Chaquitaclla, stratégies de labour et intensification en agriculture andine

* illus. 25 ref.National audienceBeche d'origine prehispanique, la chaquitaclla n'a pas ete eliminee par les outils introduits depuis la conquete. Dans les Andes du Perou et de Bolivie, elle reste actuellement l'outil le mieux adapte aux conditions de montagne pour labourer la longue jachere paturee, caracteristique des systemes agropastoraux d'altitude. Face a la faible productivite du labour a la chaquitaclla, les paysans ont mis au point des strategies de labour qui tendent a optimiser la production par jour de travail investi, independamment des rendements par hectare obtenus. Ces strategies se traduisent par trois itineraires techniques differencies afin de tirer parti de la diversite des conditions agroecologiques. La comprehension des logiques de production revele que les paysans andins ont su developper une agriculture de pente, ignoree dans les evaluations du milieu ou les terres sont reduites aux terres mecanisables. L'intensification, en eliminant la jachere favorise l'emploi de l'araire en traction attelee mais, dans ces regions d'altitude ou les processus d'intensification restent limites, les interrelations entre agriculture et elevage persistent a travers la jachere paturee et la chaquitaclla reste un instrument de labour indispensable. Cet article souligne la necessite de la connaissance des pratiques paysannes et des dynamiques agraires dans la definition d'une recherche technologique sur les outils de travail du sol

Chakitaklla : estrategia de barbecho e intensificacion de la agricultura andina

Ce document est un apport au débat sur le travail du sol et la modernisation dans l'agriculture andine. C'est le résultat d'une synthèse d'expériences sur le terrain et de recherches menées pendant de nombreuses années par les auteurs dans le Centre des Andes, le Sud du Pérou et le Nord-Ouest de la Bolivi

Limited ecological opportunity influences the tempo of morphological evolution in birds

Funding Information: J.P.D., J.C., and H.M. received funding from the Hubert Curien Alliance (project 607280675 ). J.R. received funding from the Agence Nationale de la Recherche ( CEBA : ANR-10-LABX-25-01, TULIP : ANR-10-LABX-0041 , JCJC : ANR-23-CE02-0005-01 ). Collection of trait data was supported by Natural Environment Research Council ( NE/I028068/1 , NE/P004512/1 to J.A.T.). We thank Erandi Bonillas-Monge, Dan Nesbit, Christophe Patterson, Trevor Price, Francisco Henao Diaz, and several anonymous reviewers for helpful comments.Peer reviewe

Integrating ecology into macroevolutionary research

On 9 March, over 150 biologists gathered in London for the Centre for Ecology and Evolution spring symposium, ‘Integrating Ecology into Macroevolutionary Research’. The event brought together researchers from London-based institutions alongside others from across the UK, Europe and North America for a day of talks. The meeting highlighted methodological advances and recent analyses of exemplar datasets focusing on the exploration of the role of ecological processes in shaping macroevolutionary patterns

Macroevolution of the plant–hummingbird pollination system

ABSTRACTPlant–hummingbird interactions are considered a classic example of coevolution, a process in which mutually dependent species influence each other's evolution. Plants depend on hummingbirds for pollination, whereas hummingbirds rely on nectar for food. As a step towards understanding coevolution, this review focuses on the macroevolutionary consequences of plant–hummingbird interactions, a relatively underexplored area in the current literature. We synthesize prior studies, illustrating the origins and dynamics of hummingbird pollination across different angiosperm clades previously pollinated by insects (mostly bees), bats, and passerine birds. In some cases, the crown age of hummingbirds pre‐dates the plants they pollinate. In other cases, plant groups transitioned to hummingbird pollination early in the establishment of this bird group in the Americas, with the build‐up of both diversities coinciding temporally, and hence suggesting co‐diversification. Determining what triggers shifts to and away from hummingbird pollination remains a major open challenge. The impact of hummingbirds on plant diversification is complex, with many tropical plant lineages experiencing increased diversification after acquiring flowers that attract hummingbirds, and others experiencing no change or even a decrease in diversification rates. This mixed evidence suggests that other extrinsic or intrinsic factors, such as local climate and isolation, are important covariables driving the diversification of plants adapted to hummingbird pollination. To guide future studies, we discuss the mechanisms and contexts under which hummingbirds, as a clade and as individual species (e.g. traits, foraging behaviour, degree of specialization), could influence plant evolution. We conclude by commenting on how macroevolutionary signals of the mutualism could relate to coevolution, highlighting the unbalanced focus on the plant side of the interaction, and advocating for the use of species‐level interaction data in macroevolutionary studies

Expression analysis of the TAB2 protein in adult mouse tissues

Background: The Interleukin-1 (IL-1) signaling component TAK1 binding protein 2 (TAB2) plays a role in activating the NFκB and JNK signaling pathways. Additionally, TAB2 functions in the nucleus as a repressor of NFκB-mediated gene regulation. Objective: To obtain insight into the function of TAB2 in the adult mouse, we analyzed the in vivo TAB2 expression pattern. Materials and methods: Cell lines and adult mouse tissues were analyzed for TAB2 protein expression and localization. Results: Immunohistochemical staining for TAB2 protein revealed expression in the vascular endothelium of most tissues, hematopoietic cells and brain cells. While TAB2 is localized in both the nucleus and the cytoplasm in cell lines, cytoplasmic localization predominates in hematopoietic tissues in vivo. Conclusions: The TAB2 expression pattern shows striking similarities with previously reported IL-1 receptor expression and NFκB activation patterns, suggesting that TAB2 in vivo is playing a role in these signaling pathways

Strong Neutral Spatial Effects Shape Tree Species Distributions across Life Stages at Multiple Scales

Traditionally, ecologists use lattice (regional summary) count data to simulate tree species distributions to explore species coexistence. However, no previous study has explicitly compared the difference between using lattice count and basal area data and analyzed species distributions at both individual species and community levels while simultaneously considering the combined scenarios of life stage and scale. In this study, we hypothesized that basal area data are more closely related to environmental variables than are count data because of strong environmental filtering effects. We also address the contribution of niche and the neutral (i.e., solely dependent on distance) factors to species distributions. Specifically, we separately modeled count data and basal area data while considering life stage and scale effects at the two levels with simultaneous autoregressive models and variation partitioning. A principal coordinates of neighbor matrix (PCNM) was used to model neutral spatial effects at the community level. The explained variations of species distribution data did not differ significantly between the two types of data at either the individual species level or the community level, indicating that the two types of data can be used nearly identically to model species distributions. Neutral spatial effects represented by spatial autoregressive parameters and the PCNM eigenfunctions drove species distributions on multiple scales, different life stages and individual species and community levels in this plot. We concluded that strong neutral spatial effects are the principal mechanisms underlying the species distributions and thus shape biodiversity spatial patterns

Molecular phylogenetics and temporal diversification in the genus Aeromonas based on the sequences of five housekeeping genes

Several approaches have been developed to estimate both the relative and absolute rates of speciation and extinction within clades based on molecular phylogenetic reconstructions of evolutionary relationships, according to an underlying model of diversification. However, the macroevolutionary models established for eukaryotes have scarcely been used with prokaryotes. We have investigated the rate and pattern of cladogenesis in the genus Aeromonas (γ-Proteobacteria, Proteobacteria, Bacteria) using the sequences of five housekeeping genes and an uncorrelated relaxed-clock approach. To our knowledge, until now this analysis has never been applied to all the species described in a bacterial genus and thus opens up the possibility of establishing models of speciation from sequence data commonly used in phylogenetic studies of prokaryotes. Our results suggest that the genus Aeromonas began to diverge between 248 and 266 million years ago, exhibiting a constant divergence rate through the Phanerozoic, which could be described as a pure birth process

Extant diversity of bryophytes emerged from successive post-Mesozoic diversification bursts

Unraveling the macroevolutionary history of bryophytes, which arose soon after the origin of land plants but exhibit substantially lower species richness than the more recently derived angiosperms, has been challenged by the scarce fossil record. Here we demonstrate that overall estimates of net species diversification are approximately half those reported in ferns and similar to 30% those described for angiosperms. Nevertheless, statistical rate analyses on time-calibrated large-scale phylogenies reveal that mosses and liverworts underwent bursts of diversification since the mid-Mesozoic. The diversification rates further increase in specific lineages towards the Cenozoic to reach, in the most recently derived lineages, values that are comparable to those reported in angiosperms. This suggests that low diversification rates do not fully account for current patterns of bryophyte species richness, and we hypothesize that, as in gymnosperms, the low extant bryophyte species richness also results from massive extinctions.Assembling the Tree of Life programme at NSF; NSF [EF-0531730-002, EF-0531680, EF-0531750]; Scottish Government's Rural and Environment Science and Analytical Services Division; BeiPD-cofund Marie Curie fellowshipinfo:eu-repo/semantics/publishedVersio