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One of the biggest challenges facing Colombian society is related to the existence of historical punitive models built within one of Latin America’s longest internal armed conflicts. The other challenge is related to the presence of institutional issues resulting from the new governmental apparatus, which was developed in the transitional model, and which claims other non-punitive and vertical forms of justice. This text outlines in its thematic horizon the challenge raised by the demands for justice and the institutional incorporation of new ways of repairing the damages caused by an armed conflict of more than 60 years. Similarly, the signing of the peace agreement (on September 26, 2021) between one of the oldest active guerrillas in the continent and Juan Manuel Santos’ government, within the context of the transitional period resulting from such agreement, raises a series of questions related to the transformations in the violence dynamics, the changes associated with the social processes affected by the war, and the transformations experienced by the victims of war. Uno de los mayores retos a los cuales se encuentra abocada la sociedad colombiana está relacionado con la existencia de históricos modelos punitivos construidos en el marco de uno de los conflictos armados internos más prolongados de América Latina, y por otro, la existencia de unos retos institucionales que trae consigo el nuevo aparataje gubernamental elaborado en el modelo transicional, el cual reivindica otras formas no punitivas y verticales de la justicia. El reto entre las demandas por la justicia y la incorporación institucional de nuevas maneras para reparar los daños ocasionados por más de 60 años de un conflicto armado perfila en el horizonte temático construido en el presente texto. A su vez, la firma del acuerdo de paz alcanzado en Colombia el 26 de septiembre de 2021, entre una de las guerrillas activas más antiguas del continente y el gobierno de Juan Manuel Santos, suscita en el marco del periodo transicional incubado en dicho acuerdo una serie de interrogantes alusivos a las transformaciones en las dinámicas de las violencias, los cambios relacionados con los procesos sociales afectados por la guerra y las transformaciones experimentadas por las víctimas de las guerras. Um dos maiores desafios da sociedade colombiana está relacionado à existência de modelos históricos punitivos construídos no âmbito de um dos mais longos conflitos armados internos da América Latina e, por outro lado, à existência de desafios institucionais trazidos pelo novo aparelho governamental elaborado no modelo de transição, que reivindica outras formas não punitivas e verticais de justiça. O desafio entre as exigências de justiça e a incorporação institucional de novas formas de reparar os danos causados por mais de 60 anos de conflito armado está delineado no horizonte temático construído neste texto. Por sua vez, a assinatura do acordo de paz alcançado na Colômbia em 26 de setembro de 2021, entre um dos mais antigos guerrilheiros ativos do continente e o governo de Juan Manuel Santos, levanta uma série de questões no âmbito do período de transição incubado neste acordo, aludindo às transformações na dinâmica da violência, às mudanças relacionadas aos processos sociais afetados pela guerra e às transformações vividas pelas vítimas das guerras.

This article examines the emergence of young peasant singers in the region of General Carlos Ibáñez del Campo, in southern Chile, who through local music denounce the harmful effects of the possible construction of damns in the rivers Baker and Pascua. From a folk communication perspective, the paper addresses the pre-eminence of regional singers who use popular poetry mainly as a vehicle to convey information and denunciation. Two elements are observed: first, the resisting voices in rural areas proximate to the project are that of young people and second, they use musical structures that facilitate narration as an instrument of communication. Methodologically, semi-structured interviews as well as formal analysis of the means used for community denunciation were conducted. El siguiente artículo aborda la emergencia de jóvenes cantores campesinos en la Región del General Carlos Ibáñez del Campo, quienes a través de música local denuncian los efectos nocivos ante la eventual construcción de represas en los ríos Baker y Pascua. Desde una perspectiva folkcomunicacional se aborda la preeminencia de cantores regionales que utilizan prioritariamente la poesía popular cantada para expresar informaciones y denuncias. De este modo, se observan dos elementos: primero, las voces resistentes en las zonas rurales cercanas al proyecto son asumidas por jóvenes y, segundo, se valen de estructuras musicales que facilitan la narración como instrumento de comunicación. En términos metodológicos, se realizaron entrevistas semi-estructuradas y análisis formal del medio utilizado para la denuncia comunitaria. O seguinte artigo aborda a emergência de jovens cantores camponeses na região de General Carlos Ibáñez del Campo. Eles denunciam os efeitos nocivos da eventual construção de represas nos rios Baker e Pascua através da música local. Desde uma perspectiva folkcomunicacional aborda-se a preeminência de cantores regionais que utilizam prioritariamente a poesia popular cantada para expressar informações e denúncias. Deste modo, observam-se dois elementos: primeiro, as vozes resistentes nas áreas rurais próximas ao projeto são assumidas por jovens e, segundo, valem-se de estruturas musicais que facilitam a narração como instrumento de comunicação. Em termos metodológicos, realizaram-se entrevistas semi estruturadas e análises formais do meio utilizado para a denúncia comunitária. Para acceder al artículo utilice el link: http://revistascientificas.filo.uba.ar/index.php/runa/article/view/1166

REF.:Crea Facultades de Pesqueríay Oceanografía y Ciencías Jurídicasy Sociales en carácter que indica.

18 pages; International audience; The potential for biological colonization of Antarctic shores is an increasingly important topic in the context of anthropogenic warming. Successful Antarctic invasions to date have been recorded exclusively from terrestrial habitats. While non-native marine species such as crabs, mussels and tunicates have already been reported from Antarctic coasts, none have as yet established there. Among the potential marine invaders of Antarctic shallow waters is Halicarcinus planatus (Fabricius, 1775), a crab with a circum-Subantarctic distribution and substantial larval dispersal capacity. An ovigerous female of this species was found in shallow waters of Deception Island, South Shetland Islands in 2010. A combination of physiological experiments and ecological modelling was used to assess the potential niche of H. planatus and estimate its future southward boundaries under climate change scenarios. We show that H. planatus has a minimum thermal limit of 1°C, and that its current distribution (assessed by sampling and niche modelling) is physiologically restricted to the Subantarctic region. While this species is presently unable to survive in Antarctica, future warming under both ‘strong mitigation’ and ‘no mitigation’ greenhouse gas emission scenarios will favour its niche expansion to the Western Antarctic Peninsula (WAP) by 2100. Future human activity also has potential to increase the probability of anthropogenic translocation of this species into Antarctic ecosystems.

International audience; Maerl beds are vital habitats for a diverse array of marine species across trophic levels, but they are increasingly threatened by human activities and climate change. Furthermore, little is known about the genetic diversity of maerl‐forming species and the population structure of maerl beds, both of which are important for understanding the ability of these species to adapt to changing environments and for informing marine reserve planning. In this study, we used a whole genome genotyping approach to explore the population genomics of Phymatolithon calcareum, a maerl‐forming red algal species, whose geographic distribution spans the north‐east Atlantic, from Norway to Portugal. Our results, using 14,150 genome‐wide SNPs (single nucleotide polymorphisms), showed that P. calcareum maerl beds across the north‐east Atlantic are generally structured geographically, a pattern likely explained by low dispersal potential and limited connectivity between regions. Additionally, we found that P. calcareum from the Fal Estuary, south‐west England, is genetically distinct from all other P. calcareum sampled, even from The Manacles, a site located only 13 km away. Further analysis revealed that this finding is not the result of introgression from two closely related species, P. purpureum or Lithothamnion corallioides. Instead, this unique diversity may have been shaped over time by geographical isolation of the Fal Estuary maerl bed and a lack of gene flow with other P. calcareum populations. The genomic data presented in this study suggest that P. calcareum genetic diversity has accumulated over large temporal and spatial scales, the preservation of which will be critical for maximising the resilience of this species to changes in climate and the environment. Moreover, our findings underline the importance of managing the conservation of maerl beds across western Europe as distinct units, at a site‐by‐site level.

International audience; Catastrophic events can have profound effects on the demography of a population and consequently on genetic diversity. The dynamics of postcatastrophic recovery and the role of sexual versus asexual reproduction in buffering the effects of massive perturbations remain poorly understood, in part because the opportunity to document genetic diversity before and after such events is rare. Six natural (purely sexual) and seven cultivated (mainly clonal due to farming practices) populations of the red alga Agarophyton chilense were surveyed along the Chilean coast before, in the days after and 2 years after the 8.8 magnitude earthquake in 2010. The genetic diversity of sexual populations appeared sensitive to this massive perturbation, notably through the loss of rare alleles immediately after the earthquake. By 2012, the levels of diversity returned to those observed before the catastrophe, probably due to migration. In contrast, enhanced rates of clonality in cultivated populations conferred a surprising ability to buffer the instantaneous loss of diversity. After the earthquake, farmers increased the already high rate of clonality to maintain the few surviving beds, but most of them collapsed rapidly. Contrasting fates between sexual and clonal populations suggest that betting on strict clonality to sustain production is risky, probably because this extreme strategy hampered adaptation to the brutal environmental perturbation induced by the catastrophe.

International audience; During the domestication process, farmers influence the reproduction and care of organisms to ensure a predictable supply of the resource of interest, causing changes in phenotypic and genotypic character frequencies. In Chile, as a result of unconscious selection and domestication process, farmed populations of the red alga Agarophyton chilensis have most likely undergone a reduction in genetic diversity and a modification in life-history traits compared to wild populations. In order to understand the implications that these processes may have in A. chilensis, we investigated how temperature variations (10 °C, 15 °C, and 20 °C) affect growth and photosynthetic responses of natural and farmed populations from three different localities along the Chilean coast. Natural population’s growth decreased at low and high temperature levels while all three farmed populations respond in a very similar way to temperature variation. We propose that a possible outcome of farming, in the A. chilensis, vegetatively propagated crops, could have been the selection of general-purpose-genotypes able to perform adequately across the range of temperature tested in our experiment. Furthermore, our results showed that photosynthetic activity was also affected by temperature treatments (e.g., different maximum maximal electron transport rate and quantum yield values depending on the population type and temperature). In a context of climate change, A. chilensis farmed populations may be better able to cope with impacts of anthropogenic activities than natural populations due to the buffer effect of their general-purpose-genotypes, tolerant to a wide range of conditions.

International audience; A recent molecular taxonomic study along the Chilean coast (18° S–53° S) described 18 candidate species of bladed Bangiales of which only two were formally described. Few studies focused on local genetic and morphological diversity of bladed Bangiales and attempted to determine their intertidal distribution in contrasting habitats, and none were performed in Chile. To delimit intertidal distributions of genetic species, 66 samples of bladed Bangiales were collected at Maitencillo (32° S) in four zones: a rocky platform, a rocky wall, and two boulders zones surrounded by sandy and rocky bottoms, respectively. These samples were identified based on sequences of the mitochondrial COI and chloroplast rbcL markers. We also collected 87 specimens for morphological characterization of the most common species, rapidly assessing their putative species identity using newly developed species‐diagnostic (PCR‐RFLP) markers. Eight microscopic and two macroscopic morphological traits were measured. We described and named three of four species that predominate in Maitencillo (including Pyropia orbicularis): Pyropia variabilis Zapata, Meynard, Ramírez, Contreras‐Porcia, sp. nov., Porphyra luchea Meynard, Ramírez, Contreras‐Porcia sp. nov., and Porphyra longissima Meynard, Ramírez, Contreras‐Porcia, sp. nov. With the exception of Po. longissima restricted to boulders surrounded by sandy bottom, and a morphotype of Py. variabilis restricted to rocky walls, the other species/morphotypes have overlapping intertidal distributions. Except for Po. longissima, which is clearly differentiated morphologically (longest and thinnest blades), we conclude that morphology is not sufficient to differentiate bladed Bangiales. Our findings underscore the importance of refining our knowledge of intrinsic and environmental determinants on the distribution of bladed Bangiales.

International audience; The Caviahue-Copahue Volcanic Complex (CCVC) hosts one of Argentina's most important geothermal systems. To provide new insights into origin, circulation, and residence time of fluids, the chemical and isotopic composition (3 He/ 4 He, δ 2 H-δ 18 O in H 2 O; δ 13 C-δ 18 O in CO 2 ; 87 Sr/ 86 Sr) of thermal waters was measured together with the 3 H and 14 C activities. Water samples were collected from hot springs (LM, TC, LMM, CB and AF) representing the five major thermal zones of the CCVC and assumed to be steam-heated meteoric waters, and a well condensate (COP-2). The LMM, CB, and AF chemical composition and 87 Sr/ 86 Sr ratios show that water chemistry is acquired locally from exchange with volcanic rocks (Sr, SiO 2 , among others) and from steam (H 2 S). Two surface geothermal manifestations (LM and TC), along with the well condensate, COP-2, contain a higher contribution of deeporiginating fluids, with 87 Sr/ 86 Sr indicating possible contribution from deep-seated granitoids or sediments from the underlying basement. Radiocarbon-based residence times indicate ages ranging between 13,540 and 17,520 yrs. BP, representing the minimum age for the geothermal reservoir waters. Tritium is mainly absent in hot spring waters except for LMM and CB where the activity is close to the detection limit. This indicates a minimum age older than 70 yrs. for the water circulating in the shallow circuit. This result suggests that shallow meteoric water have a more complex and/or deeper circuit, resulting in older residence times. Helium isotopes in the CCVC span a wide range, from a pure mantle-derived value, of 8.35Ra, to a more crustal radiogenic signature, of 4.6Ra. The spatial variation is explained by associating the geochemical data with the geological context, which includes the distribution of fault-fracture meshes and different sources of magmatic volatiles underlying the Copahue volcano. The first order control on helium isotope signatures observed in this study seems to be dominated by the degree of crustal assimilation of the magmatic sources, which is in turn controlled by the local arrays of faults.

Low levels of diversity and endemism, when compared to red or brown algae, have been reported for Antarctic green marine macroalgae (Chlorophyta). However, recent studies including the use of molecular markers have allowed us to revisit the taxonomical status of species thought to be well known, underlying the existence of unexpected Antarctic flora diversity at local and regional scale. In the present study, samples of green macroalgae along the Western Antarctic Peninsula (from the 62°S down to the 66°S) were sequenced for two genetic markers regularly used for species determination and barcoding in Chlorophyta (i.e., the plastid genes tufA and rbcL). From the 122 specimens of Chlorophyta sampled, 85 were sequenced for the gene tufA and 16 for the gene rbcL. Using the NCBI Nucleotide Blast Tool to compare our sequences to the ones available in public data depositories allowed the identification of 11 species. Three new species were reported for the area: Rosenvingiella radicans (Kutz.) Rindi, L.McIvor & Guiry, Urospora wormskioldii (Mertens) Rosenvinge and Ulvella islandica R.Nielsen & K.Gunnarsson. Furthermore, molecular identification revealed strong match (> 95%) between our Antarctic sequences and the ones obtained for samples from the northern hemisphere for Acrosiphonia arcta (Dillwyn) Gain, Prasiola crispa (Lightfoot) Kutzing, Prasiola antarctica Kutzing 1849, R. radicans, Ulva sp. A-GW, U. islandica, Urospora penicilliformis (Roth) Areschoug and U. wormskioldii confirming the amphipolar distribution of various taxa of Antarctic Trebouxiophyceae and Ulvophyceae. Amphipolar distribution seems more common in green than red or brown Antarctic seaweeds, so here we hypothesize that recurrent occurrence of long dispersal events could explain the low level of endemism observed for this phylum along the Antarctic coasts.

Partially clonality is an incredibly common reproductive mode found across all the major eukaryotic lineages. Yet, population genetic theory is based on exclusive sexuality or exclusive asexuality, and partial clonality is often ignored. This is particularly true in haplodiplontic eukaryotes, including algae, ferns, mosses, and fungi, where somatic development occurs in both the haploid and diploid stages. Haplodiplontic life cycles are predicted to be correlated with asexuality, but tests of this prediction are rare. Moreover, there are unique consequences of having long-lived haploid and diploid stages in the same life cycle. For example, clonal processes uncouple the life cycle such that the repetition of the diploid stage via clonality leads to the loss of the haploid stage. Here, we surveyed the literature to find studies that had genotyped both haploid and diploid stages and recalculated population genetic summary metrics for seven red algae, one green alga, three brown algae, and three mosses. We compared these data to recent simulations that explicitly addressed the population genetic consequences of partial clonality in haplodiplontic life cycles. Not only was partial clonality found to act as a homogenizing force, but the combined effects of proportion of haploids, rate of clonality, and the relative strength of mutation versus genetic drift impacts the distributions of population genetic indices. We found remarkably similar patterns across commonly used population genetic metrics between our empirical and recent theoretical expectations. To facilitate future studies, we provide some recommendations for sampling and analyzing population genetic parameters for haplodiplontic taxa.

The formation of planetesimals was a key step in the assemblage of planetary bodies, yet many aspects of their formation remain poorly constrained. Notably, the mechanism by which chondrules -- sub-millimetric spheroids that dominate primitive meteorites -- were incorporated into planetesimals remains poorly understood. Here we classify and analyze particle-size distributions in various CO carbonaceous chondrites found in the Atacama Desert. Our results show that the average circle-equivalent diameters of chondrules define a positive trend with the petrographic grade, which reflects the progressive role of thermal metamorphism within the CO parent body. We show that this relationship could not have been established by thermal metamorphism alone but rather by aerodynamic sorting during accretion. By modeling the self-gravitational contraction of clumps of chondrules, we show that (i) the accretion of the CO parent body(ies) would have generated a gradual change of chondrule size with depth in the parent body, with larger chondrules being more centrally concentrated than smaller ones, and (ii) any subsequent growth by pebble accretion would have been insignificant. These findings give substantial support to the view that planetesimals formed via gravitational collapse., Comment: Accepted in ApJL. 24 pages, 3 figures, 2 tables, 1 appendix

International audience; Plocamium Lamouroux is a widespread genus for which 45 species are currently recognized. However, classical taxonomy based only on morphological characters, is problematic within this genus. The use of molecular tools has uncovered cryptic genetic species, mistakenly grouped under the name of mor-phological species that are common and widespread (including the generitype Plocamium cartilagineum (Linnaeus) P.S.Dixon). The aim of this work was to evaluate the species diversity of Plocamium in Southern Chile. For this purpose, three independent molecular markers were sequenced in samples collected from seven populations located between 41°S and 54°S. The species diversity was evaluated using phylogenetic reconstructions and two independent methods for species delimitation (ABGD and GMYC). The outcomes of each method were congruent, suggesting the presence of three species in Southern Chile. One species, named Plocamium sp. 1, is restricted to Punta Guabún, the only locality sampled north of the biogeographic barrier of the 42°S. The other two species, Plocamium sp. 2 and 3 are distributed in sympatry in Patagonia and Tierra del Fuego. The three Chilean species form a clade phylogenetically close to sequences obtained from New Zealand and Australia and a divergence along the coasts of Chile after past transoceanic dispersal is proposed. We propose that divergence in glacial microrefugia could have subsequently happen in the southern part of the coast, this hypothesis being supported by the strong impact of glacial maxima on population dynamics, especially in Plocamium sp. 3; es données moléculaires révèlent la présence de trois espèces de Plocamium Lamouroux présentant un patron de distribution complexe dans le sud du Chili. Quarante-cinq espèces sont actuellement reconnues dans le genre Plocamium Lamouroux, un genre présentant une très ample distribution. Cependant, la taxonomie classique, basée uniquement sur les caractères morphologiques, est problématique au sein de ce genre. L’utilisation d’outils moléculaires a permis de révéler l’existence d’espèces génétiques cryptiques, groupées par erreur sous un même nom, celui d’espèces morphologiques courantes et répandues (y compris l’espèce type du genre Plocamium : Plocamium cartilagineum (Linnaeus) P.S.Dixon)). L’objectif de notre travail était d’évaluer la diversité d’espèces de Plocamium dans le sud du Chili. À cet effet, trois marqueurs moléculaires indépendants ont été séquencés pour des échantillons prélevés dans sept populations situées entre 41°S et 54°S. La diversité en terme d’espèces a été évaluée à l’aide de reconstructions phylogénétiques et de deux méthodes indépendantes de délimitation d’espèces génétiques (ABGD et GMYC). Les résultats des différentes méthodes sont congruents, suggérant la présence de trois espèces dans le sud du Chili. Une espèce, nommée Plocamium sp. 1, est limitée à Punta Guabún, la seule localité échantillonnée au nord de la barrière biogéographique du 42°S. Les deux autres espèces, Plocamium sp. 2 et 3 sont distribuées en sympatrie en Patagonie et en Terre de Feu. Les trois espèces chiliennes forment un clade phylogénétiquement proche de séquences obtenues en Nouvelle-Zélande et en Australie et une divergence le long des côtes du Chili après un évènement historique de dispersion transocéanique passée pourrait expliquer ce résultat. Nous proposons des phénomènes postérieurs de divergence en micro-refuges glaciaires comme moteur de la spéciation en Patagonie et en Terre de Feu. Cette hypothèse est étayée par le fort impact des maxima glaciaires sur la dynamique des populations, en particulier dans le cas de Plocamium sp. 3.

International audience; Conditional differentiation between haploids and diploids has been proposed to drive the evolutionary stability of isomorphic biphasic life cycles. The cost of producing and maintaining genetic information has been posed as a possible driver of this conditional differentiation. Under this hypothesis, haploids benefit over diploids in resource‐limited environments by halving the costs of producing and maintaining DNA. Spared resources can be allocated to enhance survival, growth or fertility. Here we test in the field whether indeed haploids have higher growth rates than diploids. Individuals of the red seaweed Agarophyton chilense, were mapped and followed during 2 years with 4‐month census intervals across different stands within the Valdivia River estuary, Chile. As hypothesized, haploids grew larger and faster than diploids, but this was sex‐dependent. Haploid (gametophyte) females grew twice as large and 15% faster than diploids (tetrasporophytes), whereas haploid males only grew as large and as fast as the maximum obtained by diploids in summer. However, haploid males maintained their maximum sizes and growth rates constant year‐round, while diploids were smaller and had lower growth rates during the winter. In conclusion, our results confirm the conditional differentiation in size and growth between haploids and diploids but also identified important differences between males and females. Besides understanding life cycle evolution, the dynamics of A. chilense frond growth reported informs algal farmers regarding production optimization and should help in determining best planting and harvesting strategies.

International audience; Molecular studies have reported the coexistence of two species of Agarophyton in New Zealand: the newly described A. transtasmanicum with an apparently restricted distribution to some sites in the North Island, and the more widespread A. chilense. Here, we compared the distribution, genetic diversity, and structure of both Agarophyton species throughout the archipelago using sequences of the nuclear Internal Transcribed Spacer 2 (ITS2) marker. Agarophyton chilense's distribution was continuous and extensive along the North and South Islands, Stewart Island, and Chatham Island, and the genetic clusters were mostly concordant with boundaries between biogeographic regions. In contrast, specimens of A. transtasmanicum were collected in four sites broadly distributed in both the North and South Islands, with no clear spatial structure of the genetic diversity. Populations, where the species co-occurred, tended to display similar levels in genetic diversity for the two species. Demographic inferences supported a postglacial demographic expansion for two A. chilense genetic clusters, one present in the South Island and the eastern coast of the North Island, and the other present in northern South Island. A third genetic cluster located on the western coast of the North Island had a signature of long-term demographic stability. For A. transtasmanicum, the skyline plot also suggested a postglacial demographic expansion. Last, we developed a new molecular tool to quickly and easily distinguish between the two Agarophyton species, which could be used to ease future fine-scale population studies, especially in areas where the two species coexist.

Marine multicellular organisms inhabiting waters with natural high fluctuations in pH appear more tolerant to acidification than conspecifics occurring in nearby stable waters, suggesting that environments of fluctuating pH hold genetic reservoirs for adaptation of key groups to ocean acidification (OA). The abundant and cosmopolitan calcifying phytoplankton Emiliania huxleyi exhibits a range of morphotypes with varying degrees of coccolith mineralization. We show that E. huxleyi populations in the naturally acidified upwelling waters of the eastern South Pacific, where pH drops below 7.8 as is predicted for the global surface ocean by the year 2100, are dominated by exceptionally over-calcified morphotypes whose distal coccolith shield can be almost solid calcite. Shifts in morphotype composition of E. huxleyi populations correlate with changes in carbonate system parameters. We tested if these correlations indicate that the hyper-calcified morphotype is adapted to OA. In experimental exposures to present-day vs. future pCO2 (400 vs. 1200 µatm), the over-calcified morphotypes showed the same growth inhibition (−29.1±6.3 %) as moderately calcified morphotypes isolated from non-acidified water (−30.7±8.8 %). Under the high-CO2–low-pH condition, production rates of particulate organic carbon (POC) increased, while production rates of particulate inorganic carbon (PIC) were maintained or decreased slightly (but not significantly), leading to lowered PIC ∕ POC ratios in all strains. There were no consistent correlations of response intensity with strain origin. The high-CO2–low-pH condition affected coccolith morphology equally or more strongly in over-calcified strains compared to moderately calcified strains. High-CO2–low-pH conditions appear not to directly select for exceptionally over-calcified morphotypes over other morphotypes, but perhaps indirectly by ecologically correlated factors. More generally, these results suggest that oceanic planktonic microorganisms, despite their rapid turnover and large population sizes, do not necessarily exhibit adaptations to naturally high-CO2 upwellings, and this ubiquitous coccolithophore may be near the limit of its capacity to adapt to ongoing ocean acidification.

International audience; Biological invasions offer interesting situations for observing how novel interactions between closely related, formerly allopatric species may trigger phenotypic evolution in situ. Assuming that successful invaders are usually filtered to be competitively dominant, invasive and native species may follow different trajectories. Natives may evolve traits that minimize the negative impact of competition, while trait shifts in invasives should mostly reflect expansion dynamics, through selection for colonization ability and transiently enhanced mutation load at the colonization front. These ideas were tested through a large-scale common-garden experiment measuring life-history traits in two closely related snail species, one invasive and one native, co-occurring in a network of freshwater ponds in Guadeloupe. We looked for evidence of recent evolution by comparing uninvaded or recently invaded sites with long-invaded ones. The native species adopted a life history favoring rapid population growth (i.e., increased fecundity, earlier reproduction, and increased juvenile survival) that may increase its prospects of coexistence with the more competitive invader. We discuss why these effects are more likely to result from genetic change than from maternal effects. The invader exhibited slightly decreased overall performances in recently colonized sites, consistent with a moderate expansion load resulting from local founder effects. Our study highlights a rare example of rapid life-history evolution following invasion.