Inferring Reciprocal Evolutionary Histories in Associated Species of Plants and Insects in Two European Pollination Systems
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Inferring reciprocal evolutionary histories in associated species of plants and insects in two European pollination systems Thèse présentée à la Faculté des Sciences Institut de Biologie Université de Neuchâtel Pour l’obtention du grade de docteur ès sciences par María Anahí Espíndola Acceptée sur proposition du jury: Dr. Nadir Alvarez, co-directeur de thèse Prof. Martine Rahier, co-directeur de thèse Prof. Bryan C. Carstens (Louisiana State University, USA), rapporteur Dr. Laurence Després (Université de Grenoble, France), rapporteur Dr. Marc Gibernau (CNRS Toulouse, France), rapporteur Dr. Felix Gugerli (WSL, Birmensdorf, Zürich, Suisse), rapporteur Prof. Philippe Küpfer (Université de Neuchâtel, Suisse), rapporteur Soutenue le 17 Novembre 2010 Université de Neuchâtel 2010 «Toy with different perspectives. Look for the unusual. Try consciously to innovate. Train yourself to imagine new schemes and innovative ways to fit the pieces together. Seek the joy of discovery. Always test your new thoughts against the facts, of course, in rigorous, cold-blooded, unemotional scientific manner. But play the great game of the visionary and the innovator as well.» J. E. Oliver « Gracias a la vida, que me ha dado tanto… » V. Parra A Cristina y Ricardo, mis padres. Contents Summary / Résumé..………..………………………………………………………………… ix Acknowledgements/ Remerciements………………………….………………………….. xiii General introduction ………………………………………….……………………………… 1 Chapter one ……………………………………………………….…………………………… 33 New insights into the phylogenetics and biogeography of Arum (Araceae): unravelling its evolutionary history Chapter two ………………………………………………………………………….………… 55 Molecular relationships in the sub-family Psychodinae (Diptera: Psychodidae) Chapter three ………………………………………………………………………….…….… 85 Variation in the proportion of flower visitors of Arum maculatum along its distributional range in relation with community-based climatic niche analyses Chapter four ………………………………………………………………………….………… 99 Size-advantage model and pollination strategies in plants Chapter five …………………………………………………………………………………….. 131 Comparative phylogeography in a specific and obligate pollination antagonism Chapter six ……………………………………………………………………………………… 163 Evolutionary history of Chiastocheta species interacting with Trollius europaeus Chapter seven ………………………………………………………………………………….. 209 No fossils, no answers? Inferring postglacial genetic consequences in cold-adapted species when neither ancient DNA nor macroremains are available Chapter eight…………………………………………………………………………………… 247 Phylogeography of mutualists and the effect of the host on the genetic structure of its partners General Discussion …………………………………………………………………………... 283 General Conclusion …………………………………………………………………….…….. 295 Appendix 1: Curriculum vitae ………………………………………………………….……... 299 vii Keywords: specific interactions, coevolution, Arum maculatum, Trollius europaeus, Chiastocheta, Psychodidae, antagonism, mutualism, ecological niche model, comparative phylogeography, biogeography, diversification, hindcasting methods, arctic-alpine species, Size-Advantage Model, taxonomy, statistical phylogeography Summary 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 ix 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. x Mots-clés: interactions spécifiques, coévolution, Arum maculatum, Trollius europaeus, Chiastocheta, Psychodidae, antagonisme, mutualisme, modèle de niche écologique, phylogéographie comparée, biogéographie, diversification, méthodes de prédictions de distributions passées, espèce arctique-alpine, modèle d’avantage de taille, taxonomie, phylogéographie statistique Résumé La coévolution est définie comme la série de changements réciproques apparaissant entre des organismes. Malgré le fait que tous les organismes suivent des processus de coévolution, les cas des relations spécifiques un-un sont relativement rares. Ces types d’interactions spécifiques sont par contre très intéressants pour les évolutionnistes, notamment à cause du nombre réduit d’organismes qu’elles comprennent, ce qui permet de tester des hypothèses évolutives dans un cadre simple. Malgré le fait que l’histoire et l’évolution des interactions coévolutives sont des processus assez explorés, le thème reste difficile à étudier spécialement à cause du grand nombre de facteurs influençant les espèces concernées. D’un autre côté, beaucoup est à ce jour connu à des petites échelles spatio-temporelles, alors que très peu a été fait à des dimensions plus larges et plus intégrées. Le jeune domaine de la phylogéographie s’intéresse à la compréhension de la distribution des lignées génétiques dans l’espace et dans le temps. Malgré que l’idée de l’étude parallèle des histories phylogéographiques de plusieurs espèces est un concept simple, il n’a été exploré que pour quelques cas isolés. D’un point de vue théorique, nous pouvons proposer que dans des interactions spécifiques, nous devrions attendre à voir des patrons phylogéographiques liés au type d’interaction étudiée, spécialement à cause de l’interdépendance des espèces concernées. Alors que des partenaires mutualistes devraient présenter des histories démographiques similaires, ceci ne devrait pas être le cas des espèces liées par des interactions de type antagoniste. Le but ultime de ce travail est alors de comprendre s’il est possible d’identifier des patrons phylogéographiques spécifiques aux types d’interactions. Afin de répondre à cette question, nous testons nos hypothèses sur deux interactions européennes spécifiques et obligées: l’antagonisme formé par Arum maculatum L. (Aracée) et ses pollinisateurs de la famille Psychodidae (Diptères) ; le mutualisme de crèche présent entre Trollius