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Rhamnus persicifolia Moris is an endemic small tree belonging to the Rhamnus cathartica group, growing along mountainous streams of Central-Eastern Sardinia (Italy). ISSR markers were used to detect the genetic diversity within and among six populations representative of the species distribution range. In spite of the limited distribution of this endemic taxon, fairly high levels of genetic diversity were detected. Percentage of polymorphic bands (PPB), gene diversity (HS and HT) and Shannon information measure (Sh) were calculated both at population (PPB = 30.70%, HS = 0.1105, Sh = 0.1646) and at species level (PPB = 68.42%, HT = 0.2066, Sh = 0.3139).The existence of a spatial distribution of genetic diversity in R. persicifolia was revealed by a low gene flow, a fairly high level of genetic differentiation (GST = 0.4583) among populations and a positive correlation between genetic and geographic distances (Mantel test, r = 0.71, p = 0.016). The spatial genetic structure was also confirmed with BAPS analysis. Our results show that a certain level of isolation by distance and sex-ratio bias may explain the distribution of genetic diversity among populations. Conservation measures are suggested on the basis of the genetic diversity detected, by implementing an integrated in situ and ex situ conservation program for each population, in order to ensure effective protection for this endemic species. © 2011 Elsevier Ltd.

Measuring levels of population genetic diversity is an important step for assessing theconservation status of rare or endangered plant species and implementing appropriateconservation strategies. Populations of Ribes multiflorum subsp. sandalioticum andR. sardoum, two endangered endemic species from Sardinia, representing the wholegenus on the island, were investigated using ISSR and SSR markers to determine levelsand structure of genetic variability in their natural populations. Results indicatedmedium to low genetic diversity at the population level: Nei’s gene diversity for ISSRmarkers ranged from 0.0840 to 0.1316; the expected heterozygosity (H E ) for SSR ran-ged from 0.4281 to 0.7012. In addition, only one remnant population of R. sardoumshowed a high level of inbreeding, in accordance with its very small size. Regardingthe structure of the six R. sandalioticum populations, both principal coordinatesanalysis (PCoA) and STRUCTURE analysis of ISSR and SSR data highlighted low pop-ulation structure, although two populations appeared to be clearly distinct from theothers. The genetic pattern of the two taxa associated with their different ecologicalpositions indicated resilience of R. sandalioticum populations in fresh and humidhabitats and uncertain future resistance for the residual R. sardoum population inxeric calcareous stands. Hence, this study highlights the importance of an integratedconservation approach (genetic plus in situ and ex situ conservation studies/measures)for activating management programmes in these endemic and threatened taxa thatcan be considered as crop wild relatives of cultivated Ribes species.INTRODUCTIONEndangered species with small and isolated populations havebeen the subject of numerous conservation studies in the lastdecade. Their aims were to avoid biodiversity loss and under-stand survival/extinction mechanisms in an evolutionary con-text (Beissinger 2000; Freville et al. 2007; Abeli et al. 2009).The extinction process can be related to ecological factors suchas competition, predation, parasitism, disease and environ-mental stresses (Jones 2008). In recent years, habitat alterationdue to shifts in climatic characters, human activities and sto-chastic events are among the main current causes of biodiver-sity loss (Chapin et al. 2000). As a consequence, threatenedspecies may have low numbers of populations or small popula-tion size (e.g. Ellstrand & Elam 1993). In particular, island en-demics are thought to be even more susceptible to extinction(Frankham 1997, 1998) due to an increased probability of sto-chastic events on populations and phenomena of genetic driftand inbreeding depression, resulting in reduced genetic diver-sity (Izawa et al. 2007; Bruni et al. 2013). Given these threats,conservation of endangered species in their biogeographic con-text requires a thorough knowledge of the genetic structure oftheir populations (Rao & Hodgkin 2002). In this framework,maintaining these species’ genetic diversity is of pivotal impor-tance as it is associated with population viability and the evolu-tionary potential to adapt to environmental changes (Reedet al. 2002; Reed & Frankham 2003).Ribes L. (Grossulariaceae) is a genus of ca. 200 taxa distrib-uted in temperate regions of the Northern Hemisphere and inthe Andes (Mabberley 2008). Ribes sardoum Martelli andR. multiflorum Kit ex Roem et Schult. subsp. sandalioticumArrigoni (hereafter, R. sandalioticum) are the only two membersof this genus present in Sardinia, and both are endemic to theisland. Sardinia is the only Mediterranean island where thisgenus is represented exclusively by endemic taxa, while on thenearest island systems the genus is absent (i.e. Tuscan archipel-ago) or represented only by widely distributed species (see Fenuet al. 2012 and references therein). R. sardoum is a threatenedspecies with only one small population found in the Supramon-tes region (CE Sardinia; Bacchetta et al. 2008) and categorisedas critically endangered (CR) on the IUCN Red List. R. sandali-oticum has 13 populations established in three biogeographicsubsectors, mainly distributed in CE and NE Sardinia, and iscategorised as endangered (EN; Fenu et al. 2012).

Seed germination (effects of light, temperature, NaCl and KNO 3 ) of the coastal endangered species Crucianella maritima was investigated by testing seeds from three different populations. Data were analyzed by means of Generalized Linear Mixed Model (GLMM). The principal results showed that germination of C. maritima seeds was characterized by photoinhibition, absence of primary dormancy and salt-induced secondary dormancy, with no need for high nutrient availability (KNO 3 ). Intraspecific differences in germination pattern emerged, apparently due to a different seed mass. These results show important germination traits of C. maritima which should be taken into account in possible reintroduction attempts aimed at restoring threatened populations of this species.

A study on the vascular flora of the Gennargentu Massif (Central-Eastern Sardinia) is presented. According to our results, the flora consists of 948 taxa: 686 species, 249 sub- species, 10 varieties and 3 hybrids, belonging to 97 families and 427 genera. Three taxa are new findings for the flora of Italy and eight for that of Sardinia. Life form analysis revealed, in particular, dominance of 35.65 % hemicryptophytes, 34.6 % therophytes, 12.13 % geophytes and 11.6 % (nano)-phanero- phytes. As concerns chorology, the Mediterranean element is largely prevailing (68.14%), mainly represented by circum- Medit. (29.1 %) and Euro-Medit. (23.07 %). Endemics are 14.87% of the whole flora (141 taxa), with a large prevalence of Sardo-Corsican (39.01 %) and Sardinian taxa (35.46 %), i.e. 74.47% of the total. Due to the high number of taxa (9) of Gennargentu exclusive endemics and the geologic and geo- morphologic peculiarities, it is here proposed a biogeographic classification for these territories serving to the identification of an autonomous sector. L’étude de la flore vasculaire du massif du Gennargentu (Sardaigne centre-est) est présentée. Les investigations floris- tiques ont établi la présence de 948 taxa, dont 686 espèces, 249 sous-espèces, 10 variétés et 3 hybrides, appartenant a 97 familles et 427 genres. Trois nouveaux taxa sont signalés pour la flore d’Italie et huit pour la flore Sarde. L’analyse du spectre biologique établit, en particulier, la dominance d’hémicryptophytes (35,65 %), de thérophytes (34,6 %), de géophytes (12,13 %) et de (nano-)phanérophytes (11,6 %). L’analyse du spectre chorologique met en évidence la prédo- minance de composantes méditerranéennes (68,14 %), princi- palement représentées par des taxa circum-méditerranéens (29,1 %) et euro-méditerranéens (23,07 %). Les entités endé- miques représentent 14,87% (141 taxa) de la flore, avec une majorité d’éléments corsico-sardes (39,01%) et sardes (35,46%) formant ensemble 74,47% des endémiques. En raison du nombre élevé de taxa (9) d’espèces endémiques exclusives du Gennargentu et des particularités géologiques et géomorpho- logiques, une classification biogéographique est proposée pour ces territoires servant à l’identification d’un secteur autonome.