Variación morfológica y genética en Cicindela lusitanica (Coleoptera, Carabidae, Cicindelinae): implicaciones para su conservación

The establishment of taxonomic and geographical boundaries is a common problem when analysing clinal distributions. This is of particular concern when the assessment of intraspecific groupings is required for conservation management. The tiger beetle Cicindela lusitanica Mandl, 1935 (Coleoptera, Carabidae) is a typical case in which two recognised subspecies are distributed in a clinal latitudinal fashion in the dune systems along the Atlantic coast of Portugal. This habitat is increasingly under threat, and conservation measures are needed. We investigated the validity of the two named subspecies, based on a re-analysis of elytral and genitalic measurements using multivariate analysis. We also analysed variation in mitochondrial Cytochrome Oxidase I gene for a total of six populations along the cline. Multivariate analysis supported the idea of a morphological cline and revealed a clear distinction of the southernmost population and also some degree of distinctiveness of the most northern populations, partially supporting the recognised subspecific ranking. The mtDNA analysis identified two main groups corresponding to northern and southern populations. Both sets of markers showed that variation within the C. lusitanica assemblage is complex, with the boundaries between morphological and mtDNA groups not in agreement. However, populations at either end of the distributional range are clearly distinct from each other, and should be considered as provisional units for conservation programmes.El reconocimiento de límites taxonómicos y geográficos de la variabilidad observada es un problema habitual cuando se analizan distribuciones clinales. Esto es particularmente problemático cuando se requiere la determinación de agrupamientos intraespecíficos para tomar medidas de conservación. El cicindélido Cicindela lusitanica Mandl, 1935 (Coleoptera, Carabidae) constituye un caso típico en el que dos subespecies reconocidas se hayan distribuidas a lo largo de una clina latitudinal en los sistemas dunares de la costa Atlántica Portuguesa. Este hábitat se encuentra cada vez más amenazado y se requiere tomar medidas de conservación. En este trabajo hemos investigado la validez de las dos subespecies propuestas basándonos en un reanálisis de medidas elitrales y de la genitalia usando análisis multivariante. También hemos estudiado la variación en el gen de la Citocromo Oxidasa I para un total de seis poblaciones a lo largo de la clina. El análisis multivariante confirmó la idea de la existencia de una clina morfológica y reveló una clara distinción de la población más meridional y también una cierta distinción de las poblaciones más septentrionales, apoyando parcialmente los rangos subespecíficos reconocidos. El análisis del ADN mitocondrial identificó dos grupos principales correspondientes a las poblaciones del norte y las del sur. Ambos conjuntos de marcadores evidenciaron que la variación en C. lusitanica es compleja, con límites discordantes entre los grupos definidos por la morfología y por el ADN mitocondrial. Sin embargo, las poblaciones en los extremos del área de distribución son claramente distintas entre sí, y deberían ser consideradas unidades provisionales en programas de conservación

Ultracold Atoms as a Target: Absolute Scattering Cross-Section Measurements

We report on a new experimental platform for the measurement of absolute scattering cross-sections. The target atoms are trapped in an optical dipole trap and are exposed to an incident particle beam. The exponential decay of the atom number directly yields the absolute total scattering cross-section. The technique can be applied to any atomic or molecular species that can be prepared in an optical dipole trap and provides a large variety of possible scattering scenarios

Molecular phylogeny of brachiopods and phoronids based on nuclear-encoded small subunit ribosomal RNA gene sequences

Brachiopod and phoronid phylogeny is inferred from SSU rDNA sequences of 28 articulate and nine inarticulate brachiopods, three phoronids, two ectoprocts and various outgroups, using gene trees reconstructed by weighted parsimony, distance and maximum likelihood methods. Of these sequences, 33 from brachiopods, two from phoronids and one each from an ectoproct and a priapulan are newly determined. The brachiopod sequences belong to 31 different genera and thus survey about 10% of extant genus-level diversity. Sequences determined in different laboratories and those from closely related taxa agree well, but evidence is presented suggesting that one published phoronid sequence (GenBank accession UO12648) is a brachiopod-phoronid chimaera, and this sequence is excluded from the analyses. The chiton, Acanthopleura, is identified as the phenetically proximal outgroup; other selected outgroups were chosen to allow comparison with recent, non-molecular analyses of brachiopod phylogeny. The different outgroups and methods of phylogenetic reconstruction lead to similar results, with differences mainly in the resolution of weakly supported ancient and recent nodes, including the divergence of inarticulate brachiopod sub-phyla, the position of the rhynchonellids in relation to long- and short-looped articulate brachiopod clades and the relationships of some articulate brachiopod genera and species. Attention is drawn to the problem presented by nodes that are strongly supported by non-molecular evidence but receive only low bootstrap resampling support. Overall, the gene trees agree with morphology-based brachiopod taxonomy, but novel relationships are tentatively suggested for thecideidine and megathyrid brachiopods. Articulate brachiopods are found to be monophyletic in all reconstructions, but monophyly of inarticulate brachiopods and the possible inclusion of phoronids in the inarticulate brachiopod clade are less strongly established. Phoronids are clearly excluded from a sister-group relationship with articulate brachiopods, this proposed relationship being due to the rejected, chimaeric sequence (GenBank UO12648). Lineage relative rate tests show no heterogeneity of evolutionary rate among articulate brachiopod sequences, but indicate that inarticulate brachiopod plus phoronid sequences evolve somewhat more slowly. Both brachiopods and phoronids evolve slowly by comparison with other invertebrates. A number of palaeontologically dated times of earliest appearance are used to make upper and lower estimates of the global rate of brachiopod SSU rDNA evolution, and these estimates are used to infer the likely divergence times of other nodes in the gene tree. There is reasonable agreement between most inferred molecular and palaeontological ages. The estimated rates of SSU rDNA sequence evolution suggest that the last common ancestor of brachiopods, chitons and other protostome invertebrates (Lophotrochozoa and Ecdysozoa) lived deep in Precambrian time. Results of this first DNA-based, taxonomically representative analysis of brachiopod phylogeny are in broad agreement with current morphology-based classification and systematics and are largely consistent with the hypothesis that brachiopod shell ontogeny and morphology are a good guide to phylogeny

The mitogenome of Hydropsyche pellucidula (Hydropsychidae): first gene arrangement in the insect order Trichoptera

International audienceWe describe the mitochondrial genome of Hydropsyche pellucidula Curtis 1834, which is first described for the suborder Annulipalpia and the first in the order Trichoptera to show a non-canonical gene order. The mitogenome was obtained by de novo assembly of shotgun sequenced total genomic DNA using Illumina Miseq technology, which produced an average coverage of 115× and a minimum coverage of 48×. The mitochondrial genome includes 13 protein-coding genes, 2 rRNAs and 22 tRNAs. The genome is characterized by a rearrangement in the relative position of protein-coding and ribosomal genes. This mitogenome sequence will be useful for studying the family Hydropsychidae, which is commonly used for freshwater pollution biomonitoring

Cicrumnuclear Supernova Remnants and HII Regions in NGC 253

Archival VLA data has been used to produce arcsecond-resolution 6- and 20-cm images of the region surrounding the nuclear 200-pc (~15") starburst in NGC 253. Twenty-two discrete sources stronger than 0.4 mJy have been detected within ~2 kpc (~3') of the galaxy nucleus; almost all these sources must be associated with the galaxy. None of the radio sources coincides with a detected X-ray binary, so they appear to be due to supernova remnants and H II regions. The region outside the central starburst has a derived radio supernova rate of <~0.1/yr, and may account for at least 20% of the recent star formation in NGC 253. Most of the newly identified sources have steep, nonthermal radio spectra, but several relatively strong thermal sources also exist, containing the equivalent of tens of O5 stars. These stars are spread over tens of parsecs, and are embedded in regions having average ionized gas densities of 20-200/cm^3, much lower than in the most active nuclear star-forming regions in NGC 253 or in the super star clusters seen in other galaxies. The strongest region of thermal emission coincides with a highly reddened area seen at near-infrared wavelengths, possibly containing optically obscured H II regions.Comment: 17 pages, 3 postscript figures, AASTeX format, in press for Astronomical Journal, July 200

Elemental Abundances of Nearby Galaxies through High Signal-to-Noise XMM-Newton Observations of ULXs

(abridged) In this paper, we examined XMM Newton EPIC spectra of 14 ultra-luminous X-ray sources (ULXs)in addition to the XMM RGS spectra of two sources (Holmberg II X-1 and Holmberg IX X-1). We determined oxygen and iron abundances of the host galaxy's interstellar medium (ISM) using K-shell (O) and L-shell (Fe) X-ray photo-ionization edges towards these ULXs. We found that the oxygen abundances closely matched recent solar abundances for all of our sources, implying that ULXs live in similar local environments despite the wide range of galaxy host properties. Also, we compare the X-ray hydrogen column densities (n_H) for 8 ULX sources with column densities obtained from radio H I observations. The X-ray model n_H values are in good agreement with the H I n_H values, implying that the hydrogen absorption towards the ULXs is not local to the source (with the exception of the source M81 XMM1). In order to obtain the column density and abundance values, we fit the X-ray spectra of the ULXs with a combined power law and one of several accretion disk models. We tested the abundances obtained from the XSPEC models bbody, diskbb, grad, and diskpn along with a power law, finding that the abundances were independent of the thermal model used. We comment on the physical implications of these different model fits. We also note that very deep observations allow a breaking of the degeneracy noted by Stobbart et al. (2006) favoring a high mass solution for the absorbed grad + power law model.Comment: 18 pages, accepted to Ap

XMM-Newton Archival Study of the ULX Population in Nearby Galaxies

We present the results of an archival XMM-Newton study of the bright X-ray point sources (L_X > 10^38 erg/s) in 32 nearby galaxies. From our list of approximately 100 point sources, we attempt to determine if there is a low-state counterpart to the Ultraluminous X-ray (ULX) population, searching for a soft-hard state dichotomy similar to that known for Galactic X-ray binaries and testing the specific predictions of the IMBH hypothesis. To this end, we searched for "low-state" objects, which we defined as objects within our sample which had a spectrum well fit by a simple absorbed power law, and "high-state" objects, which we defined as objects better fit by a combined blackbody and a power law. Assuming that ``low-state'' objects accrete at approximately 10% of the Eddington luminosity (Done & Gierlinski 2003) and that "high-state" objects accrete near the Eddington luminosity we further divided our sample of sources into low and high state ULX sources. We classify 16 sources as low-state ULXs and 26 objects as high-state ULXs. As in Galactic black hole systems, the spectral indices, Gamma, of the low-state objects, as well as the luminosities, tend to be lower than those of the high-state objects. The observed range of blackbody temperatures for the high state is 0.1-1 keV, with the most luminous systems tending toward the lowest temperatures. We therefore divide our high-state ULXs into candidate IMBHs (with blackbody temperatures of approximately 0.1 keV) and candidate stellar mass BHs (with blackbody temperatures of approximately 1.0 keV). A subset of the candidate stellar mass BHs have spectra that are well-fit by a Comptonization model, a property similar of Galactic BHs radiating in the "very-high" state near the Eddington limit.Comment: 54 pages, submitted to ApJ (March 2005), accepted (May 2006); changes to organization of pape

Temperature-dependence of minimum resource requirements alters competitive hierarchies in phytoplankton

Resource competition theory is a conceptual framework that provides mechanistic insights into competition and community assembly of species with different resource requirements. However, there has been little exploration of how resource requirements depend on other environmental factors, including temperature. Changes in resource requirements as influenced by environmental temperature would imply that climate warming can alter the outcomes of competition and community assembly