Spacing and movement in the green porcelain crab Petrolisthes armatus: evidence for male competition and mate guarding

The green porcelain crab, Petrolisthes armatus, is a common invasive species on inter-tidal oyster reefs in the South Atlantic Bight whose behavior is largely unknown. We assessed the effects of the presence of opposite-sex conspecifics on adult crab spacing at a low density to infer potential mate acquisition behaviors. Adult crabs held in all-male, all-female, and mixed-sex treatments were observed twice daily over five days to determine nearest-neighbor (NN) distances and relative activity. Males in the mixed-sex treatment with the shortest NN distances (NN₁) were most commonly (1) closest to females, and, when compared to NN₁ males in the all-male treatment, were (2) closer to their NN and (3) had lower activity levels. Female movement did not differ between treatments. Percent ovigerous females at the end of trials were higher in the mixed-sex treatment, reflecting mating activity, which when observed, involved inter-molt females. Mate guarding, rather than pure-searching behavior, was the mating behavior most consistent with observed spacing and movement patterns.     

Biogeography and genetic consequences of anagenetic speciation of Rhaphithamnus venustus (Verbenaceae) in the Juan Fernández archipelago,Chile: insights from AFLP and SSR markers

The genus R haphithamnus (Verbenaceae) consists of two species, one in South America and another endemic to the Juan Fernández archipelago, Chile. The genus represents an example of anagenetic speciation in which the island populations have diverged from their colonizing ancestors to the point where they are recognized as a distinct species. The island species R haphithamnus venustus differs from the continental R . spinosus primarily by floral traits associated with adaptation to hummingbird pollination. Two molecular markers, amplified fragment length polymorphisms (AFLPs) and microsatellites, were used to estimate divergence between the continental and insular species, and to compare diversity in the two species. The comparable or greater diversity in the insular species observed in some diversity indices of AFLPs would support the hypothesis that during the course of anagenetic speciation it has recovered from any reduction of genetic diversity associated with colonization of the archipelago. This pattern of comparable or higher diversity in insular species is seen with other instances of anagenetic speciation in the Juan Fernández archipelago. By contrast, the lower genetic diversity in the insular R . venustus found in microsatellites is likely to be the result of a founder effect from the original colonization of the archipelago; prior molecular studies suggest recent colonization of the Juan Fernández archipelago by R haphithamnus . The seeming non‐concordance between the present results and the widely accepted biogeography of R haphithamnus inferred from other data is discussed and an explanation is presented.     

Vegetation recovery after fuel management in Mediterranean shrublands

Question: What is the effect of fuel management practices in the recovery capacity of seeder‐dominated shrublands? Location: Ulex parviflorus shrubland localities in Mediterranean regions of eastern Spain. Methods: We applied prescribed burning and brush‐chipping as fuel management techniques in three young and three mature shrublands, and evaluated the effects in the following four years. Results: Canopy opening by the treatments allowed increasing species richness through the four years of secondary succession. The treatments produced a change in community structure and dominant species, from the woody seeder Ulex parviflorus to the resprouter grass Brachypodium retusum. Vegetation response was conditioned by both shrubland developmental stage and treatment applied. Burning resulted in more severe modification of the ecosystem, increasing bare soil cover. Four years after fuel management in different aged Mediterranean gorse shrublands, vegetation response followed a similar pattern with the exception of the young, brush‐chipped shrublands. The treatments applied for controlling Ulex parviflorus were seen to be very effective, with the exception of brush‐chipping in young shrublands. Conclusions: Selective brush‐chipping in middle‐aged or mature gorse shrublands would combine a drastic reduction in fire hazard with ecosystem conservation and regeneration.     

Genomic organization of the structural genes controlling the astaxanthin biosynthesis pathway of Xanthophyllomyces dendrorhous

The cloning and nucleotide sequence of the genes (idi, crtE, crtYB, crtl and crtS) controlling the astaxanthin biosynthesis pathway of the wild-type ATCC 24230 strain of Xanthophyllomyces dendrorhous in their genomic and cDNA version were obtained. The idi, crtE, crtYB, crtl and crtS genes were cloned, as fragments of 10.9, 11.5, 15.8, 5.9 and 4 kb respectively. The nucleotide sequence data analysis indicates that the idi, crtE, crtYB, crtl and crtS genes have 4, 8,4, 11, and 17 introns and 5, 9, 5, 12 and 18 exons respectively. In addition, a highly efficient site-directed mutagenesis system was developed by transformation by integration, followed by mitotic recombination (the double recombinant method). Heterozygote idi (idi+/idi-::hph), crtE (crtE+/crtE-::hph), crtYB (crtYB+/crtYB-::hph), crtI (crtI+/crtI-::hph) and crtS (crtS+/crtS-::hph) and homozygote mutants crtYB (crtYB-::hph/crtYB-::hph), crtI (crtI-::hph/crtI-::hph) and crtS (crtS-::hph/crtS-::hph) were constructed. All the heterozygote mutants have a pale phenotype and produce less carotenoids than the wild-type strain. The genetic analysis of the crtYB, crtl and crtS loci in the wild-type, heterozygote, and homozygote give evidence of the diploid constitution of ATCC 24230 strains. In addition, the cloning of a truncated form of the crtYB that lacks 153 amino acids of the N-terminal region derived from alternatively spliced mRNA was obtained. Their heterologous expression in Escherichia coli carrying the carotenogenic cluster of Erwinia uredovora result in trans-complementation and give evidence of its functionality in this bacterium, maintaining its phytoene synthase activity but not the lycopene cyclase activity.     

Phylogeography of the invasive weed Hypochaeris radicata (Asteraceae): from Moroccan origin to worldwide introduced populations

In an attempt to delineate the area of origin and migratory expansion of the highly successful invasive weedy species Hypochaeris radicata, we analysed amplified fragment length polymorphisms from samples taken from 44 populations. Population sampling focused on the central and western Mediterranean area, but also included sites from Northern Spain, Western and Central Europe, Southeast Asia and South America. The six primer combinations applied to 213 individuals generated a total of 517 fragments of which 513 (99.2%) were polymorphic. The neighbour-joining tree presented five clusters and these divisions were supported by the results of Bayesian analyses: plants in the Moroccan, Betic Sierras (Southern Spain), and central Mediterranean clusters are all heterocarpic. The north and central Spanish, southwestern Sierra Morena, and Central European, Asian and South American cluster contain both heterocarpic (southwestern Sierra Morena) and homocarpic populations (all other populations). The Doñana cluster includes two homocarpic populations. Analyses of fragment parameters indicate that the oldest populations of H. radicata are located in Morocco and that the species expanded from this area in the Late Quaternary via at least three migratory routes, the earliest of which seems to have been to the southwestern Iberian Peninsula, with subsequent colonizations to the central Mediterranean area and the Betic Sierras. Homocarpic populations originated in the southwestern Iberian Peninsula and subsequently spread across north and central Spain, Central Europe and worldwide, where they became a highly successful weed.     

Biodegradation of Chilean native wood species,Drimys winteri and Nothofagus dombeyi,by Ganoderma australe

Drimys winteri and Nothofagus dombeyi, two native Chilean wood species with high potential for pulp production, were biodegraded by Ganoderma australe. This fungus is known to provoke extensive and selective biodelignification of these wood species in the field. Under laboratory conditions, N. dombeyi underwent higher weight and component losses than D. winteri. In neither case was the lignin removal selective, because glucan loss was almost simultaneous with lignin degradation. The decayed wood chips became progressively discoloured throughout the biodegradation time. The brightness increase was only partly reversed in thermal reversion assays. Nothofagus dombey solubility in 1% NaOH increased by 13.7% after 9 weeks of biodegradation, while D. winteri solubility increased by 14.2% in a shorter period (6 weeks). In both cases, the solubility increase was proportional to the liquor absorbance increase at 272 nm, which indicates that the wood solubility in 1% NaOH was dependent of lignin solubilization.     

Rapid down regulation of pyroglutamyl peptidase II activity by arachidonic acid in primary cultures of adenohypophyseal cells

Thyrotropin releasing hormone (TRH; pglu-his-proNH2) is inactivated, in the extracellular space, by pyroglutamyl aminopeptidase II (PPII), a narrow specificity ectopeptidase. In adenohypophysis, multiple hormones regulate PPII surface activity. The intracellular pathways of regulation are still poorly understood. Since some of the neurohormones which regulate PPII activity, including TRH and dopamine, transduce in part their effect through modulation of arachidonic acid (AA) mobilization, we have tested its role in regulation of PPII activity in primary cultures of rat adenohypophyseal cells. Melittin concentrations from 0.25 to 1 ug/ml induced a rapid decrease of PPII activity; 0.5 ug/ml caused a maximum effect (38-45% inhibition) at 20-30 min. AA (0.5 or 5 uM) also inhibited PPII activity (42-72%, maximum at 20 min); AA effect was reversible, with values approaching control at 1 h. The inhibitory effect of AA was blocked by lipoxygenase (10 uM nordihidroguaiaretic acid) but not ciclooxygenase inhibitors (10 uM indomethacin) suggesting the involvement of the lipoxygenase pathway. These data show that production of arachidonic acid by adenohypophyseal cells can rapidly but transiently down regulate surface PPII activity. This is the first evidence that AA mobilization can regulate the activity of an ectopeptidase.