Direct and Indirect Effects of Climate on Demography and Early Growth of Pinus sylvestris at the Rear Edge: Changing Roles of Biotic and Abiotic Factors

Global change triggers shifts in forest composition, with warming and aridification being particularly threatening for the populations located at the rear edge of the species distributions. This is the case of Scots pine (Pinus sylvestris) in the Mediterranean Basin where uncertainties in relation to its dynamics under these changing scenarios are still high. We analysed the relative effect of climate on the recruitment patterns of Scots pine and its interactions with local biotic and abiotic variables at different spatial scales. Number of seedlings and saplings was surveyed, and their annual shoot growth measured in 96 plots located across altitudinal gradients in three different regions in the Iberian Peninsula. We found a significant influence of climate on demography and performance of recruits, with a non-linear effect of temperature on the presence of juveniles, and a positive effect of precipitation on their survival. Abundance of juveniles of P. sylvestris that underwent their first summer drought was skewed towards higher altitudes than the altitudinal mean range of the conspecific adults and the optimum elevation for seedlings'' emergence. At local level, light availability did not influence juveniles'' density, but it enhanced their growth. Biotic interactions were found between juveniles and the herb cover (competition) and between the number of newly emerged seedlings and shrubs (facilitation). Results also highlighted the indirect effect that climate exerts over the local factors, modulating the interactions with the pre-existing vegetation that were more evident at more stressful sites. This multiscale approach improves our understanding of the dynamics of these marginal populations and some management criteria can be inferred to boost their conservation under the current global warming.     

Lkb1 Loss Promotes Tumor Progression of BRAFV600E-Induced Lung Adenomas

Aberrant activation of MAP kinase signaling pathway and loss of tumor suppressor LKB1 have been implicated in lung cancer development and progression. Although oncogenic KRAS mutations are frequent, BRAF mutations (BRAF^V600E) are found in 3% of human non-small cell lung cancers. Contrary to KRAS mutant tumors, BRAF^V600E-induced tumors are benign adenomas that fail to progess. Interestingly, loss of tumor supressor LKB1 coexists with KRAS oncogenic mutations and synergizes in tumor formation and progression, however, its cooperation with BRAF^V600E oncogene is unknown. Our results describe a lung cell population in neonates mice where expression of BRAF^V600E leads to lung adenoma development. Importantly, expression of BRAF^V600E concomitant with the loss of only a single-copy of Lkb1, overcomes senencence–like features of BRAF^V600E-mutant adenomas leading malignization to carcinomas. These results posit LKB1 haploinsufficiency as a risk factor for tumor progression of BRAF^V600E mutated lung adenomas in human cancer patients.     

Outbreak analysis of an SIS epidemic model with rewiring

This paper is devoted to the analysis of the early dynamics of an SIS epidemic model defined on networks. The model, introduced by Gross et al. (Phys Rev Lett 96:208701, 2006), is based on the pair-approximation formalism and assumes that, at a given rewiring rate, susceptible nodes replace an infected neighbour by a new susceptible neighbour randomly selected among the pool of susceptible nodes in the population. The analysis uses a triple closure that improves the widely assumed in epidemic models defined on regular and homogeneous networks, and applies it to better understand the early epidemic spread on Poisson, exponential, and scale-free networks. Two extinction scenarios, one dominated by transmission and the other one by rewiring, are characterized by considering the limit system of the model equations close to the beginning of the epidemic. Moreover, an analytical condition for the occurrence of a bistability region is obtained.     

Evaluation of DNA extraction methods from complex phototrophic biofilms

Phototrophic biofilms are used in a variety of biotechnological and industrial processes. Understanding their structure, ie microbial composition, is a necessary step for understanding their function and, ultimately, for the success of their application. DNA analysis methods can be used to obtain information on the taxonomic composition and relative abundance of the biofilm members. The potential bias introduced by DNA extraction methods in the study of the diversity of a complex phototrophic sulfide-oxidizing biofilm was examined. The efficiency of eight different DNA extraction methods combining physical, mechanical and chemical procedures was assessed. Methods were compared in terms of extraction efficiency, measured by DNA quantification, and detectable diversity (16S rRNA genes recovered), evaluated by denaturing gradient gel electrophoresis (DGGE). Significant differences were found in DNA yields ranging from 116 ± 12 to 1893 ± 96 ng of DNA. The different DGGE fingerprints ranged from 7 to 12 bands. Methods including phenol–chloroform extraction after enzymatic lysis resulted in the greatest DNA yields and detectable diversity. Additionally, two methods showing similar yields and retrieved diversity were compared by cloning and sequencing. Clones belonging to members of the Alpha-, Beta- and Gamma- proteobacteria, Bacteroidetes, Cyanobacteria and to the Firmicutes were recovered from both libraries. However, when bead-beating was applied, clones belonging to the Deltaproteobacteria were also recovered, as well as plastid signatures. Phenol–chloroform extraction after bead-beating and enzymatic lysis was therefore considered to be the most suitable method for DNA extraction from such highly diverse phototrophic biofilms.     

Responses of ‘Conference’ Pear to Deficit Irrigation: Water Relations, Leaf Discrimination Against 13CO2, Tree Starch Content, Growth, and Recovery After Rewatering

Responses to deficit irrigation (DI) throughout the fruit-growing season were studied in ‘Conference’ pear grafted onto quince M-A rootstock and grown in large containers. The treatments were (1) full irrigation (FI), (2) DI during Stage I of fruit growth (DI-Stage I), and (3) DI during Stage II of fruit growth (DI-Stage II). Four whole trees were sampled before Stage I and from all treatments at the end of Stage I, end of Stage II (fruit harvest), and before leaf fall. There was less discrimination against ¹³CO₂ in DI leaves, indicative of reduced photosynthetic capacity. DI treated trees had lower starch content in branches and trunks but root starch concentration was the same between DI- and FI-treated trees. Compared to FI-treated trees, leaf, shoot, branch, and trunk dry biomass was reduced by 34, 50, 37, and 32 %, respectively, in DI-Stage I and by 45, 73, 37, and 22 % in DI-Stage II. Root growth was not affected by DI. Trees had limited capacity for storing starch in roots. Recovery of the aboveground starch concentration for DI treatments occurred within 1 month after rewatering but total starch content never recovered.     

Description of a new species of Neralsia Cameron with a wide distribution in the American continent: N. incompleta n. sp. (Hymenoptera: Figitidae: Figitinae)

In this study a new species of Neralsia is described, N. incompleta n. sp. The radial cell shape allows to distinguish it clearly from the rest of species of the genus. The distribution of Neralsia incompleta n. sp. is probably the entire American continent, having been collected from Canada to Paraguay. In spite of its abundance, the associated biology is unknown, although it should be related with parasitism of Diptera Cyclorrhapha.     

Formation and growth of a heronry in a managed wetland in Doñana,southwest Spain

Capsule A newly created wetland has been beneficial for the breeding of five heron species and for the settlement and expansion of Glossy Ibises in the region.

Aim To determine whether created wetland would lead to the establishment of a heron and ibis breeding colony, and if so, to determine its effects on the distribution of these species in the wider region.

Methods Number of pairs breeding at the new wetland and in the region were estimated annually from 1996 to 2008. We investigated whether the growth of the new colony was explained by redistribution of breeding pairs within the region.

Results Purple Herons, Squacco Herons and Glossy Ibises colonised the new wetland in 1996. Black‐crowned Night Herons settled in 1998, while Cattle and Little Egrets were the last species to establish in the mixed colony in 2001. The population increase was particularly marked for Glossy Ibises (which had bred in Doñana only sporadically through the 20th century). Our findings suggest that simple redistribution of pairs does not explain the formation and growth of the new colony. Since the first year of establishment numbers of Glossy Ibises and Purple Herons have shown a significant growth trend at both the new colony and in Doñana.

Conclusion The creation and management of a new wetland has been successful for the conservation of heron and egret species and promoted the expansion of the Glossy Ibis population across the western Mediterranean region.     

Population Composition and Ectoparasite Prevalence on Bats (Sturnira ludovici; Phyllostomidae) in Forest Fragments and Coffee Plantations of Central Veracruz,Mexico

Studies comparing the abundance of frugivorous bats in shade‐coffee plantations and forest fragments report contradictory results, and have not taken into account the landscape context in which coffee plantations are immersed. Variables of population composition such as abundance, sex proportion, and reproductive condition, together with biological tags (i.e., bat fly prevalence), can provide information about spatiotemporal dynamics of habitats used by bats. In the central part of Veracruz, Mexico, we compared population variables and ectoparasite prevalence of the highland yellow‐shouldered bat (Sturnira ludovici) in two landscapes, one dominated by shade‐coffee plantations and another by forest fragments. Comparing these attributes between these two landscapes will increase our knowledge about the role of this agro‐ecosystem in the conservation of this species, which is an important seed disperser of cloud forest vegetation. Total abundance and proportion of females was greater in forest fragments than in coffee plantations, whereas the percentage of reproductive females and bat fly prevalence was similar between landscapes. Our results show that landscapes with forest fragments harbor the greatest abundance of S. ludovici, but shade‐coffee plantations also are utilized by S. ludovici and likely adjacent forest remnants provide enough food resources for this species and other frugivores. Moreover, this study provides more evidence documenting the importance of preserving the last cloud forest fragments in the central region of Veracruz, Mexico, and suggests that using shade‐coffee plantations to connect forest fragments may be an effective way of maintaining populations of S. ludovici and likely other volant frugivores.     

Recent Dinoflagellate cyst distribution in the North Canary Basin,NW Africa

The North Canary Basin (NW Africa) falls within a major eastern boundary upwelling system. This part of the coastal upwelling system is seasonal and is characterised by the development of large filaments migrating seawards. Hence, 16 samples from this location were selected to identify an “upwelling signal” in the composition of the dinoflagellate cyst assemblages.

Samples closest to the most intense upwelling cells are dominated by L. machaerophorum and G. catenatum and Protoperidinium spp. These make up the “upwelling signal” characteristic for the system. Moreover, the “upwelling signal” can be advected offshore, with filaments that may extend as far as 300 km. Finally, the finding of cysts from G. catenatum, a toxic dinoflagellate, raises the need for a better understanding of the relationship between its presence and distribution in the region, and the coastal upwelling system.