2,180 research outputs found
Ecology, Evolution, and Sexual Selection in the Invasive, Globally Distributed Small Indian Mongoose (\u3ci\u3eUrva auropunctata\u3c/i\u3e)
Introduced species provide rare opportunities to test evolutionary hypotheses in situ by creating so-called natural experiments. Natural experiments are situations in nature that resemble laboratory studies by allowing for comparisons of a âcontrolâ group (i.e., a speciesâ native range) with âexperimentalâ groups (i.e., a speciesâ introduced range). In particular, introduced animals allow us to investigate evolutionary dynamics in complex, long-lived organisms in ways that would otherwise be impossible in a laboratory setting. One such introduced animal is the small Indian mongoose (Urva auropunctata, formerly Herpestes auropunctatus). Native to South Asia, the small Indian mongooseâs introduction to more than 70 mostly tropical island locations worldwide represents an excellent natural experiment: the dates of introduction and numbers introduced are well documented, most locations of introduction are reproductively isolated from each other and thus provide numerous experimental replicates, and most introduced populations have been reproducing for at least 200 generations. In its introduced range, the small Indian mongoose is released from interspecific competition and predation, and as a result, it has become densely populated and highly invasive. In fact, the IUCN named it one of the 100 worst invasive species on the planet. Consequently, the vast majority of the literature on this species is devoted to understanding its ecological impacts on local biodiversity. In contrast, however, relatively little is known of its ecology and natural history in its native range where, in some regions, it is protected. Lacking entirely, for instance, are data pertaining to the operation of sexual selection and its mate choice behavior. Finally, while four studies have investigated evolutionary changes that small Indian mongooses have undergone since introduction, only one has investigated adaptive changes, and this study mistakenly included individuals of a separate species in its analysis, leaving its results and conclusions uninterpretable. In this dissertation, I present an exhaustive review of the available literature on the small Indian mongoose (Chapter 1), report on the first quantitative natural history data ever collected in its native range (Chapter 2), identify, for the first time in this species, features under sexual selection (Chapter 3), and, taking advantage of its natural experiment, demonstrate the rapid adaptive evolution of two of its sexually selected traits (Chapter 4).
In Chapter 1, I review literature on all ecologically relevant information of the small Indian mongoose including, their taxonomy; native and introduced ranges, and history of introduction; basic biology; impacts as an invasive species, including their status as a failed biological control, the local species they have impacted, the various management efforts around the globe, and their role in disease transmission; and finally, their use as an evolutionary model system.
In Chapter 2, I collect basic morphological measurements of small Indian mongooses from several populations in their native range in northern India. I also radio-collared and tracked 17 individuals for several months, and estimate that home ranges sizes in the native range are comparable to, though generally smaller than, estimates in the introduced range. I also find that small Indian mongooses prefer areas of human habitation and avoid forested and open areas.
In Chapter 3, I report on an investigation of the small Indian mongoose on the island of Hawaii. I conclude that the anal pad, their scent-marking tool, is a sexually selected trait in males, as indicated by its high male-biased sexual size dimorphism, and its condition-dependence and positive relationship with body size in males, but not females. From these results, I infer that males likely use scent as a sexual signal.
Finally, in Chapter 4, in an effort to understand how sexually selected traits change after becoming established, I collect similar morphological data to those collected in Chapter 2 and Chapter 3 from three additional areas of introduction, Jamaica, St. Croix, and Mauritius. I then compare these data together with those collected from the island of Hawaii, to data from the native range in India. I find that male, but not female, anal pads decreased in size according to time since introduction, and its relation to body size and condition weakened. In addition, I find that testis size increased after introduction. My results suggest an inversion in the relative contributions to fitness of two sexually selected traits in males, demonstrated by the rapid evolution of these features after introduction. Thus, I conclude that, relative to the native range, the increased encounter rates on islands of introduction (due to the markedly denser populations) have relaxed sexual selection on scent marking in males, but intensified sperm competition. My findings demonstrate that the fitness of sexually selected traits, like any other traits under natural selection, is determined by environment in which the traits are expressed
The Small Indian Mongoose (Herpestes auropunctatus): A Locally Protected Yet Internationally Persecuted Invasive Species
Modulation of impulsive behaviours using transcranial random noise stimulation
Non peer reviewe
Optimal statistic for detecting gravitational wave signals from binary inspirals with LISA
A binary compact object early in its inspiral phase will be picked up by its
nearly monochromatic gravitational radiation by LISA. But even this innocuous
appearing candidate poses interesting detection challenges. The data that will
be scanned for such sources will be a set of three functions of LISA's twelve
data streams obtained through time-delay interferometry, which is necessary to
cancel the noise contributions from laser-frequency fluctuations and
optical-bench motions to these data streams. We call these three functions
pseudo-detectors. The sensitivity of any pseudo-detector to a given sky
position is a function of LISA's orbital position. Moreover, at a given point
in LISA's orbit, each pseudo-detector has a different sensitivity to the same
sky position. In this work, we obtain the optimal statistic for detecting
gravitational wave signals, such as from compact binaries early in their
inspiral stage, in LISA data. We also present how the sensitivity of LISA,
defined by this optimal statistic, varies as a function of sky position and
LISA's orbital location. Finally, we show how a real-time search for inspiral
signals can be implemented on the LISA data by constructing a bank of templates
in the sky positions.Comment: 22 pages, 15 eps figures, Latex, uses iopart style/class files. Based
on talk given at the 8th Gravitational Wave Data Analysis Workshop,
Milwaukee, USA, December 17-20, 2003. Accepted for publication in Class.
Quant. Gra
The impact of lifestyle factors on the intensity of adverse effects in single and repeated session protocols of transcranial electrical stimulation : an exploratory pilot study
Transcranial electrical stimulation (tES) has shown promise in the treatment of conditions such as depression and chronic pain
with mild-to-moderate adverse effects (AEs). Few previous studies have attempted to identify factors predicting tES-induced
AEs. In particular, AEs resulting from repeated sessions of tES remain understudied. We conducted an exploratory retrospective
analysis of two independent randomized controlled studies to investigate whether lifestyle factors (i.e. chronic alcohol use,
smoking, exercise, and quality and length of sleep) modify the severity and frequency of tES-induced AEs, and evaluated the
progression of AEs over repeated sessions.
We utilized two double-blinded samples: 1) a male sample (n=82) randomized to receive transcranial direct current
stimulation (tDCS) or sham for 5 days, and 2) a mixed-sex sample (n=60) who received both transcranial random noise
stimulation (tRNS) and sham in a crossover setting. The severity of AEs was recorded on a scale of 0-100. The data was
analysed using negative binomial models. In addition, we performed power calculations and, to guide future research,
evaluated the numbers of individuals needed to detect non-significant observations as significant.
By day 5, the tDCS group experienced more sensations under the electrodes than the sham group. Alcohol use, smoking,
exercise, or quality or duration of sleep did not appear to be associated with the intensity of the AEs. The subsequent power
analyses indicated that substantially larger samples would be needed to detect the observed associations as significant.
Repetitive sessions do not appear to introduce additional AE burden to individuals receiving either tDCS or tRNS, at
least with protocols lasting up to 5 days. Alcohol use, smoking, exercise, or quality or duration of sleep appear to only have
an effect of negligible size, if any, on AEs induced by tDCS or tRNS, and studies with sample sizes ranging from roughly 100
individuals to hundreds of thousands of individuals would be required to detect such effects as significant
Does the early bird really get the worm? How chronotype relates to human intelligence
Objectives: Chronotype impacts our state at a given time of day, however, chronotype is also heritable, trait-like, and varies systematically as a function of age and sex. However, only a handful of studies support a relationship between chronotype and trait-like cognitive abilities (i.e., intelligence), and the evidence is sparse and inconsistent between studies. Typically, studies have: (1) focused on limited subjective measures of chronotype, (2) focused on young adults only, and (3) have not considered sex differences. Here, using a combination of cognitive aptitude and ability testing, subjective chronotype, and objective actigraphy, we aimed to explore the relationship between trait-like cognitive abilities and chronotype. Design: Participants (N = 61; 44 females; age = 35.30 ± 18.04 years) completed the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) to determine subjective chronotype and wore an activity monitor for 10 days to objectively assess bedtime, rise-time, total sleep time, inter-daily stability, intra-daily variability, and relative amplitude. Cognitive ability (e.g., Verbal, Reasoning and Short-Term Memory) testing took place at the completion of the study. Results: Higher MEQ scores (i.e., more morning) were associated with higher inter-daily stability scores. Superior verbal abilities were associated with later bedtimes, younger age, but paradoxically, higher (i.e., more morning) MEQ scores. Superior STM abilities were associated with younger age only. The relationships between chronotype and trait-like cognitive abilities were similar for both men and women and did not differ between younger and older adults. Conclusions: The present study demonstrates that chronotype, measured by the MEQ, is highly related to inter-daily stability (i.e., the strength of circadian synchronization). Furthermore, although evening types have superior verbal abilities overall, higher (i.e., more morning) MEQ scores were related to superior verbal abilities after controlling for âevening typeâ behaviours
The hippocampi of children with chromosome 22q11.2 deletion syndrome have localized anterior alterations that predict severity of anxiety
BACKGROUND: Individuals with 22q11.2 deletion syndrome (22q11.2DS) have an elevated risk for schizophrenia, which increases with history of childhood anxiety. Altered hippocampal morphology is a common neuroanatomical feature of 22q11.2DS and idiopathic schizophrenia. Relating hippocampal structure in children with 22q11.2DS to anxiety and impaired cognitive ability could lead to hippocampus-based characterization of psychosis-proneness in this at-risk population. METHODS: We measured hippocampal volume using a semiautomated approach on MRIs collected from typically developing children and children with 22q11.2DS. We then analyzed hippocampal morphology with Localized Components Analysis. We tested the modulating roles of diagnostic group, hippocampal volume, sex and age on local hippocampal shape components. Lastly, volume and shape components were tested as covariates of IQ and anxiety. RESULTS: We included 48 typically developing children and 69 children with 22q11.2DS in our study. Hippocampal volume was reduced bilaterally in children with 22q11.2DS, and these children showed greater variation in the shape of the anterior hippocampus than typically developing children. Children with 22q11.2DS had greater inward deformation of the anterior hippocampus than typically developing children. Greater inward deformation of the anterior hippocampus was associated with greater severity of anxiety, specifically fear of physical injury, within the 22q11.2DS group. LIMITATIONS: Shape alterations are not specific to hippocampal subfields. CONCLUSION: Alterations in the structure of the anterior hippocampus likely affect function and may impact limbic circuitry. We suggest these alterations potentially contribute to anxiety symptoms in individuals with 22q11.2DS through modulatory pathways. Altered hippocampal morphology may be uniquely linked to anxiety risk factors for schizophrenia, which could be a powerful neuroanatomical marker of schizophrenia risk and hence protection
GeMInA, Genomic Metadata for Infectious Agents, a geospatial surveillance pathogen database
The Gemina system (http://gemina.igs.umaryland.edu) identifies, standardizes and integrates the outbreak metadata for the breadth of NIAID category AâC viral and bacterial pathogens, thereby providing an investigative and surveillance tool describing the Who [Host], What [Disease, Symptom], When [Date], Where [Location] and How [Pathogen, Environmental Source, Reservoir, Transmission Method] for each pathogen. The Gemina database will provide a greater understanding of the interactions of viral and bacterial pathogens with their hosts and infectious diseases through in-depth literature text-mining, integrated outbreak metadata, outbreak surveillance tools, extensive ontology development, metadata curation and representative genomic sequence identification and standards development. The Gemina web interface provides metadata selection and retrieval of a pathogen's; Infection Systems (Pathogen, Host, Disease, Transmission Method and Anatomy) and Incidents (Location and Date) along with a hosts Age and Gender. The Gemina system provides an integrated investigative and geospatial surveillance system connecting pathogens, pathogen products and disease anchored on the taxonomic ID of the pathogen and host to identify the breadth of hosts and diseases known for these pathogens, to identify the extent of outbreak locations, and to identify unique genomic regions with the DNA Signature Insignia Detection Tool
Foveal Curvature and Its Associations in UK Biobank Participants
PURPOSE. To examine whether sociodemographic, and ocular factors relate to optical coherence tomography (OCT)-derived foveal curvature (FC) in healthy individuals. METHODS. We developed a deep learning model to quantify OCT-derived FC from 63, 939 participants (age range, 39-70 years). Associations of FC with sociodemographic, and ocular factors were obtained using multilevel regression analysis (to allow for right and left eyes) adjusting for age, sex, ethnicity, height (model 1), visual acuity, spherical equivalent, corneal astigmatism, center point retinal thickness (CPRT), intraocular pressure (model 2), deprivation (Townsend index), higher education, annual income, and birth order (model 3). Fovea curvature was modeled as a z-score. RESULTS. Males had on average steeper FC (0.077; 95% confidence interval [CI] 0.077-0.078) than females (0.068; 95% CI 0.068-0.069). Compared with whites, non-white individuals showed flatter FC, particularly those of black ethnicity. In black males, -0.80 standard deviation (SD) change when compared with whites (95% CI -0.89, -0.71; P 5.2e10-68). In black females, -0.70 SD change when compared with whites (95% CI -0.77, -0.63; p 2.3e10-93). Ocular factors (visual acuity, refractive status, and CPRT) showed a graded inverse association with FC that persisted after adjustment. Macular curvature showed a positive association with FC. Income showed a linear trend increase in males (P for linear trend = 0.005). CONCLUSIONS. We demonstrate marked differences in FC with ethnicity on the largest cohort studied for this purpose to date. Ocular factors showed a graded association with FC. Implementation of FC quantification in research and on the clinical setting can enhance the understanding of clinical macular phenotypes in health and disease
Agricultural intensification heightens food safety risks posed by wild birds
Agricultural intensification and simplification are key drivers of recent declines in wild bird populations, heightening the need to better balance conservation with food production. This is hindered, however, by perceptions that birds threaten food safety. While birds are known reservoirs of foodborne pathogens, there remains uncertainty about the links between landscape context, farming practices, and actual crop contamination by birds. Here, we examine relationships between landscape context, farming practices, and pathogen contamination by birds using a barrier-to-spillover approach. First, we censused bird communities using point count surveys. Second, we collected 2,024 faecal samples from captured birds alongside 1,215 faecal samples from brassica fields and food processing areas across 50 farms spanning the USA West Coast. We then estimated the prevalence of three foodborne pathogens across landscape and livestock intensification gradients. Finally, we quantified the number of plants with faeces. Campylobacterspp. were detected in 10.2% of faeces from captured birds and 13.1% of faeces from production areas. Non-native birds were 4.1 times more likely to haveCampylobacterspp. than native birds.Salmonellaspp. were detected in 0.2% of faeces from production areas and were never detected in captured birds. We detected evidence of Shiga toxigenicE. coliin one sample across the >3,200 tested. Campylobacterspp. prevalence in faeces from production areas increased with increasing mammalian livestock densities in the landscape but decreased with increasing amounts of natural habitat. We encountered bird faeces on 3.3% of plants examined. Despite the impact on pathogen prevalence, amount of natural habitat in the landscape did not increase the number of plants with bird faeces, although on-farm mammalian livestock density slightly did. Synthesis and applications. Food safety and wildlife conservation are often thought to be in conflict. However, our findings suggest that natural habitat around farms may reduce crop contamination rates by birds. This is perhaps because natural habitat can promote native birds that are less likely to harbour foodborne pathogens or because it decreases contact with livestock waste. Our results suggest that preservation of natural habitats around farms could benefit both conservation and food safety, contrary to current standards for 'best practices'
- âŠ