0000000000222282
AUTHOR
Sylvain Gerber
showing 8 related works from this author
Microevolutionary relationships between phylogeographical history, climate change and morphological variability in the common vole (Microtus arvalis)…
2011
Aim In this study, we analyse microevolutionary processes in common voles (Microtus arvalis) through the investigation of tooth morphological structure, in order to assess the relative impact of climate and phylogeographical history. Microevolutionary studies have shown that climate change may play a role in both population phylogeography and phenotypic differentiation. However, relatively little is known about the precise relationship between phylogeography and phenotypic variability and about how organisms respond to climate change. Location France, from sea level to the Alps (5 to > 2300 m a.s.l.). Methods This morphological analysis is based on first lower molar measurements from 16 geo…
Morphometry of Middle Bronze Age palstaves by discrete cosine transform.
2009
9 pages; International audience; The Discrete Cosine Transform (DCT) is a Fourier-related transform widely used in signal processing and well suited to the analysis of open outlines. This method was applied here to evaluate the discrimination power of the inner lateral rib for two palstave populations dating from the Middle Bronze Age, excavated in northwest France. A corpus of almost 400 palstaves (bronze axes) of the Breton and Norman types was processed, and compared to specimens found at Sermizelles in Burgundy. The procedure is robust and produces a discrimination in good agreement with the traditional typology. Besides the definition of a ‘standard' shape for each population, the morp…
Les Ammonoïdes (Mollusca, Cephalopoda) : avancées et contributions récentes à la paléobiologie évolutive.
2009
12 pages; Les ammonoïdes qui perdurent 335 Ma constituent un modèle de choix dans l'analyse du fait évolutif. Cet article de synthèse se propose d'aborder (1) : leur place phylogénétique au sein des céphalopodes et le choix d'un modèle actuel de référence ; (2) : la construction d'espaces phénotypiques qui offrent un angle d'étude pertinent de l'évolution biologique ; (3) : les concordances et discordances entre reconstruction phylogénétique et registre fossile et (4) : les reconquêtes postcrises, modèles d'étude de l'évolution à grande échelle. Il ressort que les ammonoïdes peuvent servir d'appui à de nombreuses thématiques paléontologiques (dynamique de la biodiversité, analyse phylogénét…
Allometric space and allometric disparity: a developmental perspective in the macroevolutionary analysis of morphological disparity.
2008
8 pages; International audience; Here, we advance novel uses of allometric spaces--multidimensional spaces specifically defined by allometric coefficients--with the goal of investigating the focal role of development in shaping the evolution of morphological disparity. From their examination, operational measures of allometric disparity can be derived, complementing standard signals of morphological disparity through an intuitive and process-oriented refinement of established analytical protocols used in disparity studies. Allometric spaces thereby become a promising context to reveal different patterns of evolutionary developmental changes and to assess their relative prevalence and import…
Impact of sewage pollution on two species of sea urchins in the Mediterranean Sea (Cortiou, France): radial asymmetry as a bioindicator of stress.
2015
9 pages; International audience; BackgroundThe surroundings of the Cortiou sewage are among the most polluted environments of the French Mediterranean Sea (Marseilles, France). So far, no studies have precisely quantified the impact of pollution on the development of organisms in this area.MethodsWe used a fluctuating asymmetry (FA) measure of developmental instability (DI) to assess environmental stress in two species of radially symmetric sea urchins (Arbacia lixula and Paracentrotus lividus). For six sampling sites (Cortiou, Riou, Maire, East Maire, Mejean, and Niolon), levels of FA were calculated from continuous and discrete skeletal measures of ambulacral length, number of pore pairs …
Combining ontogenetic and evolutionary scales of morphological disparity: a study of early Jurassic ammonites
2007
SUMMARY Two major research themes in Evolutionary Developmental Biology and in Paleobiology, respectively, have each become central for the analysis and interpretation of morphological changes in evolution: the study of ontogeny/ phylogeny connections, mainly within the widespread and controversial framework of heterochrony; and the study of morphological disparity, the morphological signal of biodiversity, describing secular changes in morphospace occupation during the history of any given clade. Although enriching in their respective fields, these two themes have remained rather isolated to date, despite the potential value of integrating them as some recent studies begin to suggest. Here…
Developmental aspects of morphological disparity dynamics: a simple analytical exploration
2011
15 pages; International audience; We devised a simple model for assessing the role of development in shaping the evolution of morphological disparity. Disparity of a clade at any given time is expressed in terms of the developmental dynamics that lead to the variety of adult morphotypes observed. We use assumed phenotypic manifestations of developmental processes, as they could be detected from allometric characterizations, to distinguish a few, nonexclusive types of evolutionary changes in ontogeny. On the basis of this formalization, we describe the diversification of hypothetical clades, using the standard curve of adult morphological disparity, the curve of juvenile disparity, and the c…
Productions en série vers 1500 avant notre ère. Des règles de fabrication au Bronze moyen entre la Manche et les Alpes à la lumière d’une étude morph…
2013
Some European Bronze Age objects were produced by what has been described as serial metalworking. One particularexample is the Middle Bronze Age palstave, massively produced and used in Western Europe during the mid-second millennium BC.These artefacts were often voluntarily buried together in hoards, meaning they were removed from the production network, thus avoidingany recycling. They are found intact, either as rough castings or ready for use. These homogeneous objects are grouped in sets of severalitems, or in tens, or even in hundreds. Such discoveries have immediately led to numerous questions as to the possible interpretation ofthis behaviour. It is clear that prehistoric craftsmen …