Aldo Musacchio

Università della Calabria, Rende, Calabria, Italy

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Publications (51)99.03 Total impact

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    ABSTRACT: Orchid species of Mediterranean genus Serapias often live in sympatry, exhibit similar floral morphology, bloom in the same period and share the same pollinators. Previous studies on Serapias species have ascertained that reproductive isolation is based on pre-pollination barriers, that secretory cells and trichomes are typically distributed on the floral labellum and that flowers produce aliphatic compounds. In this study we compare the floral scent composition of four widespread, co-occurring Serapias species, namely Serapias lingua, Serapias parviflora, Serapias vomeracea and Serapias cordigera. Our goals are to assess if differences in floral scent may act as interspecific pre-pollination barriers and if these olfactory signals may be involved in the pollination strategy of Serapias. We find that all the selected species produce C20–C29 alkanes and alkenes and, in addition, have detected the presence in S. cordigera of large amounts of oleate and stearate ethyl ester. Our findings help to clarify that the sympatric Serapias species have slightly different floral scent signatures that may account for their relevant role as pre-pollination barriers. Therefore, the pollination strategy of Serapias relies not only on the tubular shape of their floral corolla but also on the production of olfactory signals that may lure potential pollinators and even assure a sufficient degree of pollinator fidelity.
    Plant Systematics and Evolution 08/2012; 298:1837-1843. · 1.31 Impact Factor
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    ABSTRACT: Despite highly specialized pollination strategies, hybridization is a common phenomenon among Mediterranean deceptive orchids. Food-deceptive species sire a progeny of F1 unfertile plants, which work as a late post-zygotic barrier. Conversely, when pre-zygotic barriers of sexually deceptive (Ophrys) species are absent, the hybrids are fertile and an extensive introgression may occur. Here, we have performed molecular analysis and hand pollination treatments to characterize a hybrid zone of two food-deceptive species, O. mascula and O pauciflora. Hybrids (called O. × colemanii) have shown different amounts of parental nrDNA, strongly supporting that they are F2 and/or successive hybrid generations. Comparable high levels of reproductive success have been detected in natural conditions and in experimental crosses suggesting the absence of effective reproductive barriers either between hybrids, either between hybrids and parental species. In light of ecological and distributional features of O. × colemanii across its distribution range, we hypothesize that these populations have originated by secondary contact in the periglacial belt of Apennines. Moreover, the rare and localized O. pauciflora could benefit a genetic enrichment by hybridizing with a widespread related species. O. × colemanii is not a dead end population, but may have a role as potential reserve of adaptive variability and is an unusual stage along the speciation process.
    Flora - Morphology Distribution Functional Ecology of Plants 07/2012; 207:753-761. · 1.72 Impact Factor
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    ABSTRACT: A great variety of colours, shapes, scents, energy‐rich rewards and other floral traits form an integrated system that increases pollination efficiency or reduces pollen loss. Flowers lacking energetic rewards possess a more elaborate morphology to ensure co‐specific pollination. Despite the prevalence of deceptive species among Euro‐Mediterranean orchids, the study of their floral micromorphology is still in its infancy. In this work, we examine the floral micromorphology of four sympatric species of the widespread Mediterranean genus Serapias. Electron microscopy (scanning, transmission) was performed on flowers of four sympatric species of the deceptive genus Serapias, the widespread S. cordigera, S. lingua, S. parviflora and S. vomeracea. Each species has a characteristic combination of specialized, secretory epidermal cells and trichomes on the labellum and, to a lesser extent, the petals. Serapias lingua is highly specialized in that it produces olfactory signals and has two types of trichome with secretory apical cells, one of which is also present in S. parviflora. In addition to striated, conical secretory cells, S. cordigera and S. vomeracea also have characteristic, atypical secretory trichomes with bilobulate or dome‐like protuberances. The labellar micromorphology of S. lingua and S. parviflora is adapted for scent production, whereas S. vomeracea and S. cordigera possess trichomes that may also provide visual and/or tactile cues. Owing to the combined effect of the specific floral fragrance and labellar micromorphology in pollinator selection, the pollination ecology of Serapias spp. is even more specialized than previously thought. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 714–724.
    Botanical Journal of the Linnean Society 02/2012; 169:714-724. · 2.59 Impact Factor
  • Flora - Morphology Distribution Functional Ecology of Plants 01/2012; 207:753-761. · 1.72 Impact Factor
  • Plant Systematics and Evolution 01/2012; 298:1837-1843. · 1.31 Impact Factor
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    ABSTRACT: To date, current research involving pollen viability has been evaluated in a relatively low number of orchid species. In the present study, we focused on five related Mediterranean orchid genera (Anacamptis, Orchis, Dactylorhiza, Ophrys and Serapias) that are characterized by different types of deceptive pollination. The in vitro germination ability of increasingly aged pollinaria of eight food-, seven sexually and two shelter-deceptive species was evaluated. Pollination experiments on two food-, one sexually and one shelter-deceptive species were also performed and the percentage of embryonate seeds derived from the increasingly aged pollinaria was checked. All of the examined species showed long-term viabilities (=50 % pollen tube growth) that ranged from 8 to 35 d. Species with the same deceptive pollination strategies exhibited the same pollen viability trends. Interestingly, pollen viabilities of species groups with different deception types have shown significant differences, with sexually and shelter- deceptive species exhibiting a shorter life span than food-deceptive species. This study confirms the prolonged germination and fertilization capacities of orchid pollinaria, and to our knowledge is the first report demonstrating a clear relationship between pollen viability and pollination system. It is proposed that this relationship is attributed to the different types of reproductive barriers, pre- or post-zygotic, that characterize Ophrys and Serapias and the food-deceptive species, respectively.
    Annals of Botany 11/2010; 106(5):769-74. · 3.45 Impact Factor
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    ABSTRACT: Recent work, based on morphological and cytotaxonomical information, claimed the independence of Plantago brutia Ten., a narrow endemic of South Italy, with respect to Plantago media L. Here, we present a further evaluation of the systematic relationships occurring between these two taxa as revealed by molecular studies. We sampled P. brutia in most of the known populations and P. media in several European stands, from Sweden to the Iberian Peninsula and Balkans. We then investigated the relationships among the sampled populations by using as molecular markers the internal transcribed spacer regions ITS1 and ITS2. Furthermore, we considered cpDNA to gain further insight into the relationships among P. brutia/P. media populations. Based on nrDNA data, P. brutia appeared to be nested within the P. media complex, but as a well distinct subunit. This is congruent with a subspecific rank for this taxon within P. media. The cpDNA revealed the occurrence of several haplotypes in the studied material. Most of the assessed haplotypes were exclusive for single populations and thus phylogenetically uninformative. Nonetheless, we have found some haplotypes that are shared by different cytotypes or populations throughout the species range, suggesting possible explanations for the phylogenetic relationships occurring between P. brutia and the autopolyploid complex P. media.
    Plant Biosystems 09/2010; 144(3):573-581. · 1.91 Impact Factor
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    ABSTRACT: Knowledge of genetic spatial structure may provide insights into the causes of population disjunctions in plants. Serapias politisii is a narrow endemic with only a few populations scattered along the opposite coasts of the Otranto strait (southern Adriatic Sea). It was originally considered to be of hybrid origin between S. vomeracea ssp. laxiflora and S. parviflora, a possibility suggested also by a DNA phylogenetic study that grouped Italian and Greek populations in two distinct clades. In this study we have carried out additional plastid DNA sequencing and an AFLP analysis of the three taxa. Whereas the geographical distribution of four plastid DNA haplotypes supports the likelihood of a double hybrid origin or of a plastid capture, AFLP data do not support such a hypothesis, because S. politisii shows several private alleles, some of which are shared by Italian and Greek populations. In light of the floristic specificity of the coasts bordering the Otranto strait, we consider that the present-day disjunction of S. politisii could have originated either by a long-distance seed dispersal or by a fragmentation of an old polymorphic population. The pairwise mismatch distribution excludes a recent expansion of the populations examined. In light of recent evidence concerning the Mediterranean Lago-Mare period and the westward haplotype evolution detected in some Euro-Mediterranean trees, we argue that fragmentation of a previously continuous population could be an intriguing possibility. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162, 572–580.
    Botanical Journal of the Linnean Society 04/2010; 162(4):572 - 580. · 2.59 Impact Factor
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    ABSTRACT: Understanding the genetic architecture of admixed hybridizing populations helps in evaluating the nature of species boundaries and the levels of gene exchange between co-occurring species. In the present study, we examined a contact zone between Serapias vomeracea and Serapias cordigera, two unrewarding Mediterranean orchid species with a non-specific pollination strategy. Fruit production and seed viability from interspecific hand-pollination treatments pointed out the weaknesses of post-pollination barriers. The occurrence of hybridization was molecularly confirmed in the genus Serapias for the first time, as parts of plants with a transitional morphology were observed in both alleles of the parental LEAFY intron. Amplified fragment length polymorphism analysis revealed that plants with uncertain morphology and classified as one of the other parental species are actually backcrosses, attesting to an extensive interspecific gene exchange. Overall, the contact zone is more similar to a hybrid zone of Ophrys species, well known for their highly specialized pollination, than to a hybrid zone of unspecialized food-deceptive orchids. Therefore, species boundaries in Serapias are maintained by pre-pollination mechanisms that need to be better investigated. In light of the intriguing similarities between Serapias and Ophrys underlined by the present study, we hypothesize that the emission of floral scents could be involved in the maintenance of species boundaries in Serapias.
    Plant Species Biology 03/2010; 25(1):68 - 76. · 1.28 Impact Factor
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    ABSTRACT: Mediterranean orchids that grow in admixed, co-flowering populations, and frequently show hybrid progenies are interesting to use to study the nature and the strength of post-zygotic barriers. However, examination of pre- and post-pollination pre-zygotic isolating mechanisms requires sympatric, co-flowering species pairs that do not produce hybrid swarms. In this study, we analyzed a contact zone between Orchis italica and O. papilionacea, in which hybrid forms have never been reported, although hybridization between members of their groups of appurtenance has been signaled. We investigated pre-pollination barriers observing the floral phenology of both species and identified pollinators by means of molecular analysis of pollinaria collected on the insects captured in the study site. Post-pollination barriers were tested performing manual crosses in order to evaluate pollen germination/pollen tube growth in vivo and fruit and seed formation. Floral phenologies of O. italica and O. papilionacea display nearly overlapping trends, and two common pollinators have been identified by molecular analysis of pollinaria. Thus, pre-pollination barriers are very weak or nonexistent. Bidirectional crosses have shown that the growth of heterospecific pollen tubes is fully blocked in stigmatic cell layers. Since no fruit formation was detected in bidirectional interspecific crosses, we assume that reproductive isolation between the examined species is fully guaranteed by post-pollination pre-zygotic mechanisms acting at stigmatic level. Such condition has been rarely described and may mask the potential action of post-zygotic mechanisms.
    Sexual Plant Reproduction 03/2010; 23(4):281-9. · 2.07 Impact Factor
  • Botanical Studies 01/2010; 51:351-356. · 0.86 Impact Factor
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    ABSTRACT: Many factors have contributed to the richness of narrow endemics in the Mediterranean, including long-lasting human impact on pristine landscapes. The abandonment of traditional land-use practices is causing forest recovery throughout the Mediterranean mountains, by increasing reduction and fragmentation of open habitats. We investigated the population genetic structure and habitat dynamics of Plantago brutia Ten., a narrow endemic in mountain pastures of S Italy. Some plants were cultivated in the botanical garden to explore the species' breeding system. Genetic diversity was evaluated based on inter-simple sequence repeat (ISSR) polymorphisms in 150 individuals from most of known stands. Recent dynamics in the species habitat were checked over a 14-year period. Flower phenology, stigma receptivity and experimental pollinations revealed protogyny and self-incompatibility. With the exception of very small and isolated populations, high genetic diversity was found at the species and population level. amova revealed weak differentiation among populations, and the Mantel test suggested absence of isolation-by-distance. Multivariate analysis of population and genetic data distinguished the populations based on genetic richness, size and isolation. Landscape analyses confirmed recent reduction and isolation of potentially suitable habitats. Low selfing, recent isolation and probable seed exchange may have preserved P. brutia populations from higher loss of genetic diversity. Nonetheless, data related to very small populations suggest that this species may suffer further fragmentation and isolation. To preserve most of the species' genetic richness, future management efforts should consider the large and isolated populations recognised in our analyses.
    Plant Biology 11/2009; 11(6):821-8. · 2.32 Impact Factor
  • G Pellegrino, F Bellusci, A Musacchio
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    ABSTRACT: Plant species diversification entails the action of reproductive barriers, which are severely challenged when related species grow in contact and form hybrid progeny. Orchis italica and O. anthropophora are two related orchid species that produce a known hybrid form, O. xbivonae. Here, we analysed a hybrid zone of these two orchids using molecular analysis and experimental crosses. As molecular tools, we employed both real-time PCR and PCR amplification of nuclear markers to evaluate the occurrence of backcross recombination. With these approaches, we demonstrated that all examined hybrids belong to the F(1) generation. Chloroplast DNA analysis showed that O. anthropophora was the maternal species of most of hybrid specimens and that cytoplasmic introgression was lacking in both parental species. Pollination experiments showed that the two orchid species were strictly out-crossing, although self-compatible, and have comparable levels of reproductive fitness in all crossing treatments. Conversely, hybrids demonstrated low reproductive success in all intra- and back-crossing treatments. The absence of any backcross generations and plastid introgression suggest that O. xbivonae does not represent a bridge to gene flow between O. italica and O. anthropophora. Indeed, the low hybrid fitness testifies to the effectiveness of late post-zygotic barriers occurring between the parental species.
    Plant Biology 06/2009; 11(3):434-41. · 2.32 Impact Factor
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    ABSTRACT: A. 2009: The conservation perspectives and value of small and isolated plant populations: preliminary clues for Gentianella crispata (Gentianaceae) at the western boundary of its range. — Ann. Bot. Fennici 46: 115–124. We give the first account concerning the ecology, population size, breeding system and genetic variability of the unique Italian population of Gentianella crispata, a rare orophilous species with a disjunct distribution including Balkan peninsula and southern Italy. The population is relatively small (ca. 4000 individuals) and has a frag-mented structure within a wider area covered by the grass-dominated vegetation Sesle-rio nitidae–Brometum erecti. The evaluated morphological traits (i.e. plant size, flower number per plant and length of corolla tube) greatly varied among individuals. Exami-nation of the floral structures revealed that the stigma becomes receptive before anther dehiscence. Observations on the topological relationships between stigma and anther suggested that in young flowers protogyny is paralleled by herkogamy (i.e. hyper-stigmatic condition). However, the anther dehiscence appeared to be accompanied by a reduction of the spatial separation between female and male organs. This suggested the occurrence of a mixed breeding system, as also sustained by ISSR analysis. The ITS-based phylogeny showed an interesting relationship with G. caucasea, conferring a peculiar evolutionary interest to the species and its westernmost, severely isolated Italian population. According to the IUCN Red List criteria, G. crispata in Italy meets the requirements for critically endangered species.
    05/2009;
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    ABSTRACT: Sobel and Randle (2009) challenge several methodological choices in the comparative study of the evolution of reproductive isolation in Mediterranean deceptive orchids of Scopece et al. (2007) including the species concept used and the selection of taxa, together with the perceived comparison of clades of different ages. They further criticize that pollinator information was taken from the literature and that two different methods were used to estimate pollinator specificity in food-deceptive and sexually deceptive orchids, respectively. Here we reply to these challenges.
    Evolution 04/2009; 63(8):2205-9. · 4.86 Impact Factor
  • F. Bellusci, G. Pellegrino, A. Musacchio
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    ABSTRACT: We quantified inbreeding depression for fruit production, embryo vitality and seed germination in three deceptive orchids, Serapias vomeracea, S. cordigera and S. parviflora, which do not provide any reward to their pollinators, and are predicted to experience high outcrossing. Of the three species examined only S. parviflora was autonomously selfing. Both S. vomeracea and S. cordigera showed highly significant differences in fitness between selfed and outcrossed progenies, resulting in high levels of inbreeding depression, which increased in magnitude from seed set to seed germination. Inbreeding depression may promote outcrossing in Serapias by acting as a post-pollination barrier to selfing. Cumulative inbreeding depression across three stages in S. parviflora was lower that in both outcrossing species. The large difference in germination between selfed and outcrossed seeds is an important issue in conservation biology.
    Biologia Plantarum 01/2009; 53(1):175-178. · 1.69 Impact Factor
  • Plant Biology 01/2009; 11:434-441. · 2.32 Impact Factor
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    Biologia Plantarum 01/2009; 53:175-178. · 1.69 Impact Factor
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    ABSTRACT: A molecular phylogenetic analysis was performed on 14 species of the Mediterranean unrewarding orchid genus Serapias using sequences of four noncoding regions of chloroplast DNA. This study has led to a new interpretation of the evolutionary relationships in this genus. The well-defined phylogenetic tree supports a division of taxa into two main clades, each including two minor groups. The molecular relationships found in this study differ from those defined by traditional systematic morphological assessments. By comparing the variation in sequence to variations in floral traits, we propose that the split in the two main lineages reflects an early differentiation of flower size, perhaps due to the shift from allo- to self-pollination. Conversely, the relationships within each minor group do not reflect floral size variation; therefore, we presume that this diversification resulted from genetic drift, local selection forces, and multiple, independent transitions towards self-pollination and polyploidy.
    Molecular Phylogenetics and Evolution 07/2008; 47(3):986-91. · 4.07 Impact Factor

Publication Stats

335 Citations
99.03 Total Impact Points

Institutions

  • 1998–2012
    • Università della Calabria
      Rende, Calabria, Italy
  • 2001–2009
    • University of Naples Federico II
      • Department of Biology
      Napoli, Campania, Italy
  • 2002
    • Policlinico Federico II di Napoli
      Napoli, Campania, Italy