The succession of ecological divergence and reproductive isolation in adaptive radiations.

Adaptive radiation is a major source of biodiversity but the way in which known components of ecological opportunity, ecological differentiation, and reproductive isolation underpin such biodiversity patterns remains elusive. Much is known about the evolution of ecological differentiation and reproductive isolation during single speciation events, but exactly how those processes scale up to complete adaptive radiations is less understood. Do we expect complete reproductive barriers between newly formed species before the ecological differentiation continues, or does proper species formation occur much later, long after the ecological diversification? Our goal is to improve our mechanistic understanding of adaptive radiations by analyzing an individual-based model that includes a suite of mechanisms that are known to contribute to biodiversity. The model includes variable biogeographic settings, ecological opportunities, and types of mate choice, which makes several different scenarios of an adaptive radiation possible. We find that evolving clades tend to exploit ecological opportunities early whereas reproductive barriers evolve later, demonstrating a decoupling of ecological differentiation and species formation. In many cases, we also find a long-term trend where assortative mating associated with ecological traits is replaced by sexual selection of neutral display traits as the primary mechanism for reproductive isolation. Our results propose that reticulate phylogenies are likely common and stem from initially low reproductive barriers, rather than the previously suggested idea of repeated hybridization events between well-separated species.

Pregnancy outcomes in young mothers with perinatally and behaviorally acquired HIV infections in Rio de Janeiro.

BACKGROUND: Perinatally HIV-infected children are surviving into adulthood, and getting pregnant. There is a scarcity of information on health and pregnancy outcomes in these women. AIM: To evaluate characteristics related to HIV disease and pregnancy outcomes in perinatally infected women, and to compare these women with a group of youth with behaviorally acquired HIV-infection, at a reference hospital in Rio de Janeiro, Brazil. METHODS: A cohort study. Epidemiological, clinical, and laboratory data were compared between perinatally (PHIV) and behaviorally HIV-infected (BHIV) pregnant youth with the primary aim to study pregnancy outcomes in the PHIV group and compare with outcomes to BHIV group. RESULTS: Thirty-two pregnancies occurred in PHIV group, and 595 in BHIV group. A total of seven (22%) PHIV women and 64 (11%) BHIV women had a premature delivery (p=0.04), however, when adjusting for younger age at pregnancy, and antiretroviral therapy initiation in 1st trimester of pregnancy (OR=18.66, 95%CI=5.52-63.14), the difference was no longer significant. No cases of mother-to-child HIV transmission (MTCT) were observed in the PHIV group while there was a 2% MTCT rate in BHIV group. CONCLUSION: Pregnancy among PHIV was as safe as among BHIV. The differences between those groups were probably related to treatment and prolonged care in the first group.

Pregnancy outcomes in young mothers with perinatally and behaviorally acquired HIV infections in Rio de Janeiro

ABSTRACT Background: Perinatally HIV-infected children are surviving into adulthood, and getting pregnant. There is a scarcity of information on health and pregnancy outcomes in these women. Aim: To evaluate characteristics related to HIV disease and pregnancy outcomes in perinatally infected women, and to compare these women with a group of youth with behaviorally acquired HIV-infection, at a reference hospital in Rio de Janeiro, Brazil. Methods: A cohort study. Epidemiological, clinical, and laboratory data were compared between perinatally (PHIV) and behaviorally HIV-infected (BHIV) pregnant youth with the primary aim to study pregnancy outcomes in the PHIV group and compare with outcomes to BHIV group. Results: Thirty-two pregnancies occurred in PHIV group, and 595 in BHIV group. A total of seven (22%) PHIV women and 64 (11%) BHIV women had a premature delivery (p = 0.04), however, when adjusting for younger age at pregnancy, and antiretroviral therapy initiation in 1st trimester of pregnancy (OR = 18.66, 95%CI = 5.52-63.14), the difference was no longer significant. No cases of mother-to-child HIV transmission (MTCT) were observed in the PHIV group while there was a 2% MTCT rate in BHIV group. Conclusion: Pregnancy among PHIV was as safe as among BHIV. The differences between those groups were probably related to treatment and prolonged care in the first group.

Principles of niche expansion.

Niche expansion is attained by adaptations in two generalized phenotypical traits-niche position and niche width. This gives room for a wide range of conceptual ways of niche filling. The niche variation hypothesis reduces the range by predicting that expansion occurs by increasing variation in niche position, which has been debated on empirical and theoretical grounds as also other options seem possible. Here, we propose a general theory of niche expansion. We review empirical data and show with an eco-evolutionary model how resource diversity and a trade-off in resource acquisition steer niche evolution consistent with observations. We show that the range can be reduced to a discrete set of two orthogonal ways of niche filling, through (1) strict phenotypical differentiation in niche position or (2) strict individual generalization. When individual generalization is costly, niche expansion undergoes a shift from (2) to (1) at a point where the resource diversity becomes sufficiently large. Otherwise, niche expansion always follows (2), consistent with earlier results. We show that this either-or response can operate at both evolutionary and short-term time scales. This reduces the principles of niche expansion under environmental change to a notion of orthogonality, dictated by resource diversity and a resource-acquisition trade-off.

The Biogeography of Adaptive Radiations and the Geographic Overlap of Sister Species.

The biogeography of speciation and what can be learned about the past mode of speciation from current biogeography of sister species are recurrent problems in evolution. We used a trait- and individual-based, eco-evolutionary model to simulate adaptive radiations and recorded the geographical overlap of species during and after evolutionary branching (speciation). We compared the spatial overlap among sister species in the fully saturated community with the overlap at the speciation event. The mean geographic overlap at speciation varied continuously from complete (sympatry) to none (allopatry), depending on local and regional environmental heterogeneity and the rate of dispersal. The distribution of overlap was, however, in some cases considerably bimodal. This tendency was most expressed at large values of regional heterogeneity, corresponding to sharp environmental contrasts. The mean geographic overlap also varied during the course of a radiation, sometimes with a consistent negative trend over time. The speciations that resulted in currently observable end community sister species were therefore not an unbiased sample of all speciations throughout the radiation. Postspeciation range shifts (causing increased overlap) occurred most frequently when dispersal was high or when local habitat heterogeneity was low. Our results help us understand how the patterns of geographic mode of speciation emerge. We also show the difficulty in inferring the geographical speciation mode from phylogenies and the biogeography of extant species.

On the evolutionary stability of partial migration.

The evolution of partial migration in birds is typically assumed to be the result of an optimization process. The fitness rewards for individuals choosing to migrate are balanced against the rewards of remaining in the breeding area all year around. This balancing is often thought to result in an evolutionarily stable strategy (ESS) such that an optimal fraction of the population becomes migratory through adaptive evolution. Here I show that this solution can indeed be reached through adaptive evolution, but that the equilibrium is a neutral or "weak" ESS. The equilibrium fraction of migrants is more reminiscent of the Fisherian sex ratio. I also show that this individual-based evolutionary solution may deviate significantly from the optimal solution for the population (maximum population size), quite in line with previous findings. Finally, I show that partial migration is very unlikely without density- or frequency-dependent selection.

Political institutions and their historical dynamics.

Traditionally, political scientists define political institutions deductively. This approach may prevent from discovery of existing institutions beyond the definitions. Here, a principal component analysis was used for an inductive extraction of dimensions in Polity IV data on the political institutions of all nations in the world the last two centuries. Three dimensions of institutions were revealed: core institutions of democracy, oligarchy, and despotism. We show that, historically and on a world scale, the dominance of the core institutions of despotism has first been replaced by a dominance of the core institutions of oligarchy, which in turn is now being followed by an increasing dominance by the core institutions of democracy. Nations do not take steps from despotic, to oligarchic and then to democratic institutions, however. Rather, nations hosting the core democracy institutions have succeeded in historically avoiding both the core institutions of despotism and those of oligarchy. On the other hand, some nations have not been influenced by any of these dimensions, while new institutional combinations are increasingly influencing others. We show that the extracted institutional dimensions do not correspond to the Polity scores for autocracy, "anocracy" and democracy, suggesting that changes in regime types occur at one level, while institutional dynamics work on another. Political regime types in that sense seem "canalized", i.e., underlying institutional architectures can and do vary, but to a considerable extent independently of regime types and their transitions. The inductive approach adds to the deductive regime type studies in that it produces results in line with modern studies of cultural evolution and memetic institutionalism in which institutions are the units of observation, not the nations that acts as host for them.

Phylogenetic analysis suggests that habitat filtering is structuring marine bacterial communities across the globe.

The phylogenetic structure and community composition were analysed in an existing data set of marine bacterioplankton communities to elucidate the evolutionary and ecological processes dictating the assembly. The communities were sampled from coastal waters at nine locations distributed worldwide and were examined through the use of comprehensive clone libraries of 16S ribosomal RNA genes. The analyses show that the local communities are phylogenetically different from each other and that a majority of them are phylogenetically clustered, i.e. the species (operational taxonomic units) were more related to each other than expected by chance. Accordingly, the local communities were assembled non-randomly from the global pool of available bacterioplankton. Further, the phylogenetic structures of the communities were related to the water temperature at the locations. In agreement with similar studies, including both macroorganisms and bacteria, these results suggest that marine bacterial communities are structured by "habitat filtering", i.e. through non-random colonization and invasion determined by environmental characteristics. Different bacterial types seem to have different ecological niches that dictate their survival in different habitats. Other eco-evolutionary processes that may contribute to the observed phylogenetic patterns are discussed. The results also imply a mapping between phenotype and phylogenetic relatedness which facilitates the use of community phylogenetic structure analysis to infer ecological and evolutionary assembly processes.

Recruitment of members from the rare biosphere of marine bacterioplankton communities after an environmental disturbance.

A bacterial community may be resistant to environmental disturbances if some of its species show metabolic flexibility and physiological tolerance to the changing conditions. Alternatively, disturbances can change the composition of the community and thereby potentially affect ecosystem processes. The impact of disturbance on the composition of bacterioplankton communities was examined in continuous seawater cultures. Bacterial assemblages from geographically closely connected areas, the Baltic Sea (salinity 7 and high dissolved organic carbon [DOC]) and Skagerrak (salinity 28 and low DOC), were exposed to gradual opposing changes in salinity and DOC over a 3-week period such that the Baltic community was exposed to Skagerrak salinity and DOC and vice versa. Denaturing gradient gel electrophoresis and clone libraries of PCR-amplified 16S rRNA genes showed that the composition of the transplanted communities differed significantly from those held at constant salinity. Despite this, the growth yields (number of cells ml(-1)) were similar, which suggests similar levels of substrate utilization. Deep 454 pyrosequencing of 16S rRNA genes showed that the composition of the disturbed communities had changed due to the recruitment of phylotypes present in the rare biosphere of the original community. The study shows that members of the rare biosphere can become abundant in a bacterioplankton community after disturbance and that those bacteria can have important roles in maintaining ecosystem processes.

Inflammation increases NT-proBNP and the NT-proBNP/BNP ratio.

Plasma BNP and NT-proBNP are often regarded as interchangeable parameters in assessing heart failure (HF) severity and prognosis. Renal failure results in disproportionate increases of NT-proBNP and an increased NT-proBNP/BNP ratio. Low kidney function is therefore considered particularly when NT-proBNP is used to assess HF. The purpose of this study was to identify other conditions affecting the NT-proBNP/BNP ratio. We examined the NT-proBNP/BNP ratio, 26 other lab parameters, and clinical factors in 218 patients admitted to the HF ward. In addition to renal function, we also found significant correlations between the NT-proBNP/BNP ratio and inflammation as measured by orosomucoid (r = 0.525, p < 0.0001), CRP (r = 0.333, p < 0.0001), haptoglobulin (r = 0.201, p = 0.02), and alpha1-antitrypsin (r = 0.223, p = 0.01). Reverse correlation was found with transferrin (r = -0.323, p < 0.0001), albumin (r = -0.251, p = 0.003), and S-Fe (r = -0.205, p = 0.02), parameters known to decrease during inflammation. Inflammation increased levels of NT-proBNP more than BNP, resulting in an increased NT-proBNP/BNP ratio. Our findings indicate that NT-proBNP should be evaluated concomitantly with inflammatory status to avoid overestimation of HF severity.

Seizure risk associated with neuroactive drugs: data from the WHO adverse drug reactions database.

PURPOSE: To explore the association between the use of neuroactive drugs and reports of epileptic seizures. MATERIAL: Using the WHO adverse drug reactions (ADR) database, VigiBase, we surveyed reports of suspected seizures from 1968 until February 2006. Case reports of ADRs, that were classified as convulsions were collected and compared to the total number of ADRs reported. RESULTS: The total number of ADRs was 7,375,325. The number of convulsive events was 71,471. The ratio of convulsive ADRs to the total number of ADRs reported for each drug was evaluated and expressed as a percentage. The 10 drugs most frequently associated with convulsive ADRs were maprotilene (14.42%), escitaloprame (9.78%), buproprione (9.49%), clozapine (9.0%), chlorprothiexene (8.89%), amoxapine (8.74%), donepezil (8.40%), rivastigmine (6.41%), quetiapine (5.90%) and trimipramine (5.69%). CONCLUSIONS: Based on the reports in VigiBase, ADR reports relating to antidepressants, antipsychotic and cholinomimetic drugs included seizures more often than other neuroactive drugs.

RAMI: a tool for identification and characterization of phylogenetic clusters in microbial communities.

MOTIVATION: The most common approach to estimate microbial diversity is based on the analysis of DNA sequences of specific target genes including ribosomal genes. Commonly, the sequences are grouped into operational taxonomic units based on genetic distance (sequence similarity) instead of genetic change (patristic distance). This method may fail to adequately identify clusters of evolutionary related sequences and it provides no information on the phylogenetic structure of the community. An ease-of-use web application for this purpose has been missing. RESULTS: We have developed RAMI, which clusters related nodes in a phylogenetic tree based on the patristic distance. RAMI also produces indices of cluster properties and other indices used in population and community studies on-the-fly. AVAILABILITY: RAMI is licensed under GNU GPL and can be run or downloaded from http://www.acgt.se/online.html. SUPPLEMENTARY INFORMATION: http://www.acgt.se/RAMI/SuppInfo.

Quantitative trait evolution and environmental change.

BACKGROUND: Given the recent changes in climate, there is an urgent need to understand the evolutionary ability of populations to respond to these changes. METHODOLOGY/PRINCIPAL FINDINGS: We performed individual-based simulations with different shapes of the fitness curve, different heritabilities, different levels of density compensation, and different autocorrelation of environmental noise imposed on an environmental trend to study the ability of a population to adapt to changing conditions. The main finding is that when there is a positive autocorrelation of environmental noise, the outcome of the evolutionary process is much more unpredictable compared to when the noise has no autocorrelation. In addition, we found that strong selection resulted in a higher load, and more extinctions, and that this was most pronounced when heritability was low. The level of density-compensation was important in determining the variance in load when there was strong selection, and when genetic variance was lower when the level of density-compensation was low. CONCLUSIONS: The strong effect of the details of the environmental fluctuations makes predictions concerning the evolutionary future of populations very hard to make. In addition, to be able to make good predictions we need information on heritability, fitness functions and levels of density compensation. The results strongly suggest that patterns of environmental noise must be incorporated in future models of environmental change, such as global warming.

Hepcidin, interleukin-6 and hematological iron markers in males before and after heart surgery.

Anemia of inflammation in patients with acute or chronic acute-phase activation is a common clinical problem. Hepcidin is a peptide shown to be the principal regulator of the absorption and systemic distribution of iron. Main inducers of hepcidin are iron overload, hypoxia and inflammation, where the latter has been linked to hepcidin via increased interleukin-6 (IL-6). This article addresses the impact and time course of postoperative acute-phase reaction in humans following heart surgery on prohepcidin, hepcidin, hematological markers and IL-6 concentrations. Serum concentrations of prohepcidin, hepcidin, IL-6 and hematological iron parameters were studied in five male patients without infection before and after heart surgery. This study, which is the first to report the impact on serum hepcidin and serum prohepcidin concentrations in patients following surgery, clearly demonstrates the induction of hypoferremia due to the postoperative acute-phase reaction. Significant changes were seen for serum iron concentration, transferrin saturation, total iron binding capacity and hemoglobin concentration. A significant increase in ferritin concentration was seen 96-144 h postoperatively. Additionally, there were significant alterations in both serum hepcidin after 96-144 h and serum prohepcidin after 48 h compared with preoperative values. Serum prohepcidin decreased, whereas serum hepcidin increased. In conclusion, changes in serum prohepcidin were followed by an increase in serum hepcidin. This speaks in favor of a chain of action where proteolytic trimming of serum prohepcidin results in increased serum hepcidin. However, hypoferremia appeared prior to the changes in serum prohepcidin and serum hepcidin.

Plasma levels of natriuretic peptide type B and A in children with heart disease with different types of cardiac load or systolic dysfunction.

Natriuretic peptide levels B (BNP) and A (ANP) have been described in children with different diagnose of congenital heart defects (CHD). However, the impact of the type of cardiac load per se on natriuretic peptide levels, irrespective of diagnosis, has not been reported. The aim of the present study was to evaluate the levels of BNP and ANP in children with congenital and acquired heart disease according to different types of cardiac load. Plasma BNP and ANP were analysed in 137 children with CHD/heart disease, median age 2.9 (0.3-16.7) years. Haemodynamic load was classified as: no overload, pressure overload, volume overload of right and/or left ventricle and systolic ventricular dysfunction. Twenty-three children without heart disease served as controls for the natriuretic peptide measurements. The highest BNP and ANP values were observed in the systolic dysfunction, 613 ng l(-1) (81.8-3910) and 431 (43.8-1990), and volume groups, 29.8 (5.5-352) and 93.0 (15.9-346), respectively, whereas the values in the pressure, 17.9 (0.7-315) and 51.9 (8.7-210), and no overload groups, 10.3 (0.2-28.1) and 28.6 (8.6-105), respectively, were only slightly higher than those in the controls 4.7 (0.0-17.7) and 32.9 (11.7-212.2), respectively. The highest BNP and ANP values were seen in children with systolic dysfunction, while volume overload in the absence of heart failure resulted in higher levels than pressure overload.

Increased natriuretic peptide type B level after the second palliative step in children with univentricular hearts with right ventricular morphology but not left ventricular morphology.

We analyzed the natriuretic peptide type B (BNP) and A (ANP) levels in the plasma of 38 children with stable functionally univentricular heart defects, 10 of whom had undergone the first palliative step (Shunt), 13 of whom had undergone the second palliative step (Glenn), and 15 of whom had completed total cavopulmonary connection (TCPC). The levels of BNP and ANP were significantly higher after the first palliative step, 31.6 ng/l (8.3-122) (median and range) and 101.2 ng/l (17.1-203), respectively, than after the Glenn procedure, 6.7 ng/l (0.0-16.0) and 23.6 ng/l (15.7-54.4), respectively, as well as after completed TCPC, 9.0 ng/l (0.0-39.1) and 20.9 ng/l (11.2-28.3), respectively, and, in a control group of children without heart defects, 5.8 ng/l (0.0-38.7) and 32.9 ng/l (11.7-212.1), respectively (p = 0.0003 and p = 0.0003, respectively). After the first palliative step, the BNP and ANP levels were the same in children with right and left ventricular morphology (p = 0.67 and p = 0.52, respectively). After unloading the ventricle (Glenn and TCPC together), BNP levels were higher in children with right ventricular morphology compared with those with left ventricular morphology and controls (p = 0.02). Children with functionally univentricular hearts in stable condition have increased BNP and ANP levels after the first palliative procedure. After the second and third palliative steps, the BNP and ANP levels were low and similar to those of children without heart defects. However, BNP levels in children with a systemic ventricle of right ventricular morphology were higher than those in children with left ventricular morphology.

The influence of vigilance on intraguild predation.

Theoretical work on intraguild predation suggests that if a top predator and an intermediate predator share prey, the system will be stable only if the intermediate predator is better at exploiting the prey, and the top predator gains significantly from consuming the intermediate predator. In mammalian carnivore systems, however, there are examples of top predator species that attack intermediate predator species, but rarely or never consume the intermediate predator. We suggest that top predators attacking intermediate predators without consuming them may not only reduce competition with the intermediate predators, but may also increase the vigilance of the intermediate predators or alter the vigilance of their shared prey, and that this behavioral response may help to maintain the stability of the system. We examine two models of intraguild predation, one that incorporates prey vigilance, and a second that incorporates intermediate predator vigilance. We find that stable coexistence can occur when the top predator has a very low consumption rate on the intermediate predator, as long as the attack rate on the intermediate predator is relatively large. However, the system is stable when the top predator never consumes the intermediate predator only if the two predators share more than one prey species. If the predators do share two prey species, and those prey are vigilant, increasing top predator attack rates on the intermediate predator reduces competition with the intermediate predator and reduces vigilance by the prey, thereby leading to higher top predator densities. These results suggest that predator and prey behavior may play an important dynamical role in systems with intraguild predation.

Brain natriuretic peptide assessed at long-term follow-up before and after maximal exercise in surgically palliated patients with functionally univentricular hearts.

We evaluated the concentrations of brain natriuretic peptide in the plasma as a marker of systolic ventricular function before and after maximal exercise in 15 surgically palliated patients with functionally univentricular hearts, with apparently good ventricular function. Of the patients, 6 with median age of 14.6 years, and a range from 12.5 to 17.9 years, had been palliated by construction of a total cavopulmonary connection, while the other 9 patients, with a median age of 32.1 years, and a range from 15.6 to 54.2 years, had undergone the classical Fontan procedure. We used 8 healthy individuals, with a median age of 13.9 years, and a range from 12.8 to 14.2 years, as a control group for the measurements of brain natriuretic peptide. The values of the peptide were significantly higher in those with the classical Fontan procedure, both before, when the median value was 131.8 nanogram per litre, with a range from 0.5 to 296.4, and after maximal exercise, when the median value was 108.1, with a range from 0.1 to 235.9. The comparable values in those with a total cavopulmonary connection were a median of 12.8, and a range from 0.5 to 39.1 before, and a median of 9.7, with a range from 2.7 to 26.2 after maximal exercise. The median value for the control group was 13.1, with a range from 2.6 to 38.7 before exercise (p = 0.016), and a median of 24.1, with a range from 5.8 to 66.7 after maximal exercise (p = 0.03), respectively. In the control subjects, the level of the peptide increased by a median of 9.7 nanograms per litre, with a range from 1.2 to 28.0 after maximal exercise (p = 0.008). The level was unchanged after maximal exercise in those with classical Fontan procedures and total cavopulmonary connections, with a difference between levels before and after exercise of a median of 5.9 nanogram per litre, and a range from -23.7 to 31.0 (p = 0.96), and a median of -1.0 nanogram per litre, with a range from -12.0 to 3.9 (p > 0.99), respectively. We conclude that maximal exercise did not increase the level of brain natriuretic peptide level in those patients with the classical Fontan procedure, nor those with a total cavopulmonary connection, findings which may indicate that systolic ventricular dysfunction is not the major cause of the decreased working capacity observed in patients with well functioning palliated functionally univentricular hearts.