Spatial analysis of Euterpe edulis (Arecaceae) in the Atlantic Forest. Does adult density affect the spatial distribution of the seedlings?

Análisis espacial en plántulas de Euterpe edulis (Arecaceae) en el bosque Atlántico ¿Afecta la densidad de adultos a su distribución? Las actividad de frugívoros y dispersores de semillas determina la distribución de las plantas. Estudiamos la influencia de la dispersión de semillas en la distribución espacial del palmito (Euterpe edulis) en el bosque atlántico de Isla do Cardoso, Brasil. Nuestras preguntas fueron: 1) ¿condiciona la densidad de adultos de palmito la distribución de sus plántulas? y 2) ¿se distribuyen las plántulas de palmito de forma similar al resto de plántulas de especies leñosas de la zona? Para responderlas seleccionamos dos parcelas (10 m x 10 m) en las que mapeamos todos los individuos presentes en el área, y analizamos su distribución espacial. Encontramos una mayor cantidad, densidad y agregación de plántulas tanto de palmito como de otras especies en la parcela con mayor número de palmitos adultos. Además, la varianza del número de plántulas/0.25 m2 y la distancia en la que la varianza se estabiliza, fueron también mayores en la parcela con alta densidad de palmitos adultos que en la de menor densidad. La densidad de adultos de E. edulis parece condicionar no sólo la cantidad sino también la distribución a pequeña escala de las plántulas de conespecíficos así como de otras especies a través de la actividad de los frugívoros. La abundancia de juveniles sugiere sin embargo que mecanismos denso-dependientes actuando en etapas sucesivas del ciclo de vida, modifican estos patrones espaciales creados en inicio por los frugívoros.Spatial analysis of Euterpe edulis (Arecaceae) seedlings in the Atlantic Forest. Does adult density affect their spatial distribution? The activity of frugivores and seed dispersers can affect the spatial distribution of plants. We evaluated whether seed dispersal affected the spatial distribution of palmetto, Euterpe edulis, in the atlantic forest of Ihla do Cardoso, Brazil. Our specific questions were: 1) can adult density affect seedling distributions? and 2) do E. edulis seedlings distribute spatially similar to the seedlings of other woody species in the area? To answer these questions, we selected two (10 m x 10 m) plots and spatially mapped all the individuals occurring in them. We found more seedlings, higher densities and seedling clumping both for palmetto and other species in the plot with more E. edulis adults. Furthermore, both the variance in number of seedlings/0.25 m2 and the distance at which the variance estabilized were higher within the plot with higher adult density. These results suggest that the density of palmetto adults influences not only the quantity but also the spatial distribution of its seedlings and the seedlings of other species at finer spatial scales through the activity of frugivores. However, sapling´s abundance suggests that diverse density-dependence mechanisms acting on successive life-stages may modify the initial spatial pattern created by frugivores

Suitability of the management of habitat complexity, acorn burial depth, and a chemical repellent for post-fire reforestation of oaks

Acorn sowing is a reforestation technique that can potentially render high-quality oak seedlings and high seedling survival, although it is often discarded due to high rates of seed predation. Predator activity can be modified by habitat complexity due to its effects on accessibility and protection for different predators. In this study we analysed how habitat complexity generated by different post-fire management treatments, sowing depth, and capsaicin (a chemical repellent) affect acorn predation by two guilds of post-dispersal predators that differ in size and foraging behaviour. We carried out two acorn predation experiments. In Experiment #1 we buried acorns at two depths (2 and 8 cm) in two post-fire burnt-wood management treatments of different habitat complexity, namely: (1) Salvage Logging (SL), where the burnt trunks were cut and piled and the branches were masticated (lower habitat complexity), and (2) Non-Intervention (NI), with no action after the fire and 100% of the trees naturally fallen by 2009, thus leaving a habitat with lying burnt logs and branches (higher habitat complexity). In Experiment #2 we repeated Experiment #1, with the addition of capsaicin as a mammal repellent treatment. Most acorns were consumed in both years (ca. 90%), mainly by rodents. In Experiment #1 predation by boars accounted for 4.1% of overall predation, and it was about twice as high in SL than in NI, likely due to the physical difficulty for large mammals to forage in an area with a complex structure created by lying logs and branches. In contrast, rodents consumed ca. 1.4 times more acorns in NI than in SL, which led to overall greater predation in NI in both experiments. This was likely due to the protection provided by the branches for the rodent community. Deeper burial reduced predation by small percentages, although in Experiment #1 it had a negligible effect in NI. Capsaicin did not reduce predation, and it reduced seedling emergence to half. This study suggests that habitat complexity created by trunks and branches reduced predation by wild boars, but favoured rodent acorn predation. We conclude that other methods for the protection of individual acorns need to be identified to increase the success of oak reforestation via seeding.Ministerio de Ciencia e InnovaciónComunidad de MadridMinisterio de Ciencia y EducaciónUnión Europe

Evidence for Involvement of the Salmonella enterica Z-Ring Assembly Factors ZapA and ZapB in Resistance to Bile

Genes annotated as ygfE and yiiU in the genome of Salmonella enterica serovar Typhimurium encode proteins homologous to Escherichia coli cell division factors ZapA and ZapB, respectively. ZapA− and ZapB− mutants of S. enterica are bile-sensitive. The amount of zapB mRNA increases in the presence of a sublethal concentration of sodium deoxycholate (DOC) while zapA mRNA remains unaffected. Increased zapB mRNA level in the presence of DOC is not caused by upregulation of zapB transcription but by increased stability of zapB mRNA. This increase is suppressed by an hfq mutation, suggesting the involvement of a small regulatory RNA. We provide evidence that such sRNA is MicA. The ZapB protein is degraded in the presence of DOC, and degradation appears to involve the Lon protease. We propose that increased stability of zapB mRNA in the presence of DOC may counter degradation of bile-damaged ZapB, thereby providing sufficient level of functional ZapB protein to permit Z-ring assembly in the presence of bile.España , Ministerio de Economía, Industria y Competitividad BIO2016-75235-

Ecología de la regeneración de Quercus ilex a escala de paisaje: importancia de los dispersores y depredadores de semillas para el reclutamiento

Resumen de Tesis Doctoral, Departamento de Ecología de la Universidad de Granada, Marzo 2008. Dirección: José María Gómez Reyes y Mario Díaz Esteban