Thesis Subject - Diversity, speciation and phylogeography of marine planktonic protists.
principal location: Unité d’Ecologie, Systématique et Evolution UMR 8079, Université Paris-Sud, Orsay.
Thesis supervisors : P. Lopez-Garcia, D. Moreira (Orsay) http://www.ese.u-psud.fr/microbiologie/
J.R. Dolan (Station Zoologique de Villefranche) http://www.obs vlfr.fr/~dolan/index.php
Planktonic microorganisms are the base of aquatic ecosystems. Traditionally, these organisms have been identified and classified using morphological and structural characteristics revealed by light and electron microscopy. Despite a relatively small number of characteristics, a multitude of species, often co-existing, have been catalogued many with very wide geographic distributions (the 'paradox of the plankton'). Remarkably, new data from molecular biology (e.g., amplification, cloning and sequencing of 18s rRNA) has shown that traditional species can represent groups of cryptic species, that is forms which are morphologically similar but genetically distinct, adapted to different ecological conditions. On the other hand, many protists are variable in morphology so some catalogued species may not be species but rather variants. Thus, at present, the extent and nature of planktonic protist diversity is unknown despite their key position in aquatic food webs.
The research proposed focuses on tintinnid ciliates; a species-rich group of marine ciliates easily identified (and traditionally classified) via the shell, or lorica, morphology. The types of hypotheses to be examined include: i) common, wide-spread forms are in reality assemblages of cryptic species, that is morphologically similar, but genetically distinct forms, ii) genetically distinct forms are adapted to distinct ecological conditions, iii) distinct cryptic species can co-exist in the same locality, iv) some apparently perennial species actually represent a succession of cryptic species.
The hypotheses will be evaluated by exploring the morphological, genetic and physiological diversity of tintinnids commonly found in coastal marine waters. The primary focus will be on species found in the N.W. Mediterranean Sea. The genetic structure of tintinnids will be studied at different scales of time and space using single-cell techniques and cultures; several genetic markers will be targeted (rRNA, ITS, proteins). Genetic analyses will be coupled with morphometric and physiological analyses. In parallel, development of specific primers for tintinnids will be used to evaluate presence and diversity in different oceanic regions.
The study will furnish data which will improve our understanding of the mechanisms involved in the adaptation, speciation and ecology of planktonic protists. The major part of the work will consist of employment of molecular lab techniques (classic PCR and single-cell techniques) and data analysis (genetic and phylogenic analysis) coupled with morphological and physiological studies of selected taxa.
A fellowship is available, financed by the ANR Biodiversity project '"Aquaparadox". The multi-institution project will facilitate collaboration for the student. The thesis will be conducted at the University of Paris-Sud and directed by P. López-García and D. Moreira (Univ. Paris-Sud) and secondarily by J. Dolan (Station Zoologique, Villefranche-sur-Mer). The study will include field work (2 - 4 weeks per year) at the Zoological Station in Villefranche. French language skills are desirable but not required.
Background information on the topic:
Dolan, J.R. 2005. An introduction to the biogeography of aquatic microbes. Aquat Microb Ecol 41: 39-48.
Slapeta, J., Moreira, D. & López-García, P. (2005) The extent of protist diversity: insights from molecular ecology of freshwater environments. Proc R Soc Lond B Biol Sci 272: 2073-2081.
Dolan, J.R., Jacquet, S., Torreton, J.-P. 2006. Comparing taxonomic and morphological biodiversity of tintinnids (planktonic ciliates) of New Caledonia. Limnol Oceanogr 51:950-958.
Slapeta, J., López-García, P., Moreira, D. 2006. Global dispersal and ancient cryptic species in the smallest marine eukaryotes. Mol Biol Evol 23: 23-29
Contacts : puri.lopez@u-psud.fr, david.moreira@u-psud.fr
principal location: Unité d’Ecologie, Systématique et Evolution UMR 8079, Université Paris-Sud, Orsay.
Thesis supervisors : P. Lopez-Garcia, D. Moreira (Orsay) http://www.ese.u-psud.fr/microbiologie/
J.R. Dolan (Station Zoologique de Villefranche) http://www.obs vlfr.fr/~dolan/index.php
Planktonic microorganisms are the base of aquatic ecosystems. Traditionally, these organisms have been identified and classified using morphological and structural characteristics revealed by light and electron microscopy. Despite a relatively small number of characteristics, a multitude of species, often co-existing, have been catalogued many with very wide geographic distributions (the 'paradox of the plankton'). Remarkably, new data from molecular biology (e.g., amplification, cloning and sequencing of 18s rRNA) has shown that traditional species can represent groups of cryptic species, that is forms which are morphologically similar but genetically distinct, adapted to different ecological conditions. On the other hand, many protists are variable in morphology so some catalogued species may not be species but rather variants. Thus, at present, the extent and nature of planktonic protist diversity is unknown despite their key position in aquatic food webs.
The research proposed focuses on tintinnid ciliates; a species-rich group of marine ciliates easily identified (and traditionally classified) via the shell, or lorica, morphology. The types of hypotheses to be examined include: i) common, wide-spread forms are in reality assemblages of cryptic species, that is morphologically similar, but genetically distinct forms, ii) genetically distinct forms are adapted to distinct ecological conditions, iii) distinct cryptic species can co-exist in the same locality, iv) some apparently perennial species actually represent a succession of cryptic species.
The hypotheses will be evaluated by exploring the morphological, genetic and physiological diversity of tintinnids commonly found in coastal marine waters. The primary focus will be on species found in the N.W. Mediterranean Sea. The genetic structure of tintinnids will be studied at different scales of time and space using single-cell techniques and cultures; several genetic markers will be targeted (rRNA, ITS, proteins). Genetic analyses will be coupled with morphometric and physiological analyses. In parallel, development of specific primers for tintinnids will be used to evaluate presence and diversity in different oceanic regions.
The study will furnish data which will improve our understanding of the mechanisms involved in the adaptation, speciation and ecology of planktonic protists. The major part of the work will consist of employment of molecular lab techniques (classic PCR and single-cell techniques) and data analysis (genetic and phylogenic analysis) coupled with morphological and physiological studies of selected taxa.
A fellowship is available, financed by the ANR Biodiversity project '"Aquaparadox". The multi-institution project will facilitate collaboration for the student. The thesis will be conducted at the University of Paris-Sud and directed by P. López-García and D. Moreira (Univ. Paris-Sud) and secondarily by J. Dolan (Station Zoologique, Villefranche-sur-Mer). The study will include field work (2 - 4 weeks per year) at the Zoological Station in Villefranche. French language skills are desirable but not required.
Background information on the topic:
Dolan, J.R. 2005. An introduction to the biogeography of aquatic microbes. Aquat Microb Ecol 41: 39-48.
Slapeta, J., Moreira, D. & López-García, P. (2005) The extent of protist diversity: insights from molecular ecology of freshwater environments. Proc R Soc Lond B Biol Sci 272: 2073-2081.
Dolan, J.R., Jacquet, S., Torreton, J.-P. 2006. Comparing taxonomic and morphological biodiversity of tintinnids (planktonic ciliates) of New Caledonia. Limnol Oceanogr 51:950-958.
Slapeta, J., López-García, P., Moreira, D. 2006. Global dispersal and ancient cryptic species in the smallest marine eukaryotes. Mol Biol Evol 23: 23-29
Contacts : puri.lopez@u-psud.fr, david.moreira@u-psud.fr
No comments:
Post a Comment