Global scale same-specimen morpho-genetic analysis of Truncorotalia truncatulinoides: A perspective on the morphological species concept in planktonic foraminifera Frédéric Quillévéré a, ⁎, Raphaël Morard a,b , Gilles Escarguel a , Christophe J. Douady c,d , Yurika Ujiié e , Thibault de Garidel-Thoron f , Colomban de Vargas b a Laboratoire de Géologie de Lyon: Terre, Planètes, Environnement, UMR CNRS 5276, Université Lyon 1, 27-43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France b UPMC Univ Paris 06, UMR CNRS 7144, EPPO: Evolution du Plancton et PaléoOcéans, Station Biologique, BP 74, 29682 Roscoff, France c UMR CNRS 5023 Ecologie des Hydrosystèmes Fluviaux, Université Claude Bernard Lyon 1, 27-43 Boulevard 11 Novembre 1918, 69622 Villeurbanne Cedex, France d Institut Universitaire de France, France e Shinshu University, Department of Biology, Faculty of Science, Asahi 3-1-1, Matsumoto City, Nagano 390-8621, Japan f Université Aix-Marseille, CNRS/INSU, CdF, IRD, CEREGE, Europôle Méditerranéen de l'Arbois, BP 80, 13545 Aix-en-Provence Cedex 4, France abstract article info Article history: Received 23 September 2010 Received in revised form 28 February 2011 Accepted 13 March 2011 Available online 21 March 2011 Keywords: Planktonic foraminifera Biogeography Ribosomal DNA Morphometrics Species concept Genetic analyses of planktonic foraminifera have unveiled significant levels of cryptic diversity, thus calling into question the usefulness of the morphological species concept for paleoceanographic reconstructions. Here, we present single-specimen combined genetic and morphological analyses performed on living Truncorotalia truncatulinoides collected across the world oceans. A combined morphogenetic analysis allows us to (1) detect five different genetic types (Types I to V) within the morphospecies T. truncatulinoides, (2) statistically analyze shape variations among these genotypes, and (3) assess the biogeographic patterns and the links between surface ocean properties and the distribution of morphological and genetic diversity within T. truncatulinoides. Of the five genetic types, Type I appears to inhabit the warm (sub)tropical waters of the South Hemisphere, Types II and V are found in the warm (sub)tropical waters of the Atlantic and NW Pacific, respectively, and Types III and IV appear to be restricted to the productive subtropical and the cold subpolar frontal zones of the Southern Ocean, respectively. Same-specimen morphogenetic comparisons reveal significant differences in test morphology between the warm (sub)tropical cluster of genotypes (Types I, II, and V) and the colder subpolar cluster of genotypes (Types III and IV). These results indicate that changes in shell conicalness, observed across the subtropical fronts in the Southern Ocean and for a long time interpreted as ecophenotypic variation, reflect genetic differentiation, with large, highly conical left (Indian Ocean) or right-coiled (Pacific Ocean) specimens north of the North Subtropical Front representing genetic Type I, and small, axially compressed and biconvex left-coiled specimens south of this front representing genetic Types III and IV. Our morphogenetic data are consistent with the scenario of a late Pleistocene invasion of the Southern Ocean by newly evolved T. truncatulinoides genotypes, specifically adapted to cold water masses. Finally, we build a model based upon test outline analyses, which correctly assigns up to 75% of the specimens to their corresponding cluster of genotypes. Application of this model to sediment samples may contribute to the reconstruction of migrations of the Subtropical Front during the late Pleistocene. © 2011 Elsevier B.V. All rights reserved. 1. Introduction Calcareous shells (tests) of planktonic foraminifera are commonly used in paleoceanographic studies to reconstruct sea surface condi- tions and upper ocean structure (e.g., Mulitza et al., 1997). These studies assume that each morphospecies has its own ecological preferences that can be used for reconstruction of past water mass properties (e.g., Kennett, 1968; Malmgren et al., 2001). Therefore, the use of species-specific paleoproxies requires a high degree of taxonomic consistency. Since the CLIMAP global reconstruction of glacial oceanic conditions (CLIMAP, 1976), the morphological defini- tion of planktonic foraminiferal species has been set very broadly, and morphological variation has been classically regarded as intra-specific variability or ecophenotypy (e.g., Hecht et al., 1976; Kennett, 1976; Healy-Williams and Williams, 1981; Healy-Williams et al., 1985). A growing body of molecular studies has revealed that the classical, morphological definition of species in planktonic foraminif- era hides higher levels of genetic and ecological differentiation (de Palaeogeography, Palaeoclimatology, Palaeoecology 391 (2013) 2–12 ⁎ Corresponding author. Tel.: +33 4 72 44 83 81; fax: +33 4 72 44 83 82. E-mail address: frederic.quillevere@univ-lyon1.fr (F. Quillévéré). 0031-0182/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2011.03.013 Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo