Similar local but different systemic metabolomic responses of closely related pine subspecies to folivory by caterpillars of the processionary moth

Plants respond locally and systemically to herbivore attack. Most of the research conducted on plant-herbivore relationships at elemental and molecular levels have focused on the elemental composition or/and certain molecular compounds or specific families of defensive metabolites showing that herbivores tend to select plant individuals or species with higher nutrient concentrations and to avoid those with higher levels of defensive compounds. We performed stoichiometric and metabolomics, local and systemic, analyses in two subspecies of Pinus sylvestris under the attack by the caterpillars of the pine processionary moth, an important pest in the Mediterranean Basin. Both pine subspecies responded locally to folivory mainly by increasing the relative concentrations of terpenes and some phenolics. Systemic responses differed between subspecies and most of the metabolites presented intermediate concentrations between those of the affected parts and unattacked trees. Our results support the hypothesis that foliar nutrient concentrations are not a key factor of an alleged plant selection by adult female processionary moths for oviposition since folivory was not associated with any of the elements analyzed. Phenolic compounds did not generally increase in the attacked trees questioning thus their commonly proposed induction by folivory attack and their anti-feeding properties. Herbivory attack produced a general systemic shift in pines, including both primary and secondary metabolisms, that was less intense and chemically different from the local responses. Local pine responses were similar between subspecies while systemic responses were more distant between them

Are the metabolomic responses to folivory of closely related plant species linked to macroevolutionary and plant-folivore coevolutionary processes?

Altres ajuts: MAGRAMA/OAPN-022/2008The debate whether the coevolution of plants and insects or macroevolutionary processes (phylogeny) is the main driver determining the arsenal of molecular defensive compounds of plants remains unresolved. Attacks by herbivorous insects affect not only the composition of defensive compounds in plants but also the entire metabolome. Metabolomes are the final products of genotypes and are constrained by macroevolutionary processes, so closely related species should have similar metabolomic compositions and may respond in similar ways to attacks by folivores. We analyzed the elemental compositions and metabolomes of needles from three closely related Pinus species with distant coevolutionary histories with the caterpillar of the processionary moth respond similarly to its attack. All pines had different metabolomes and metabolic responses to herbivorous attack. The metabolomic variation among the species and the responses to folivory reflected their macroevolutionary relationships, with P. pinaster having the most divergent metabolome. The concentrations of terpenes were in the attacked trees supporting the hypothesis that herbivores avoid plant individuals with higher concentrations. Our results suggest that macroevolutionary history plays important roles in the metabolomic responses of these pine species to folivory, but plant-insect coevolution probably constrains those responses. Combinations of different evolutionary factors and trade-offs are likely responsible for the different responses of each species to folivory, which is not necessarily exclusively linked to plant-insect coevolution

Positive adjacency effects mediated by seed disperser birds in pine plantations

This study examines the consequences of adjacent elements for a given patch, through their effects on zoochorous dispersion by frugivorous birds. The case study consists of pine plantations (the focal patch) adjacent to other patches of native vegetation (mixed patches of native forest and shrublands), and/or pine plantations. Our hypothesis is that input of native woody species propagules generated by frugivorous birds within plantations strongly depends on the nature of the surrounding vegetation. To test this hypothesis, we studied frugivorous-bird abundance, seed dispersion, and seedling establishment in nine pine plantation plots in contact with patches of native vegetation. To quantify adjacency arrangement effects, we used the percentage of common border between a patch and each of its adjacent elements. Frugivorous bird occurrence in pine plantations is influenced by the adjacent vegetation: the greater the contact with native vegetation patches, the more abundant were the frugivorous birds within pine plantations. Furthermore, frugivorous birds introduce into plantations the seeds of a large sample of native fleshy-fruited species. The results confirm the hypothesis that zoochorous seed rain is strongly determined by the kind of vegetation surrounding a given plantation. This finding underlines the importance of the composition of the mosaic surrounding plantations and the availability of mobile link species as key landscape features conditioning passive restoration processes

Demografía y crecimiento primario durante la regeneración de tres especies de pino a lo largo de gradientes climáticos

13 páginas, 4 figuras y 3 tablasLa regeneración es un proceso crítico en la dinámica de los bosques, que presenta una marcada heterogeneidad temporal y espacial. En este trabajo se pretende avanzar en el conocimiento de las variables bióticas y abióticas que determinan a escala local la presencia, abundancia y crecimiento primario de plántulas de tres especies de pino: Pinus sylvestris, P. nigra y P. uncinata, y determinar el efecto relativo del clima. Para ello se muestrearon 216 parcelas distribuidas a lo largo de gradientes climáticos en siete localidades montañosas. Se censaron las plántulas recién emergidas y el resto de juveniles, y se midieron los crecimientos anuales. Los resultados mostraron diferencias significativas entre especies con efectos directos e indirectos del clima sobre la demografía y el estado de los juveniles. En las tres especies se apreció que la supervivencia de los juveniles aparecía desplazada hacia altitudes mayores respecto donde se producía el óptimo de la emergencia. Las relaciones locales de competencia y facilitación ejercieron efectos importantes sobre la regeneración de las tres especies, siendo éstos modulados por el clima.Ministerio Español de Innovación y Ciencia Consolider-Montes (CSD2008_00040), Los autores agradecen a toda la gente que hizo posible el trabajo de campo: R. Freire, B. Santamaría, J. Martínez, D. López, R. Ruíz-Puche, E. Molina, L. Ivorra, S. Martín, B. Ros y C. Boubekeur. También el apoyo estadístico de R. Manson.Proyecto europeo BACCARA (CE: FP7-226299, 7FP)Peer reviewe

A review of the combination among global change factors in forests, shrublands and pastures of the Mediterranean Region : beyond drought effects

Research in CRAG is also supported byCERCA institution (Generalitat de Catalunya).Climate change, alteration of atmospheric composition, land abandonment in some areas and land use intensification in others, wildfires and biological invasions threaten forests, shrublands and pastures all over the world. However, the impacts of the combinations between global change factors are not well understood despite its pressing importance. Here we posit that reviewing global change factors combination in an exemplary region can highlight the necessary aspects in order to better understand the challenges we face, warning about the consequences, and showing the challenges ahead of us. The forests, shrublands and pastures of the Mediterranean Basin are an ideal scenario for the study of these combinations due to its spatial and temporal heterogeneity, increasing and diverse human population and the historical legacy of land use transformations. The combination of multiple global change factors in the Basin shows different ecological effects. Some interactions alter the effects of a single factor, as drought enhances or decreases the effects of atmospheric components on plant ecophysiology. Several interactions generate new impacts: drought and land use changes, among others, alter water resources and lead to land degradation, vegetation regeneration decline, and expansion of forest diseases. Finally, different factors can occur alone or simultaneously leading to further increases in the risk of fires and biological invasions. The transitional nature of the Basin between temperate and arid climates involves a risk of irreversible ecosystem change towards more arid states. However, combinations between factors lead to unpredictable ecosystem alteration that goes beyond the particular consequences of drought. Complex global change scenarios should be studied in the Mediterranean and other regions of the world, including interregional studies. Here we show the inherent uncertainty of this complexity, which should be included in any management strategy

Plasticity in dendroclimatic response across the distribution range of Aleppo pine (Pinus halepensis)

We investigated the variability of the climate-growth relationship of Aleppo pine across its distribution range in the Mediterranean Basin. We constructed a network of tree-ring index chronologies from 63 sites across the region. Correlation function analysis identified the relationships of tree-ring index to climate factors for each site. We also estimated the dominant climatic gradients of the region using principal component analysis of monthly, seasonal, and annual mean temperature and total precipitation from 1,068 climatic gridpoints. Variation in ring width index was primarily related to precipitation and secondarily to temperature. However, we found that the dendroclimatic relationship depended on the position of the site along the climatic gradient. In the southern part of the distribution range, where temperature was generally higher and precipitation lower than the regional average, reduced growth was also associated with warm and dry conditions. In the northern part, where the average temperature was lower and the precipitation more abundant than the regional average, reduced growth was associated with cool conditions. Thus, our study highlights the substantial plasticity of Aleppo pine in response to different climatic conditions. These results do not resolve the source of response variability as being due to either genetic variation in provenance, to phenotypic plasticity, or a combination of factors. However, as current growth responses to inter-annual climate variability vary spatially across existing climate gradients, future climate-growth relationships will also likely be determined by differential adaptation and/or acclimation responses to spatial climatic variation. The contribution of local adaptation and/or phenotypic plasticity across populations to the persistence of species under global warming could be decisive for prediction of climate change impacts across populations. In this sense, a more complex forest dynamics modeling approach that includes the contribution of genetic variation and phenotypic plasticity can improve the reliability of the ecological inferences derived from the climate-growth relationships.This work was partially supported by Spanish Ministry of Education and Science co-funded by FEDER program (CGL2012-31668), the European Union and the National Ministry of Education and Religion of Greece (EPEAEK- Environment – Archimedes), the Slovenian Research Agency (program P4-0015), and the USDA Forest Service. The cooperation among international partners was supported by the COST Action FP1106, STREeSS

Individual diet variations in a wintering population of Black Redstart Phoenicurus ochruros: relationships with bird morphology and food availability

Ecomorphology in birds has usually centered on the analysis of closely related species, and only seldom has focused on individual differences within species. In the present study, I used the Black Redstart Phoenicurus ochruros to analyse the main assumption of ecomorphological hypothesis - that is, the correlation between morphology and ecology, on an individual level. I collected both biometric data and faecal samples from 14 selected individuals in a winter population of the Guadix Basin (SE Spain), in which birds overwinter while enduring harsh climatic conditions and food scarcity. I analysed individual correlations between morphology and diet, as well as individual differences in diet selection according to availability. Diet data were highly variable between individual birds, though always based on worker ants and soil weevils, and in general showed no significant similarity with availability data. Also, birds showed individual differences in selectivity patterns. However, there was little correlation between morphological bird traits and prey characteristics. Individual birds based their diet on ants and weevils, ate other prey when found, and used sheltered roosts in order ta maintain high fat stores with which to survive unpredictable wintering conditions. I suggest that the scarcity and low quality of available prey in this area force Black Redstart to display a generalist foraging strategy, and do not allow individual specialization in any prey type.Chez les oiseaux, les études écomorphologiques se sont en général focalisées sur l’analyse d’espèces étroitement apparentées, plus rarement sur les différences individuelles infraspécifiques. Le présent travail, relatif au Rougequeue noir Phoenicurus ochruros, analyse la principale hypothèse de la théorie écomorpho-logique, à savoir l’existence d’une corrélation au niveau de l’individu entre morphologie et écologie. Des données biométriques et des échantillons de fèces ont été recueillis sur 14 individus d’une population hivernale du bassin de Guadix (sud-est de l’Espagne) où les oiseaux hivernent, éprouvant des conditions climatiques difficiles et une nourriture raréfiée. Les données relatives au régime alimentaire variaient fortement entre les individus bien que soulignant toujours une base de fourmis et de charançons du sol et, en général, ne montraient aucune relation significative avec les données sur la disponibilité de la nourriture. Les oiseaux affichaient également des différences individuelles dans leurs patrons de sélection des proies. Toutefois, la corrélation était faible entre les traits morpho- logiques des oiseaux et les caractéristiques des proies. Les individus fondaient leur régime alimentaire sur les fourmis et les charançons, consommant d’autres proies au fil des rencontres et utilisant des reposoirs protégés afin de maintenir de fortes réserves adipeuses leur permettant de survivre dans des conditions hivernales imprévisibles. Il est suggéré que la rareté et la faible qualité des proies disponibles dans la région d’une part forcent le Rougequeue noir à se comporter en généraliste dans sa stratégie d’approvisionnement alimentaire et, d’autre part, n’autorisent aucune spécialisation individuelle sur un quelconque type de proie.Hódar José A. Individual diet variations in a wintering population of Black Redstart Phoenicurus ochruros: relationships with bird morphology and food availability. In: Revue d'Écologie (La Terre et La Vie), tome 53, n°1, 1998. pp. 77-91