Florian Jabbour

Publications (8)22.46 Total impact

• Article: A phylogeny of Delphinieae (Ranunculaceae) shows that Aconitum is nested within Delphinium and that Late Miocene transitions to long life cycles in the Himalayas and Southwest China coincide with bursts in diversification.

  Florian Jabbour, Susanne S Renner
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  ABSTRACT: The tribe Delphinieae (Ranunculaceae) comprises two species-rich genera, Aconitum and Delphinium, the latter including Consolida and Aconitella. The 650-700 species are distributed in Eurasia and North America; three species occur on tropical African mountains. Maximum likelihood analyses of 2088 aligned nucleotides of plastid and nuclear sequences obtained from up to 185 species of Delphinieae from throughout the geographic range (plus relevant outgroups) show that three short-lived (facultative annual or biennial) Mediterranean species belonging to Delphinium subgenus Staphisagria are the sister clade to all other Delphinieae, implying that Staphisagria needs to be raised to genus status if Delphinium and Aconitum are to become mutually monophyletic. Molecular clock dating suggests an origin of the sampled Delphinieae in the Early Oligocene (c. 32.3 Ma) and expansion to North America of Aconitum and Delphinium around 3.3 and 2.9 Ma ago, respectively; the East African Mts. were reached by long-distance dispersal some 2.4 Ma ago, coincident with the major uplift of the East African Rift system. The ancestral growth form of the Delphinieae could not be reconstructed, but Late Miocene bursts in diversification rates in the Himalayan and southwestern Chinese clades of Aconitum and Delphinium appear to be associated with transitions from short-lived to long-lived life histories.
  Molecular Phylogenetics and Evolution 12/2011; 62(3):928-42. · 3.61 Impact Factor
• Article: Consolida and Aconitella are an annual clade of Delphinium (Ranunculaceae) that diversified in the Mediterranean basin and the Irano-Turanian region

  Florian Jabbour, Susanne S. Renner
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  ABSTRACT: The Mediterranean and Irano-Turanian biogeographic regions are biodiversity hotspots for mesophytic and xerophytic species, including many Delphinieae. This phylogenetically poorly understood tribe of Ranunculaceae consists of Consolida and Aconitella, with together ca. 52 species, and Delphinium and Aconitum, each with ca. 300 species. To infer the phylogeny of Consolida and Aconitella, we analyzed nuclear and chloroplast DNA sequences from 39 of their species and subspecies (44 taxa) plus a set of 30 exemplar species of Delphinium and Aconitum. We used a Bayesian relaxed clock model to estimate divergence times and a maximum likelihood approach to reconstruct ancestral areas. Aconitella forms a clade embedded in Consolida, and the latter is embedded in Delphinium. Consolida s.l. (including Aconitella) comprises two clades in the Irano-Turanian region and three in the Mediterranean basin. The latter clades' inferred crown ages of 5.1, 4.4, and 2.8 Ma suggests that the repeated drying-up of the Mediterranean, concomitant with and following the Messinian salinity crisis (5.96-5.33 Ma), may have facilitated their westward expansion. While there is clear geographic structure towards the tips of the Consolida s.l. tree, a likely ancestral area could not be inferred. However, the initial diversification of Consolida s.l., which occurred ca. 17 Ma ago, falls in a period when the climate in the Anatolian region became more arid, which may have favoured the annual life cycle that characterizes all species in this clade. To achieve a classification of mutually monophyletic genera in Delphinieae may require transferring the species of Aconitella and Consolida into Delphinium.
  Taxon 07/2011; 60(4):1029-1040. · 2.70 Impact Factor
• Article: Resurrection of the genus Staphisagria J. Hill, sister to all the other Delphinieae (Ranunculaceae).

  Florian Jabbour, Susanne S Renner
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  ABSTRACT: Molecular sequence data show that the three species oDelphinium subg. Staphisagria (J. Hill) Peterm. form the sister clade to Aconitum L., Aconitella SpachConsolida (DC.) S.F. Gray, and all remaining species of Delphinium L. To account for this finding we resurrect Staphisagria J. Hill (1756). Names in Staphisagria are available for two of the species. We here make the required new combination for the third species, Staphisagria picta (Willd.) F. Jabbour, provide a key to the species, and illustrate one of them.
  PhytoKeys. 01/2011;
• Article: Establishment of zygomorphy on an ontogenic spiral and evolution of perianth in the tribe Delphinieae (Ranunculaceae).

  Florian Jabbour, Louis P Ronse De Craene, Sophie Nadot, Catherine Damerval
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  ABSTRACT: Ranunculaceae presents both ancestral and derived floral traits for eudicots, and as such is of potential interest to understand key steps involved in the evolution of zygomorphy in eudicots. Zygomorphy evolved once in Ranunculaceae, in the speciose and derived tribe Delphinieae. This tribe consists of two genera (Aconitum and Delphinium s.l.) comprising more than one-quarter of the species of the family. In this paper, the establishment of zygomorphy during development was investigated to cast light on the origin and evolution of this morphological novelty. METHODS; The floral developmental sequence of six species of Ranunculaceae, three actinomorphic (Nigella damascena, Aquilegia alpina and Clematis recta) and three zygomorphic (Aconitum napellus, Delphinium staphisagria and D. grandiflorum), was compared. A developmental model was elaborated to break down the successive acquisitions of floral organ identities on the ontogenic spiral (all the species studied except Aquilegia have a spiral phyllotaxis), giving clues to understanding this complex morphogenesis from an evo-devo point of view. In addition, the evolution of symmetry in Ranunculaceae was examined in conjunction with other traits of flowers and with ecological factors. In the species studied, zygomorphy is established after organogenesis is completed, and is late, compared with other zygomorphic eudicot species. Zygomorphy occurs in flowers characterized by a fixed merism and a partially reduced and transformed corolla. It is suggested that shifts in expression of genes controlling the merism, as well as floral symmetry and organ identity, have played a critical role in the evolution of zygomorphy in Delphinieae, while the presence of pollinators able to exploit the peculiar morphology of the flower has been a key factor for the maintenance and diversification of this trait.
  Annals of Botany 08/2009; 104(5):809-22. · 4.03 Impact Factor
• Article: Evolutionary trends in the flowers of Asteridae: is polyandry an alternative to zygomorphy?

  Florian Jabbour, Catherine Damerval, Sophie Nadot
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  ABSTRACT: Floral symmetry presents two main states in angiosperms, actinomorphy (polysymmetry or radial symmetry) and zygomorphy (monosymmetry or bilateral symmetry). Transitions from actinomorphy to zygomorphy have occurred repeatedly among flowering plants, possibly in coadaptation with specialized pollinators. In this paper, the rules controlling the evolution of floral symmetry were investigated to determine in which architectural context zygomorphy can evolve. Floral traits potentially associated with perianth symmetry shifts in Asteridae, one of the major clades of the core eudicots, were selected: namely the perianth merism, the presence and number of spurs, and the androecium organ number. The evolution of these characters was optimized on a composite tree. Correlations between symmetry and the other morphological traits were then examined using a phylogenetic comparative method. The analyses reveal that the evolution of floral symmetry in Asteridae is conditioned by both androecium organ number and perianth merism and that zygomorphy is a prerequisite to the emergence of spurs. The statistically significant correlation between perianth zygomorphy and oligandry suggests that the evolution of floral symmetry could be canalized by developmental or spatial constraint. Interestingly, the evolution of polyandry in an actinomorphic context appears as an alternative evolutionary pathway to zygomorphy in Asteridae. These results may be interpreted either in terms of plant-pollinator adaptation or in terms of developmental or physical constraints. The results are discussed in relation to current knowledge about the molecular bases underlying floral symmetry.
  Annals of Botany 09/2008; 102(2):153-65. · 4.03 Impact Factor
• Source

  Available from: Guislaine Refrégier

  Article: Cophylogeny of the anther smut fungi and their caryophyllaceous hosts: prevalence of host shifts and importance of delimiting parasite species for inferring cospeciation.

  Guislaine Refrégier, Mickaël Le Gac, Florian Jabbour, Alex Widmer, Jacqui A Shykoff, Roxana Yockteng, Michael E Hood, Tatiana Giraud
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  ABSTRACT: Using phylogenetic approaches, the expectation that parallel cladogenesis should occur between parasites and hosts has been validated in some studies, but most others provided evidence for frequent host shifts. Here we examine the evolutionary history of the association between Microbotryum fungi that cause anther smut disease and their Caryophyllaceous hosts. We investigated the congruence between host and parasite phylogenies, inferred cospeciation events and host shifts, and assessed whether geography or plant ecology could have facilitated the putative host shifts identified. For cophylogeny analyses on microorganisms, parasite strains isolated from different host species are generally considered to represent independent evolutionary lineages, often without checking whether some strains actually belong to the same generalist species. Such an approach may mistake intraspecific nodes for speciation events and thus bias the results of cophylogeny analyses if generalist species are found on closely related hosts. A second aim of this study was therefore to evaluate the impact of species delimitation on the inferences of cospeciation. We inferred a multiple gene phylogeny of anther smut strains from 21 host plants from several geographic origins, complementing a previous study on the delimitation of fungal species and their host specificities. We also inferred a multi-gene phylogeny of their host plants, and the two phylogenies were compared. A significant level of cospeciation was found when each host species was considered to harbour a specific parasite strain, i.e. when generalist parasite species were not recognized as such. This approach overestimated the frequency of cocladogenesis because individual parasite species capable of infecting multiple host species (i.e. generalists) were found on closely related hosts. When generalist parasite species were appropriately delimited and only a single representative of each species was retained, cospeciation events were not more frequent than expected under a random distribution, and many host shifts were inferred.Current geographic distributions of host species seemed to be of little relevance for understanding the putative historical host shifts, because most fungal species had overlapping geographic ranges. We did detect some ecological similarities, including shared pollinators and habitat types, between host species that were diseased by closely related anther smut species. Overall, genetic similarity underlying the host-parasite interactions appeared to have the most important influence on specialization and host-shifts: generalist multi-host parasite species were found on closely related plant species, and related species in the Microbotryum phylogeny were associated with members of the same host clade. We showed here that Microbotryum species have evolved through frequent host shifts to moderately distant hosts, and we show further that accurate delimitation of parasite species is essential for interpreting cophylogeny studies.
  BMC Evolutionary Biology 02/2008; 8:100. · 3.52 Impact Factor
• Article: The Evolution of Floral Symmetry

  Hélène Citerne, Florian Jabbour, Sophie Nadot, Catherine Damerval
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  ABSTRACT: Symmetry is a defining feature of floral diversity. Here we review the evolutionary and ecological context of floral symmetry (adding new data regarding its distribution), as well as the underlying developmental and molecular bases. Two main types of symmetry are recognized: radial symmetry or actinomorphy and bilateral symmetry or zygomorphy. The fossil record suggests that zygomorphy evolved in various lineages ∼50 MY (million years) after the emergence of angiosperms, coinciding with the diversification of specialized insect pollinators. Among extant angiosperms, zygomorphy is a highly homoplastic trait, and is associated with species radiation thereby satisfying the definition of key innovation. The evolution of symmetry may be influenced by clade-specific floral and inflorescence characteristics, possibly indicating different underlying constraints. Ecological studies suggest that zygomorphy may promote cross-fertilization through increased precision in pollen placement on the pollinator’s body. The molecular bases of flower symmetry are beginning to be unravelled in core eudicots, and available evidence underlines the repeated recruitment of CYC2 genes, associated with frequent gene duplications. Future prospects are discussed, emphasizing symmetry as a model character for understanding the evolutionary bases of homoplastic floral traits.
  Advances in Botanical Research 54:85-137. · 2.86 Impact Factor
• Source

  Available from: Sophie Nadot

  Article: Evolution of floral symmetry: a state of the art.

  Florian Jabbour, Sophie Nadot, Catherine Damerval
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  ABSTRACT: The genetic determinants of the organisation and variation of the flower, a striking feature of the angiosperms, are only beginning to be deciphered. Floral symmetry has recurrently evolved among angiosperms, zygomorphy (monosymmetry) being a key innovation due to its role in the plant-pollination interaction. As such, it represents a case study for evo-devo. Phylogenetic comparative studies conducted in two eudicot clades, the Ranunculales and the Asteridae sensu APGII, have shown that the evolution of this trait is dependent upon the architectural context of the flower. Genetic and developmental bases of zygomorphy have been investigated in several unrelated model species. In all these species, zygomorphy appears to be controlled, at least partially, by genes belonging to the TCP gene family of transcription factors and named CYC-like genes. Exploring the molecular bases of zygomorphy in non-model species spanning the diversity of angiosperms, but also the developmental processes involved, are now essential to understand the evolution of floral symmetry.
  Comptes rendus biologies 332(2-3):219-31. · 1.71 Impact Factor