Declining fruit production before death in a widely distributed tree species, Sorbus aucuparia L.

International audienceAbstractKey messageTrees are commonly thought to increase their seed production before death. We tested this terminal investment hypothesis using long-term data on rowan trees (Sorbus aucuparia) and found no support. Rather, seed production declined significantly before death, which points to the potential detrimental effects of reproductive senescence on regeneration in stands of old trees.ContextAging poses a fundamental challenge for long-lived organisms. As mortality changes with with age due to actuarial senescence, reproductive senescence may also lead to declines in fertility. However, life history theory predicts that reproductive investment should increase before mortality to maximize lifetime reproductive success, a phenomenon termed terminal investment.AimsTo date, it is unclear whether long-lived, indeterminantly growing trees experience reproductive senescence or display terminal investment.MethodsWe investigated fruit production of rowan (Sorbus aucuparia L.), widely distributed trees that live up to 150 years, as they approached death.ResultsIn our study population in Poland’s Carpathian Mountains, 79 trees that died produced up to 20% fewer fruits in the years before their demise compared to 199 surviving trees of the same population.ConclusionThe pattern of reproductive investment in S. aucuparia is suggestive of age-independent reproductive senescence rather than terminal investment. These findings highlight that the understanding of the generality of life history strategies across diverse taxa of perennial plants is still in its infancy

Testing the Terminal Investment Hypothesis in California Oaks

The terminal investment hypothesis—which proposes that reproductive investment should increase with age-related declines in reproductive value—has garnered support in a range of animal species but has not been previously examined in long-lived plants, such as trees. We tested this hypothesis by comparing relative acorn production and radial growth among 1,0001 mature individuals of eight species of California oaks (genus Quercus) followed for up to 37 years, during which time 70 trees died apparently natural deaths. We found no significant differences in the radial growth, acorn production, or index of reproductive effort, taking into consideration both growth and reproduction among dying trees relative to either conspecific trees at the same site that did not die or growth and reproduction from earlier years for the focal trees that did eventually die. Furthermore, we found no consistent trade-off between growth and reproduction among trees that died, nor did dying trees significantly alter their relative investment in reproduction even as they underwent physical decline. Trees approaching the end of their lives are often in poor physical condition but do not appear to differentially invest more of their diminished resources in reproduction compared with healthy trees

Unraveling a Paradox of Habitat Relationships: Scale-Dependent Drivers of Temporal Occupancy-Abundance Relationships in a Cooperatively Breeding Bird

Context Spatial occupancy and local abundance of species often positively covary, but the mechanisms driving this widespread relationship are poorly understood. Resource dynamics and habitat changes have been suggested as potential drivers, but long-term studies relating them to abundance and occupancy are rare. In this 34-year study of acorn woodpeckers (Melanerpes formicivorus), a cooperatively breeding species, we observed a paradoxical response to changes in habitat composition: despite a reduction in the availability of high-quality breeding habitat, the population increased considerably. Objectives We investigated the role of annual variation in food availability and long-term changes in habitat composition as predictors of population dynamics. Methods Using model selection, we contrasted competing hypotheses on the effects of changing resource availability on occupancy and social group size across three spatial scales: territory, neighborhood, and landscape. Results The increase in abundance was largely determined by the formation of new social groups, driven by a landscape-level expansion of canopy cover and its interaction with neighborhood-level acorn abundance, indicative of long-term increases in overall acorn productivity. Group size increased with neighborhood acorn crop two years earlier but groups were smaller in territories with more canopy cover. Conclusions Our results indicate that scale-dependent processes can result in paradoxical relationships in systems with spatial and temporal resource heterogeneity. Moreover, the findings support the role of resources in driving changes in abundance and occupancy at a landscape scale, suggesting that colonization of marginal habitat drives the positive occupancy-abundance relationship in this cooperatively breeding species

A full year of turbulence measurements from a drift campaign in the Arctic Ocean 2019-2020

Ocean turbulent mixing is a key process in the global climate system, regulating ocean circulation and the uptake and redistribution of heat, carbon, nutrients, oxygen and other tracers. In polar oceans, turbulent heat transport additionally affects the sea ice mass balance. Due to the inaccessibility of polar regions, direct observations of turbulent mixing are sparse in the Arctic Ocean. During the year-long drift expedition “Multidisciplinary drifting Observatory for the Study of Arctic Climate” (MOSAiC) from September 2019 to September 2020, we obtained an unprecedented data set of vertical profiles of turbulent dissipation rate and water column properties, including oxygen concentration and fluorescence. Nearly 1,700 profiles, covering the upper ocean down to approximately 400 m, were collected in sets of 3 or more consecutive profiles every day, and complemented with several intensive sampling periods. This data set allows for the systematic assessment of upper ocean mixing in the Arctic, and the quantification of turbulent heat and nutrient fluxes, and can help to better constrain turbulence parameterizations in ocean circulation models.publishedVersio

From theory to experiments for testing the proximate mechanisms of mast seeding: an agenda for an experimental ecology

Highly variable and synchronised production of seeds by plant populations, known as masting, is implicated in many important ecological processes, but how it arises remains poorly understood. The lack of experimental studies prevents underlying mechanisms from being explicitly tested, and thereby precludes meaningful predictions on the consequences of changing environments for plant reproductive patterns and global vegetation dynamics. Here we review the most relevant proximate drivers of masting and outline a research agenda that takes the biology of masting from a largely observational field of ecology to one rooted in mechanistic understanding. We divide the experimental framework into three main processes: resource dynamics, pollen limitation, and genetic and hormonal regulation, and illustrate how specific predictions about proximate mechanisms can be tested, highlighting the few successful experiments as examples. We envision that the experiments we outline will deliver new insights into how and why masting patterns might respond to a changing environment

Quantitative evaluation of healthy epidermis by means of multiphoton microscopy and fluorescence lifetime imaging microscopy

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A multivariate approach to investigate the associations of electrophysiological indices with schizophrenia clinical and functional outcome

Abstract Background Different electrophysiological (EEG) indices have been investigated as possible biomarkers of schizophrenia. However, these indices have a very limited use in clinical practice, as their associations with clinical and functional outcomes remain unclear. This study aimed to investigate the associations of multiple EEG markers with clinical variables and functional outcomes in subjects with schizophrenia (SCZs). Methods Resting-state EEGs (frequency bands and microstates) and auditory event-related potentials (MMN-P3a and N100-P3b) were recorded in 113 SCZs and 57 healthy controls (HCs) at baseline. Illness- and functioning-related variables were assessed both at baseline and at 4-year follow-up in 61 SCZs. We generated a machine-learning classifier for each EEG parameter (frequency bands, microstates, N100-P300 task, and MMN-P3a task) to identify potential markers discriminating SCZs from HCs, and a global classifier. Associations of the classifiers’ decision scores with illness- and functioning-related variables at baseline and follow-up were then investigated. Results The global classifier discriminated SCZs from HCs with an accuracy of 75.4% and its decision scores significantly correlated with negative symptoms, depression, neurocognition, and real-life functioning at 4-year follow-up. Conclusions These results suggest that a combination of multiple EEG alterations is associated with poor functional outcomes and its clinical and cognitive determinants in SCZs. These findings need replication, possibly looking at different illness stages in order to implement EEG as a possible tool for the prediction of poor functional outcome

DIFERENTES OLHARES SOBRE A DEPRESSÃO

O Significado da depressão vem do latim, que significa deprimère, no seu sentido literal, “pressionar para baixo”. No nosso cotidiano costumamos chamar a depressão como uma doença, e podemos sim classifica-la dessa maneira, contudo, explicaremos em nosso trabalho o porquê dela não ser considerada realmente uma doença e sim um quadro clínico. Desde antigamente, ela é diagnosticada de diversas formas, a ponto de ser considerada como loucura ou bruxaria. Atualmente, as coisas são bem diferentes, a “doença” é considerada como um Transtorno Depressivo e é fundamental o acompanhamento médico tanto para o diagnóstico quanto para o tratamento. Devido ser um tema tão comentado, nosso projeto tem como ideia central conscientizar as pessoas sobre o quanto a doença é importante e merece ser encarada com devida seriedade. Iremos apresentar em forma de palestra como a depressão tem um grande impacto na sociedade contemporânea e porquê ela se tornou tão comum ao decorrer do tempo. Temos como complemento um folder informativo que trata-se da opinião de três especialistas de diferentes áreas, dentre elas: Psicologia, Psiquiatria e Psicanálise. A opinião deles será de acordo com as perguntas que o grupo elaborou. Esse folder tem como função informar as pessoas que existem três áreas para serem escolhidas para diagnosticar e tratar a doença. Abordaremos questões sociais e biológicas sobre esse quadro clínico, tais como sintomas, tratamentos, psicologia das cores, hereditariedade, efeitos dos antidepressivos no corpo e a falta de conhecimento da sociedade com as pessoas que sofrem com depressão. Palavras-chave: Transtorno Depressivo. Quadro Clínico. Diagnóstico. Sociedade

Effects of lipid composition on membrane permeation

© 2018 The Royal Society of Chemistry. Passive permeation through lipid membranes is an essential process in biology. In vivo membranes typically consist of mixtures of lamellar and nonlamellar lipids. Lamellar lipids are characterized by their tendency to form lamellar sheet-like structures, which are predominant in nature. Nonlamellar lipids, when isolated, instead form more geometrically complex nonlamellar phases. While mixed lamellar/nonlamellar lipid membranes tend to adopt the ubiquitous lamellar bilayer structure, the presence of nonlamellar lipids is known to have profound effects on key membrane properties, such as internal distributions of stress and elastic properties, which in turn may alter related biological processes. This work focuses on one such process, i.e., permeation, by utilising atomistic molecular dynamics simulations in order to obtain transfer free energy profiles, diffusion profiles and permeation coefficients for a series of thirteen small molecules and drugs. Each permeant is tested on two bilayer membranes of different lipid composition, i.e., purely lamellar and mixed lamellar/nonlamellar. Our results indicate that the presence of nonlamellar lipids reduces permeation for smaller molecules (molecular weight 100). This work represents an advancement towards the development of more realistic in silico permeability assays, which may have a substantial future impact in the area of rational drug design