Petagnaea

Abstract: ITS and rps16 intron sequences of altogether 83 species ofApiaceae subff. Saniculoideae (66 spp.), Apioideae (11 spp.), Mackinlayoideae, Azorelloideae (1 sp. each), Araliaceae subff. Hydrocotyloideae (2 spp.), Aralioideae (1 sp.) and Griseliniaceae (1 sp.) were analysed to reconstruct the phylogeny ofApiaceae subf. Saniculoideae tribe Saniculeae. Particular emphasis was placed on Eryngium, with 230-250 spp. the largest genus ofApiaceae, which was represented by 52 species. It was found that the southern African genera Alepidea and Arctopus are (probably successive) sister to the remainder of the subfamily, followed by the Southwest Asian Actinolema and the western Eurasian Astrantia as sister genera. The cosmopolitan Sanicula and Hacquetia from Central Europe, Petagnaea from Sicily and two major (plus two smaller) clades of the cosmopolitan Eryngium form an unresolved polytomy. Eryngium consists mainly of one large clade distributed exclusively in the Old World, and a second large clade with mostly American species. The first branches of this latter clade are distributed mainly in the Iberian peninsula, implying an Old World origin of this New World clade. It also contains Australian species which apparently arrived there from South America. Although Eryngium is not resolved as monophyletic by the molecular data, it is argued that Eryngium is best interpreted as a monophyletic genus. The tribe is of southern African origin. From there, it reached western Eurasia between 49.3 and 44.6 million years ago (mya). Eryngium entered the New World between 7.4 and 6.6 mya, and Australia was reached between 2.6 and 2.2 mya.

Abstract: Our investigation aims to understand the genetic structure and evolutionary history of Petagnaea gussonei, an ancient and endangered species belonging to the Saniculoideae subfamily (Apiaceae). It is paleoendemic to Sicily, with a small number of populations in the Nebrodi Mountains. A total of seven chloroplast microsatellite repeat loci and 12 AFLP primer combinations were used to screen 115 individuals corresponding to 17 populations. The ratio of seed to pollen flow was also calculated using the modified Ennos equation. A relatively high level of genetic diversity was detected with AFLPs (e.g., 0.045 < H < 0.278), and a moderate variation was also found using cpSSRs (0 < Hk < 0.667). Two different haplotypes (B and W) were identified, with five populations being monomorphic for haplotype B. There was no genetic differentiation on the basis of haplotypic frequency (G ST) and similarity (R ST), and no phylogeographic structure was detected among the populations. AFLP values also confirmed that the populations are not very genetically differentiated. The principal component analysis based on pairwise genetic differences showed three groupings without a geographical correlation. The AMOVA analysis indicates that the amount of variation is higher within populations (82 %) than among populations (18 %). Results of the pollen flow/seed flow ratio indicated positive values for each population, indicating that gene flow by seed is not more efficient than by pollen. Instead, the total pollen/seed flow for all population presents a negative value, suggesting that pollen dispersal does not appear to be more effective over the long range for gene flow than seed dispersal. This differentiation level supports the hypothesis that the fragmentation and isolation of the residual populations is in progress. This phenomenon is due not only to post-ice age climate changes, but also to direct and indirect anthropic actions.

Abstract: Petagnaea gussonei (Apiaceae) is an endangered species endemic to the Nebrodi mountains (north-eastern Sicily). Although an increasing number of studies have been performed on this species, its reproductive biology remains poorly understood. The aim of this study was to investigate in detail the structure of the flower and the fruit of Petagnaea, and the possible implications for its breeding system and seed dispersal mechanism. Results from fieldwork, light microscopy and scanning electron microscopy suggest (1) the presence of protandrous hermaphrodite flowers; (2) geitonogamy, autogamy, and allogamy as breeding system mechanisms of P. gussonei, even if asexual reproduction is preferred by the plant; and (3) epizoochory and hydrochory as possible modalities of fruit dispersal.