121 research outputs found
ENVIRONMENTAL VARIATION AND SEXUAL SELECTION IN THE MOUNTAIN BLUEBIRD (SIALIA CURRUCOIDES)
Sexual selection acts on traits that increase mating success, either through mating preferences or intrasexual competition for access to mates. For traits to be honest, we expect sexually selected traits to reflect individual condition at the time of trait development. Furthermore, when sexual selection operates through mating preferences, we also expect traits to indicate benefits (direct or indirect) that females receive for exercising their preference. If sexual selection acts through differential success in intrasexual contests over mates, we expect traits to indicate resource holding potential, or fighting ability. These links between individual condition, trait quality, and performance maintain honesty, because high condition individuals have high quality traits, and conspecifics can therefore use information from sexually selected traits when entering contests or choosing between prospective mates.
Based on the above logic, we expect sexually selected traits to be consistently and positively related to performance. However, individuals may differ in their sensitivity to environmental variation such that sexually selected traits are not always honest indicators of individual condition, benefits to females or offspring, or competitive ability. Environmental variation could affect trait honesty if individuals vary in their ability to respond to environmental variation. For example, trait honesty may disappear in poor environments, if individuals with highly developed sexually selected traits only perform well in high quality environments. Alternatively, individuals with more elaborate traits may be more adept at responding to environmental challenge, and trait honesty could increase when environmental conditions are poor.
For my dissertation I examined variation in trait development and honesty under varying conditions in the mountain bluebird, Sialia currucoides. Mountain bluebirds display sexually dimorphic UV-blue coloration, and males with more intense coloration sire more offspring at their own nest and at other nests through extra-pair fertilizations. However, it is unclear what benefits and costs receivers experience when using this trait to asses mates or rivals, and what processes regulate the development of this sexually selected trait. Therefore, in chapter one I explored the function of this signal during agonistic contests for territories. I performed simulated territorial intrusions to understand whether male aggressive behavior was related to his coloration. I also measured food availability to determine if males with more intense coloration obtained higher quality territories. Overall, my results provide evidence for the function of this signal during agonistic contests. Furthermore, while a single aggressive behavior (number of attacks) was repeatable across the egg laying period, my integrated metric of aggression, which accounted for many aggressive behaviors and was related to male coloration, was not. Lastly, I found that males with more saturated coloration obtained territories with greater insect abundance.
In chapter two, I performed an experiment to understand the mechanisms of condition dependence of blue coloration. Individuals may vary in their sensitivity to environmental variation during trait development; such high condition individuals preserve trait quality during environmental challenge while poor condition individuals do not. Martin et al. (2011) suggest that endocrine systems are an important mediator of phenotypic variation because hormones both respond to environmental conditions and regulate internal response and resulting phenotype. The hormone corticosterone (CORT) is released by the adrenal glands in response to challenge to divert resources towards self-preservation. A rapid, transient increase in CORT can help individuals to survive challenging situations. However, prolonged or frequent CORT secretion can cause damage to other physiological systems and potentially decrease fitness. For example, CORT-implanted white crowned sparrows abandon their high-elevation breeding territories and retreat to low elevations during storms. This increases survival but decreases reproductive success. Also, CORT-implanted male song sparrows increase fat stores, but are less likely to respond aggressively to a simulated territorial intrusion. These links between environmental conditions and potential fitness consequences make CORT an ideal regulator of sexually selected traits.
To this end, I brought 14 hatch year mountain bluebirds into captivity to study how individual variation in CORT physiology during resource limitation predicted coloration. I wanted to understand whether CORT predicted blue coloration when resources were abundant, limiting, or both. I found that when birds were food limited, variation in CORT levels increased. Furthermore, CORT and coloration were negatively associated in my food limitation treatment, as predicted if poor condition males mount larger stress responses, but this association disappeared when birds were given ad lib food. I also measured feather structure variables to determine how coloration was related to feather quality and feather performance (measured as resistance to airflow) across my resource availability treatments. I found that the component of feather structure that was related to coloration (barbule density) was sensitive to CORT only when resources were limiting. Conversely, the feather structure variable that determined feather performance (interbarb distance) was not sensitive to CORT in either treatment and did not predict feather coloration. These results indicate that feather coloration in bluebirds is only sensitive to variation in physiology when resources were limiting, and that this was mirrored by concurrent changes in condition-sensitive feather structure. However, feather performance was not sensitive to individual variation in physiology or variation in environmental conditions.
While chapters one and two demonstrated that blue coloration is condition dependent and related to aggressive behavior, male bluebirds still provide a significant amount of parental care. This means that females may be using coloration to select mates and obtain benefits for themselves and their offspring. In chapter three, I examined the effect of environmental variation on the relationship between bluebird coloration and direct benefits to females, expressed as offspring quality (nestling mass). Three years of data on free-living bluebirds suggests that the relationship between male coloration and nestling mass varied across years and between broods. In some contexts, more elaborate males had heavier nestlings, while in other contexts they raised the lightest nestlings. I found that this variation was not driven by resource abundance, but instead appeared due to changes in optimal reproductive effort. When average nestling mass at my study site was higher, bluer males raised heavier nestlings than they did when average nestling mass was lower. This variation in nestling mass occurred independently of resource availability.
Overall, these results demonstrate that the honesty of blue coloration varies across environmental contexts. While coloration is positively related to aggressive behavior, males vary in their sensitivity to resource limitation, and blue coloration does not consistently predict direct benefits in the wild. My data indicate that the process of sexual selection is context-dependent, and sexually selected traits vary in the extent to which they predict individual performance and quality
Buffering against maladaptive perfectionism in bipolar disorder:The role of self-compassion
Background Maladaptive perfectionism is a transdiagnostic risk and maintaining factor for a range of mental health conditions, including bipolar disorder (BD). Self-compassion represents a potential protective factor against maladaptive perfectionism, however no studies to date have examined the relationship of these constructs in BD. The aim of the present study was to examine associations between maladaptive perfectionism, self-compassion and symptoms among individuals with BD. Methods Baseline data were collected from 302 participants with a DSM-IV diagnosis of BD participating in an international randomised controlled trial. Participants completed measures of maladaptive perfectionism, self-compassion, symptom severity and emotion regulation difficulties. Clinician-administered measures of depression and mania severity were additionally collected. Correlation and mediation analyses were conducted. Results Maladaptive perfectionism was positively associated with depression, anxiety and emotion regulation difficulties. Lower levels of self-compassion correlated with greater self-reported depression, anxiety and emotion regulation difficulties. Self-compassion partially mediated relationships between maladaptive perfectionism, depression, anxiety and emotion regulation difficulties. Limitations The cross-sectional design limits conclusions about causal relationships between study variables. Results may not be generalizable to other BD populations. The role of maladaptive perfectionism and self-compassion in elevated mood states of BD remains unclear. Conclusion Self-compassion represents one mechanism through which maladaptive perfectionism influences symptoms of depression, anxiety and emotion regulation difficulties in BD. Self-compassion represents a modifiable treatment target; individuals with BD exhibiting maladaptive perfectionistic tendencies may benefit from interventions fostering self-compassion
Bonderstraat te Lafelt (gem. Riemst. Archeologische opgraving.
Dit rapport werd ingediend bij het agentschap samen met een aantal afzonderlijke digitale bijlagen. Een aantal van deze bijlagen zijn niet inbegrepen in dit pdf document en zijn niet online beschikbaar. Sommige bijlagen (grondplannen, fotos, spoorbeschrijvingen, enz.) kunnen van belang zijn voor een betere lezing en interpretatie van dit rapport. Indien u deze bijlagen wenst te raadplegen kan u daarvoor contact opnemen met: [email protected]
Towards a better future for Canadians with bipolar disorder:principles and implementation of a community-based participatory research model
The Collaborative RESearch Team to study psychosocial factors in bipolar disorder (CREST.BD) is a multidisciplinary network dedicated to advancing science and practice around psychosocial issues associated with bipolar disorder (BD), improving the care and wellness of people living with bipolar disorder, and strengthening services and supports for these individuals. CREST.BD specializes in community-based participatory research, in which research is conducted as a partnership between researchers and community members. This article describes the evolution of the CREST.BD network and CREST.BD’s commitment to community-based participatory research in bipolar disorder research. Examples of CREST.BD projects using community-based participatory research to study stigma, quality of life, psychosocial interventions, and creativity in bipolar disorder are highlighted, and opportunities and challenges of engaging in community-based participatory research in bipolar disorder specifically and the mental health field more broadly are discussed. This article demonstrates how CBPR can be used to enhance the relevance of research practices and products through community engagement, and how community-based participatory research can enrich knowledge exchange and mobilization
Metallicities and dust content of proximate damped Lyman alpha systems in the Sloan Digital Sky Survey
Composite spectra of 85 proximate absorbers (log N(HI)>20 and velocity
difference between the absorption and emission redshift, dv<10,000 km/s) in the
SDSS are used to investigate the trends of metal line strengths with velocity
separation from the QSO. We construct composites in 3 velocity bins: dv<3000
km/s, 30006000 km/s, with further sub-samples to
investigate the metal line dependence on N(HI) and QSO luminosity. Low (e.g.
SiII and FeII) and high ionization (e.g. SiIV and CIV) species alike have
equivalent widths (EWs) that are larger by factors of 1.5 -- 3 in the dv<3000
km/s composite, compared to the dv>6000 km/s spectrum. The EWs show an even
stronger dependence on dv if only the highest neutral hydrogen column density
(log N(HI)>20.7) absorbers are considered. We conclude that PDLAs generally
have higher metallicities than intervening absorbers, with the enhancement
being a function of both dv and N(HI). It is also found that absorbers near
QSOs with lower rest-frame UV luminosities have significantly stronger metal
lines. We speculate that absorbers near to high luminosity QSOs may have had
their star formation prematurely quenched. Finally, we search for the signature
of dust reddening by the PDLAs, based on an analysis of the QSO continuum
slopes relative to a control sample and determine a limit of E(B-V)<0.014 for
an SMC extinction curve. This work provides an empirical motivation for
distinguishing between proximate and intervening DLAs, and establishes a
connection between the QSO environment and galaxy properties at high redshifts.Comment: Accepted for publication in MNRA
The nature of proximate damped Lyman alpha systems
We present high resolution echelle spectra of 7 proximate damped Lyman alpha
(PDLA) systems whose relative velocity separation from the background quasar is
Delta V < 3000 km/s. Combining our sample with a further 9 PDLAs from the
literature we compare the chemical properties of the proximate systems with a
control sample of intervening DLAs. Taken at face value, the sample of 16 PDLAs
exhibits a wide range of metallicities, ranging from Z ~ 1/3 Z_sun down to Z ~
1/1000 Z_sun, including the DLA with the lowest N(SiII)/N(HI) yet reported in
the literature. We find several pieces of evidence that indicate enhanced
ionization and the presence of a hard ionizing spectrum in PDLAs which lead to
properties that contrast with the intervening DLAs, particularly when the N(HI)
is low. The abundances of Zn, Si and S in PDLAs with log N(HI) > 21, where
ionization corrections are minimized, are systematically higher than the
intervening population by a factor of around 3. We also find possible evidence
for a higher fraction of NV absorbers amongst the PDLAs, although the
statistics are still modest. 6/7 of our echelle sample show high ionization
species (SiIV, CIV, OVI or NV) offset by >100 km/s from the main low ion
absorption. We analyse fine-structure transitions of CII* and SiII* to
constrain the PDLA distance from the QSO. Lower limits range from tens of kpc
up to >160 kpc for the most stringent limit. We conclude that (at least some)
PDLAs do exhibit different characteristics relative to the intervening
population out to 3000 km/s (and possibly beyond). Nonetheless, the PDLAs
appear distinct from lower column density associated systems and the inferred
QSO-absorber separations mean they are unlikely to be associated with the QSO
host. We speculate that the PDLAs preferentially sample more massive galaxies
in more highly clustered regions of the high redshift universe.Comment: Accepted for publication in MNRAS. Abstract abridged
Submillimeter Follow-up of WISE-Selected Hyperluminous Galaxies
We have used the Caltech Submillimeter Observatory (CSO) to follow-up a
sample of WISE-selected, hyperluminous galaxies, so called W1W2-dropout
galaxies. This is a rare (~ 1000 all-sky) population of galaxies at high
redshift (peaks at z=2-3), that are faint or undetected by WISE at 3.4 and 4.6
um, yet are clearly detected at 12 and 22 um. The optical spectra of most of
these galaxies show significant AGN activity. We observed 14 high-redshift (z >
1.7) W1W2-dropout galaxies with SHARC-II at 350 to 850 um, with 9 detections;
and observed 18 with Bolocam at 1.1 mm, with five detections. Warm Spitzer
follow-up of 25 targets at 3.6 and 4.5 um, as well as optical spectra of 12
targets are also presented in the paper. Combining WISE data with observations
from warm Spitzer and CSO, we constructed their mid-IR to millimeter spectral
energy distributions (SEDs). These SEDs have a consistent shape, showing
significantly higher mid-IR to submm ratios than other galaxy templates,
suggesting a hotter dust temperature. We estimate their dust temperatures to be
60-120 K using a single-temperature model. Their infrared luminosities are well
over 10^{13} Lsun. These SEDs are not well fitted with existing galaxy
templates, suggesting they are a new population with very high luminosity and
hot dust. They are likely among the most luminous galaxies in the Universe. We
argue that they are extreme cases of luminous, hot dust-obscured galaxies
(DOGs), possibly representing a short evolutionary phase during galaxy merging
and evolution. A better understanding of their long-wavelength properties needs
ALMA as well as Herschel data.Comment: Will be Published on Sep 1, 2012 by Ap
Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis
BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
A Call for Data-Driven Networks to Address Equity in the Context of Undergraduate Biology
National efforts to improve equitable teaching practices in biology education have led to an increase in research on the barriers to student participation and performance, as well as solutions for overcoming these barriers. Fewer studies have examined the extent to which the resulting data trends and effective strategies are generalizable across multiple contexts or are specific to individual classrooms, institutions, or geographic regions. To address gaps in our understanding, as well as to establish baseline information about students across contexts, a working group associated with a research coordination network (Equity and Diversity in Undergraduate STEM, EDU-STEM) convened in Las Vegas, Nevada, in No-vember of 2019. We addressed the following objectives: 1) characterize the present state of equity and diversity in undergraduate biology education research; 2) address the value of a network of educators focused on science, technology, engineering, and mathematics equity; 3) summarize the status of data collection and results; 4) identify and prioritize questions and interventions for future collaboration; and 5) construct a recruitment plan that will further the efforts of the EDU-STEM research coordination network. The report that follows is a summary of the conclusions and future directions from our discussion
- …