Spatio-temporal Functional Regression on Paleo-ecological Data

The influence of climate on biodiversity is an important ecological question. Various theories try to link climate change to allelic richness and therefore to predict the impact of global warming on genetic diversity. We model the relationship between genetic diversity in the European beech forests and curves of temperature and precipitation reconstructed from pollen databases. Our model links the genetic measure to the climate curves through a linear functional regression. The interaction in climate variables is assumed to be bilinear. Since the data are georeferenced, our methodology accounts for the spatial dependence among the observations. The practical issues of these extensions are discussed

Trafic routier et distances de sécurité : Le dilemme de l’agriculture en Ile-de-france

Les distances de sécurité représentent la solution la plus facilement applicable lorsqu’il s’agit de protéger les cultures agricoles de pollutions diffuses aux effets encore mal connus. Dans les années 90, certains acteurs de la filière céréales ont adopté des distances de sécurité entre les routes et les champs pour se prémunir de risques éventuels de contamination due à la pollution du trafic routier. Puis, ces mesures ont été partiellement délaissées en filière céréale alors qu’elles apparaissaient, moyennant des aménagements notoires, dans d’autres filières (herbes aromatiques). Notre étude porte sur la région Île-de-France, dont l’occupation agricole du territoire est importante et qui présente également une forte densité de réseaux routiers très fréquentés. Par une approche interdisciplinaire, notre objectif est donc de clarifier cette situation pour le moins complexe, de comprendre la genèse et l’évolution de ces distances tout en essayant d’en mesurer les effets en termes de gestion de risques (en lien avec divers usages du principe de précaution) tant sur le plan social que technique.The application of isolation distances is the easiest response for protecting agricultural crops from diffuse pollution effects still unknown. In the 90’s, some actors in the cereal supply chains have tried to limit potential risks by producing technical guidelines, including isolation distances between major roads and fields farmed under contract. These measures were then partially abandoned in the cereal sector but appeared later on in other sectors (aromatic herbs) with notable improvements. Our study focuses on the Ile-de-France region, which presents both a large agricultural area and an important road network. Through an interdisciplinary approach, our goal is to clarify this complex situation, to understand the genesis and evolution of these distances while measuring the effects concerning risk management (in connection with various uses of the precautionary principle) both socially and technically

Sex-biased dispersal promotes adaptive parental effects

<p>Abstract</p> <p>Background</p> <p>In heterogeneous environments, sex-biased dispersal could lead to environmental adaptive parental effects, with offspring selected to perform in the same way as the parent dispersing least, because this parent is more likely to be locally adapted. We investigate this hypothesis by simulating varying levels of sex-biased dispersal in a patchy environment. The relative advantage of a strategy involving pure maternal (or paternal) inheritance is then compared with a strategy involving classical biparental inheritance in plants and in animals.</p> <p>Results</p> <p>We find that the advantage of the uniparental strategy over the biparental strategy is maximal when dispersal is more strongly sex-biased and when dispersal distances of the least mobile sex are much lower than the size of the environmental patches. In plants, only maternal effects can be selected for, in contrast to animals where the evolution of either paternal or maternal effects can be favoured. Moreover, the conditions for environmental adaptive maternal effects to be selected for are more easily fulfilled in plants than in animals.</p> <p>Conclusions</p> <p>The study suggests that sex-biased dispersal can help predict the direction and magnitude of environmental adaptive parental effects. However, this depends on the scale of dispersal relative to that of the environment and on the existence of appropriate mechanisms of transmission of environmentally induced traits.</p

Plant traits correlated with generation time directly affect inbreeding depression and mating system and indirectly genetic structure

<p>Abstract</p> <p>Background</p> <p>Understanding the mechanisms that control species genetic structure has always been a major objective in evolutionary studies. The association between genetic structure and species attributes has received special attention. As species attributes are highly taxonomically constrained, phylogenetically controlled methods are necessary to infer causal relationships. In plants, a previous study controlling for phylogenetic signal has demonstrated that Wright's <it>F</it>_ST, a measure of genetic differentiation among populations, is best predicted by the mating system (outcrossing, mixed-mating or selfing) and that plant traits such as perenniality and growth form have only an indirect influence on <it>F</it>_STvia their association with the mating system. The objective of this study is to further outline the determinants of plant genetic structure by distinguishing the effects of mating system on gene flow and on genetic drift. The association of biparental inbreeding and inbreeding depression with population genetic structure, mating system and plant traits are also investigated.</p> <p>Results</p> <p>Based on data from 263 plant species for which estimates of <it>F</it>_ST, inbreeding (<it>F</it>_IS) and outcrossing rate (<it>t</it>_m) are available, we confirm that mating system is the main influencing factor of <it>F</it>_ST. Moreover, using an alternative measure of <it>F</it>_STunaffected by the impact of inbreeding on effective population size, we show that the influence of <it>t</it>_mon <it>F</it>_STis due to its impact on gene flow (reduced pollen flow under selfing) and on genetic drift (higher drift under selfing due to inbreeding). Plant traits, in particular perenniality, influence <it>F</it>_STmostly via their effect on the mating system but also via their association with the magnitude of selection against inbred individuals: the mean inbreeding depression increases from short-lived herbaceous to long-lived herbaceous and then to woody species. The influence of perenniality on mating system does not seem to be related to differences in stature, as proposed earlier, but rather to differences in generation time.</p> <p>Conclusion</p> <p>Plant traits correlated with generation time affect both inbreeding depression and mating system. These in turn modify genetic drift and gene flow and ultimately genetic structure.</p