Joan Simon

Reproductive biology, genetic variation and conservation of the rare endemic dysploid Delphinium bolosii (Ranunculaceae)

Abstract Delphinium bolosii C. Blanche and Molero (Ranunculaceae), is a very rare endemic plant known from only two populations in Catalonia, having fewer than 1500 individuals. A biological survey of this species included: (a) reproductive biology, comprising pollination ecology, breeding systems, seed set and pollen viability; and (b) enzyme electrophoresis to measure genetic variation within and between two populations. A trend to increasing self-pollination rates (up to 20%) and to low levels of genetic variation (1.6–1.7 alleles per locus), together with high rates of nectar robber visits are reported. The hypothetic evolutionary relationships (chromosomal changes and geographic isolation) of this species with its related widespread ancestor Delphinium fissum are also discussed. The main threats to this species are catastrophic events (especially as soil erosion), human impact activities (both agriculture and tourism) and decreasing pollination. The small populations and low genetic variation reinforce its endangered status. Some conservation measures are suggested, including in-situ and ex-situ strategies.

Conservation biology of the Pyrenean larkspur (Delphinium montanum): a case of conflict of plant versus animal conservation?

Abstract Delphinium montanum is a larkspur endemic to the Pyrenees. It has c. 4000 individuals and is classified as vulnerable following the IUCN categories. Pollination ecology results demonstrated that it is strictly dependent on pollinator activity (mainly bumblebees) to set seeds. Genetic diversity estimated by allozyme variation at 7 loci showed quite high levels of variation related to its polyploidy. Predation by Pyrenean chamois ( Rupicapra rupicapra pyrenaica ), first detected in 1993, caused a continuous loss of >90% of seed set in a protected area. The maintenance of high genetic diversity suggests the buffer effect of polyploidy and seed bank strategy to counter animal grazing, but long-term effects on conservation are expected. These results stressed: (1) the need for a plan to monitor this animal–plant interaction; and (2) the need to monitor closely the population number of individuals of certain protected animal species in Natural Reserves, particularly if ecological competition has been disturbed by human intervention.

Breeding systems in tribe Delphinieae (Ranunculaceae) in the western Mediterranean area

Summary The breeding system of 30 populations belonging to 20 species of Aconitum, Delphinium and Consolida ( Delphinieae, Ranunculaceae) in the western Mediterranean area was studied and its relation with life-span and systematic position is discussed. To assess the breeding system we measured seed set in response to different pollination treatments. We performed greenhouse tests for agamospermy, spontaneous self-pollination, induced self-pollination, geitonogamy, cross-pollination and, in some cases, insect exclusion tests in the field. Morphological characters like stamen number, pollen production, ovule production and pollen: ovule ratio (P/O) were quantified. Most species are facultative xenogamous and partially self-compatible. P/O ratios were rather consistent with the observed xenogamy, although there is no relation between P/O values and selfing rates. P/O ratio was positively correlated with seed weight, but is heavily influenced by one species. A trend towards increased autogamy in annuals, especially in subgenus Staphisagria, was detected. In these taxa xenogamy and insect pollination are evolutionary primitive, and autogamy is derived. Similar reproductive patterns in closely related taxa suggest that only slight differentiation occurred after primary strain diversification of this group.

Population genetics and conservation priorities for the critically endangered island endemic Delphinium pentagynum subsp. formenteranum (Ranunculaceae)

Isozyme electrophoresis was used to evaluate levels of genetic diversity and population genetic structure of the critically endangered (CR) perennial larkspur, Delphinium pentagynum subsp. formenteranum (Ranunculaceae), endemic to the island of Formentera (Balearic Islands, Spain). There is only one known population for this taxon, containing only 480 individuals. Moderate values of diversity were detected (P = 40.7%, A = 1.6 and He = 0.180), within the range observed in other surveyed larkspurs, but higher than most island endemics. Moderate levels of inbreeding were detected, probably as a consequence of the populations genetic structuring (biparental inbreeding). Threats to this taxon are mainly anthropogenic (fires, grazing, pathway works, and building pressures), although given that only one population exists, stochastic risks cannot be ignored. Conservation of D. pentagynum subsp. formenteranum requires in situ strategies, such as implementing a monitoring program and establishing a ‘botanical reserve’, and ex situ strategies, such as collection and long-term storage of seeds.

T-duality covariance of SuperD-branes

T-duality realized on SuperD-brane effective actions probing in constant Gmn and bmn backgrounds is studied from a pure world volume point of view. It is proved that requiring T-duality covariance of such actions “fixes” the T-duality transformations of the world volume dynamical fields, and consequently, of the NS–NS and R–R coupling superfields. The analysis is extended to uncover the mapping of the symmetry structure associated with these SuperD-brane actions. In particular, we determine the T-duality transformation properties of kappa symmetry and supersymmetry, which allow us to prove that bosonic supersymmetric world volume solitons of the original theory generate, through T-duality, the expected ones in the T-dual theory. The latter proof is generalized to arbitrary bosonic backgrounds. We conclude with some comments on extensions of our approach to arbitrary kappa symmetric backgrounds, non-BPS D-branes and non-abelian SuperD-branes.

T duality and effective D-brane actions

T-duality realized on D-brane effective actions is studied from a pure worldvolume point of view. It is proved that invariance in the form of the Dirac-Born-Infeld and Wess-Zumino terms fixes the T-duality transformations of the NS-NS and R-R background fields, respectively. The analysis is extended to uncover the mapping of global symmetries of the corresponding pair of D-branes involved in the transformation.

The rigid symmetries of bosonic D-strings

Abstract We analyse the classical symmetries of bosonic D-string actions and generalizations thereof. Among others, we show that the simplest actions of this type have infinitely many nontrivial rigid symmetries which act nontrivially and nonlinearly both on the target space coordinates and on the U(1) gauge field, and form a Kac-Moody version of the Weyl algebra (= Poincare algebra + dilatations).

Brane-intersection dynamics from branes in brane backgrounds

Abstract We derive the dynamics of M-brane intersections from the worldvolume action of one brane in the background supergravity solution of another one. In this way we obtain an effective action for the self-dual string boundary of an M2-brane in an M5-brane, and show that the dynamics of the 3-brane intersection of two M5-branes is described by a Dirac-Born-Infeld action.

D-String on Near Horizon Geometries and Infinite Conformal Symmetry

We show that the symmetries of effective D-string actions in constant dilaton backgrounds are directly related to homothetic motions of the background metric. In the presence of such motions, there are infinitely many nonlinearly realized rigid symmetries forming a loop (or looplike) algebra. Near horizon (anti ‐ deSitter) D3 and D1 1 D5 backgrounds are discussed in detail and shown to provide 2D interacting field theories with infinite conformal symmetry. [S0031-9007(98)06979-8] PACS numbers: 11.25.Hf, 11.30.Na The recent past has seen an increasing interest in the conjecture of a correspondence between large N limits of certain d-dimensional conformal field theories and supergravity on the product of sd 1 1d-dimensional anti ‐de Sitter (AdS) space with a compact manifold [1,2]. This suggested consideration of world-volume brane actions on near horizon backgrounds. M2-, M5-, and D3-branes have been studied [1,3,4] and interacting sp 1 1d-dimensional theories in Minkowski space-time with conformal SOs2, p 1 1d 3 SOsd 2 p 2 1d symmetry were found [5]. The conformal symmetries of these branes reflect the isometries of AdSp12 3 S d2p22 . The case of a D-string in the near horizon geometry of a sD1 1 D5d-brane was also considered in [5]. In this work we study the rigid symmetries of effective D-string actions of the Born-Infeld type on curved backgrounds with constant dilaton. We find that the symmetries are related with homothetic motions of the background metric. Each of these motions gives rise to infinitely many nonlinearly realized rigid symmetries, with the Born-Infeld gauge field transforming in a nontrivial way. The algebra of these symmetries is a loop generalization of the algebra associated with the homothetic motions. We spell out the symmetry transformations before gauge fixing and in the static gauge for the world-sheet diffeomorphisms. The gauged fixed transformations generate infinitely many symmetries of interacting s1 1 1ddimensional field theories in a flat space-time. We then specify these general results for particularly interesting D3- and sD1 1 D5d-brane backgrounds and show that the gauge fixed field theories in the respective near horizon (AdS) backgrounds have infinite conformal symmetry. In the case of the D3 background the symmetry group is a loop generalization of ISOs1, 3d 3 SOs6d. In the near horizon limit there is an enhancement of the symmetry to the loop generalization of conformal SOs2, 4d 3 SOs6d due to the AdS geometry. The symmetry group contains as a subgroup a loop version of conformal SOs2, 2d with nonlinearly realized special conformal

Genetic Diversity Within and among Disjunct Populations of the Mediterranean Island Endemic Delphinium pictum and D. requienii (Ranunculaceae)

Allozyme diversity was assessed in 13 populations of Delphinium pictum and D. requienii, two short-lived and closely related insular Mediterranean endemics. While D. pictum has scattered distribution in Corsica, Sardinia and Majorca, D. requienii is found in a few small populations restricted to the Hyères Archipelago. Eleven enzyme systems were assayed, and 15 loci were resolved. Both species harboured moderate levels of genetic diversity, comparable to the values expected for endemic plants. All genetic parameters suggested higher diversity in D. pictum (A = 1.93, P = 40, He = 0.106) than in D. requienii (A = 1.30, P = 26.7, He = 0.096); FIS values revealed higher inbreeding in D. requienii. Although the two species did not harbour species-specific alelles in the surveyed loci, the UPGMA dendrogram based on Nei’s genetic similarity index supported divergence between them. These results, together with significant morphological similarity and evidence of successful hybridization between the species, support the hypothesis of a recent speciation event. The moderate levels of both genetic variability and population divergence observed for D. pictum are likely attributable to its ability to establish seed banks. Given that the allozyme variation detected for D. pictum was significantly partitioned among islands, we suggest the implementation of conservation programs throughout its distribution range, and not only in Corsica as it occurs nowadays. Management strategies are also desirable for D. requienii to maintain population size and control inbreeding.