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Background and AimsThe hypothesis of an ancient introduction, i.e. archaeophyte origin, is one of the most challenging questions in phylogeography. Arundo donax (Poaceae) is currently considered to be one of the worst invasive species globally, but it has also been widely utilzed by man across Eurasia for millennia. Despite a lack of phylogenetic data, recent literature has often speculated on its introduction to the Mediterranean region.MethodsThis study tests the hypothesis of its ancient introduction from Asia to the Mediterranean by using plastid DNA sequencing and morphometric analysis on 127 herbarium specimens collected across sub-tropical Eurasia. In addition, a bioclimatic species distribution model calibrated on 1221 Mediterranean localities was used to identify similar ecological niches in Asia.Key ResultsDespite analysis of several plastid DNA hypervariable sites and the identification of 13 haplotypes, A. donax was represented by a single haplotype from the Mediterranean to the Middle East. This haplotype is shared with invasive samples worldwide, and its nearest phylogenetic relatives are located in the Middle East. Morphometric data characterized this invasive clone by a robust morphotype distinguishable from all other Asian samples. The ecological niche modelling designated the southern Caspian Sea, southern Iran and the Indus Valley as the most suitable regions of origin in Asia for the invasive clone of A. donax.ConclusionsUsing an integrative approach, an ancient dispersion of this robust, polyploid and non-fruiting clone is hypothesized from the Middle East to the west, leading to its invasion throughout the Mediterranean Basin.

Using iconography and ancient texts, we list and discuss Arundo and Phragmites taxa (canes and reeds, respectively), their uses, such as writing, units of measurement, medicines, fuels, food, fodders, rural lifestyles, construction materials, ship building, musical wind instruments, throwing weapons, and sacred symbols. These plants that were essential in the daily life of Mediterranean civilizations for millennia could still play a very useful role (bioremediation, CO 2 fixation, biogas), for future generations.

Aim Although recognized as hotspots of biodiversity, Mediterranean peninsulas have been poorly studied with regard to the evolutionary legacy of Quaternary environmental changes for endemic lowland biota. Using the phylogeography of the lowland Arundo plinii Turra (Poaceae), we evaluated two hypotheses regarding the genetic structure of southern European species, that there is: (H 1 ) a decrease in regional genetic diversity with increasing latitude induced by past contractions towards southern refugia; and (H 2 ) a strong differentiation between isolated refugia without a latitudinal gradient in genetic diversity. Location Italian and Balkan peninsulas, Mediterranean Basin. Methods Arundo plinii from 59 localities across six geographical areas was analysed for three genetic markers: (1) five intergenic spacers (4590 bp) of plastid DNA, investigated by molecular dating and phylogeographical analyses; (2) six primer pairs (852 fragments) of amplified fragment length polymorphism (AFLP) fingerprinting, analysed as indices of genetic structure and diversity; and (3) chromosome counts regarding the prevalence of polyploidy in the genus Arundo. Results Chloroplast DNA and AFLP both described a gradient of genetic diversity in Italy, from the highest values in Sicily to uniform genetic clusters in northern Italy, versus relatively high genetic diversities in both northern and southern parts of the Balkans. Moreover, they supported a strong genetic differentiation between the two peninsulas, despite the distinction of one admixed genotype located in Croatia. Polyploid events were detected in northern and southern margins of the species' distribution. Main conclusions The results support distinct Pleistocene evolutionary histories for A. plinii within the two peninsulas. In Italy, this species probably persisted mainly in southern regions (Calabria and Sicily) during the Pleistocene glaciations, leading to the more recent formation of the northern populations. Conversely, the Balkan populations probably persisted at different latitudes during the Pleistocene, as illustrated by the conservation of equivalent genetic diversities in both the northern and southern Balkans.

Among the 12 subfamilies currently considered in the systematics of Poaceae, the Arundinoideae have long been considered as a dustbin group, with a diversity of forms putatively hiding incertae sedis. Because this subfamily has been poorly investigated using molecular markers for the last two decades, the present study provides the first complete phylogeny of the Arundinoideae based on five plastid DNA loci sequenced for 12 genera, and analysed with and without plastome data from previous studies. The refined Arundinoideae appear to be a robust evolutionary lineage of Poaceae, divided into three tribes with some biogeographical patterns: (1) tribe Arundineae, the most heterogeneous tribe, including Eurasian Arundo, Australian Amphipogon and Monachather, and South African Dregeochloa; (2) tribe Crinipedeae (described here), including Crinipes, Elytrophorus, Styppeiochloa and Pratochloa (described here), with a South and East African distribution; and (3) tribe Molinieae, including Hakonechloa, Molinia and Phragmites, with a Eurasian distribution. Despite reduction in size, this small subfamily conserves a high diversity of morphological forms, with several small but highly differentiated genera. Finally, the molecular dating approach provides an evolutionary framework to understand the diversification of Arundinoideae, refuting Gondwanan vicariance between genera and suggesting capability for long distance dispersal.

The systematics of the genus Arundo (Poaceae) remains poorly resolved because of the overlap of morphological characters classically used in the taxonomy of the genus and insufficient variation of DNA sequences. The main aim of this study is to delimit genetic clusters with AFLP fingerprints and to compare them with morphological data. On the basis of extensive sampling in the Mediterranean area, AFLP markers clearly showed five clusters. Despite overlapping values, morphometric analyses strongly confirm these clusters, and new qualitative features allow the recognition of five taxa: the Taiwanese A. formosana, the cosmopolitan A. donax, the circum-Mediterranean A. micrantha, the Italo-Balkan A. plinii and the Franco-Ligurian A. donaciformis (Loisel.) Hardion & al. comb. nov. Additionally, this study shows a correlation between genetic diversity, caryopsis production and ploidy level. However, the lack of genetic diversity for A. micrantha and A. donax in the Mediterranean area remains enigmatic.

From their introduction in the beginning of the 19th century in the Lez river at Montpellier, the American Ludwigia have, progressively, colonized the whole of France. In spite of their real nuisance for natural habitats, these ornamental hydrophytes are still for sale. The management of these invasive species requires their precise identification, but this appears to be extremely complex. A morphological and cytogenetic study allowed to confirm the presence of two different taxa in France, and the absence of hybrids in the mixed zones that were monitored. The diploids (2n = 16) correspond to L. peploides subsp. montevidensis (Spreng.) Raven, and the decaploids (2n = 80) to L. grandiflora subsp. hexapetala (Hook. & Arn.) Nesom & Kartesz. The diploids colonize especially the Mediterranean region (except the Southeastern part), while the polyploids predominate throughout the other regions. Both taxa exhibit an intense vegetative growth, however they have a distinct breeding system: the self-compatible diploids were always found very fructiferous, whereas the self-incompatible polyploids were often observed as sterile. The breeding system difference could explain the substitution of L. grandiflora (first wave of invasion in the 19th century) by L. peploides, in the 20th century, in the southern part of France.

The island of Corsica is a Mediterranean hotspot of plant biodiversity characterized by a high rate of plant endemism, but also by a lack of studies combining genetic diversity and conservation. In Corsica, the dioecious and Corso-Sardinian endemic Mercurialis corsica Cosson (Euphorbiaceae) occurs across a wide ecological gradient, but the number of populations have decreased considerably over the last century. The main aim of this study was to examine the patterns of genetic diversity occurring in the Corsican populations of M. corsica , depending on their location and demographic structure. The rDNA sequences did not show the existence of any polymorphism, whereas the cpDNA sequences revealed the divergence of the western Corsican populations. By contrast, when the AFLP markers were examined, although significant levels of differentiation were detected between populations, no distinct geographical patterns were observed except for the pronounced isolation of the Cap Corse genotypes. No significant correlations were found to exist between population size and the genetic diversity indexes used. The results of this study suggest that M. corsica has undergone a complex gene flow history involving past population admixtures, followed by fragmentation processes resulting in population differentiation but no geographical patterns of isolation. These results support the existence of three evolutive conservation units which have to be monitored in priority to determine whether the current pattern of demographic structure is still declining or has stabilized.