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

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

Exposure to Phthalates and Phenols during Pregnancy and Offspring Size at Birth

Background: Data concerning the effects of prenatal exposures to phthalates and phenols on fetal growth are limited in humans. Previous findings suggest possible effects of some phenols on male birth weight

Exploring Species Limits in Two Closely Related Chinese Oaks

Background. The species status of two closely related Chinese oaks, Quercus liaotungensis and Q. mongolica, has been called into question. The objective of this study was to investigate the species status and to estimate the degree of introgression between the two taxa using different approaches. [br/] Methodology/Principal Findings. Using SSR (simple sequence repeat) and AFLP (amplified fragment length polymorphism) markers, we found that interspecific genetic differentiation is significant and higher than the differentiation among populations within taxa. Bayesian clusters, principal coordinate analysis and population genetic distance trees all classified the oaks into two main groups consistent with the morphological differentiation of the two taxa rather than with geographic locations using both types of markers. Nevertheless, a few individuals in Northeast China and many individuals in North China have hybrid ancestry according to Bayesian assignment. One SSR locus and five AFLPs are significant outliers against neutral expectations in the interspecific FST simulation analysis, suggesting a role for divergent selection in differentiating species.[br/] Main Conclusions/Significance. All results based on SSRs and AFLPs reached the same conclusion: Q. liaotungensis and Q. mongolica maintain distinct gene pools in most areas of sympatry. They should therefore be considered as discrete taxonomic units. Yet, the degree of introgression varies between the two species in different contact zones, which might be caused by different population history or by local environmental factors

Lipid-Induced Peroxidation in the Intestine Is Involved in Glucose Homeostasis Imbalance in Mice

BACKGROUND: Daily variations in lipid concentrations in both gut lumen and blood are detected by specific sensors located in the gastrointestinal tract and in specialized central areas. Deregulation of the lipid sensors could be partly involved in the dysfunction of glucose homeostasis. The study aimed at comparing the effect of Medialipid (ML) overload on insulin secretion and sensitivity when administered either through the intestine or the carotid artery in mice. METHODOLOGY/PRINCIPAL FINDINGS: An indwelling intragastric or intracarotid catheter was installed in mice and ML or an isocaloric solution was infused over 24 hours. Glucose and insulin tolerance and vagus nerve activity were assessed. Some mice were treated daily for one week with the anti-lipid peroxidation agent aminoguanidine prior to the infusions and tests. The intestinal but not the intracarotid infusion of ML led to glucose and insulin intolerance when compared with controls. The intestinal ML overload induced lipid accumulation and increased lipid peroxidation as assessed by increased malondialdehyde production within both jejunum and duodenum. These effects were associated with the concomitant deregulation of vagus nerve. Administration of aminoguanidine protected against the effects of lipid overload and normalized glucose homeostasis and vagus nerve activity. CONCLUSIONS/SIGNIFICANCE: Lipid overload within the intestine led to deregulation of gastrointestinal lipid sensing that in turn impaired glucose homeostasis through changes in autonomic nervous system activity

Ancient DNA--unlocking plants' fossil secrets

Disillusion rather than enthusiasm had predominated among scientists after the first reports of successful but sometimes hardly repeatable retrieval of ancient DNA (aDNA) from very ancient specimens such as Miocene fossil leaf samples or even dinosaur eggs. In the past few years, however, scrupulous studies including a suite of controls for authenticity have provided the basis for regained confidence in the field of palaeogenetics. Furthermore, it has now been shown that animal and especially plant aDNA is not only present in fossil tissues but may even be indirectly retrieved from secondary samples such as fossil faeces (Poinar et al., 1998; Poinar et al., 2001) or sediments (Willerslev et al., 2003). The recent Bordeaux symposium on the use of plant aDNA provided a forum for this renewed enthusiasm and illustrated the substantial progresses that are currently being made. A particular focus was on the main European forest tree species during the Quaternary period – using aDNA as a link between phylogeographic and classical palaeoecological reconstructions (the topic of the FOSSILVA project, which brought together teams of geneticists and palaeoecologists, coordinated by Jacques-Louis de Beaulieu (CNRS – Marseille, France))

Developmental Biology and Genetic Diversity of Sessile and Pedunculate Oak.

Ce manuscrit est une synthèse des travaux réalisés sur l'analyse de la diversité génétique des Chênes sessile et pédonculé à l'échelle de l'aire de distribution des espèces prenant en compte la diversité moléculaire et phénotypique. La confrontation de données génétiques et historiques (pollens fossiles) a permis de reconstituer les principaux mécanismes qui ont façonné cette diversité et notamment ceux qui ont accompagné la colonisation post-glaciaire. Confinés dans trois zones refuges au cours du dernier âge glaciaire, les Chênes ont très rapidement, en moins de 8 000 ans, colonisé l'Europe grâce notamment à des dispersions rares mais à longue distance. La distribution géographique du polymorphisme de l'ADN chloroplastique témoigne encore de cette migration. Après la recolonisation, les flux de pollen ont homogénéisé au plan génétique les massifs forestiers et la sélection naturelle a, depuis, généré des différences pour les caractères adaptatifs. L'hybridation a joué un rôle très important au cours de cette histoire, en permettant notamment au Chêne sessile de migrer et de coloniser des espaces nouveaux par introgression dans les peuplements de Chêne pédonculé déjà établis.The manuscript is a synthesis of ten years of research on the distribution of genetic diversity of European oaks (Quercus petraea and Quercus robur) including molecular and phenotypic diversity. By comparing the genetic and historical data (fossil pollen), the main mechanisms that shaped diversity and especially the dynamics of postglacial colonisation were identified. Oaks were restricted in three refuge areas during the last glacial period and recolonised in less than 800 years the whole European continent. The rapid colonisation was mostly due to rare but long distance dispersion events as witnessed by the extant geographic distribution of chloroplast DNA polymorphism. After colonisation, pollen flow among forests contributed to erase the genetic differentiation among stands. Finally natural selection pressures induced new genetic differences among provenances. Interspecific hybridisation was also an important dispersion mechanism enabling Quercus petraea to colonise new sites by introgression into Quercus robur stands

Data from: Two highly informative dinucleotide SSR multiplexes for the conifer Larix decidua (European larch)

We have designed two highly polymorphic microsatellite multiplexes for Larix decidua Mill. (European larch), a coniferous tree species with a fragmented distribution across Europe. The multiplexes combine microsatellites previously designed for the sister species L. kaempferi and newly identified microsatellites obtained by pyrosequencing of an enriched microsatellite library and subsequent marker candidate selection. As we wanted to target highly polymorphic markers, only microsatellite motifs with a high number of repeats (≥12) were selected. An important proportion of the marker candidates presented multiple bands, bad amplification or insufficient polymorphism. Such difficulties were expected owing to the large genome size of the studied species. Our strategy for marker validation followed most recent recommendations for microsatellite development, e.g. verifying marker quality in terms of polymorphism and accurate allele binning before multiplexing. The most promising loci were combined in two multiplexes, a 7-plex and a 6-plex. These were tested on a sample of 413 individuals from 18 populations distributed across the natural range. The 13 loci had from 9 to 36 alleles. Markers were successfully tested in another laboratory, confirming robustness of the marker protocols. We also tested transferability on six other larch species from Asia and North America. Overall, this study shows that, even in species with large genome size and relatively low overall polymorphism, microsatellites can be successfully developed using next-generation sequencing technologies provided that some additional precautions are taken compared to species lacking these characteristics