L’ange Gabriel dans la forêt du centre du Chili

Dans cet essai ethnographique, j’explore la façon dont la forêt du centre du Chili se transforme. D’abord intéressée par les processus écologiques qui influencent la recomposition de la forêt après les perturbations anthropiques, je constate que la forêt devient difficile à situer dans le paysage socioéconomique. Dans une légende locale, l’ange Gabriel tue le diable pris dans la forêt par les fils de son poncho, qui se défait en s’accrochant aux arbres. Mais le diable ne meurt pas. De la même manière, j’essaie de repérer et de sonder les questions d’inégalités sociales et de transformations économiques qui déterminent comment la forêt est utilisée et pour qui elle l’est. Et même si les inégalités et les exploitations du passé sont supprimées – analytiquement, symboliquement, en pratique – elles réapparaissent sous une autre forme. La forêt se transforme avec les changements socioéconomiques.In this ethnographic essay, I explore how the forest in Central Chile is being transformed. Initially interested in the ecological processes that influence the recomposition of the forest after anthropogenic disturbances, I find that the forest becomes difficult to situate in the socio-economic landscape. In a local legend, the angel Gabriel kills the devil caught in the forest by the yarn of his poncho, which comes unravelled, tangled in the trees. But the devil does not die. In a similar way, I try to trace and trap the issues of social inequality and economic transformations that determine what and for whom the forest is used. And even if the inequalities and exploitations of the past are killed - analytically, symbolically, in practice - they reappear in another form. The forest transforms itself with socio-economic changes

Small mammals as indicators of cryptic plant species diversity in the central Chilean plant endemicity hotspot

AbstractIndicator species could help to compensate for a shortfall of knowledge about the diversity and distributions of undersampled and cryptic species. This paper provides background knowledge about the ecological interactions that affect and are affected by herbaceous diversity in central Chile, as part of the indicator species selection process. We focus on the ecosystem engineering role of small mammals, primarily the degu Octodon degus. We also consider the interacting effects of shrubs, trees, avian activity, livestock, slope, and soil quality on herbaceous communities in central Chile. We sampled herbaceous diversity on a private landholding characterized by a mosaic of savanna, grassland and matorral, across a range of degu disturbance intensities. We find that the strongest factors affecting endemic herbaceous diversity are density of degu runways, shrub cover and avian activity. Our results show that the degu, a charismatic and easily identifiable and countable species, could be used as an indicator species to aid potential conservation actions such as private protected area uptake. We map areas in central Chile where degus may indicate endemic plant diversity. This area is larger than expected, and suggests that significant areas of endemic plant communities may still exist, and should be identified and protected

The Ribosome as a Missing Link in Prebiotic Evolution III: Over-Representation of tRNA- and rRNA-Like Sequences and Plieofunctionality of Ribosome-Related Molecules Argues for the Evolution of Primitive Genomes from Ribosomal RNA Modules

We propose that ribosomal RNA (rRNA) formed the basis of the first cellular genomes, and provide evidence from a review of relevant literature and proteonomic tests. We have proposed previously that the ribosome may represent the vestige of the first self-replicating entity in which rRNAs also functioned as genes that were transcribed into functional messenger RNAs (mRNAs) encoding ribosomal proteins. rRNAs also encoded polymerases to replicate itself and a full complement of the transfer RNAs (tRNAs) required to translate its genes. We explore here a further prediction of our “ribosome-first” theory: the ribosomal genome provided the basis for the first cellular genomes. Modern genomes should therefore contain an unexpectedly large percentage of tRNA- and rRNA-like modules derived from both sense and antisense reading frames, and these should encode non-ribosomal proteins, as well as ribosomal ones with key cell functions. Ribosomal proteins should also have been co-opted by cellular evolution to play extra-ribosomal functions. We review existing literature supporting these predictions. We provide additional, new data demonstrating that rRNA-like sequences occur at significantly higher frequencies than predicted on the basis of mRNA duplications or randomized RNA sequences. These data support our “ribosome-first” theory of cellular evolution

Predicting the direction and magnitude of small mammal disturbance effects on plant diversity across scales

Despite years of research on small mammal disturbance effects on plant diversity, predicting the direction and magnitude of these effects remains elusive. Models such as the intermediate disturbance hypothesis, the perturbation hypothesis, or the ecosystem engineering hypothesis of small mammal disturbance, show considerable overlap but fail to account for key variable interactions and thus provide mainly post hoc explanations. Recent reviews have emphasized the importance of small mammals to basic and applied ecology. Re‐examining the mechanisms underlying their disturbance effects is thus timely. Here I present the Slope‐Hump Model, which integrates previous models and insights from the literature, and which is capable of predicting the direction and relative magnitude of disturbance effects on plant diversity. These predictions qualitatively match the results of recent meta‐analyses. The model also suggests new patterns and predictions that can stimulate both pure and applied ecology research

Why Do Birds False Alarm Flight?

False alarm flighting in avian flocks is common, and has been explained as a maladaptive information cascade. If false alarm flighting is maladaptive per se, then its frequency can only be explained by it being net adaptive in relation to some other benefit or equilibrium. However, I argue that natural selection cannot distinguish between false and true alarm flights that have similar energetic costs, opportunity costs, and outcomes. False alarm flighting cannot be maladaptive if natural selection cannot perceive the difference between true and false alarm flighting. Rather, the question to answer is what false and true alarm flighting both have in common that is adaptive per se. The fire drill hypothesis of alarm flighting posits that false alarm flights are an adaptive investment in practicing escape. The fire drill hypothesis predicts that all individuals can benefit from practicing escape, particularly juveniles. Flighting practice could improve recognition of and response time to alarm flighting signals, could compensate for inter-individual and within-day weight differences, and could aid the development of adaptive escape tactics. Mixed-age flocks with many juveniles are expected to false alarm flight more than adult flocks. Flocks that inhabit complex terrain should gain less from escape practice and should false alarm flight less. Behavioural ecology framings can be fruitfully complemented by other research traditions of learning and behaviour that are more focused on maturation and motor learning processes

Predicting the direction and magnitude of small mammal disturbance effects on plant diversity across scales

<p>Despite years of research on small mammal disturbance effects on plant diversity, predicting the direction and magnitude of these effects remains elusive. Models such as the intermediate disturbance hypothesis, the perturbation hypothesis, or the ecosystem engineering hypothesis of small mammal disturbance, show considerable overlap but fail to account for key variable interactions and thus provide mainly post hoc explanations. Recent reviews have emphasized the importance of small mammals to basic and applied ecology. Re<span>‐</span>examining the mechanisms underlying their disturbance effects is thus timely. Here I present the Slope<span>‐</span>Hump Model, which integrates previous models and insights from the literature, and which is capable of predicting the direction and relative magnitude of disturbance effects on plant diversity. These predictions qualitatively match the results of recent meta<span>‐</span>analyses. The model also suggests new patterns and predictions that can stimulate both pure and applied ecology research.</p><br /

The ribosome as a missing link in prebiotic evolution III: over-representation of tRNA- and rRNA-like sequences and plieofunctionality of ribosome-related molecules argues for the evolution of primitive genomes from Rrbosomal RNA Modules

We propose that ribosomal RNA (rRNA) formed the basis of the first cellular genomes, and provide evidence from a review of relevant literature and proteonomic tests. We have proposed previously that the ribosome may represent the vestige of the first self-replicating entity in which rRNAs also functioned as genes that were transcribed into functional messenger RNAs (mRNAs) encoding ribosomal proteins. rRNAs also encoded polymerases to replicate itself and a full complement of the transfer RNAs (tRNAs) required to translate its genes. We explore here a further prediction of our ribosome-first theory: the ribosomal genome provided the basis for the first cellular genomes. Modern genomes should therefore contain an unexpectedly large percentage of tRNA- and rRNA-like modules derived from both sense and antisense reading frames, and these should encode non-ribosomal proteins, as well as ribosomal ones with key cell functions. Ribosomal proteins should also have been co-opted by cellular evolution to play extra-ribosomal functions. We review existing literature supporting these predictions. We provide additional, new data demonstrating that rRNA-like sequences occur at significantly higher frequencies than predicted on the basis of mRNA duplications or randomized RNA sequences. These data support our ribosome-first theory of cellular evolution