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Rahier, Martine

Nom
Rahier, Martine
Affiliation principale
Fonction
Professeure ordinaire
Email
Martine.Rahier@unine.ch
Identifiants
https://libra.unine.ch/handle/123456789/99

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  • Publication
    Accès libre
    Multi-species phylogeographic investigations in closely-related taxa and mutualistic plant-insect systems
    (2010)
    Triponez, Yann
    ;
    Alvarez, Nadir
    ;
    Rahier, Martine 
    La phylogéographie se définit comme l’étude des processus historiques responsables de la distribution géographique actuelle des individus et des lignées génétiques. Etudier les espèces dans l’espace et dans le temps sur la base d’approches combinant la génétique et l’écologie représente un fantastique défi pour la biologie de l’évolution. En Europe, mais aussi ailleurs dans le monde, de telles approches ont été appliquées à de nombreux organismes, mais jusqu’ici la plupart de ces études n’ont toutefois été faites qu’au niveau d’espèces uniques. Le moment est donc venu de développer des études regroupant plusieurs espèces à la fois dans le domaine nouveau de la phylogéographie comparée, en utilisant par exemple des taxons très proches, ou alors des organismes interdépendants au sein de fortes interactions écologiques. Les espèces sélectionnées pour ce travail couvrent une large variété de groupes de plantes et d’insectes, tels que des coléoptères alpins, des orchidées de régions tempérées, ainsi que certaines espèces de plantes productrices d’huiles et d’abeilles mutualistes spécialisées dans la récolte de cette huile. Les méthodes d’analyses bio- et phylogéographiques permettant de dévoiler l’histoire des organismes étudiés associent des techniques de pointe telles que le séquençage génétique et le screening génomique, avec des descriptions et des modélisations de niches écologiques. Les principaux résultats obtenus confirment certains paradigmes mis en évidence jusqu’à présent, mais ils amènent également des notions nouvelles. Grâce à une approche globale, combinant les histoires évolutives de plusieurs lignées, les patrons biogéographiques d’une espèce en particulier peuvent être mieux compris en se basant sur les résultats obtenus parallèlement pour des taxons proches, ou pour des partenaires associés écologiquement. Les méthodes utilisées ici ont également permis de tirer des conclusions et d’entrevoir certaines perspectives au-delà de la phylogéographie ou de l’écologie évolutive : des considérations sur la diversité génétique, utiles en biologie de la conservation, ou des problèmes liés à la délimitation des espèces, applicables à la taxonomie, sont quelques uns des domaines additionnels (mais aussi complémentaires) que cette thèse aborde., Phylogeography is the study of historical processes responsible for the contemporary geographic distributions of individuals and gene lineages. Studying species in space and time combining ecology and genetics allows disentangling patterns at the boundary between biogeography, population genetics and evolutionary ecology. As until now in Europe (but also in a very large portion of the World) many organisms have been considered by singlespecies phylogeographic approaches, it is time to develop a multi-species approach in the nascent field of comparative phylogeography, either considering closely-related taxa or organisms involved in tight ecological interactions. In this study, the fate of several species spanning a large variety of insect and plant systems is investigated. Among them are found alpine leaf-beetles, temperate widespread orchids, and mutualistic oil-producing flowers and oil-collecting bees. The methods used to fulfil the bio- and phylogeographic analyses in order to unravel past histories of these associate organisms state-of-the-art methods in genetics and ecology, by combining gene sequencing and genome fingerprinting, with ecological descriptors and niche modelling. Main results obtained confirm several paradigms addressed in the field of classical phylogeography but also bring new insights into the broad picture of phylogeography of European organisms. Thanks to our multi-species approach, the biogeographic patterns of a particular species can be studied in a global framework, including results obtained for related taxa or ecologically associated partners. In addition, the methods used here allow inferring further conclusions and perspectives in other fields: for instance, evaluation of genetic diversity indices useful in conservation biology, or analytical elements about species delimitation applicable to taxonomy, represent some of the supplementary (but also complementary) topics addressed in this thesis.
  • Publication
    Accès libre
    Inferring reciprocal evolutionary histories in associated species of plants and insects in two european pollination systems
    (2010)
    Espíndola, María Anahí
    ;
    Alvarez, Nadir
    ;
    Rahier, Martine 
    ;
    Carstens, Bryan C.
    ;
    Després, Laurence
    ;
    Gibernau, Marc
    ;
    Gugerli, Felix
    ;
    Küpfer, Philippe 
    Coevolution is defined as reciprocal evolutionary changes that might arise at any spatiotemporal scale. Despite every organism on Earth undergoes coevolutionary interactions, cases of one-to-one specific relationships are generally rare. However, because of the reduced number of interacting species they concern, these species-specific associations are interesting to evolutionary biologists because they allow testing hypotheses in simple frameworks. Despite the history and evolution of coevolutionary interactions have been studied in several cases in the last decade, this topic remains difficult to fully circumscribe because of the multiplicity of factors that affect one or the other species concerned. Moreover, a lot is known about coevolution at a small scale, but little has been done at larger and more integrative scales spanning wider spatiotemporal ranges. Phylogeography is a young area of biology that allows understanding the distribution of lineages in space and time. Despite that the idea of parallely studying the history of species involved in specific interactions appears simple, this has rarely been done until now probably because of the technical efforts this would represent. From a theoretical point of view, we could propose that in specific interactions, because of the dependence between the partners involved, we should observe some phylogeographic pattern associated to the type of interaction studied. In this way, while partners of mutualistic interactions should present similar postglacial histories, this should not be true for those associated by antagonistic relationships. In this thesis, we exploit different techniques and approaches to test this general hypothesis. The final aim of this study is thus to understand if it is possible to identify a pattern of comparative phylogeography in relation to the type of interaction, using as case-studies two specific and obligate European interactions: the antagonistic relationship established between Arum maculatum L. (Araceae) and its Psychodid (Diptera) pollinating flies, and the nursery pollination mutualism involving Trollius europaeus L. (Ranunculaceae) and the Chiastocheta (Diptera: Anthomyiidae) species complex. Before testing our comparative phylogeographic hypotheses and because studying the phylogeography of interactions requires a wide knowledge of the environmental, taxonomic and historical frameworks in which these ecological relationships arose, it was first needed to clearly delimitate the identity of species, their distribution and the environmental factors influencing their survival to finally understand their comparative history. We thus took advantage of the potentialities that interdisciplinary approaches provide, applying molecular taxonomy, biological and evolutionary methods, biogeographic inferences, ecological niche models and hindcasting techniques, as well as classical and recently-developed phylogeographic analyses. Our results indicate that the phylogeographic patterns of these specific and obligate antagonistic and mutualistic relationships appear to be related to the type of interaction. Antagonistic partners presented incongruent phylogeographic patterns, what can be notably explained by differences in their life-history traits. Species involved in mutualistic interactions partly showed congruent phylogeographic patterns (particularly in the cases of T. europaeus and C. dentifera). Flies interacting with T. europaeus appear moreover to present different histories, regardless of their important ecological similarities. These results demonstrate that the systems studied appear to be far more complex than initially supposed, with crossed effects of environmental and historical features on the dynamics of the interaction. Because of the high complexity and interdependency of factors affecting one or the other partner, performing investigations in an interdisciplinary framework appears indispensable to disentangle the dynamics of interactions.