data (psbA-trnH spacer, matK gene). Based on the phylogeny of the group divergence times were estimated and ancestral distribution areas reconstructed. Our data confirm the monophyly of Triglochin and resolve relationships between the major lineages of the genus. The sister group relationship between the Mediterranean/African T. bulbosa complex and the American T. scilloides (formerly Lilaea s.) is strongly supported. This clade is sister to the rest of the genus which contains two main clades. In the first, the widespread T. striata is sister to a clade comprising annual Triglochin species from Australia. The second clade comprises T. palustris as sister to the T. maritima complex, of which the latter is further divided into a Eurasian and an American subclade. Taxonomic diversity in some clades appears to be linked to habitat shifts and is not present in old but ecologically invariable lineages such as the non-monophyletic T. maritima. Diversification in Triglochin began in the Miocene or Oligocene, and most disjunctions in Triglochin were dated to the Miocene.

Premise of the study Substrate specialization is often considered an important factor in evolutionary diversification. A classic example of divergence related to different substrate types is the dichotomy between calcicole and calcifuge plants on calcareous and siliceous substrates as found in the European Alps. When closely related species with contrasting substrate preferences are found in the same area, it is generally hypothesized that they diverged where they now occur. However, it is possible that Alpine edaphic diversity instead allows the coexistence of related species whose edaphic differentiation took place deeper in the phylogeny, in some other part of the range of their clades. Methods We used sequences of the nuclear internal and external transcribed spacer regions to examine the origin of substrate differentiation in Minuartia series Laricifoliae, which contains many edaphic endemics, including a pair of Alpine taxa with contrasting substrate preferences: Minuartia langii (calcicole) and M. laricifolia (calcifuge). Key results MINUARTIA LANGII and M. laricifolia are each more closely related to Balkan species than they are to each other and reached the Alps independently. The clade to which they belong is ancestrally calcicole. Minuartia langii inherited the ancestral ecology, while M. laricifolia is part of a subclade with serpentine endemics and one substrate generalist. Conclusions In the study group, taxa with contrasting substrate preferences did not diverge in the Alps. Instead, taxa whose substrate differentiation arose elsewhere, likely on the Balkan Peninsula, were preadapted to take advantage of Alpine substrate diversity.

Premise of the study Floras of continental habitat islands, like those of islands, originate mostly through colonization, which can be followed by in situ speciation. We here address the question of the relative importance of colonization and in situ diversification in the high-altitude areas of the eastern African high mountains, the tropical Afroalpine Region, using the most species-rich genus in the region, Senecio, as an example. Methods We expanded earlier Senecioneae phylogenies by adding more tropical African species and analyzed our phylogenetic tree biogeographically. Key results Senecio contains at least five clades with tropical African species, all of them containing tropical afroalpine species. Between four to 14 independent colonization events into the tropical Afroalpine most likely from montane regions in southern Africa were found. Additionally, relationships of tropical afroalpine species to Palearctic and South American taxa were identified. Although some in situ diversification occurred in Senecio in the tropical Afroalpine, the resulting number of species per clade is never higher than seven. Conclusion Like other genera, Senecio colonized the tropical Afroalpine several times independently. Comparison with Mt. Kinabalu, a small tropical alpine-like region in Southeast Asia, and alpine-like regions in the Andes implies that rates of in situ speciation might be linked to area size.

The perennial herb Meconopsis cambrica, a western European endemic, is the only European species of the otherwise Himalayan genus Meconopsis and has been interpreted as a Tertiary relict species. Using rbcL and ITS sequence variation, we date the split between M. cambrica and its sister clade Papaver s.str. to the Middle to Upper Miocene (12.8 Myr, 6.4–19.2 Myr HPD). Within M. cambrica, cpDNA sequence variation reveals the existence of two groups of populations with a comparable level of genetic variation: a northern group from Great Britain, the Massif Central, the western Pyrenees and the Iberian System, and a southern group from the central and eastern Pyrenees. Populations from the Cantabrian Mountains were placed in both groups. Based on ITS sequence variation, the divergence between these two groups can be dated to 1.5 Myr (0.4–2.8 Myr HPD), and the age of the British populations is estimated as 0.37 Myr (0.0–0.9 Myr HPD). Amplified fragment length polymorphism results confirm the distinctive nature of the populations from Britain, the Massif Central and the central and eastern Pyrenees. These patterns of latitudinal variation of M. cambrica differ from patterns of longitudinal differentiation found in many other temperate species and imply glacial survival of the northern populations in northerly refugia. The primary differentiation into northern and southern cpDNA groups dates to near the onset of the Quaternary and suggests that an ancient phylogeographic pattern has survived through several glacial periods. Our data provide evidence that the species has persisted for a long period with a highly fragmented and probably very localized distribution.

Hybridization is an important evolutionary factor in the diversification of many plant and animal species. Of particular interest is that historical hybridization resulting in the origin of new species or introgressants has occurred between species now geographically separated by great distances. Here, we report that Senecio massaicus, a tetraploid species native to Morocco and the Canary Islands, contains genetic material of two distinct, geographically separated lineages: a Mediterranean lineage and a mainly southern African lineage. A time-calibrated internal transcribed spacer phylogeny indicates that the hybridization event took place up to 6.18 Ma. Because the southern African lineage has never been recorded from Morocco or the Canary Islands, we hypothesize that it reached this area in the distant past, but never became permanently established. Interestingly, the southern African lineage includes S. inaequidens, a highly invasive species that has recently become widespread throughout Europe and was introduced at the end of the 19th century as a ‘wool alien’. Our results suggest that this more recent invasion of Europe by S. inaequidens represents the second arrival of this lineage into the region.

The long history of the deliberate or accidental and human-mediated dispersal of flowering plants has led to the introduction of foreign genotypes of many species into areas of Europe hitherto occupied by potentially distinct native populations. Studies of the genetic and evolutionary consequences of such changes are handicapped by the difficulty of identifying the surviving native populations of many species in the absence of clear morphological differences. We investigated the relationship between putative native and introduced populations of the herbaceous perennial Meconopsis cambrica (Papaveraceae), as the isolated native populations of this species can be identified by historical and ecological evidence. In Britain, the species is scarce and declining as a native, but has become increasingly frequent in recent decades as a garden escape. Native populations from Spain and France were compared with native and introduced British populations using internal transcribed spacer and cpDNA sequences and amplified fragment length polymorphisms (AFLPs). Ten of the twelve British populations could be unambiguously assigned to native or introduced groups using cpDNA and AFLPs. The introduced plants appear to originate from the central and eastern Pyrenees rather than from native British sites. Two populations (including one previously considered native) cannot be classified unambiguously. There is unequivocal evidence for unidirectional gene flow from native plants into two of the introduced populations and possible evidence for hybridization in three other sites (two native). The absence of biological barriers to hybridization suggests that the native and introduced gene pools of M. cambrica in Britain might eventually merge.

One of the longstanding questions in phylogenetic systematics is how to address incongruence among phylogenies obtained from multiple markers and how to determine the causes. This study presents a detailed analysis of incongruent patterns between plastid and ITS/ETS phylogenies of Tribe Senecioneae (Asteraceae). This approach revealed widespread and strongly supported incongruence, which complicates conclusions about evolutionary relationships at all taxonomic levels. The patterns of incongruence that were resolved suggest that incomplete lineage sorting (ILS) and/or ancient hybridization are the most likely explanations. These phenomena are, however, extremely difficult to distinguish because they may result in similar phylogenetic patterns. We present a novel approach to evaluate whether ILS can be excluded as an explanation for incongruent patterns. This coalescence-based method uses molecular dating estimates of the duration of the putative ILS events to determine if invoking ILS as an explanation for incongruence would require unrealistically high effective population sizes. For four of the incongruent patterns identified within the Senecioneae, this approach indicates that ILS cannot be invoked to explain the observed incongruence. Alternatively, these patterns are more realistically explained by ancient hybridization events.

The genus Linum consists of over 180 species, the most famous being L. usitatissimum, the source of linen and linseed oil. The eight genera of Linaceae subf. Linoideae, of which Linum is the largest, exhibit a complex biogeographic distribution, inhabiting all continents except Antarctica. Numerous species in Linoideae are heterostylous, but the ancestral breeding system of the group has not been determined. We present phylogenetic analyses of 44 species representing all eight genera of subf. Linoideae and 37 species of Linum, with data from the chloroplast (ndhF, trnL-F, trnK3′ intron) and the nuclear ITS, with Hugonia (Linaceae subf. Hugonioideae) as outgroup. Sequences of rbcL from 48 species of Linaceae, including five species from Hugonioideae and seven species from other families of Malpighiales, were analyzed independently. Our results suggest that Linaceae and subf. Linoideae are monophyletic, but Linum is not. Anisadenia, Reinwardtia, and Tirpitzia are found to be the basal members of Linoideae. The rest of the subfamily forms two major lineages: a blue-flowered clade (Linum sections Linum and Dasylinum) and a yellow-flowered clade (Linum sects. Linopsis, Syllinum, and Cathartolinum, and the genera Cliococca, Hesperolinon, Radiola, and Sclerolinon). Diversification of Linoideae may have begun 46–51 mya, probably in Southeast Asia. Linum appears to have arisen in Eurasia, from which it spread to Africa, North America, South America, and Australasia. Our analyses indicate that neither heterostyly nor homostyly can yet be confirmed as the ancestral state in Linoideae or Linaceae, but provide strong evidence that breeding system is evolutionarily labile in this group.

Fossil pollen records indicate that Hippophae rhamnoides (Sea Buckthorn) was widespread on late- and early postglacial raw soils throughout much of central and northern Europe, but that Early Holocene reforestation restricted populations to northern coastal habitats, or along mountain streams in the Alps, Pyrenees, and Carpathians. We used sequence variation at the nuclear chalcone synthase intron ( Chsi ), in conjunction with chloroplast DNA–restriction fragment length polymorphism data, to investigate the intraspecific phylogeny, phylogeographic structure, and expansion demographic history of this dioecious and wind-pollinated shrub at its range-wide scale in Europe and Asia Minor. Four major Chsi phylogroups of unresolved relationships were identified with estimated divergences ∼ ∼ ∼ 172 000 years ago. Large-scale phylogeographic structures of nuclear and cytoplasmic markers were congruent in identifying (i) southeastern Europe as the most likely source of colonization into central Europe and Scandinavia, and (ii) the area just north of the Alps as a contact zone between populations from the Alps and the east/central EuropeanScandinavian lineage. Coalescence-based analyses (i.e. nested clade analysis and mismatch distributions) of Chsi variation were able to detect at least four major episodes of population growth, all within about the last 40 000 years. In particular, these analyses identified a nearly synchronized timing of population expansions in various parts of the species’ range in central-eastern Europe/Asia Minor, most likely correlating with the Younger Dryas Stadial (∼ 13 000–11 600 years ago). It remains to be established whether the phylogeographic history of H. rhamnoides , and particularly its rapid response to the rapid environmental changes of the Younger Dryas cold snap, is unique to the species, or whether it is shared with other cold-tolerant shrub (or grassland) species known from late-glacial raw soils in Europe.

Soldanella contains 16 species of herbaceous perennials that are endemic to the central and south European high mountains. The genus is ecogeographically subdivided into forest/montane and alpine species. Evolutionary relationships and large-scale biogeographic patterns were inferred from parsimony analyses of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA, and genetic distance analyses based on amplified fragment length polymorphism (AFLP) markers. The ITS region proved useful for examining subgeneric relationships and testing hypotheses on genus-wide divergence times, whereas the AFLP markers were suitable for studying relationships among closely related taxa and biogeographic patterns of divergence. Neither ITS nor AFLP data supported sectional delimitations, particularly those related to the grouping of S. alpina (sect. Soldanella) with S. pusilla (sect. Tubiflores), which may be the result of hybridization. Additional results and conclusions drawn are (1) Soldanella is derived from an ancestor of Asian origin with a montane ecology; (2) estimates of divergence times suggest a late Quaternary origin of the genus; (3) alpine species of sect. Tubiflores diverged from within a paraphyletic sect. Soldanella of mainly montane species; (4) alpine and montane species of Soldanella experienced different cycles of range expansion and contraction during late Quaternary climatic changes, resulting in differential patterns of geographic distribution; and (5) AFLP divergence among montane species from eastern Europe was lower than between alpine species; we hypothesize that the latter differentiated in allopatric regions of expansion during glacials, while the former experienced secondary contact at lower elevations in more southern refugia.

The exclusively coastal Cakile maritima and Eryngium maritimum represent a linear biogeographical system. Genetic variation among 25 individuals of C. maritima and 16 individuals of E. maritimum, from the coasts of Europe, North Africa and the Canary Islands, was analysed using random amplified polymorphic DNAs (RAPDs) and intersimple sequence repeats (ISSRs). Genetic distances (Dice) were calculated and used to investigate the correlation between genetic and geographical distances, to construct Neighbour Joining (NJ) trees, and to compare mean genetic distances between areas within and across species. Genetic distances and geographical distances measured along the coast are well correlated in Cakile and Eryngium. This implies that dispersal in both species is largely along the coast. The NJ analyses resulted in the recognition of Atlantic and Mediterranean clusters in both Cakile and Eryngium. The genetic distance between these two clusters is much larger in Eryngium (0. 285) than in Cakile (0.037). Mean genetic distances are substantially higher in the Mediterranean than in the Atlantic clusters in both species, and higher in Cakile than in Eryngium particularly in the Atlantic cluster. It is argued that all similarities and differences between the two species can be explained with the presumed distribution of the two species in the Würm glacial as reconstructed from their extant temperature requirements, the distribution of ice cover, permafrost, and sea surface temperatures in that period, and indirect fossil evidence.

Phylogenetic relationships in the Olea europaea complex and the phylogeography of 24 populations of the Macaronesian olive (O. europaea ssp. cerasiformis) were assessed by using three molecular markers: nuclear ribosomal internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and intersimple sequence repeats (ISSR). Parsimony analysis of the ITS-1 sequences and Neighbour-joining (NJ) analyses of RAPD and ISSR banding variation revealed four major lineages in the O. europaea complex: (1) ssp. cuspidata; (2) ssp. cerasiformis from Madeira; (3) ssp. laperrinei; and (4) ssp. cerasiformis from the Canary Islands plus ssp. europaea. These results provide unequivocal support for two independent dispersal events of Olea to the Madeira and Canary Islands. Molecular and morphological evidence led to recognition of two separate olive taxa in Macaronesia, to date included in ssp. cerasiformis. NJ analyses of the combined RAPD and ISSR data suggest that the colonization of the Canaries by O. europaea may have followed an east to west stepping-stone model. An interisland dispersal sequence can be recognized, starting from the continent to Fuerteventura, Gran Canaria, Tenerife, La Gomera, and finally La Palma. High dispersal activity of the lipid-rich Olea fruits by birds in the Mediterranean region is congruent with multiple dispersal of olives to Macaronesia and successive colonization of the archipelagos. The observation of strong genetic isolation between populations of different islands of the Canary Islands suggests, however, that subsequent interisland dispersal and establishment has been very rare or may not have occurred at all.

UNLABELLED PREMISE OF THE STUDY Heterogeneity of edaphic conditions plays a large role in driving the diversification of many plant groups. In the Alps and other European high mountains, many closely related calcicole and calcifuge plant taxa exist. To better understand patterns and processes of edaphic differentiation, the phylogeny of the edaphically variable genus Adenostyles was studied. The genus contains three species, of which A. alpina has five subspecies. Each species and subspecies is largely confined to either calcareous or noncalcareous substrates. • METHODS We analyzed the phylogeny of Adenostyles using DNA sequences of nrITS, nrETS, nuclear chalcone synthase, and three plastid markers (rpl32-trnL, psbA-trnH, and ndhF-rpl32) from 45 in-group and five out-group samples. The phylogeny was used to reconstruct ancestral edaphic associations and distribution areas. • KEY RESULTS Within Adenostyles alpina, the shifts of edaphic association from calcicole to calcifuge in subsp. briquetii (Corsica) and in a clade of subsp. macrocephala (southernmost Italy) plus subsp. pyrenaica (Pyrenees) coincide with dispersal events. • CONCLUSIONS We conclude that colonization of areas with novel edaphic conditions via dispersal can trigger shifts of edaphic association. Accordingly, edaphic niche shifts can result from chance events.

The genetic basis of differences in speed of development from germination to first bud formation was investigated in Senecio vulgaris var. vulgaris and S. vulgaris ssp. denticulatus, and also in S. vernalis sampled from Israel and Germany. In the case of S. vulgaris, F2 segregation analysis and the recovery of very late and very early lines from extreme F2 phenotypes showed that differences can be explained by a single major gene model, whereas segregation data from F2 and backcross progenies in S. vernalis are not incompatible with a digenic model of inheritance. Senecio vernalis from Israel and S. vulgaris var. vulgaris reached the different developmental stages in a substantially shorter time than did C. European S. vernalis and S. vulgaris ssp. denticulatus. In both species the increased speed of development was achieved through drastic abbreviation of the rosette stage of development rather than through an acceleration of the entire developmental programme. It is suggested that the genes controlling speed of development in S. vulgaris and S. vernalis may be homologous to major heterochronic genes identified from mutants of Arabidopsis thaliana (e.g. early flowering [elf1–3]).

A comparison of chloroplast DNA (cpDNA) and isozyme diversity in Senecio nebrodensis L., a species restricted to certain mountain ranges in Spain, and S. viscosus L., a widespread ruderal species in Europe, revealed that S. viscosus possessed the more common of two cpDNA haplotypes resolved in S. nebrodensis and contained only a small subset of the alleles found in S. nebrodensis at enzyme coding loci. The two species shared one restriction length mutation and one site mutation in their cpDNA, which distinguished them from other European Senecio species examined previously. Taken overall, these results support the hypothesis that S. nebrodensis and S. viscosus are related as a progenitor-derivative pair of species. The fact that no novel alleles were found in S. viscosus would suggest a relatively recent origin of the species, most probably in late glacial or postglacial times.

Serpentine soils harbour a unique flora that is rich in endemics. We examined the evolution of serpentine endemism in Minuartia laricifolia, which has two ecologically distinct subspecies with disjunct distributions: subsp. laricifolia on siliceous rocks in the western Alps and eastern Pyrenees and subsp. ophiolitica on serpentine in the northern Apennines. We analysed AFLPs and chloroplast sequences from 30 populations to examine their relationships and how their current distributions and ecologies were influenced by Quaternary climatic changes. Minuartia laricifolia was divided into four groups with a BAPS cluster analysis of the AFLP data, one group consisted only of subsp. ophiolitica, while three groups were found within subsp. laricifolia: Maritime Alps, north-western Alps and central Alps. The same groups were recovered in a neighbour-joining tree, although subsp. ophiolitica was nested within the Maritime Alps group of subsp. laricifolia. Subspecies ophiolitica contained three different chloroplast haplotypes, which were also found in the Maritime Alps group of subsp. laricifolia. Given its high genetic diversity, subsp. ophiolitica appears to have arisen from subsp. laricifolia by vicariance instead of by long-distance dispersal. Genetic and geographic evidence point to the Maritime Alps populations of subsp. laricifolia as the closest relatives of subsp. ophiolitica. We hypothesize that M. laricifolia was also able to grow on nonserpentine rocks in the northern Apennines during glacial periods when the vegetation was more open, but that only the serpentine-adapted populations were able to persist until the present due to their competitive exclusion from more favourable habitats.

Various explanations can be offered for the incongruence between phylogenetic hypotheses resulting from morphological and molecular data sets. Of these, the possibility that incongruence may result from the mutation of major morphogenetic genes leading to dramatic morphological divergence unaccompanied by equivalent change of the phylogenetic marker molecule(s) used is discussed in detail. As evidence for this hypothesis, several examples for such incongruence are surveyed. It seems possible that in many cases the genetic basis of the morphological characters responsible for the incongruence found may be simple, and that the genes involved may be homologous to genes known from mutant systems. It is suggested that: 1. the systematic documentation of incongruence between molecular and morphological phylogenies may help to assess the frequency of evolutionary change through the mutation of major morphogenetic genes, and that 2. the identification of major morphological characters distinguishing closely related taxa with mutant phenotypes known from mutant systems eventually may allow an experimental approach to the problem of evolutionary change resulting from major genes. Natural taxa suspected to be the result of such processes could be changed morphologically through transformation with the relevant genes.

PREMISE OF THE STUDY: The correct assessment of homology is an important prerequisite for reconstructing phylogenetic relationships and character evolution. Old World Papaveroideae (Papaver, Meconopsis, Roemeria, Stylomecon) show substantial diversity in gynoecium and capsule morphology. In particular, capsules can have distinct styles (Meconopsis p.p., Stylomecon) or a sessile stigmatic disc (Papaver). Molecular phylogenetic analyses of Old World Papaveroideae had shown that neither taxa with styles nor those with stigmatic discs represent monophyletic lineages. We here investigate whether either styles or stigmatic discs have arisen repeatedly during the diversification of Old World Papaveroideae. METHODS: We investigated gynoecium ontogeny in Papaver rhoeas, P. californicum, Meconopsis cambrica, and Stylomecon heterophylla by scanning electron microscopy for the first time. Our observations were interpreted on the background of a well-resolved molecular phylogeny of the taxa investigated. KEY RESULTS: Papaver rhoeas and P. californicum share the presence of a developmentally complex garland-like stage in gynoecium ontogeny. The styles of M. cambrica and S. heterophylla result from growth in a ring-like zone beneath the carpel tips. This zone is also present in Papaver. In M. cambrica, traces of a garland-like stage can be seen. Style formation and stigma formation begin more or less simultaneously in M. cambrica, but style formation clearly precedes stigma formation in S. heterophylla. CONCLUSIONS: The styles present in M. cambrica and S. heterophylla are considered to have arisen in parallel from ancestors with a stigmatic disc. We speculate that style formation may have been a means to reduce selfing.

To explore the biogeographic history of Mediterranean/arid plant disjunctions, Old and New World Senecio sect. Senecio were analyzed phylogenetically using nuclear ribosomal DNA sequences (ITS). A clade corresponding to sect. Senecio was strongly supported. Area optimization indicated this clade to be of southern African origin. The Mediterranean and southern African floras were not distinguishable as sources of the main New World lineage, estimated to have become established during the middle Pliocene. Another previously suspected recent dispersal to the New World from the Mediterranean was confirmed for the recently recognized disjunction in S. mohavensis. The loss of suitable land connections by the Miocene means that both New World lineages must represent long-distance dispersal, providing the first evidence of repeat intercontinental dispersal in a Mediterranean group. In contrast, migration within Africa may have utilized an East African arid corridor. Recent dispersal to northern Africa is supported for S. flavus, which formed part of a distinct southern African lineage. Novel pappus modifications in both disjunct species may have enabled dispersal by birds. An estimated early Pliocene origin of sect. Senecio coincides with the appearance of summer-dry climate. However, diversification from 1.6 BP highlights the importance of Pleistocene climate fluctuations for speciation.

The dating of recent events in the history of organisms needs divergence rates based on molecular fingerprint markers. Here, we used amplified fragment length polymorphisms (AFLPs) of three distantly related alpine plant species co-occurring in the Spanish Sierra Nevada, the Pyrenees and the southwestern Alps/Massif Central to establish divergence rates. Within each of these species (Gentiana alpina, Kernera saxatilis and Silene rupestris), we found that the degree of AFLP divergence (D(N72)) between mountain phylogroups was significantly correlated with their time of divergence (as inferred from palaeoclimatic/palynological data), indicating constant AFLP divergence rates. As these rates did not differ significantly among species, a regression analysis based on the pooled data was utilized to generate a general AFLP rate. The application of this latter rate to AFLP data from other herbaceous plant species (Minuartia biflora: Schonswetter et al. 2006; Nigella degenii: Comes et al. 2008) resulted in a plausible timing of the recolonization of the Svalbard Islands and the separation of populations from the Alps and Scandinavia (Minuartia), and of island population separation in the Aegean Archipelago (Nigella). Furthermore, the AFLP mutation rate obtained in our study is of the same magnitude as AFLP mutation rates published previously. The temporal limits of our AFLP rate, which is based on intraspecific vicariance events at shallow (i.e. late glacial/Early Holocene) time scales, remains to be tested.

The genomic evolution of triploid plants with regular bivalent formation is discussed. The conclusion is reached that although all the progeny of an originally triploid individual will be triploid numerically, only part of the progeny will be triploid genomically. The consequences of this for triploid identification by means of chromosome morphology and isozyme numbers is discussed.

Nuclear DNA sequence variation of the internal transcribed spacer (ITS) and amplified fragment length polymorphisms (AFLPs) were used to illuminate the evolutionary history of Pritzelago alpina, a herbaceous perennial of (sub)alpine to nival habitats of the European high mountains. Maximum likelihood analysis of ITS sequences of P. alpina, Hornungia petraea and Hymenolobus procumbens (the 'Pritzelago alliance') resolved P. alpina and H. petraea as sister taxa. ITS divergence estimates support an origin for P. alpina in the Late Tertiary, while intraspecific diversification started in the Late Quaternary (0.4-0.9 million years ago). AFLP analysis of 76 individuals of P. alpina, representing 24 localities across its entire west-east distribution, identified four mountain lineages in Cantabria, the Pyrenees, (south-) western Alps, and northeastern Alps/Tatras/Carpathians. In an analysis of molecular variance (amova), 14.3% of the total variation derived from this separation. However, relationships among these lineages remained unresolved in neighbour-joining and principal co-ordinates analyses, suggesting a population history of near simultaneous vicariance. Comparison with our previous ITS/AFLP study of Anthyllis montana (Fabaceae) indicates that the two co-distributed but altitudinally differentiated plant species exhibit temporally concordant but spatially discordant patterns of genetic variation. Moreover, levels of AFLP divergence were significantly lower in P. alpina than in the submediterranean, lower-elevation A. montana. Together, these data are consistent with a 'displacement refugia model', which predicts that European mountain plant species associated with lower- and upper-elevation habitats had a different cycle of range contraction into (long-term) glacial and (short-term) interglacial refugia, respectively.

Anthyllis montana is a submediterranean, herbaceous plant of the southern and central European mountains. The internal transcribed spacer (ITS) regions of nuclear ribosomal DNA were sequenced from multiple accessions of the species and several closely related taxa. In addition, amplified fragment length polymorphism (AFLP) was analysed from 71 individuals of A. montana collected in 20 localities, mainly in the Pyrenees, Alps, Italian Peninsula and Balkans. Our ITS phylogeny showed a sequential branching pattern in A. montana, implying a western Mediterranean origin followed by an eastward migration. ITS clock calibrations suggest that speciation of A. montana took place at the Pliocene-Pleistocene boundary, while intraspecific divergence dates to Late Quaternary times (i.e. 0.7 million years ago). The AFLP analyses revealed a major genetic (west/east) subdivision within A. montana, probably caused by the massive glaciation of the Alps during this latter time period. The present-day absence of A. montana from vast parts of the Alps, which appear ecologically suitable for the species, together with the finding of evenly distributed AFLP variability within each of the two western and eastern lineages identified, is taken as evidence for a largely static Late Quaternary history without large-scale migration. High levels of AFLP variation observed among populations, together with weak or absent patterns of isolation by distance, seem to be in accord with long-term population insularization and distributional stasis. However, recent small-scale migration and a narrow hybrid zone between western and eastern lineages need to be postulated to explain the intermediate genetic composition of individuals from the Maritime Alps, a well-known suture-zone for other plant and animal species.

Phylogenetic analyses of various combinations of atpB and rbcL sequence data, trnK restriction sites, and morphological characters of taxa representing the Papaveraceae s.l. (Pteridophyllaceae, Fumari- aceae subfamilies Fumarioideae and Hypecoideae, Papaveraceae s. str. subfamilies Eschscholzioideae, Chelidonioideae, Papaveroideae, Platystemonoideae) are presented. Several measures of data set incongru- ency indicate considerable congruence between data sets. In order to correctly identify the root of the family, combined atpB and rbcL sequence data for the Papaveraceae s.l. and appropriate outgroups (Asarum, Illicium, Platanus, Euptelea, and representatives of the Ranunculaceae and Berberidaceae) were analyzed. Regardless of the outgroup used, all topologies obtained suggest that Pteridophyllum (Pteridophyllaceae) is sister group to Fumariaceae and Papaveraceae s. str. Data sets of the ingroup with Pteridophyllum used as the outgroup were analyzed separately and together, with results from the combined data sets showing increased bootstrap support. Contrary to recent claims, Papaveraceae s. str. remain monophyletic after the exclusion of Pteridophyl- lum and Fumariaceae. In the Papaveraceae s. str., Eschscholzioideae are sister group to Papaveroideae (including Platystemonoideae) and Chelidonioideae (including Glaucium/Dicranostigma). The evolution of floral morphology, geographical distribution, and ecology of Papaveraceae s.l. are briefly discussed.

seminal theoretical paper, "Arbeitsweise der botanischen Phylogenetik und anderer Gruppierungswissenschaften" ("Methods of botanical phylogenetics and other grouping sciences"), first published in 1931. In this paper, Zimmermann clearly ex? pressed many of the underlying principles of phylogenetic systematics?ideas that were later taken up by Hennig and formed the core of his theory. Zimmermann also focused attention on several basic meth?