Evidence for selection on coloration in a Panamanian poison frog: a coalescent-based approach

Aim The strawberry poison frog, Oophaga pumilio, has undergone a remarkable radiation of colour morphs in the Bocas del Toro archipelago in Panama. This species shows extreme variation in colour and pattern between populations that have been geographically isolated for < 10,000 years. While previous research has suggested the involvement of divergent selection, to date no quantitative test has examined this hypothesis. Location Bocas del Toro archipelago, Panama. Methods We use a combination of population genetics, phylogeography and phenotypic analyses to test for divergent selection in coloration in O. pumilio. Tissue samples of 88 individuals from 15 distinct populations were collected. Using these data, we developed a gene tree using the mitochondrial DNA (mtDNA) d-loop region. Using parameters derived from our mtDNA phylogeny, we predicted the coalescence of a hypothetical nuclear gene underlying coloration. We collected spectral reflectance and body size measurements on 94 individuals from four of the populations and performed a quantitative analysis of phenotypic divergence. Results The mtDNA d-loop tree revealed considerable polyphyly across populations. Coalescent reconstructions of gene trees within population trees revealed incomplete genotypic sorting among populations. The quantitative analysis of phenotypic divergence revealed complete lineage sorting by colour, but not by body size: populations showed non-overlapping variation in spectral reflectance measures of body coloration, while variation in body size did not separate populations. Simulations of the coalescent using parameter values derived from our empirical analyses demonstrated that the level of sorting among populations seen in colour cannot reasonably be attributed to drift. Main conclusions These results imply that divergence in colour, but not body size, is occurring at a faster rate than expected under neutral processes. Our study provides the first quantitative support for the claim that strong diversifying selection underlies colour variation in the strawberry poison frog.

Safety of non-therapeutic atomoxetine exposures - a national poison data system study

AIMS This study's objective is to assess the safety of non-therapeutic atomoxetine exposures reported to the US National Poison Database System (NPDS). METHODS This is a retrospective database study of non-therapeutic single agent ingestions of atomoxetine in children and adults reported to the NPDS between 2002 and 2010. RESULTS A total of 20 032 atomoxetine exposures were reported during the study period, and 12 370 of these were single agent exposures. The median age was 9 years (interquartile range 3, 14), and 7380 were male (59.7%). Of the single agent exposures, 8813 (71.2%) were acute exposures, 3315 (26.8%) were acute-on-chronic, and 166 (1.3%) were chronic. In 10 608 (85.8%) cases, exposure was unintentional, in 1079 (8.7%) suicide attempts, and in 629 (5.1%) cases abuse. Of these cases, 3633 (29.4 %) were managed at health-care facilities. Acute-on-chronic exposure was associated with an increased risk of a suicidal reason for exposure compared with acute ingestions (odds ratio 1.44, 95% confidence interval 1.26-1.65). Most common clinical effects were drowsiness or lethargy (709 cases; 5.7%), tachycardia (555; 4.5%), and nausea (388; 3.1%). Major toxicity was observed in 21 cases (seizures in nine (42.9%), tachycardia in eight (38.1%), coma in six (28.6%), and ventricular dysrhythmia in one case (4.8%)). CONCLUSIONS Non-therapeutic atomoxetine exposures were largely safe, but seizures were rarely observed.

Sexual dimorphism and directional sexual selection on aposematic signals in a poison frog

It is commonly assumed that natural selection imposed by predators is the prevailing force driving the evolution of aposematic traits. Here, we demonstrate that aposematic signals are shaped by sexual selection as well. We evaluated sexual selection for coloration brightness in populations of the poison frog Oophaga [Dendrobates] pumilio in Panama's Bocas del Toro archipelago. We assessed female preferences for brighter males by manipulating the perceived brightness of spectrally matched males in two-way choice experiments. We found strong female preferences for bright males in two island populations and weaker or ambiguous preferences in females from mainland populations. Spectral reflectance measurements, coupled with an O. pumilio-specific visual processing model, showed that O. pumilio coloration was significantly brighter in island than in mainland morphs. In one of the island populations (Isla Solarte), males were significantly more brightly colored than females. Taken together, these results provide evidence for directional sexual selection on aposematic coloration and document sexual dimorphism in vertebrate warning coloration. Although aposematic signals have long been upheld as exemplars of natural selection, our results show that sexual selection should not be ignored in studies of aposematic evolution.

Factors that trigger emergency physicians to contact a poison centre: findings from a Swiss study.

OBJECTIVE Poison centres offer rapid and comprehensive support for emergency physicians managing poisoned patients. This study investigates institutional, case-specific and poisoning-specific factors which influence the decision of emergency physicians to contact a poison centre. METHODS Retrospective, consecutive review of all poisoning-related admissions to the emergency departments (EDs) of a primary care hospital and a university hospital-based tertiary referral centre during 2007. Corresponding poison centre consultations were extracted from the poison centre database. Data were matched and analysed by logistic regression and generalised linear mixed models. RESULTS 545 poisonings were treated in the participating EDs (350 (64.2%) in the tertiary care centre, 195 (35.8%) in the primary care hospital). The poison centre was consulted in 62 (11.4%) cases (38 (61.3%) by the tertiary care centre and 24 (38.7%) by the primary care hospital). Factors significantly associated with poison centre consultation included gender (female vs male) (OR 2.99; 95% CI 1.69 to 5.29; p<0.001), number of ingested substances (>1 vs 1) (OR 2.84; 95% CI 1.65 to 4.9; p<0.001) and situation (accidental vs intentional) (OR 2.76; 95% CI 1.05 to 7.25; p=0.039). In contrast, age, medical history and hospital size did not influence poison centre consultation. Poison centre consultation was significantly higher during the week, and significantly less during night shifts. The poison centre was consulted significantly more when patients were admitted to intensive care units (OR 5.81; 95% CI 3.25 to 10.37; p<0.001). Asymptomatic and severe versus mild cases were associated with more frequent consultation (OR 4.48; 95% CI 1.78 to 11.26; p=0.001 and OR 2.76; 95% CI 1.42 to 5.38; p=0.003). CONCLUSIONS We found low rates of poison centre consultation by emergency physicians. It appears that intensive care unit admission and other factors reflecting either complexity or uncertainty of the clinical situation are the strongest predictors for poison centre consultation. Hospital size did not influence referral behaviour.

[Dosis sola facit venenum: outcome of intoxications in a Swiss university hospital]

Poisoning is a frequent disease in an emergency division. During four years we observed patients with poisoning related to there reason of intoxication, the degree of severity, age group and sex, and tried to make conclusions about lethal outcome on behalf of our data. The severity was defined by the «poison severity scale» (PSS). 1515 patients with intoxication in four years were documented. 152 (10%) of them had a severe intoxication or lethal outcome. In women suicide predominated as reason of severe intoxication, whereas in men an abuse of alcool and drugs was mostly seen. A multidisciplinary approach is important for handling intoxicated patients. Our investigation showed a good somatical outcome of patients with severe intoxication. Mortality was 5% (7/152 patients).