Evolutionary allometry reveals a shift in selection pressure on male horn size.

How selection pressures acting within species interact with developmental constraints to shape macro-evolutionary patterns of species divergence is still poorly understood. In particular, whether or not sexual selection affects evolutionary allometry, the increase in trait size with body size across species, of secondary sexual characters, remains largely unknown. In this context, bovid horn size is an especially relevant trait to study because horns are present in both sexes, but the intensity of sexual selection acting on them is expected to vary both among species and between sexes. Using a unique data set of sex-specific horn size and body mass including 91 species of bovids, we compared the evolutionary allometry between horn size and body mass between sexes while accounting for both the intensity of sexual selection and phylogenetic relationship among species. We found a nonlinear evolutionary allometry where the allometric slope decreased with increasing species body mass. This pattern, much more pronounced in males than in females, suggests either that horn size is limited by some constraints in the largest bovids or is no longer the direct target of sexual selection in very large species.

Neo-sex chromosomes of Ronderosia bergi: insight into the evolution of sex chromosomes in grasshoppers.

Sex chromosomes have evolved many times from morphologically identical autosome pairs, most often presenting several recombination suppression events, followed by accumulation of repetitive DNA sequences. In Orthoptera, most species have an X0♂ sex chromosome system. However, in the subfamily Melanoplinae, derived variants of neo-sex chromosomes (neo-XY♂ or neo-X1X2Y♂) emerged several times. Here, we examined the differentiation of neo-sex chromosomes in a Melanoplinae species with a neo-XY♂/XX♀ system, Ronderosia bergi, using several approaches: (i) classical cytogenetic analysis, (ii) mapping via fluorescent in situ hybridization of some selected repetitive DNA sequences and microdissected sex chromosomes, and (iii) immunolocalization of distinct histone modifications. The microdissected sex chromosomes were also used as sources for Polymerase chain reaction (PCR) amplification of RNA-coding multigene families, to study variants related to the sex chromosomes. Our data suggest that the R. bergi neo-Y has become differentiated after its formation by a Robertsonian translocation and inversions, and has accumulated repetitive DNA sequences. Interestingly, the ex autosomes incorporated into the neo-sex chromosomes retain some autosomal post-translational histone modifications, at least in metaphase I, suggesting that the establishment of functional modifications in neo-sex chromosomes is slower than their sequence differentiation.

Dolphins in a Scaled-Down Mediterranean: The Gulf of Corinth's Odontocetes.

The Gulf of Corinth is a 2400-km2 semi-enclosed inland system (a mediterraneus) in central Greece. Its continental shelf areas, steep bottom relief, and waters up to 500-900m deep offer suitable habitat to neritic and pelagic species. We used photographic capture-recapture, distribution modelling, and direct observations to investigate the abundance, status, habitat preferences, movements, and group size of four odontocete species regularly observed in the Gulf, based on five years (2011-2015) of survey effort from small boats. Striped dolphins (Stenella coeruleoalba) are more abundant (1324 individuals, 95%CI 1158-1515) than was determined from previous estimates. Striped dolphins appear to be confined to the Gulf, where they favour deep and oligotrophic waters, and were encountered in single-species and mixed-species groups. Short-beaked common dolphins (Delphinus delphis) (22 individuals, 95%CI 16-31), individuals with intermediate pigmentation (possibly striped/common dolphin hybrids) (55, 95%CI 36-83), and a single Risso's dolphin (Grampus griseus) were only encountered in mixed-species groups with striped dolphins. Short-beaked common dolphins constitute a discrete conservation unit (subpopulation), and based on the current estimate, would qualify as Critically Endangered according to International Union for the Conservation of Nature (IUCN) Red List criteria. Common bottlenose dolphins (Tursiops truncatus) (39 animals, 95%CI 33-47) occur in single-species groups; they prefer continental shelf waters and areas near fish farms in the northern sector, and several animals appear to move into and out of the Gulf. Additionally, we contribute records of marine fauna and an assessment of the fishing fleet operating in the Gulf. Our study shows that the importance of this vulnerable marine environment has been underestimated, and management action must be taken to mitigate human impact and ensure long-term protection.

[Second stage of labor: Does accelerations matter?]. / Segundo estadio del parto: importan las aceleraciones?

BACKGROUND: Accelerations role during the second stage of labor has not been studied and current classification system NICHD downplays its presence. The objective of this study is to determine validity for acidemia detection of the loss of accelerations during the second stage of labor. MATERIAL AND METHOD: This is a one year retrospective case-control study of 102 neonates with acidemia defined as an umbilical cord gas pH≤7.10 compared to 100 non acidemic controls. The last thirty minutes of CTG were evaluated by two obstetricians blind to clinical and outcome data that classified tracings into categories according to NICHD definitions, determining the presence or absence of accelerations. Validity of NICHD categories and absence of accelerations were calculated. RESULTS: 85% of fetuses presented a category II tracing in the last 30 minutes of labor. Absence of accelerations was associated with neonatal acidemia (ORa 4.43). Category II tracings were not associated with acidemia after adjusting for confounding factors.Validity of the absence of accelerations during the second stage of labor was higher in terms of sensitivity (80.3%), specificity (54%) and global value (67%) to that of the presence of a category II tracing (96%, 24% and 60% respectively) in this period. CONCLUSIONS: The absence of accelerations during the second stage of labor shows a bigger validity for neonatal acidemia than the presence of a category II tracing.

Disruptive viability selection on adult exploratory behaviour in eastern chipmunks.

Heterogeneous forces of selection associated with fluctuating environments are recognized as important factors involved in the maintenance of inter-individual phenotypic variance within populations. Consistent behavioural differences over time and across situations (e.g. personality) are increasingly cited as examples of individual variation observed within populations. However, the suggestion that heterogeneous selective pressures target different animal personalities remains largely untested in the wild. In this 5-year study, we investigated the dynamics of viability selection on a personality trait, exploration, in a population of eastern chipmunks (Tamias striatus) experiencing substantial seasonal variations in weather conditions and food availability associated with masting trees. Contrary to our expectations, we found no evidence of fluctuating selection on exploration. Instead, we found strong disruptive viability selection on adult exploration behaviour, independent of seasonal variations. Individuals with either low or high exploration scores were almost twice as likely to survive over a 6-month period compared with individuals with intermediate scores. We found no evidence of viability selection on juvenile exploration. Our results highlight that disruptive selection might play an important role in the maintenance of phenotypic variance of wild populations through its effect on different personality types across temporally varying environmental conditions.

Digging through model complexity: using hierarchical models to uncover evolutionary processes in the wild.

The growing interest for studying questions in the wild requires acknowledging that eco-evolutionary processes are complex, hierarchically structured and often partially observed or with measurement error. These issues have long been ignored in evolutionary biology, which might have led to flawed inference when addressing evolutionary questions. Hierarchical modelling (HM) has been proposed as a generic statistical framework to deal with complexity in ecological data and account for uncertainty. However, to date, HM has seldom been used to investigate evolutionary mechanisms possibly underlying observed patterns. Here, we contend the HM approach offers a relevant approach for the study of eco-evolutionary processes in the wild by confronting formal theories to empirical data through proper statistical inference. Studying eco-evolutionary processes requires considering the complete and often complex life histories of organisms. We show how this can be achieved by combining sequentially all life-history components and all available sources of information through HM. We demonstrate how eco-evolutionary processes may be poorly inferred or even missed without using the full potential of HM. As a case study, we use the Atlantic salmon and data on wild marked juveniles. We assess a reaction norm for migration and two potential trade-offs for survival. Overall, HM has a great potential to address evolutionary questions and investigate important processes that could not previously be assessed in laboratory or short time-scale studies.

Simple estimation and test procedures in capture-mark-recapture mixed models.

The need to consider in capture-recapture models random effects besides fixed effects such as those of environmental covariates has been widely recognized over the last years. However, formal approaches require involved likelihood integrations, and conceptual and technical difficulties have slowed down the spread of capture-recapture mixed models among biologists. In this article, we evaluate simple procedures to test for the effect of an environmental covariate on parameters such as time-varying survival probabilities in presence of a random effect corresponding to unexplained environmental variation. We show that the usual likelihood ratio test between fixed models is strongly biased, and tends to detect too often a covariate effect. Permutation and analysis of deviance tests are shown to behave properly and are recommended. Permutation tests are implemented in the latest version of program E-SURGE. Our approach also applies to generalized linear mixed models.

Heritability of short-scale natal dispersal in a large-scale foraging bird, the wandering albatross.

Natal dispersal is a key life history trait for the evolution and adaptation of wild populations. Although its evolution has repeatedly been related to the social and environmental context faced by individuals, parent-offspring regressions have also highlighted a possible heritable component. In this study, we explore heritability of natal dispersal, at the scale of the sub-Antarctic Possession Island, for a large-scale foraging seabird, the Wandering albatross Diomedea exulans, exploiting a pedigree spanning over four decades and a maximum of four generations. The comparison of three different methods shows that heritability on the liability scale can vary drastically depending on the type of model (heritability from 6% to 86%), with a notable underestimation by restricted maximum likelihood animal models (6%) compared to Bayesian animal models (36%). In all cases, however, our results point to significant additive genetic variance in the individual propensity to disperse, after controlling for substantial effects of sex and natal colony. These results reveal promising evolutionary potential for short-scale natal dispersal, which could play a critical role for the long-term persistence of this species on the long run.

Individual heterogeneity in studies on marked animals using numerical integration: capture-recapture mixed models.

In conservation and evolutionary ecology, quantifying and accounting for individual heterogeneity in vital rates of open populations is of particular interest. Individual random effects have been used in capture-recapture models, adopting a Bayesian framework with Markov chain Monte Carlo (MCMC) to carry out estimation and inference. As an alternative, we show how numerical integration via the Gauss-Hermite quadrature (GHQ) can be efficiently used to approximate the capture-recapture model likelihood with individual random effects. We compare the performance of the two approaches (MCMC vs. GHQ) and finite mixture models using two examples, including data on European Dippers and Sociable Weavers. Besides relying on standard statistical tools, GHQ was found to be faster than MCMC simulations. Our approach is implemented in program E-SURGE. Overall, capture recapture mixed models (CR2Ms), implemented either via a GHQ approximation or MCMC simulations, have potential important applications in population biology.

Combining capture-recapture data and pedigree information to assess heritability of demographic parameters in the wild.

Quantitative genetic analyses have been increasingly used to estimate the genetic basis of life-history traits in natural populations. Imperfect detection of individuals is inherent to studies that monitor populations in the wild, yet it is seldom accounted for by quantitative genetic studies, perhaps leading to flawed inference. To facilitate the inclusion of imperfect detection of individuals in such studies, we develop a method to estimate additive genetic variance and assess heritability for binary traits such as survival, using capture-recapture (CR) data. Our approach combines mixed-effects CR models with a threshold model to incorporate discrete data in a standard 'animal model' approach. We employ Markov chain Monte Carlo sampling in a Bayesian framework to estimate model parameters. We illustrate our approach using data from a wild population of blue tits (Cyanistes caeruleus) and present the first estimate of heritability of adult survival in the wild. In agreement with the prediction that selection should deplete additive genetic variance in fitness, we found that survival had low heritability. Because the detection process is incorporated, capture-recapture animal models (CRAM) provide unbiased quantitative genetics analyses of longitudinal data collected in the wild.

Decrease in social cohesion in a colonial seabird under a perturbation regime.

Social interactions, through influence on behavioural processes, can play an important role in populations' resilience (i.e. ability to cope with perturbations). However little is known about the effects of perturbations on the strength of social cohesion in wild populations. Long-term associations between individuals may reflect the existence of social cohesion for seizing the evolutionary advantages of social living. We explore the existence of social cohesion and its dynamics under perturbations by analysing long-term social associations, in a colonial seabird, the Audouin's gull Larus audouinii, living in a site experiencing a shift to a perturbed regime. Our goals were namely (1) to uncover the occurrence of long-term social ties (i.e. associations) between individuals and (2) to examine whether the perturbation regime affected this form of social cohesion. We analysed a dataset of more than 3500 individuals from 25 years of monitoring by means of contingency tables and within the Social Network Analysis framework. We showed that associations between individuals are not only due to philopatry or random gregariousness but that there are social ties between individuals over the years. Furthermore, social cohesion decreased under the perturbation regime. We sustain that perturbations may lead not only to changes in individuals' behaviour and fitness but also to a change in populations' social cohesion. The consequences of decreasing social cohesion are still not well understood, but they can be critical for the population dynamics of social species.

Modeling survival at multi-population scales using mark-recapture data.

The demography of vertebrate populations is governed in part by processes operating at large spatial scales that have synchronizing effects on demographic parameters over large geographic areas, and in part, by local processes that generate fluctuations that are independent across populations. We describe a statistical model for the analysis of individual monitoring data at the multi-population scale that allows us to (1) split up temporal variation in survival into two components that account for these two types of processes and (2) evaluate the role of environmental factors in generating these two components. We derive from this model an index of synchrony among populations in the pattern of temporal variation in survival, and we evaluate the extent to which environmental factors contribute to synchronize or desynchronize survival variation among populations. When applied to individual monitoring data from four colonies of the Atlantic Puffin (Fratercula arctica), 67% of between-year variance in adult survival was accounted for by a global spatial-scale component, indicating substantial synchrony among colonies. Local sea surface temperature (SST) accounted for 40% of the global spatial-scale component but also for an equally large fraction of the local-scale component. SST thus acted at the same time as both a synchronizing and a desynchronizing agent. Between-year variation in adult survival not explained by the effect of local SST was as synchronized as total between-year variation, suggesting that other unknown environmental factors acted as synchronizing agents. Our approach, which focuses on demographic mechanisms at the multi-population scale, ideally should be combined with investigations of population size time series in order to characterize thoroughly the processes that underlie patterns of multi-population dynamics and, ultimately, range dynamics.

[Diagnosis of hemoglobinopathies in newborns in Venezuela hospitals]. / Diagnóstico de hemoglobinopatías a partir de sangre del talón de recién nacidos en diferentes centros hospitalarios de Venezuela.

OBJECTIVES: Hemoglobinopathies are the most common hereditary disorders in humans representing a public health problem in Venezuela. In this study the prevalence of hemoglobinopathies was evaluated in newborns from different areas of Venezuela, in cooperation with the neonatal screening system of the Study Unit of Inborn Errors of Metabolism (IDEA). MATERIALS AND METHODS: The heel blood samples of 101,301 newborns were analysed by high performance liquid chromatography (HPLC-CE) technique using Variant* Bio Rad System with the Sickle Cell Short program for the filter paper samples in and the Beta Tal Short program for the family studies. RESULTS: We found a high prevalence of newborns heterozygous for hemoglobin S and C (Hb S and Hb C). It was observed that 1.96% (1989) of the newborns were carriers, with Hb FAS (67.92) being the most frequent phenotype, followed by Hb FAC (23.18%), Hb FAD (7.49%), Hb FSC (0.96%),) and Hb FSD (0.20%). All the neonatal positives cases were confirmed at 3 months of age. CONCLUSIONS: The frequencies of the variants found in this study confirms that the hemoglobin disorders are a public health problem in Venezuela, emphasizing the importance of instituting a national program of screening for hemoglobinopathies throughout the country, comprising not only an early treatment, but also an educational program and genetic counseling for the family group.

Small cell sweat gland carcinoma of childhood.

Small cell sweat gland carcinoma appears to represent a very unusual histological type of sweat gland anlage tumour presenting in children. The differential diagnosis from other small blue cell tumours involving the skin is often difficult. The present report confirms the original observation describing two patients of 2 and 5 years of age harbouring cutaneous tumours. The histology of these lesions showed a monomorphic proliferation of small cells with a high mitotic rate and areas of necrosis. Immunohistochemically, the cells were negative for desmin, cytokeratin 7, cytokeratin 20, Cam 5.2, CD99, chromogranin, CD56, synaptophysin, and S-100, and focally positive for the pancytokeratin marker AE1/AE3, carcinoembryonic antigen (one case), and neurone specific enolase (one case). The prognosis of this type of tumour seems to be good. As more cases are added, the clinical pathological spectrum of the lesion will become better defined.

Assessing the impact of climate variation on survival in vertebrate populations.

The impact of the ongoing rapid climate change on natural systems is a major issue for human societies. An important challenge for ecologists is to identify the climatic factors that drive temporal variation in demographic parameters, and, ultimately, the dynamics of natural populations. The analysis of long-term monitoring data at the individual scale is often the only available approach to estimate reliably demographic parameters of vertebrate populations. We review statistical procedures used in these analyses to study links between climatic factors and survival variation in vertebrate populations. We evaluated the efficiency of various statistical procedures from an analysis of survival in a population of white stork, Ciconia ciconia, a simulation study and a critical review of 78 papers published in the ecological literature. We identified six potential methodological problems: (i) the use of statistical models that are not well-suited to the analysis of long-term monitoring data collected at the individual scale; (ii) low ratios of number of statistical units to number of candidate climatic covariates; (iii) collinearity among candidate climatic covariates; (iv) the use of statistics, to assess statistical support for climatic covariates effects, that deal poorly with unexplained variation in survival; (v) spurious detection of effects due to the co-occurrence of trends in survival and the climatic covariate time series; and (vi) assessment of the magnitude of climatic effects on survival using measures that cannot be compared across case studies. The critical review of the ecological literature revealed that five of these six methodological problems were often poorly tackled. As a consequence we concluded that many of these studies generated hypotheses but only few provided solid evidence for impacts of climatic factors on survival or reliable measures of the magnitude of such impacts. We provide practical advice to solve efficiently most of the methodological problems identified. The only frequent issue that still lacks a straightforward solution was the low ratio of the number of statistical units to the number of candidate climatic covariates. In the perspective of increasing this ratio and therefore of producing more robust analyses of the links between climate and demography, we suggest leads to improve the procedures for designing field protocols and selecting a set of candidate climatic covariates. Finally, we present recent statistical methods with potential interest for assessing the impact of climatic factors on demographic parameters.

Profile, mean residence time of ACTH and cortisol responses after low and standard ACTH tests in healthy volunteers.

OBJECTIVE: No consensus exists until now about the suitable dose of tetracosactin in the ACTH stimulation test for detecting adrenal insufficiency. Our aim was to characterize both the ACTH(1-24) and the cortisol profiles after standard high-dose test (250 microg) (HDT) and low-dose test (1 microg) (LDT) in healthy subjects in order to provide a deeper knowledge about the relationship between stimulus and response. DESIGN AND PATIENTS: ACTH tests were performed in 10 healthy volunteers (five men, five women) with at least 1 week of difference. MEASUREMENTS: Plasma ACTH(1-24) and ACTH(1-39) and serum cortisol were measured before tetracosactin i.v. injection and at 5, 15, 30, 45, 60, 75 and 90 min after stimulus. Area under the curve (AUC) of ACTH(1-24) and cortisol, as well as mean residence time (MRT) for ACTH(1-24) were calculated in both tests. RESULTS: Elimination of ACTH(1-24) was faster in HDT than in LDT (MRTs of 0.14 vs 0.37, respectively, P = 0.008), but plasma concentrations were higher up to 60 min cortisol production in HDT reaching a higher maximum concentration (Cmax: 1144 vs 960 nmol/l) but delayed in time (75 vs 52.5 min). No significant relationship was observed between AUC or Cmax of ACTH(1-24) and AUC, Cmax and increment of cortisol in any of the tests. However, a negative correlation of basal cortisol values was observed with relative cortisol increment (HDT: r = 0.77 P = 0.009; LDT: r = 0.94 P < 0.0001), but not so with Cmax (HDT: r = 0.22 P = 0.55; LDT: r = 0.57 P = 0.09). CONCLUSIONS: The elimination rate of ACTH in healthy volunteers was significantly lower in LDT than in HDT, but cortisol production rate appears to be identical in both tests, so that a maximum adrenal stimulation seems to exist. The use of LDT may be more adequate, although data from patients need studying.

Semiparametric regression in capture-recapture modeling.

Capture-recapture models were developed to estimate survival using data arising from marking and monitoring wild animals over time. Variation in survival may be explained by incorporating relevant covariates. We propose nonparametric and semiparametric regression methods for estimating survival in capture-recapture models. A fully Bayesian approach using Markov chain Monte Carlo simulations was employed to estimate the model parameters. The work is illustrated by a study of Snow petrels, in which survival probabilities are expressed as nonlinear functions of a climate covariate, using data from a 40-year study on marked individuals, nesting at Petrels Island, Terre Adélie.

Establishment of reference values for standard dose short synacthen test (250 microgram), low dose short synacthen test (1 microgram) and insulin tolerance test for assessment of the hypothalamo-pituitary-adrenal axis in normal subjects.

OBJECTIVE: To assess the integrity of the hypothalamo-pituitary-adrenal(HPA) axis, many authors have proposed the short synacthen test (ACTH1-24, Tetracosactrin) as a replacement for the insulin tolerance test (ITT). The aim of this study was to compare the plasma cortisol response obtained with both short synacthen tests (high dose (HDT, 250 microgram) and low dose (LDT, 1 microgram)) with the peak reached during the ITT in healthy volunteers, and to establish the plasma cortisol cut-off level in each test. SUBJECTS AND METHODS: Thirty healthy subjects (16 F, 14 M), mean age 34 years, underwent both short synacthen tests. Twenty healthy subjects, 15 of whom (11 F, nine M) belonged to the above group, mean age 30 years, underwent an ITT. Plasma cortisol was measured using a chemiluminiscence immunoassay. RESULTS: There were no differences between plasma cortisol 30 minutes after both short synacthen tests (HDT: 684 +/- 123, LDT: 669 +/- 119 nmol/l) and the peaks reached with the LDT (691 +/- 123 nmol/l) and the ITT (673 +/- 99 nmol/l). The only difference (P < 0.001) was found in the comparison of plasma cortisol peak reached with the HDT (802 +/- 142 nmol/l) with the other tests. Plasma cortisol levels obtained in the 5th percentile in each test were: at + 30 minutes: (HDT: 537, LDT: 489 nmol/l), peak: (HDT 649, LDT 498, ITT: 539 nmol/l). CONCLUSIONS: Comparison of the plasma cortisol response at + 30 minutes with both short ACTH tests and the peak in the insulin tolerance test did not reveal differences. Each test, for each time point and for each biochemical method, requires its own minimum threshold of normality to assess the hypothalamo-pituitary-adrenal axis.