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Fernández, Leonardo D.

Nom
Fernández, Leonardo D.
Affiliation principale
Fonction
Ancien.ne collaborateur.trice
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https://libra.unine.ch/handle/123456789/1049
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0000-0001-9550-1921

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  • Publication
    Accès libre
    Global distribution modelling of a conspicuous Gondwanian soil protist reveals latitudinal dispersal limitation and range contraction in response to climate warming
    (2023)
    Estelle P. Bruni 
    ;
    Olivia Rusconi 
    ;
    Olivier Broennimann
    ;
    Antoine Adde
    ;
    Jauslin, Raphaël 
    ;
    Valentyna Krashevska
    ;
    Anush Kosakyan 
    ;
    Eric Armynot du Châtelet
    ;
    João P. B. Alcino
    ;
    Louis Beyens
    ;
    Quentin Blandenier 
    ;
    Anatoly Bobrov
    ;
    Luciana Burdman
    ;
    Clément Duckert 
    ;
    Leonardo D. Fernández 
    ;
    Maria Beatriz Gomes e Souza
    ;
    Thierry J. Heger
    ;
    Isabelle Koenig 
    ;
    Daniel J. G. Lahr
    ;
    Michelle McKeown
    ;
    Ralf Meisterfeld
    ;
    David Singer 
    ;
    Eckhard Voelcker
    ;
    Janet Wilmshurst
    ;
    Sebastien Wohlhauser
    ;
    David M. Wilkinson
    ;
    Antoine Guisan
    ;
    Edward A. D. Mitchell
    AbstractAimThe diversity and distribution of soil microorganisms and their potential for long‐distance dispersal (LDD) are poorly documented, making the threats posed by climate change difficult to assess. If microorganisms do not disperse globally, regional endemism may develop and extinction may occur due to environmental changes. Here, we addressed this question using the testate amoeba Apodera vas, a morphologically conspicuous model soil microorganism in microbial biogeography, commonly found in peatlands and forests mainly of former Gondwana. We first documented its distribution. We next assessed whether its distribution could be explained by dispersal (i.e. matching its climatic niche) or vicariance (i.e. palaeogeography), based on the magnitude of potential range expansions or contractions in response to past and on‐going climatic changes. Last, we wanted to assess the likelihood of cryptic diversity and its potential threat from climate and land‐use changes (e.g. due to limited LDD).LocationDocumented records: Southern Hemisphere and intertropical zone; modelling: Global.MethodsWe first built an updated global distribution map of A. vas using 401 validated georeferenced records. We next used these data to develop a climatic niche model to predict its past (LGM, i.e. 21 ± 3 ka BP; PMIP3 IPSL‐CM5A‐LR), present and future (IPSL‐CMP6A‐LR predictions for 2071–2100, SSP3 and 5) potential distributions in responses to climate, by relating the species occurrences to climatic and topographic predictors. We then used these predictions to test our hypotheses (dispersal/vicariance, cryptic diversity, future threat from LDD limitation).ResultsOur models show that favourable climatic conditions for A. vas currently exist in the British Isles, an especially well‐studied region for testate amoebae where this species has never been found. This demonstrates a lack of interhemispheric LDD, congruent with the palaeogeography (vicariance) hypothesis. Longitudinal LDD is, however, confirmed by the presence of A. vas in isolated and geologically young peri‐Antarctic islands. Potential distribution maps for past, current and future climates show favourable climatic conditions existing on parts of all southern continents, with shifts to higher land from LGM to current in the tropics and a strong range contraction from current to future (global warming IPSL‐CM6A‐LR scenario for 2071–2100, SSP3.70 and SSP5.85) with favourable conditions developing on the Antarctic Peninsula.Main ConclusionsThis study illustrates the value of climate niche models for research on microbial diversity and biogeography, along with exploring the role played by historical factors and dispersal limitation in shaping microbial biogeography. We assess the discrepancy between latitudinal and longitudinal LDD for A. vas, which is possibly due to contrast in wind patterns and/or likelihood of transport by birds. Our models also suggest that climate change may lead to regional extinction of terrestrial microscopic organisms, thus illustrating the pertinence of including microorganisms in biodiversity conservation research and actions.
  • Publication
    Accès libre
    Assessing the patterns and causes of diversity in free-living unicellular eukaryotes (protists) using biogeographical, macroecological and landscape genetic approaches
    (Neuchâtel, 2017)
    Fernández, Leonardo D. 
    Cette thèse de doctorat a permis de tester l’hypothèse qu’à large échelle spatiale, les patrons observés et les causes qui influencent la diversité et la structure génétique des populations d’eucaryotes unicellulaires (protistes) sont similaires à ceux observées chez des organismes multicellulaires (plantes et animaux).
    Afin de tester cette hypothèse, cette thèse s’est penchée sur (1) les patrons observés et les causes qui influencent la diversité des amibes à thèque (un groupe polyphylétique principalement représenté par les Euglyphida et Arcellinida) le long d’un gradient latitudinal à travers le Chili (de 18 à 56 ºS); (2) les patrons observés et les causes qui influencent la diversité de différents groupes de protistes du sol (Bacillariophyta, Cercomonadida, Ciliophora, Euglyphida et Kinetoplastida) en fonction de l’altitude dans des forêts de hêtre dans le Plateau Suisse et le Jura; et (3) les patrons observés et les causes qui influencent la structure génétique des populations d’une micro-algue d’eau douce (Chlorophyta: Mamiellophyceae) dans la Patagonie Argentine.
    Globalement, les analyses ont montré qu’à large échelle spatiale, les protistes ont des patrons de diversité latitudinale et altitudinale, ainsi qu’une structuration génétique semblable à ceux que l’on retrouve chez des organismes multicellulaires. De plus, les résultats montrent que ces patrons sont créés et maintenus par une combinaison de processus écologiques, historiques et évolutifs. Cette thèse a donc renforcé l’hypothèse qui considère que les patrons observés et les causes qui maintiennent la diversité des plantes et des animaux à différents niveaux écologiques d’organisation sont aussi effectifs chez les microorganismes. Les organismes modèles choisis dans cette thèse peuvent être considérés comme représentatifs de la diversité de stratégies trophiques, de morphologies, modes de locomotion ainsi que de la variété de physiologies et probablement aussi de modes de reproduction que l’on rencontre chez les protistes. Par conséquent, les résultats de cette thèse peuvent être considérés comme valides chez un grand nombre d’eucaryotes microscopiques.
    Abstract
    This PhD thesis tested the hypothesis that, at broad spatial scales, the patterns and underlying causes of diversity and population genetic structure of unicellular eukaryotes (protists) are similar to those observed for multicellular organisms (plants and animals).
    To test this hypothesis, this thesis investigated (1) the pattern and causes of latitudinal diversity in soil testate amoebae (a polyphyletic group mainly represented by Arcellinida and Euglyphida) along southwestern South America, Chile (from 18 to 56 ºS), Chile; (2) the patterns and causes of altitudinal diversity in several groups of soil protists (Bacillariophyta, Cercomonadida, Ciliophora, Euglyphida and Kinetoplastida) along an elevation gradient of beech forests in the Swiss lowlands and Jura Mountains; and (3) the pattern and causes of population genetic structure in a freshwater eukaryotic microalga (Chlorophyta: Mamiellophyceae) in the Argentinean Patagonia.
    Overall, the analyses revealed that at broad spatial scales, protists have patterns of latitudinal diversity, altitudinal diversity and population genetic structure similar to those of multicellular organisms. In addition, the evidence revealed that these patterns are originated and maintained by a combination of ecological, historical and evolutionary processes. Therefore, this thesis supported the hypothesis that the patterns and causes that produce and maintain the diversity of plants and animals at different ecological levels of organization could also be valid for microorganisms. The model organisms used in this thesis are also good representatives of the diversity of trophic, morphological, locomotive, physiological and probably reproductive strategies exhibited by protists. Consequently, the results of this thesis could be valid for a large number of eukaryotic microorganisms.
  • Publication
    Métadonnées seulement
    Microbial eukaryote communities from Patagonian-Antarctic gradient of lakes evidence robust biogeographical patterns
    (2016-9-30)
    Schiaffino, M. Romina
    ;
    Lara, Enrique 
    ;
    Fernández, Leonardo D. 
    ;
    Balagué, Vanessa
    ;
    Singer, David 
    ;
    Seppey, Christophe 
    ;
    Massana, Ramon
    ;
    Izaguirre, Irina
    Microbial eukaryotes play important roles in aquatic ecosystem functioning. Unravelling their distribution patterns and biogeography provides important baseline information to infer the underlying mechanisms that regulate the biodiversity and complexity of eco- systems. We studied the distribution patterns and factors driving diversity gradients in microeukaryote communities (total, abundant, uncommon and rare community composition) along a latitudinal gradient of lakes distributed from Argentinean Patagonia to Maritime Antarctica using both denaturing gradient gel electrophoresis (DGGE) and high-throughput sequencing (Illumina HiSeq). DGGE and abundant Illumina operational taxonomic units (OTUs) showed both decreasing richness with latitude and significant differences between Patagonian and Antarctic lakes communities. In contrast, total richness did not change significantly across the latitudinal gradient, although evenness and diversity indices were significantly higher in Patagonian lakes. Beta-diversity was characterized by a high species turnover, influenced by both environmental and geographical descriptors, although this pattern faded in the rare community. Our results suggest the co-existence of a ‘core biosphere’ containing reduced number of abundant/dominant OTUs on which classical ecological rules apply, together with a much larger seedbank of rare OTUs driven by stochastic and reduced dispersal processes. These findings shed new light on the biogeographical patterns and forces structuring inland microeukaryote composition across broad spatial scales.