The missing <i>Myopus</i>:plugging the gaps in Late Pleistocene small mammal identification in western Europe with geometric morphometrics

15 pagesInternational audienceLemmus and Myopus are two lemming species with distinct habitat requirements but which show very similar dental morphologies. They are thus extremely difficult to distinguish from one another in the fossil record on the basis of their dental remains, leading to poor understanding of the palaeobiogeographical evolution of Myopus as well as inaccurate palaeoenvrionmental reconstructions. Currently, the presence of Myopus in the fossil register from the Pleistocene is still debated and no firm occurrence of this lemming in western Europe has yet been confirmed for the Late Pleistocene. In this paper, we used geometric morphometrics on modern material to establish morphological differences between Lemmus and Myopus teeth (first lower and third upper molars). Morphological data were then used to build a robust linear discriminant model able to confidently classify isolated teeth of these two genera, and finally, linear discriminant models were used on fossil remains of Lemmus/Myopus from two Late Pleistocene archaeological/palaeontological sites (Grotte des Gorges and Gully Cave). This study demonstrates, for the first time, the presence of Myopus schisticolor in west European Late Pleistocene sites between the end of Marine Isotope Stage 3 and the beginning of the Holocene, during climatic events that favoured the development of taiga forest of birch and pine in these regions

Habitat arctique et changement global : diversité des populations actuelles et fossiles de lemmings

Lemmings are emblematic taxa of arctic environments. The cold phases of the Pleistocene allowed them to extend their distribution, so that they are present in both the European and American fossil record. This work aims to investigate the current and past diversity of three lemming genera (Dicrostonyx, Lemmus and Myopus) based on their molar morphology, allowing a direct comparison between modern and fossil populations. The study of the modern Nearctic Dicrostonyx populations highlighted some major biogeographic patterns partly caused by the history of the genus during the Upper Pleistocene. The investigations conducted on modern and fossil Lemmini populations caused a global revision of the group diversity in the European fossil record.Les lemmings sont des taxons emblématiques des environnements arctiques. Durant les phases froides du Pléistocène, ils ont pu étendre leur aire de répartition, si bien qu'ils sont présents dans les registres fossiles européens et américains. Ce travail vise à investiguer la diversité actuelle et passé de plusieurs genres de Lemming (Dicrostonyx, Lemmus, Myopus) en se basant sur l'étude de leur morphologie dentaire afin de pouvoir mettre directement en regard les populations actuelles et fossiles. L'étude des populations actuelles de Dicrostonyx néarctiques permet d'identifier les grands patterns biogéographiques de ce groupe, fortement en lien avec l'histoire du genre durant le Pléistocène supérieur. L'étude des populations actuelles et fossiles de Lemmini conduit à une révision globale de la diversité de ce groupe dans le registre fossile européen

Arctic habitat and global changes : diversity of modern and fossil lemming populations

Les lemmings sont des taxons emblématiques des environnements arctiques. Durant les phases froides du Pléistocène, ils ont pu étendre leur aire de répartition, si bien qu'ils sont présents dans les registres fossiles européens et américains. Ce travail vise à investiguer la diversité actuelle et passé de plusieurs genres de Lemming (Dicrostonyx, Lemmus, Myopus) en se basant sur l'étude de leur morphologie dentaire afin de pouvoir mettre directement en regard les populations actuelles et fossiles. L'étude des populations actuelles de Dicrostonyx néarctiques permet d'identifier les grands patterns biogéographiques de ce groupe, fortement en lien avec l'histoire du genre durant le Pléistocène supérieur. L'étude des populations actuelles et fossiles de Lemmini conduit à une révision globale de la diversité de ce groupe dans le registre fossile européen.Lemmings are emblematic taxa of arctic environments. The cold phases of the Pleistocene allowed them to extend their distribution, so that they are present in both the European and American fossil record. This work aims to investigate the current and past diversity of three lemming genera (Dicrostonyx, Lemmus and Myopus) based on their molar morphology, allowing a direct comparison between modern and fossil populations. The study of the modern Nearctic Dicrostonyx populations highlighted some major biogeographic patterns partly caused by the history of the genus during the Upper Pleistocene. The investigations conducted on modern and fossil Lemmini populations caused a global revision of the group diversity in the European fossil record

Habitat arctique et changement global : diversité des populations actuelles et fossiles de lemmings

Lemmings are emblematic taxa of arctic environments. The cold phases of the Pleistocene allowed them to extend their distribution, so that they are present in both the European and American fossil record. This work aims to investigate the current and past diversity of three lemming genera (Dicrostonyx, Lemmus and Myopus) based on their molar morphology, allowing a direct comparison between modern and fossil populations. The study of the modern Nearctic Dicrostonyx populations highlighted some major biogeographic patterns partly caused by the history of the genus during the Upper Pleistocene. The investigations conducted on modern and fossil Lemmini populations caused a global revision of the group diversity in the European fossil record.Les lemmings sont des taxons emblématiques des environnements arctiques. Durant les phases froides du Pléistocène, ils ont pu étendre leur aire de répartition, si bien qu'ils sont présents dans les registres fossiles européens et américains. Ce travail vise à investiguer la diversité actuelle et passé de plusieurs genres de Lemming (Dicrostonyx, Lemmus, Myopus) en se basant sur l'étude de leur morphologie dentaire afin de pouvoir mettre directement en regard les populations actuelles et fossiles. L'étude des populations actuelles de Dicrostonyx néarctiques permet d'identifier les grands patterns biogéographiques de ce groupe, fortement en lien avec l'histoire du genre durant le Pléistocène supérieur. L'étude des populations actuelles et fossiles de Lemmini conduit à une révision globale de la diversité de ce groupe dans le registre fossile européen

Student Teachers' Modeling of Acceleration Using a Video-Based Laboratory in Physics Education: A Multimodal Case Study

This exploratory study intends to model kinematics learning of a pair of student teachers when exposed to prescribed teaching strategies in a video-based laboratory. Two student teachers were chosen from the Francophone B.Ed. program of the Faculty of Education of a Canadian university. The study method consisted of having the participants interact with a video-based laboratory to complete two activities for learning properties of acceleration in rectilinear motion. Time limits were placed on the learning activities during which the researcher collected detailed multimodal information from the student teachers' answers to questions, the graphs they produced from experimental data, and the videos taken during the learning sessions. As a result, we describe the learning approach each one followed, the evidence of conceptual change and the difficulties they face in tackling various aspects of the accelerated motion. We then specify advantages and limits of our research and propose recommendations for further study

Migrations et changements climatiques : l’histoire évolutive des lemmings.

6 pagesNational audienc

Another mention of Meadow Vole (Microtus pennsylvanicus) found in pellets of Snowy Owl (Bubo scandiacus) in northern Ungava Peninsula, Canada

The examination of raptor pellets can be used to evaluate Arctic biodiversity. We found the remains of Meadow Vole (Microtus pennsylvanicus) and Ungava Collared Lemming (Dicrostonyx hudsonius) in pellets from Snowy Owl (Bubo scandiacus) nesting in the northern part of the Ungava Peninsula. We differentiated the two species by visual identification and geometric morphometric analysis of molar shape. The results of our study combined with historical data suggest that most commonly used range maps of Meadow Vole should be revised.Les restes de proies contenus dans les pelottes de rejection de rapace permettent d'évaluer la biodeversité arctique. Cette étude, basée sur des pelettes de harfang des neiges nichant au Nord de la Péninsule d'Ungava, rapporte la présence de&nbsp;Microtus pennsylvanicus associé à&nbsp;Dicrostonyx groenlandicus. L'identification de M. pennsylvanicus dans cette région représente l'occurence la plus au Nord connue dans la péninsule d'Ungava, ce qui suggère une révision des cartes d'aire de réparition de cette espèce

The wood lemming and the development of taiga in Late Pleistocene Central Europe.

International audienceTaxonomic identification remains a challenge for fossil small mammals, in particular in the case of morphologically close species. These identifications are especially essential in the case of species with different ecological tolerances for paleoenvironmental and paleoclimatic inferences. Among rodents which depend on peculiar environments, the wood lemming (Myopus schisticolor) only inhabits boreal forests and is a bryophage specialist burrowing under specific moss covers. In the fossil record, its identification has long been problematic and Myopus has often been mixed up with the tundra lemming (Lemmus sp.), a rodent inhabiting the arctic open landscape. By applying geometric morphometrics on fossil Lemmini specimens from Late Pleistocene Central Europe, this paper demonstrates the occurrence of Myopus at least during Marine Isotopic Stage 3 and Last Glacial Maximum in the region. Its presence has a strong impact on paleoclimatic and paleoenvironmental reconstructions as demonstrated by the application of the Bioclimatic analysis method suggesting a colder climate as well as the identification of a taiga biozone that remained undetected if this species is not included. This work definitively attests the essential contribution of geometric morphometric analyses to a better understanding of small mammal communities

Re-investigation of fossil Lemmini specimens from the early and Middle Pleistocene of Western and Central Europe: evolutionary and paleoenvironmental implications.

International audienceThe current study focuses on the emblematic Myopus/Lemmus species complex (tribe Lemmini) in the European Pleistocene fossil record. The members of the two genera occupy distinct ecological niches and have different external appearances, but they are remarkably similar in their dental morphology, so that they were commonly thought of as undistinguishable in the fossil record. Thus, more or less all European Lemmini fossils have been assigned to the genus Lemmus. In the Early Pleistocene site of Schernfeld (Germany), the species Lemmus kowalskii had been described. It was thought by some authors that all Lemmini from Early to late Middle Pleistocene belong to this species.In the current study, we investigated Lemmini molar morphology from Western and Central European sites including Schernfeld (Early Pleistocene), Sackdillinger Höhle (Sackdilling Cave), and Koněprusy C718 (both early Middle Pleistocene), as well as other fossil localities with fewer specimens, formerly assigned to Lemmus kowalskii. Using an extensive modern referential material of Lemmus and Myopus, this study proposes to re-evaluate taxonomic status of the Middle and Early Pleistocene Lemmini. This modern referential also allows a better understanding of the morphology of Lemmus kowalskii specimens and its variability.Our results highlight the very high variation within fossil populations, as well as significant statistical differences between populations of the Early and Middle Pleistocene localities. A large part of these fossil specimens is firmly identified as Myopus sp., including the L. kowalskii holotype. Our identifications demonstrate that in most Early and Middle Pleistocene sites considered in this study, both genera (Lemmus and Myopus) are present. Possible interpretations and consequences for current view of lemming history are discussed, as well as some of the paleoecological and paleoenvironmental implications