The stationary distribution of a continuously varying strategy in a class-structured population under mutation-selection-drift balance.

Many traits and/or strategies expressed by organisms are quantitative phenotypes. Because populations are of finite size and genomes are subject to mutations, these continuously varying phenotypes are under the joint pressure of mutation, natural selection and random genetic drift. This article derives the stationary distribution for such a phenotype under a mutation-selection-drift balance in a class-structured population allowing for demographically varying class sizes and/or changing environmental conditions. The salient feature of the stationary distribution is that it can be entirely characterized in terms of the average size of the gene pool and Hamilton's inclusive fitness effect. The exploration of the phenotypic space varies exponentially with the cumulative inclusive fitness effect over state space, which determines an adaptive landscape. The peaks of the landscapes are those phenotypes that are candidate evolutionary stable strategies and can be determined by standard phenotypic selection gradient methods (e.g. evolutionary game theory, kin selection theory, adaptive dynamics). The curvature of the stationary distribution provides a measure of the stability by convergence of candidate evolutionary stable strategies, and it is evaluated explicitly for two biological scenarios: first, a coordination game, which illustrates that, for a multipeaked adaptive landscape, stochastically stable strategies can be singled out by letting the size of the gene pool grow large; second, a sex-allocation game for diploids and haplo-diploids, which suggests that the equilibrium sex ratio follows a Beta distribution with parameters depending on the features of the genetic system.

MIGCLIM: Predicting plant distribution and dispersal in a changing climate

Many studies have forecasted the possible impact of climate change on plant distribution using models based on ecological niche theory. In their basic implementation, niche-based models do not constrain predictions by dispersal limitations. Hence, most niche-based modelling studies published so far have assumed dispersal to be either unlimited or null. However, depending on the rate of climatic change, the landscape fragmentation and the dispersal capabilities of individual species, these assumptions are likely to prove inaccurate, leading to under- or overestimation of future species distributions and yielding large uncertainty between these two extremes. As a result, the concepts of "potentially suitable" and "potentially colonisable" habitat are expected to differ significantly. To quantify to what extent these two concepts can differ, we developed MIGCLIM, a model simulating plant dispersal under climate change and landscape fragmentation scenarios. MIGCLIM implements various parameters, such as dispersal distance, increase in reproductive potential over time, barriers to dispersal or long distance dispersal. Several simulations were run for two virtual species in a study area of the western Swiss Alps, by varying dispersal distance and other parameters. Each simulation covered the hundred-year period 2001-2100 and three different IPCC-based temperature warming scenarios were considered. Our results indicate that: (i) using realistic parameter values, the future potential distributions generated using MIGCLIM can differ significantly (up to more than 95% decrease in colonized surface) from those that ignore dispersal; (ii) this divergence increases both with increasing climate warming and over longer time periods; (iii) the uncertainty associated with the warming scenario can be nearly as large as the one related to dispersal parameters; (iv) accounting for dispersal, even roughly, can importantly reduce uncertainty in projections.

Report on the Iowa Department of Human Services – Central Distribution Center for the year ended June 30, 2009

Report on the Iowa Department of Human Services – Central Distribution Center for the year ended June 30, 2009

Temporal changes in the expression and distribution of adhesion molecules during liver development and regeneration

We have compared by immunocytochemistry and immunoblotting the expression and distribution of adhesion molecules participating in cell-matrix and cell-cell interactions during embryonic development and regeneration of rat liver. Fibronectin and the fibronectin receptor, integrin alpha 5 beta 1, were distributed pericellularly and expressed at a steady level during development from the 16th day of gestation and in neonate and adult liver. AGp110, a nonintegrin fibronectin receptor was first detected on the 17th day of gestation in a similar, nonpolarized distribution on parenchymal cell surfaces. At that stage of development haemopoiesis is at a peak in rat liver and fibronectin and receptors alpha 5 beta 1 and AGp110 were prominent on the surface of blood cell precursors. During the last 2 d of gestation (20th and 21st day) hepatocytes assembled around lumina. AGp110 was initially depolarized on the surface of these acinar cells but then confined to the lumen and to newly-formed bile canaliculi. At birth, a marked increase occurred in the canalicular expression of AGp110 and in the branching of the canalicular network. Simultaneously, there was enhanced expression of ZO-1, a protein component of tight junctions. On the second day postpartum, presence of AGp110 and of protein constituents of desmosomes and intermediate junctions, DGI and E-cadherin, respectively, was notably enhanced in cellular fractions insoluble in nonionic detergents, presumably signifying linkage of AGp110 with the cytoskeleton and assembly of desmosomal and intermediate junctions. During liver regeneration after partial hepatectomy, AGp110 remained confined to apical surfaces, indicating a preservation of basic polarity in parenchymal cells. A decrease in the extent and continuity of the canalicular network occurred in proliferating parenchyma, starting 24 h after resection in areas close to the terminal afferent blood supply of portal veins and spreading to the rest of the liver within the next 24 h. Distinct acinar structures, similar to the ones in prenatal liver, appeared at 72 h after hepatectomy. Restoration of the normal branching of the biliary tree commenced at 72 h. At 7 d postoperatively acinar formation declined and one-cell-thick hepatic plates, as in normal liver, were observed.

Mass conservative three-dimensional water tracer distribution from Markov chain Monte Carlo inversion of time-lapse ground-penetrating radar data

Time-lapse geophysical measurements are widely used to monitor the movement of water and solutes through the subsurface. Yet commonly used deterministic least squares inversions typically suffer from relatively poor mass recovery, spread overestimation, and limited ability to appropriately estimate nonlinear model uncertainty. We describe herein a novel inversion methodology designed to reconstruct the three-dimensional distribution of a tracer anomaly from geophysical data and provide consistent uncertainty estimates using Markov chain Monte Carlo simulation. Posterior sampling is made tractable by using a lower-dimensional model space related both to the Legendre moments of the plume and to predefined morphological constraints. Benchmark results using cross-hole ground-penetrating radar travel times measurements during two synthetic water tracer application experiments involving increasingly complex plume geometries show that the proposed method not only conserves mass but also provides better estimates of plume morphology and posterior model uncertainty than deterministic inversion results.

Mental disorders in offspring of parents with bipolar and major depressive disorders.

OBJECTIVES: There is limited information on the specificity of associations between parental bipolar disorder (BPD) and major depressive disorder (MDD) and the risk of psychopathology in offspring. The chief aim of the present study was to investigate the association between mood disorder subtypes in the two parents and mental disorders in the offspring. METHODS: A total of 376 offspring (aged 6.0-17.9 years; mean=11.5years) of 72 patients with BPD (139 offspring), 56 patients with MDD (110 offspring), and 66 controls (127 offspring) participated in a family study conducted in two university hospital centers in Switzerland. Probands, offspring, and biological co-parents were interviewed by psychologists blind to proband diagnoses, using a semi-structured diagnostic interview. RESULTS: Rates of mood and anxiety disorders were elevated among offspring of BPD probands (34.5% any mood; 42.5% any anxiety) and MDD probands (25.5% any mood; 44.6% any anxiety) as compared to those of controls (12.6% any mood; 22.8% any anxiety). Moreover, recurrent MDD was more frequent among offspring of BPD probands (7.9%) than those of controls (1.6%). Parental concordance for bipolar spectrum disorders was associated with a further elevation in the rates of mood disorders in offspring (64.3% both parents versus 27.2% one parent). CONCLUSIONS:   These findings provide unique information on the broad manifestations of parental mood disorders in their offspring. The earlier onset and increased risk of recurrent MDD in the offspring of parents with BPD compared to those of controls suggests that the episodicity characterizing BPD may emerge in childhood and adolescence.

Improving the prediction of plant species distribution and community composition by adding edaphic to topo-climatic variables

Questions Soil properties have been widely shown to influence plant growth and distribution. However, the degree to which edaphic variables can improve models based on topo-climatic variables is still unclear. In this study, we tested the roles of seven edaphic variables, namely (1) pH; (2) the content of nitrogen and of (3) phosphorus; (4) silt; (5) sand; (6) clay and (7) carbon-to-nitrogen ratio, as predictors of species distribution models in an edaphically heterogeneous landscape. We also tested how the respective influence of these variables in the models is linked to different ecological and functional species characteristics. Location The Western Alps, Switzerland. Methods With four different modelling techniques, we built models for 115 plant species using topo-climatic variables alone and then topo-climatic variables plus each of the seven edaphic variables, one at a time. We evaluated the contribution of each edaphic variable by assessing the change in predictive power of the model. In a second step, we evaluated the importance of the two edaphic variables that yielded the largest increase in predictive power in one final set of models for each species. Third, we explored the change in predictive power and the importance of variables across plant functional groups. Finally, we assessed the influence of the edaphic predictors on the prediction of community composition by stacking the models for all species and comparing the predicted communities with the observed community. Results Among the set of edaphic variables studied, pH and nitrogen content showed the highest contributions to improvement of the predictive power of the models, as well as the predictions of community composition. When considering all topo-climatic and edaphic variables together, pH was the second most important variable after degree-days. The changes in model results caused by edaphic predictors were dependent on species characteristics. The predictions for the species that have a low specific leaf area, and acidophilic preferences, tolerating low soil pH and high humus content, showed the largest improvement by the addition of pH and nitrogen in the model. Conclusions pH was an important predictor variable for explaining species distribution and community composition of the mountain plants considered in our study. pH allowed more precise predictions for acidophilic species. This variable should not be neglected in the construction of species distribution models in areas with contrasting edaphic conditions.

Cation distribution and magnetization of BaFe12-2xCoxSnxO19 (x=0.9,1.28) single crystals

The distribution of Sn4+ cations within the five crystallographic sites of the magnetoplumbite (M) ‐like compound BaFe12−2xCoxSnxO19 has been analyzed using single‐crystal x‐ray‐diffraction data. The species Fe3+ and Co2+ cannot be distinguished using x rays because of their very similar atomic numbers; however, the calculation of the apparent valencies for the different sites allows an insight into the Co2+ cation segregation. The use of previous data from neutron powder diffraction allows a precise picture of the cation distribution, which indicates a pronounced site selectivity for both Sn4+ and Co2+ cations. The Sn4+ cations prefer the 4f2 sites and to a much lower extent the 12k sites, while they do not enter the octahedral 2a sites at all. Co2+ cations are distributed among tetrahedral and octahedral sites displaying a clear preference for the tetrahedral 4f1 sites. Magnetic measurements indicate that the compound still exhibits uniaxial anisotropy with the easy direction parallel to the c axis. Nevertheless, the magnetic structure shows a considerable degree of noncolinearity. A strong reduction of the magnetic anisotropy regarding that of the undoped compound is also detected.

Melanin-based coloration is a nondirectionally selected sex-specific signal of offspring development in the Alpine swift

Two mutually exclusive hypotheses have been put forward to explain the evolution and adaptive function of melanin-based color traits. According to sexual selection theory melanism is a directionally selected signal of individual quality, whereas theory on the maintenance of genetic polymorphism proposes that alternative melanin-based variants achieve equal fitness. Alpine swift (Apus melba) males and females have a conspicuous patch of white feathers on the breast with their rachis varying continuously from white to black, and hence the breast varies from white to striated. If this trait is a sexually selected signal of quality, its expression should be condition dependent and the degree of melanism directionally selected. If variation in melanism is a polymorphism, its expression should be genetically determined and fitness of melanin-based variants equal. We experimentally tested these predictions by exchanging eggs or hatchlings between randomly chosen nests and by estimating survival and reproduction in relation to melanism. We found that breast melanism is heritable and that the environment and body condition do not significantly influence its expression. Between 5 and 50 days of age nestlings were heavier and their wings longer when breast feathers of their biological father were blacker, and they also fledged at a younger age. This shows that aspects of offspring quality covary positively with the degree of melanism. However, this did not result in directional selection because nestling survival and recruitment in the local breeding population were not associated with father breast melanism. Furthermore, adult survival, age at first reproduction and probability of skipping reproduction did not covary with the degree of melanism. Genetic variation in breast melanism is therefore maintained either because nonmelanic males achieve fitness similar to melanic males via a different route than producing fast-growing offspring, or because the advantage of producing fast-growing offspring is not sufficiently pronounced to result in directional selection.

Report on the Iowa Department of Human Services – Central Distribution Center for the year ended June 30, 2010

Report on the Iowa Department of Human Services – Central Distribution Center for the year ended June 30, 2010