Federico Selvi

Evolutionary lineages of nickel hyperaccumulation and systematics in European Alysseae (Brassicaceae): evidence from nrDNA sequence data

BACKGROUND AND AIMS Nickel (Ni) hyperaccumulation is a rare form of physiological specialization shared by a small number of angiosperms growing on ultramafic soils. The evolutionary patterns of this feature among European members of tribe Alysseae (Brassicaceae) are investigated using a phylogenetic approach to assess relationships among Ni hyperaccumulators at the genus, species and below-species level. METHODS Internal transcribed spacer (ITS) sequences were generated for multiple accessions of Alysseae. Phylogenetic trees were obtained for the genera of the tribe and Alyssum sect. Odontarrhena. All accessions and additional herbarium material were tested for Ni hyperaccumulation with the dimethylglyoxime colorimetric method. KEY RESULTS Molecular data strongly support the poorly known hyperaccumulator endemic Leptoplax (Peltaria) emarginata as sister to hyperaccumulator species of Bornmuellera within Alysseae. This is contrary to current assumptions of affinity between L. emarginata and the non-hyperaccumulator Peltaria in Thlaspideae. The lineage Bornmuellera-Leptoplax is, in turn, sister to the two non-hyperaccumulator Mediterranean endemics Ptilotrichum rupestre and P. cyclocarpum. Low ITS sequence variation was found within the monophyletic Alyssum sect. Odontarrhena and especially in A. murale sensu lato. Nickel hyperaccumulation was not monophyletic in any of three main clades retrieved, each consisting of hyperaccumulators and non-hyperaccumulators of different geographical origin. CONCLUSIONS Nickel hyperaccumulation in Alysseae has a double origin, but it did not evolve in Thlaspideae. In Bornmuellera-Leptoplax it represents an early synapomorphy inherited from an ancestor shared with the calcicolous, sister clade of Mediterranean Ptilotrichum. In Alyssum sect. Odontarrhena it has multiple origins even within the three European clades recognized. Lack of geographical cohesion suggests that accumulation ability has been lost or gained over the different serpentine areas of south Europe through independent events of microevolutionary adaptation and selection. Genetic continuity and strong phenotypic plasticity in the A. murale complex call for a reduction of the number of Ni hyperaccumulator taxa formally recognized.

Biotic homogenization can decrease landscape-scale forest multifunctionality

Significance Numerous studies have demonstrated the importance of biodiversity in maintaining multiple ecosystem functions and services (multifunctionality) at local spatial scales, but it is unknown whether similar relationships are found at larger spatial scales in real-world landscapes. Here, we show, for the first time to our knowledge, that biodiversity can also be important for multifunctionality at larger spatial scales in European forest landscapes. Both high local (α-) diversity and a high turnover in species composition between locations (high β-diversity) were found to be potentially important drivers of ecosystem multifunctionality. Our study provides evidence that it is important to conserve the landscape-scale biodiversity that is being eroded by biotic homogenization if ecosystem multifunctionality is to be maintained. Many experiments have shown that local biodiversity loss impairs the ability of ecosystems to maintain multiple ecosystem functions at high levels (multifunctionality). In contrast, the role of biodiversity in driving ecosystem multifunctionality at landscape scales remains unresolved. We used a comprehensive pan-European dataset, including 16 ecosystem functions measured in 209 forest plots across six European countries, and performed simulations to investigate how local plot-scale richness of tree species (α-diversity) and their turnover between plots (β-diversity) are related to landscape-scale multifunctionality. After accounting for variation in environmental conditions, we found that relationships between α-diversity and landscape-scale multifunctionality varied from positive to negative depending on the multifunctionality metric used. In contrast, when significant, relationships between β-diversity and landscape-scale multifunctionality were always positive, because a high spatial turnover in species composition was closely related to a high spatial turnover in functions that were supported at high levels. Our findings have major implications for forest management and indicate that biotic homogenization can have previously unrecognized and negative consequences for large-scale ecosystem multifunctionality.

Anchusa L. and allied genera (Boraginaceae) in Italy

ABSTRACT A revision of the Italian entities of Anchusa and of the related genera Anchusella, Lycopsis, Cynoglottis, Hormuzakia and Pentaglottis was carried out in view of the poor systematic knowledge of some entities of the national flora. The taxonomic treatment relies on a wide comparative basis, including macro- and micromorphological, karyological, chorological and ecological data. After a general description of some poorly known microcharacters of vegetative and reproductive structures, analytical keys, nomenclatural types, synonymies, descriptions, distribution maps and iconographies are provided for each entity. Pentaglottis (P. sempervirens) and Hormuzakia (H. aggregata) are monotypic genera, while Anchusella, Cynoglottis and Lycopsis each include two species of which only one is native to Italy: A. cretica, C. barrelieri and L. arvensis, respectively. The taxonomic autonomy of these “satellite” genera is supported by morphological, palynological and karyological evidence. In Italy Anchusa includ...

Diversity, geographic variation and conservationof the serpentine flora of Tuscany (Italy)

The specialised flora of serpentine outcrops in Tuscany (Italy) is analysed in terms of species richness and geographic variation, in order to identify main centres of diversity and provide a basis for conservation programmes. Five edaphic groups are distinguished, among which obligate endemics, serpentine-preferential taxa, facultative basiphilous and facultative calcifuge serpentinophytes. Relatively low diversity (87 taxa) and high taxonomic distinctiveness (28.7% of endemics plus preferentials) underscore the insular condition of the ophiolitic outcrops. Hemicryptophytes and chamaephytes are the dominat life-forms, in line with the mainly continental character revealed by the phytogeographical analysis. Presence/absence of the taxa in 10 serpentine island systems was assessed using literature and original field data. Number of species and surface of the areas are significantly correlated. Cluster analysis identifies five groups of areas, while ordination indicates the species which are more effective in determining the floristic differences among the areas. Cecina valley, Monte Ferrato, Murlo hills and upper Tiber valley are the main centres of endemism and taxonomic diversity. However, the positive relationship between floristic and geographic distances and the remarkable proportion of species with frequency < 50% highlights a considerable among-area variation. To ‘catch’ such variation, a network of distant protected sites appears more effective than to search for single areas with high diversity. At least one site in each of the five clusters should be included in a ‘Important Plant Area’ network which would ensure the conservation of such a peculiar component of the Italian vascular flora.

Leaf surface and anatomy in Boraginaceae tribe Boragineae with respect to ecology and taxonomy

Summary The main anatomical and surface characters of the leaves of 54 specific and subspecific taxa belonging to 14 Boraginaceae genera of tribe Boragineae were analysed and compared by means of light and scanning electron microscopy. Characters concerning the vascular system appeared essentially uniform, while stomata size and density, structure of individual trichomes, type of indumentum, leaf and epidermis thickness and palisade arrangement were variable in the examined taxa. This variation was discussed in relation to the morphological and ecological diversification exhibited by the members of the tribe. Most species had typical dorsiventral leaves, but some showed an incipient isobilateral symmetry with a layer of abaxial palisade tissue. Thickness of the lamina and of the outer wall of the adaxial epidermal cells were higher in the xerophytic taxa, especially in the psammophytic species of Anchusa . The mesophytic genera Brunnera, Pentaglottis, Trachystemon and, partly, Symphytum had typical hypostomatous leaves, while the xerophytic and psammophytic species were characterized by increased stomatal density on the adaxial surface. This was higher in the taxa with thicker leaves. Abaxial stomatal density and size were inversely correlated. Mesophytic species had more densely spaced and smaller stomata than the xerophytic species. Finally, size of the abaxial stomata was higher in the taxa showing a thicker outer wall of the adaxial epidermal cells. Seven types of trichomes were recognized, five of which were eglandular and two glandular. Some of these types were systematically useful (exclusive to one or two genera) e.g., the hooked hairs of Symphytum and the lithocysts of Trachystemon and Brunnera . Energy dispersive X-ray microanalysis (EDX) showed that silica and calcium are the most abundant elements in the mineral deposits of the trichome cells. No strict correlation occurred between surface elements, trichome structure, edaphic requirements and systematic position of the 14 examined taxa, although the presence of small amounts of sulphur and phosphorus in Nonea and a remarkable abundance of Potassium in Nonea pulla and Pulmonaria picta could have systematic relevance.

Genetic diversity inferred from AFLP fingerprinting in populations of Onosma echioides (Boraginaceae) from serpentine and calcareous soils

Abstract Onosma echioides is a non-obligate serpentinophytic borage occurring discontinuously on calcareous and serpentine outcrops at the northwest limit of its range. Mean concentrations of Ca, Mg and heavy metals in root and shoot samples of eight populations from the two soil types were first determined. Subsequently, the genetic polymorphism of the same accessions was estimated by means of Amplified Fragment Length Polymorphism (AFLP) fingerprinting technique. Root and shoot samples from serpentine outcrops showed higher levels of Ni, Cr and Mg, and lower Ca/Mg ratios compared with those from calcareous soils. Based on 353 polymorphic AFLP bands, the two edaphic groups of populations showed comparable levels of genetic diversity. A remarkable genetic differentiation between populations and a high level of within-population genetic variance were found. Results of Mantels test supported a significant correlation between genetic and geographical distances, while no difference in relation to the edaphic factor was detected. Molecular data suggested isolation as the key factor shaping the infraspecific genetic structure of O. echioides, which may be in relation with the short-distance, zoochorous systems of seed dispersal and pollination of this species.

Fossil and Extant Western Hemisphere Boragineae, and the Polyphyly of “Trigonotideae” Riedl (Boraginaceae: Boraginoideae)

Abstract Boraginaceae tribe Trigonotideae comprises a heterogenous assemblage of taxa, many of which have been shown to belong to widely divergent lineages in Boraginaceae in the recent past, with some taxa now assigned to three of the four currently recognized tribes of the Boraginaceae s. s., namely the Cynoglosseae, Echiochileae, and Lithospermeae. The systematics of Moritzia and Thaumatocaryon, the only endemic South American genera of Boraginaceae, have been controversially discussed in the past, and their most recent placement was in Trigonotideae. The present study investigates the phylogenetic relationships of “Trigonotideae” based on micromorphology and molecular data (ITS including 5.8S rRNA, and the trnL-trnF spacer). Molecular data show that “Trigonotideae” are polyphyletic, and none of its members is at all closely related to Trigonotis itself. Moritzia and Thaumatocaryon are closely allied to each other and are the sister group of the Old World Boragineae. Flowers, pollen, and fruit morphology strongly support this systematic placement. Extant (native) Boragineae are absent from North America and had not previously been reported from South America, whereas members of the Cynoglosseae, Echiochileae, and Lithospermeae have been reported from both continents. Moritzia and Thaumatocaryon are thus the only native representatives of Boragineae in the Americas and represent an unexpected western Eurasian/South American disjunction. However, several (widespread and abundant) fossil taxa from the Cenozoic of North America (especially species of †Prolithospermum) can be confidently placed into Boragineae. Extant Moritzia /Thaumatocaryon likely go back to a lineage which reached North America from Europe and then migrated into South America, with subsequent extinction in North America.

Pollen morphology in theBoragineae (Boraginaceae) in relation to the taxonomy of the tribe

The results of a comparative survey on pollen morphology in theBoragineae by means of light, scanning and transmission electron microscopy are presented and discussed in relation to the taxonomy of the tribe. Multivariate analyses lead to the recognition of 15 pollen morphotypes for which a discriminant key is proposed. The discriminatory characters concern mainly the stereostructural and ultrastructural features of the grains, such as tectum sculpture and aperture morphology, while the number of apertures appears variable within genera and even single species. Seven out of the 12 investigated genera, as currently circumscribed, are matched by palynological data:Anchusella, Borago, Brunnera, Elizaldia, Lithodora, Symphytum andTrachystemon. On account of aperture shape,Lithodora is however closer to theLithospermeae than to theBoragineae. Other genera, and in particularNonea, show a wide variation in tectum ornamentation, shape of grains and number of apertures. Palynological data do not support a broad concept of the genusAnchusa, and point to the autonomy of the ‘satellite’ generaHormuzakia, Gastrocotyle, Phyllocara, Pentaglottis andCynoglottis.

Tree Diversity Limits the Impact of an Invasive Forest Pest.

The impact of invasive herbivore species may be lower in more diverse plant communities due to mechanisms of associational resistance. According to the “resource concentration hypothesis” the amount and accessibility of host plants is reduced in diverse plant communities, thus limiting the exploitation of resources by consumers. In addition, the “natural enemy hypothesis” suggests that richer plant assemblages provide natural enemies with more complementary resources and habitats, thus promoting top down regulation of herbivores. We tested these two hypotheses by comparing crown damage by the invasive Asian chestnut gall wasp (Dryocosmus kuriphilus) on chestnut trees (Castanea sativa) in pure and mixed stands in Italy. We estimated the defoliation on 70 chestnut trees in 15 mature stands sampled in the same region along a gradient of tree species richness ranging from one species (chestnut monocultures) to four species (mixtures of chestnut and three broadleaved species). Chestnut defoliation was significantly lower in stands with higher tree diversity. Damage on individual chestnut trees decreased with increasing height of neighboring, heterospecific trees. These results suggest that conservation biological control method based on tree species mixtures might help to reduce the impact of the Asian chestnut gall.

An updated checklist of the vascular flora native to Italy.

Abstract An updated inventory of the native vascular flora of Italy, providing details on the occurrence at regional level, is presented. The checklist includes 8195 taxa (6417 species and 1778 subspecies), distributed in 1092 genera and 152 families; 23 taxa are lycophytes, 108 ferns and fern allies, 30 gymnosperms and 8034 angiosperms. The taxa currently occurring in Italy are 7483, while 568 taxa have not been confirmed in recent times, 99 are doubtfully occurring in the country and 19 are data deficient. Out of the 568 not confirmed taxa, 26 are considered extinct or possibly extinct.