Percorrer por autor "Serrão, Ester"
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- Algal cover and sea urchin spatial distribution at Madeira Island (NE Atlantic)Publication . Alves, Filipe; Chícharo, Luís; Serrão, Ester; Abreu, A. D.This study describes sea urchin spatial distribution in relation to environmental factors, and the relationship between Diadema antillarum density and algal abundance. Twenty-three transects around Madeira Island were surveyed by scuba divers, and sea urchin density and algal cover were determined in situ. Sampling sites along these transects were characterised in terms of distance from the tide line, water depth, substratum type, bottom declivity and water turbulence. Diadema antillarum was the dominant sea urchin species. Paracentrotus lividus and Arbacia lixula occurred at shallower depths (2-6 m), contrasting with the distribution of Sphaerechinus granularis, which occurs among D. antillarum (4-20 m). Surveys found two alternative types of communities on rocky shores: 1) a community with high algal cover and low numbers of sea urchins, along the north and south-west coasts and; 2) a community with little algal cover and high densities of sea urchins, along the south-east coast. Macroalgal cover and D. antillarum densities were inversely correlated (adjusted R2=75.6%; n = 429; p< 0.05). The results showed that water turbulence was the most important factor limiting the distribution of D. antillarum on rocky substrates. We propose a multiple non-linear regression model (using backward stepwise analysis) to explain D. antillarum abundance on the rocky shores: D. antillarum/m2 (??)= 0.121 - 0.209 distance from shore (in m) (??) + 2.052 water depth (in m) (??) - 1.778 water turbulence level (??) - 0.007 water turbulence level4 (??); where ?? indicates data are square-root transformed (adjusted R2 = 60.99%; n = 454; p< 0.05).
- An expressed sequence tag analysis of the intertidal brown seaweeds Fucus serratus (L.) and F. vesiculosus (L.) (Heterokontophyta, Phaeophyceae) in response to abiotic stressorsPublication . Pearson, G. A.; Hoarau, G.; Lago-Lestón, Asunción; Coyer, J. A.; Kube, M.; Reinhardt, Richard; Henckel, K.; Serrão, Ester; Corre, E.; Olsen, J. L.In order to aid gene discovery and uncover genes responding to abiotic stressors in stress-tolerant brown algae of the genus Fucus, expressed sequence tags (ESTs) were studied in two species, Fucus serratus and Fucus vesiculosus. Clustering of over 12,000 ESTs from three libraries for heat shock/recovery and desiccation/rehydration resulted in identification of 2,503, 1,290, and 2,409 unigenes from heat-shocked F. serratus, desiccated F. serratus, and desiccated F. vesiculosus, respectively. Low overall annotation rates (18–31%) were strongly associated with the presence of long 3′ untranslated regions in Fucus transcripts, as shown by analyses of predicted protein-coding sequence in annotated and nonannotated tentative consensus sequences. Posttranslational modification genes were overrepresented in the heat shock/recovery library, including many chaperones, the most abundant of which were a family of small heat shock protein transcripts, Hsp90 and Hsp70 members. Transcripts of LI818-like light-harvesting genes implicated in photoprotection were also expressed during heat shock in high light. The expression of several heat-shock-responsive genes was confirmed by quantitative reverse transcription polymerase chain reaction. However, candidate genes were notably absent from both desiccation/rehydration libraries, while the responses of the two species to desiccation were divergent, perhaps reflecting the species-specific physiological differences in stress tolerance previously established. Desiccation-tolerant F. vesiculosus overexpressed at least 17 ribosomal protein genes and two ubiquitinribosomal protein fusion genes, suggesting that ribosome function and/or biogenesis are important during cycles of rapid desiccation and rehydration in the intertidal zone and possibly indicate parallels with other poikilohydric organisms such as desiccation-tolerant bryophytes.
- Analysis of sexual phenotype and prezygotic fertility in natural populations of Fucus spiralis, F. vesiculosus (Fucaceae, Phaeophyceae) and their putative hybridsPublication . Billard, E.; Serrão, Ester; Pearson, G. A.; Engel, C. R.; Destombe, C.; Valero, MyriamIn the genus Fucus, the character dioecy/hermaphroditism has undergone multiple state changes and hybridization is possible between taxa with contrasting mating systems, e.g. between the dioecious Fucus vesiculosus and the hermaphrodite F. spiralis. In the context of mating system evolution, we evaluated the potential consequences of hybridization by studying the variation in sexual phenotype and prezygotic fertility. Firstly, as a result of hybridization between the two sexual systems, gender variation may arise depending on the relative importance of genes with large versus small phenotypic effects. We thus qualitatively examined the extent of gender variation within and among individual hybrids in comparison with both parental species. Secondly, if hybridization breaks up co-adapted gene complexes, hybrid fertility may be reduced in comparison with both parental species. Therefore, we also quantified male and female prezygotic fertility in parental species and their hybrids in order to test for reduction in hybrid fitness. A total of 89 sexually mature individuals (20 F. spiralis, 40 F. vesiculosus, 10 hermaphrodite hybrids and 19 dioecious hybrids) were sampled in two geographically distant regions (France and Portugal) and six conceptacles per individual were observed. Within-individual variation was very restricted qualitatively – only one hybrid carried a conceptacle with a different sexual phenotype from the five others – as well as quantitatively. This suggests a simple genetic system for sex determination involving a few genes with major effects. In addition, analyses showed no significant decrease in hybrid fertility compared with parental species. Moreover, hybrids exhibited all sexual phenotypes, suggesting several generations of hybridization and backcrossing and, therefore, that hybrids are reproductively successful. Finally, the occurrence of sterile paraphyses in female and hermaphrodite individuals was interpreted as a relic of male function and suggests that, as in higher plants, evolution from hermaphroditism to dioecy may be the most parsimonious pathway.
- Assessing genetic diversity in clonal organisms: low diversity or low resolution? Combining power and cost efficiency in selecting markersPublication . ARNAUD-HAOND, Sophie; Alberto, F.; Teixeira, Sara; Procaccini, G.; Serrão, Ester; Duarte, C. M.The increasing use of molecular tools to study populations of clonal organisms leads us to question whether the low polymorphism found in many studies reflects limited genetic diversity in populations or the limitations of the markers used. Here we used microsatellite datasets for two sea grass species to provide a combinatory statistic, combined with a likelihood approach to estimate the probability of identical multilocus genotypes (MLGs) to be shared by distinct individuals, in order to ascertain the efficiency of the markers used and to optimize cost-efficiently the choice of markers to use for deriving unbiased estimates of genetic diversity. These results strongly indicate that conclusions from studies on clonal organisms derived using markers showing low polymorphism, including microsatellites, should be reassessed using appropriate polymorphic markers.
- Biomares, a LIFE project to restore and manage the biodiversity of Prof. Luiz Saldanha Marine ParkPublication . Cunha, A. H.; Erzini, Karim; Serrão, Ester; Gonçalves, E.; Borges, R.; Henriques, M.; Henriques, Victor; Guerra, M.; Duarte, C.; Marba, N.; Fonseca, MThe Marine Park Prof. Luiz Saldanha, in the coast of Arrabida, is the first marine park in continental Portugal. This area is a Nature 2000 site and is considered to be a hotspot for European marine biodiversity. In 2005, the management plan of the park was implemented, ending several habitat menaces, thereby allowing an application to the LIFE-NATURE Programme. The LIFE-BIOMARES project aimed at the restoration and management of the biodiversity of the marine park through several actions. The restoration of the seagrass prairies that were completely destroyed by fishing activities and recreational boating, was one of the most challenging. It included the transplanting of seagrasses from donor populations and the germination of seagrass seeds for posterior plantation to maintain genetic diversity in the transplanted area. One of the most popular actions was the implementation of environmental friendly moorings to integrate recreational use of the area with environmental protection. Several dissemination and environmental education actions concerning the marine park and the project took place and contributed to the public increase of the park acceptance. The seabed habitats were mapped along the park and a surrounding area to 100 m depth in order to create a habitat cartography of the park and to help locate alternative fishing zones. Biodiversity assessments for macrofauna revealed seasonal variations and an effect of the protection status. Preliminary results are presented and show that the marine park regulations are having a positive effect on biodiversity conservation and sustainable fisheries, thereby showing that these kind of conservation projects are important to disseminate coastal conservation best practices. The Biomares project is a model project that can be followed in the implementation of marine reserves and the establishment of the Natura 2000 marine network.
- Blue- and green-light signals for gamete release in the brown alga, Silvetia compressaPublication . Pearson, G. A.; Serrão, Ester; Dring, M.; Schmid, R.The intertidal brown alga Silvetia compressa releases gametes from receptacles (the reproductive tissue) rapidly upon a dark transfer (following a photosynthesisdependent period in the light, termed potentiation). In this study, the wavelength-dependence of this process was investigated. During the potentiation period in white light (WL), gametes are not released. However, gametes were released during potentiation in blue light (BL), or in low red light/blue light (RL/BL) ratios, but not in RL alone, high RL/BL ratios, or in broadband blue-green light (BGL) (presence of BL, but absence of RL). RL was as effective as WL for potentiation, i.e., both lead to gamete release following transfer to darkness. Rates of linear photosynthetic electron transport were similar in RL and BL. Gamete release in BL was inhibited by equal amounts of additional narrow-waveband light between the green and red regions of the spectrum, with light-induced gamete release restricted between <491 nm and 509 nm. Very little light-induced gamete release occurred between 530 nm and 650 nm. It is proposed that a BL-responsive photoreceptor is responsible for light-induced gamete release. Transfer of WL-potentiated receptacles to GL near 530 nm resulted in significant de-potentiation and reduced gamete release during a subsequent dark transfer. This effect was not seen at 509 nm or 560 nm and revealed the presence of a second photoreceptor system repressing or counteracting potentiation in the light. We propose that the restriction of gamete release to periods when irradiance is blue-shifted may constitute a depth-sensing mechanism for this intertidal alga, allowing controlled release of gametes at high tide and/or less turbid periods, thus minimizing gamete dilution, and promoting fertilization success.
- Broad scale agreement between intertidal habitats and adaptive traits on a basis of contrasting population genetic structurePublication . I Zardi, Gerardo; Nicastro, Katy R; Ferreira Costa, J.; Serrão, Ester; Pearson, G. A.Understanding the extent to which neutral processes and adaptive divergence shape the spatial structure of natural populations is a major goal in evolutionary biology and is especially important for the identification of significant levels of biodiversity. Our results identified replicated habitat-specific (adaptive) phenotypic divergence in the brown macroalga Fucus vesiculosus that is independent of population (neutral) genetic structure. F. vesiculosus inhabits contiguous and contrasting marine to estuarine intertidal habitats. Combining analyses of genetic and phenotypic traits of populations living under differential selective regimes (estuaries and open coast), we investigated levels of neutral genetic differentiation and adaptive physiological responses to emersion stress. In southwest England (SW UK) and northern Iberia (N. Iberia), populations living in estuaries and marine coastal habitats were genetically characterized at six microsatellite loci. In N. Iberia, two clades with limited admixture were recovered, each including one open coast site and the adjacent estuarine location. In contrast, SW UK samples clustered according to habitat and formed three distinct groups of genotypes; one including the two open coast locations and the other two representing each of the estuarine sites. Temperature loggers revealed distinct emersion regimes that characterized each habitat type independently of the region, while water and air temperature profiles showed site-specific trends. Despite acclimation under usual conditions, trait means of emersion stress resilience showed a strong phenotypic divergence between habitats, consistent with environmental clines in exposure time observed in the different habitats. We demonstrate that neutral genetic clusters do not reflect locally adapted population units. Our results identified replicated habitat-specific (adaptive) phenotypic divergence that is independent of population (neutral) genetic structure in F. vesiculosus. The significance of such findings extends beyond the theoretical evolutionary and ecological interest of discovering parallel adaptive responses to the broader implications for conservation of intraspecific biodiversity.
- Characterization of 12 polymorphic microsatellite markers in the sugar kelp Saccharina latissimaPublication . Paulino, Cristina; Neiva, J.; Coelho, Nelson C.; Aires, Tânia; Marba, Núria; Krause-Jensen, Dorte; Serrão, EsterSaccharina latissima is an ecologically and economically important kelp species native to the coastal regions of the Northern Hemisphere. This species has considerable phylogeographic structure and morphological plasticity, but lack of resolution of available genetic markers prevents a finer characterization of its genetic diversity and structure. Here, we describe 12 microsatellite loci identified in silico in a genomic library, and assess their polymorphism in three distant populations. Allelic richness at the species level was relatively high (5-23 alleles per locus), as was gene diversity within populations (0.42 < H (E) < 0.62). In addition, individuals readily form distinct genotypic clusters matching their populations of origin. The variation detected confirms the great potential of these markers to investigate the biogeography and population dynamics of S. latissima, and to better characterize its genetic resources for the establishing farming industry.
- Characterization of 15 polymorphic microsatellite loci in Rimicaris exoculata, and cross-amplification in other hydrothermal-vent shrimpPublication . Teixeira, Sara; Serrão, Ester; ARNAUD-HAOND, SophieAbstract Rimicaris exoculata is an alvinocarid shrimp endemic to the hydrothermal vents of the Mid-Atlantic Ridge. In order to study genetic variability and connectivity in this species, we developed fifteen polymorphic microsatellite markers. The markers were tested on one population and, except for one, all showed no departure from Hardy–Weinberg equilibrium, with an average overall observed heterozygosity of 0.63. Two primer pairs revealed possible linkage disequilibrium, and 14 crossamplified at least one of the three co-occurring shrimp species tested (Alvinocaris muricola, Alvinocaris markensis and Mirocaris fortunata). These markers therefore open perspectives for population genetic studies of hydrothermal vent shrimp species in order to unravel connectivity and evolution of populations, and to add information on possible future impact studies.
- Characterization of 15 polymorphic microsatellite loci in the temperate reef fish Lepadogaster lepadogaster, developed using 454-sequencingPublication . Teixeira, Sara; Candeias, Rui; Klein, Maria; Serrão, Ester; Borges, R.Abstract The clingfish, Lepadogaster lepadogaster is a reef fish species, abundant in temperate nearshore rocky reefs of the Eastern Atlantic and central and Eastern Mediterranean. To study genetic variability and population connectivity of this species, we developed fifteen polymorphic microsatellite markers. These were tested in one population and all but one, showed no departure from Hardy–Weinberg equilibrium. Average overall observed heterozygosity was 0.66 and allelic richness was 8.9. Two primer pairs revealed possible linkage disequilibrium. These markers open perspectives for population genetic studies of this species to unravel connectivity and population biology, vital information for future conservation studies.