A. Scrugli

Ménage À Trois—Two Endemic Species of Deceptive Orchids and One Pollinator Species

In the sexually deceptive orchid genus Ophrys, reproductive isolation is based on the specific attraction of males of a single pollinator species by mimicking the female species-specific sex pheromone. Changes in the odor composition can lead to hybridization and speciation by the attraction of a new pollinator that acts as an isolation barrier toward other sympatrically occurring Ophrys species. On Sardinia, we investigated the evolutionary origin of two sympatrically occurring endemic species, Ophrys chestermanii and O. normanii, which are both pollinated by males of the cuckoo bumblebee Bombus vestalis. Chemical and electrophysiological analyses of floral scent and genetic analyses with amplified fragment length polymorphisms and plastid-markers clearly showed that O. normanii is neither a hybrid nor a hybrid species. The two species evolved from different ancestors, viz. O. normanii from O. tenthredinifera and O. chestermanii from O. annae, and converged to the same pollinator attracted by the same bouquet of polar compounds. In spite of sympatry, pollinator sharing and overlapping blooming periods, no evidence has been obtained for gene flow between O. chestermanii and O. normanii indicating an unusual case among sexually deceptive orchids in which postmating rather than premating reproductive isolation mechanisms strongly prevent interspecific gene flow.

Confirmation of hybridization among sympatric insular populations of Orchis mascula and O. provincialis

Abstract.The localized hybridization between Orchis mascula and O. provincialis in Sardinia is investigated. The two parental species are closely related and share the same pollinators but do not hybridize in any other areas of sympatry. Artificial crosses between the two species in areas of sympatry on the continent revealed that, in absence of an ethological isolation, a strong post-pollination barrier exists and preserves species integrity in the main part of their distribution. However, on Sardinia, morphological observations, karyological and molecular analyses of intermediate phenotypes confirmed the occurrence of hybridization between the insular O. mascula ssp. ichnusae and O. provincialis and the bi-directionality of pollen flow. The occurrence of hybrids on the island indicates a failure of otherwise strong post-pollination barriers between O. mascula and O. provincialis.

Karyomorphological parameters and C-band distribution suggest phyletic relationships within the subtribeLimodorinae (Orchidaceae)

Karyotype attributes and heterochromatin distribution were used to characterize fourteen taxa of the subtribeLimodorinae (Orchidaceae). The karyotypes were established using morphometrical parameters following Feulgen staining and C-banding. No significant differences in heterochromatin content were found between specimens collected from various sites. Four species of theEpipactis helleborine group possess some chromosome pairs with quite similar heterochromatin patterns; some differences were found inE. distans with respect to other species of this group.Epipactis palustris differed significantly from otherEpipactis species in its different karyotype and its numerous terminal C-bands. The largest differences from the other genera were shown inLimodorum as far as karyomorphology and heterochromatin patterns were concerned. C-band distribution indicated similarity among non-homologous chromosomes, supporting a possible palaeo-polyploid origin for theCephalanthera andEpipactis karyotypes.

Heterochromatin distribution in selected taxa of the 42-chromosomes Orchis s. l. (Orchidaceae)

Abstract In six 42-chromosomes taxa belonging to genus Orchis s. l. heterochromatin location and distribution and staining properties were analysed by means of C-banding and of the fluorochromes 4’-6-diamidino-2-phenylindole-2HCl (DAPI) and Hoechst 33258. Most species could be distinguished on the basis of heterochromatin amounts and distribution. In the species O. mascula and O. provincialis most DAPI-positive sites did not co-localize with C-bands. DAPI revealed bright fluorescence at telomeric or subtelomeric regions of numerous chromosomes of O. mascula and particularly large/bright blocks at the telomeres of O. provincialis. In O. x penzigiana (Orchis mascula ssp. ichnusae x O. provincialis) overall heterochromatin distribution followed that of the parental species. In Neotinea group all DAPI positive bands co-localize with C-bands, but have different distribution in the taxa analysed. Present and literature data indicate a high level of plasticity of heterochromatin organization in Orchis s. l., and suggest evolutionary pathways in agreement with recent molecular data.

Karyomorphological and biochemical studies in Glebionis coronaria (L.) Spach and Glebionis segetum (L.) Fourreau from Italy

Abstract The karyotype structures and the composition and distribution of the heterochromatin in Glebionis coronaria and Glebionis segetum using Giemsa and fluorescent banding techniques were analysed. The species studied are diploids with 2n = 2x = 18 chromosomes. G. coronaria possesses the most symmetrical karyotype, comprising mainly metacentric chromosomes. G. segetum, with formula 12 m + 6 sm, showed a slightly less symmetrical karyotype. Giemsa C‐banding revealed little constitutive heterochromatin in both species. The presence of telomeric bands was restricted to two chromosome pairs. After staining with chromomycin A3, the chromosomes of G. coronaria and G. segetum revealed bright fluorescence at the telomeric regions of two chromosomes. No 4‐6‐diamidino‐2‐phenyl‐indole bright blocks were observed. To estimate genetic variability in the species under consideration, genotypic expression was also determined through isozyme electrophoresis of cytosolic ascorbate peroxidase, considered a genetic marker in the study of plant phylogenetics. The relationships between G. coronaria and G. segetum are discussed. Abbreviations: ASC, ascorbate; BSA, bovine serum albumin; cAPX, cytosolic ascorbate peroxidase; CMA, chromomycin A3; DAPI, 4‐6‐diamidino‐2‐phenyl‐indole; EDTA, ethylenediaminetetraacetic acid; PAGE, polyacrylamide gel electrophoresis

Sardinia’s bryological flora: the state of knowledge and chorological considerations

Summary Since the beginning of the 19th century, Sardinia has been the site of bryological explorations. From the numerous contributions made to date, it can be seen that Sardinias bryophyte patrimony amounts to 393 entities for Musci and 86 for Hepaticae and Anthocerotae. From the chorological viewpoint, it is seen that both mosses and liverworts present a high percentage of the Mediterranean component, which is to be placed in connection with Sardinias geographic position and its phytoclimatic conditions. Especially among mosses, the presence of boreal and arctic-alpine species, found for the most part on the islands highest peaks, is particularly significant. The main factors that influence bryophyte distribution in the island are altitude, the different kinds of phanerogamic vegetation and the nature of the substratum.

Bryophyte flora of some temporary pools in Sardinia and Corsica

Abstract A comparative study of the bryophytes in some Sardinian and Corsican wetlands of major naturalistic value, such as the “padule of Suartone” (SE Corsica) and “pauli of the Giara of Gesturi” (C Sardinia), was carried out. In Europe, these habitats (Mediterranean temporary pond) are indicated as priority natural habitats under the Habitats Directive 92/43/EEC. In the Sardinian pauli, 56 taxa (50 Bryophyta and six Marchantiophyta) were found, while in the Corsican padule, 30 taxa (21 Bryophyta and nine Marchantiophyta) are reported. Among the bryophytes collected in the padule, the discovery of Scleropodium cespitans, Riccia perennis and Campylopus introflexus is of particular phytogeographic interest. Data are here reported together with information on the phytogeography and ecology of the recorded species.

Karyomorphological analyses and chromatin characterization by banding techniques in Euphorbia characias L. and E. wulfenii Hoppe (= E. veneta Willd.) (Euphorbiaceae)

Abstract Karyomorphological analysis of Euphorbia characias L. using Giemsa and fluorescent techniques revealed a characteristic C-banding pattern. Intraspecific variation in C-banding pattern was observed within of chromosomal complements of some populations of this species. Using fluorochrome Chromomycin A3 (CMA), E. characias exhibit trait patterns of CMA+ bands in intercalary and telomeric regions. Many bands correspond to Giemsa C-band. After the double staining with chromomycin A3/DAPI numerous chromosomes have showed a distribution of rich pattern in basic G-C (CMA+/DAPI-). The present studies indicate that to determine this characteristic C-banding pattern has intervened a deep restructuring of the karyotype. The karyotypes of E. characias and E. wulfenii were indistinguishable with very similar karyomorphologies and banding patterns, and these data suggest that both entities might be geographical biotypes.

Acaulon fontiquerianum Casas et Sérgio (Musci, Pottiaceae) new to Sardinia(Italy)

Abstract Acaulon fontiquerianum Casas et Sergio ( Pottiaceae ) was found in the course of bryological research conducted in a coastal area of southeastern Sardinia. The ecological characteristics of the site and the current distribution of the species in the Mediterranean basin are reported.

Localization of rDNA loci by Fluorescent In Situ Hybridization in some wild orchids from Italy (Orchidaceae)

Abstract The 18S-5.8S-25S (pTa71) and 5S (pTa794) rDNA were used as probes for in situ hybridization to reveal the physical localisation of ribosomal genes in some species of orchids. Earlia robertiana (2n = 36) revealed one chromosome pair with both pTa71 and pTa794 signals; Anacamptis papilionacea (2n = 32) showed two pairs of 5S rDNA and one pair of 18S-25S sites; A. morio (2n = 36) had two pairs of 18S-25S rDNA and one pair of 5S sites; the natural hybrid A. x gennarii (A. morio x A. papilionacea, 34 chromosomes) showed three 18S-25S and three 5S rDNA sites; finally, A. collina (2n = 36) showed only one pair of 18S-25S rDNA and one pair of 5S rDNA sites. This preliminary contribution indicates that repetitive DNA sequences in orchids may prove very useful for the understanding of evolutionary trends.