Browsing by Issue Date, starting with "2006-10"
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- Timing and success of reproductive stages in the seagrass Zostera noltiiPublication . Alexandre, Ana; Cabaço, Susana; Santos, Rui; Serrão, EsterThe timing and success of sexual reproduction of the seagrass Zostera noltii was investigated at the Ria Formosa lagoon, Portugal. Thirty plants were tagged and monitored individually through time to determine in situ the development time of each maturation stage, from the emergence of the flowers to the production of seeds. The overall process of flowering and fruiting lasted 47 ± 4 days, during which formation and maturation of the fruits was the most time-consuming stage (27 ± 2 days). Spathe success, i.e. the percentage of spathes that produced seeds, was 22 ± 4% while spathe mortality was 34 ± 6%. A considerable percentage of spathes (37 ± 7%) was lost through leaf detachment, but some of these may still add to the reproductive success of the species by contributing to the species recruitment within the source meadow or elsewhere. Meadow seed production (MSP) of Z. noltii was estimated to be 312 ± 66 seeds m−2, whereas the potential seed production of the studied meadow was 2623 seeds m−2. Under laboratory conditions, 70% of Z. noltii seeds germinated within 26 days, but only 10% reached the seedling stage due to the high mortality of germlings. Fertility, defined as the probability of a seed to originate a new plant, was estimated to be 14 × 10−4, which is higher than what is expected for most seagrasses.
- Composition and temporal dynamics of a temperate rocky cryptobenthic fish assemblagePublication . Beldade, R.; Erzini, Karim; Gonçalves, E. J.Temporal variation in a temperate cryptobenthic fish assemblage at the Arrabida Marine Park (Portugal) was assessed by visual Surveys during 2002 and 2003. A total of 9596 fish from 11 families and 30 species was recorded. There were no changes in structure or density at the assemblage level between years, whereas diversity changed significantly due to a higher number of abundant species in the second year. A similar seasonal trend was found between years, with a significant overall density increase in autumn. This is partially explained by the arrival of new recruits of some of the most abundant species in the assemblage. Assemblage diversity and structure also changed across seasons. A group of species encompassing Gobius xanthocephalus, Tripterygion delaisi, Parablennius pilicornis, Gobius paganellus, Lepadogaster candollii and Lepadogaster spp. were analysed in detail. The temporal patterns of two of the most abundant species, G. xanthocephalus and T delaisi, mimicked the overall temporal patterns of the assemblage. We suggest that the inter-annual stability in density of this subtidal fish assemblage may be similar to what has been reported for the intertidal and that strong post-settlement processes are probably shaping this assemblage.
- Predictability modulates the affective and sensory-discriminative neural processing of painPublication . Carlsson, Katrina; Andersson, Jesper; Petrovic, Predrag; Petersson, Karl Magnus; Ohman, Arne; Ingvar, MartinKnowing what is going to happen next, that is, the capacity to predict upcoming events, modulates the extent to which aversive stimuli induce stress and anxiety. We explored this issue by manipulating the temporal predictability of aversive events by means of a visual cue, which was either correlated or uncorrelated with pain stimuli (electric shocks). Subjects reported lower levels of anxiety, negative valence and pain intensity when shocks were predictable. In addition to attenuate focus on danger, predictability allows for correct temporal estimation of, and selective attention to, the sensory input. With functional magnetic resonance imaging, we found that predictability was related to enhanced activity in relevant sensory-discriminative processing areas, such as the primary and secondary sensory cortex and posterior insula. In contrast, the unpredictable more aversive context was correlated to brain activity in the anterior insula and the orbitofrontal cortex, areas associated with affective pain processing. This context also prompted increased activity in the posterior parietal cortex and lateral prefrontal cortex that we attribute to enhanced alertness and sustained attention during unpredictability. (c) 2006 Elsevier Inc. All rights reserved.
- Reconstructing the early evolution of Fungi using a six-gene phylogenyPublication . James, T. Y.; Kauff, F.; Schoch, C. L.; Matheny, P. B.; Hofstetter, V.; Cox, C. J.; Celio, G.; Gueidan, C.; Fraker, E.; Miadlikowska, J.; Lumbsch, H. T.; Rauhut, A.; Reeb, V.; Arnold, A. E.; Amtoft, A.; Stajich, J. E.; Hosaka, K.; Sung, G. -H.; Johnson, D.; O'Rourke, B.; Crockett, M.; Binder, M.; Curtis, J. M.; Slot, J. C.; Wang, Z.; Wilson, A. W.; Schüßler, A.; Longcore, J. E.; O'Donnell, K.; Mozley-Standridge, S.; Porter, D.; Letcher, P. M.; Powell, M. J.; Taylor, J. W.; White, M. M.; Griffith, G. W.; Davies, D. R.; Humber, R. A.; Morton, J. B.; Sugiyama, J.; Rossman, A.; Rogers, J.; Pfister, D.; Hewitt, D.; Hansen, K.; Hambleton, S.; Kohlmeyer, J.; Volkmann-Kohlmeyer, B.; Spotts, R. A.; Serdani, M.; Crous, P. W.; Hughes, K. W.; Matsuura, K.; Langer, E.; Langer, G.; Untereiner, W. A.; Lucking, R.; Budel, B.; Geiser, D. M.; Aptroot, A.; Diederich, P.; Schmitt, I.; Schultz, M.; Yahr, R.; Hibbett, D. S.; Lutzoni, F.; McLaughlin, D.; Spatafora, J.; Vilgalys, R.The ancestors of fungi are believed to be simple aquatic forms with flagellated spores, similar to members of the extant phylum Chytridiomycota (chytrids). Current classifications assume that chytrids form an early-diverging clade within the kingdom Fungi and imply a single loss of the spore flagellum, leading to the diversification of terrestrial fungi. Here we develop phylogenetic hypotheses for Fungi using data from six gene regions and nearly 200 species.Our results indicate that there may have been at least four independent losses of the flagellum in the kingdom Fungi. These losses of swimming spores coincided with the evolution of new mechanisms of spore dispersal, such as aerial dispersal in mycelial groups and polar tube eversion in the microsporidia (unicellular forms that lack mitochondria). The enigmatic microsporidia seem to be derived from an endoparasitic chytrid ancestor similar to Rozella allomycis, on the earliest diverging branch of the fungal phylogenetic tree.