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Aim: Physical activity (PA) is a key component for brain health and Reserve, and it is among the main dementia protective factors. However, the neurobiological mechanisms underpinning Reserve are not fully understood. In this regard, a noradrenergic (NA) theory of cognitive reserve (Robertson, 2013) has proposed that the upregulation of NA system might be a key factor for building reserve and resilience to neurodegeneration because of the neuroprotective role of NA across the brain. PA elicits an enhanced catecholamine response, in particular for NA. By increasing physical commitment, a greater amount of NA is synthetised in response to higher oxygen demand. More physically trained individuals show greater capabilities to carry oxygen resulting in greater Vo2max – a measure of oxygen uptake and physical fitness (PF). Methods: We hypothesized that greater Vo2max would be related to greater Locus Coeruleus (LC) MRI signal intensity. In a sample of 41 healthy subjects, we performed Voxel‐Based Morphometry analyses, then repeated for the other neuromodulators as a control procedure (Serotonin, Dopamine and Acetylcholine). Results: As hypothesized, greater Vo2max related to greater LC signal intensity, and weaker associations emerged for the other neuromodulators. Conclusion: This newly established link between Vo2max and LC–NA system offers further understanding of the neurobiology underpinning Reserve in relationship to PA. While this study supports Robertson's theory proposing the upregulation of the NA system as a possible key factor building Reserve, it also provides ground for increasing LC–NA system resilience to neurodegeneration via Vo2max enhancement. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD) lack mechanistic biophysical modeling in diverse, underrepresented populations. Electroencephalography (EEG) is a high temporal resolution, cost‐effective technique for studying dementia globally, but lacks mechanistic models and produces non‐replicable results. METHODS: We developed a generative whole‐brain model that combines EEG source‐level metaconnectivity, anatomical priors, and a perturbational approach. This model was applied to Global South participants (AD, bvFTD, and healthy controls). RESULTS: Metaconnectivity outperformed pairwise connectivity and revealed more viscous dynamics in patients, with altered metaconnectivity patterns associated with multimodal disease presentation. The biophysical model showed that connectome disintegration and hypoexcitability triggered altered metaconnectivity dynamics and identified critical regions for brain stimulation. We replicated the main results in a second subset of participants for validation with unharmonized, heterogeneous recording settings. DISCUSSION: The results provide a novel agenda for developing mechanistic model‐inspired characterization and therapies in clinical, translational, and computational neuroscience settings. [ABSTRACT FROM AUTHOR]

Background: Stress exposure in childhood and adolescence has been linked to reductions in cortical structures and cognitive functioning. However, to date, most of these studies have been cross‐sectional, limiting the ability to make long‐term inferences, given that most cortical structures continue to develop through adolescence. Methods: Here, we used a subset of the IMAGEN population cohort sample (N = 502; assessment ages: 14, 19, and 22 years; mean age: 21.945 years; SD = 0.610) to understand longitudinally the long‐term interrelations between stress, cortical development, and cognitive functioning. To these ends, we first used a latent change score model to examine four bivariate relations – assessing individual differences in change in the relations between adolescent stress exposure and volume, surface area, and cortical thickness of cortical structures, as well as cognitive outcomes. Second, we probed for indirect neurocognitive effects linking stress to cortical brain structures and cognitive functions using rich longitudinal mediation modeling. Results: Latent change score modeling showed that greater baseline adolescence stress at age 14 predicted a small reduction in the right anterior cingulate volume (Std. β = −.327, p =.042, 95% CI [−0.643, −0.012]) and right anterior cingulate surface area (Std. β = −.274, p =.038, 95% CI [−0.533, −0.015]) across ages 14–22. These effects were very modest in nature and became nonsignificant after correcting for multiple comparisons. Our longitudinal analyses found no evidence of indirect effects in the two neurocognitive pathways linking adolescent stress to brain and cognitive outcomes. Conclusion: Findings shed light on the impact of stress on brain reductions, particularly in the prefrontal cortex that have consistently been implicated in the previous cross‐sectional studies. However, the magnitude of effects observed in our study is smaller than that has been reported in past cross‐sectional work. This suggests that the potential impact of stress during adolescence on brain structures may likely be more modest than previously noted. [ABSTRACT FROM AUTHOR]

Cognitive reserve supports cognitive function in the presence of pathology or atrophy. Functional neuroimaging may enable direct and accurate measurement of cognitive reserve which could have considerable clinical potential. The present study aimed to develop and validate a measure of cognitive reserve using task‐based fMRI data that could then be applied to independent resting‐state data. Connectome‐based predictive modelling with leave‐one‐out cross‐validation was applied to predict a residual measure of cognitive reserve using task‐based functional connectivity from the Cognitive Reserve/Reference Ability Neural Network studies (n = 220, mean age = 51.91 years, SD = 17.04 years). This model generated summary measures of connectivity strength that accurately predicted a residual measure of cognitive reserve in unseen participants. The theoretical validity of these measures was established via a positive correlation with a socio‐behavioural proxy of cognitive reserve (verbal intelligence) and a positive correlation with global cognition, independent of brain structure. This fitted model was then applied to external test data: resting‐state functional connectivity data from The Irish Longitudinal Study on Ageing (TILDA, n = 294, mean age = 68.3 years, SD = 7.18 years). The network‐strength predicted measures were not positively associated with a residual measure of cognitive reserve nor with measures of verbal intelligence and global cognition. The present study demonstrated that task‐based functional connectivity data can be used to generate theoretically valid measures of cognitive reserve. Further work is needed to establish if, and how, measures of cognitive reserve derived from task‐based functional connectivity can be applied to independent resting‐state data. [ABSTRACT FROM AUTHOR]

Background: Frailty, expressed as accumulation of health deficits in older adults, could contribute to the risk of cognitive decline. We cross‐sectionally studied the brain connectivity signatures of frailty in The Irish Longitudinal Study on Ageing (TILDA). Method: We included participants from Wave 3 of TILDA who underwent resting‐state functional MRI. Connectivity maps were based on Shen's parcellation and connectome‐based predictive modeling was used to find associations between connectivity and frailty as measured by Frailty Index (FI) (Table 1). On each iteration of a 10‐fold cross‐validation the training folds were utilized to perform partial Spearman correlations (adjusted for age, sex, and mean framewise displacement) between each brain connection and FI scores. Connections with p<0.001 correlations were selected. Network strength was computed by summing the correlations across all connections selected and a linear model built using the network strength to predict FI score. After 10 folds are complete the performance was measured with linear R values between predicted and true FI scores. This process was repeated 1000 times (with random cross‐validation splits) and mean performance metrics obtained. A permutation test was employed in which the above procedure was repeated 1000 times, with FI scores shuffled each time. Significance of selected connections was calculated as the number of permutations scores that were equal to or greater than the proper mean score, divided by 1000. Result: 347 participants were included (mean age 67.7 (SD 7.3) and 51.6% men). We obtained a connectivity network that positively correlated with frailty ("frailty network") (R = 0.169, p = 0.006) and another that negatively correlated with frailty ("robustness network") (R = ‐0.193, p = 0.006); and are depicted in Figure 1. The "frailty network" was more widespread and showed higher connectivity from right occipital to both prefrontal cortices, subcortical and left temporal cortex, whereas the "robustness network" exhibited higher functional connectivity in subcortical to left parietal and bilateral temporal cortices. Conclusion: Functional brain connectivity could be influenced by frailty. Further research should study the relationship of brain connectivity and different tools for frailty and establish how different patterns of deficit accumulation affect brain health across lifespan. [ABSTRACT FROM AUTHOR]

Neural oscillations, or brain rhythms, fluctuate in a manner reflecting ongoing behavior. Whether these fluctuations are instrumental or epiphenomenal to the behavior remains elusive. Attempts to experimentally manipulate neural oscillations exogenously using noninvasive brain stimulation have shown some promise, but difficulty with tailoring stimulation parameters to individuals has hindered progress in this field. We demonstrate here using electroencephalography (EEG) neurofeedback in a brain‐computer interface that human participants (n = 44) learned over multiple sessions across a 6‐day period to self‐regulate their Beta rhythm (13–20 Hz), either up or down, over the right inferior frontal cortex. Training to downregulate Beta was more effective than training to upregulate Beta. The modulation was evident only during neurofeedback task performance but did not lead to offline alteration of Beta rhythm characteristics at rest, nor to changes in subsequent cognitive behavior. Likewise, a control group (n = 38) who underwent training to up or downregulate the Alpha rhythm (8–12 Hz) did not exhibit behavioral changes. Although the right frontal Beta rhythm has been repeatedly implicated as a key component of the brain's inhibitory control system, the present data suggest that its manipulation offline prior to cognitive task performance does not result in behavioral change in healthy individuals. Whether this form of neurofeedback training could serve as a useful therapeutic target for disorders with dysfunctional inhibitory control as their basis remains to be tested in a context where performance is abnormally poor and neural dynamics are different. Using a non‐invasive brain‐computer interface, volitional self‐regulation of the right frontal Beta rhythm was achieved in the absence of exogenous brain stimulation. However, this modulation had no impact on behavior in healthy individuals. Whether this form of neurofeedback training could serve as a useful therapeutic target for disorders with dysfunctional inhibitory control as their basis remains to be tested in a context where performance is abnormally poor and neural dynamics are different. [ABSTRACT FROM AUTHOR]

Serotinous plants that both release seed and resprout after fire are thought to be resistant to wildfires within the range of intensities that have been experienced up until now. However, the frequency and scale of intense wildfires is increasing under climate change. We studied annual flowering and fruit‐set in a large population of Banksia spinulosa plants in south‐eastern Australia from the early 1990s to 2006. The results led us to predict that there would be little recruitment from seedlings after the next fire but good resprouting from very long‐lived lignotubers. Our study population burned in the widespread, high‐intensity wildfires of December 2019, providing an opportunity to test the hypothesis. Most above‐ground stems and cones were reduced to ash, and only 15 cones (on 10 plants) remained after the fire. We found no seedlings in the 0.3 ha site that had initially contained over 350 adult plants. Little natural mortality had been observed pre‐fire, but by 5 months after the fire, nearly 25% of lignotubers had failed to resprout. We conclude that even common and widespread resprouting species will suffer population decline and reduced genetic diversity as high‐intensity fires become more extensive and frequent. [ABSTRACT FROM AUTHOR]

Alcohol use disorder is characterised by disrupted reward learning, underpinned by dysfunctional cortico-striatal reward pathways, although relatively little is known about the biology of reward processing in populations who engage in risky alcohol use. Cues that trigger reward anticipation can be categorized according to their learnt valence (i.e., positive vs. negative outcomes) and motivational salience (i.e., incentive vs. neutral cues). Separating EEG signals associated with these dimensions is challenging because of their inherent collinearity, but the recent application of machine learning methods to single EEG trials affords a solution. Here, the Alcohol Use Disorders Identification Test (AUDIT) was used to quantify risky alcohol use, with participants split into high alcohol (HA) (n = 22, mean AUDIT score: 13.82) and low alcohol (LA) (n = 22, mean AUDIT score: 5.77) groups. We applied machine learning multivariate single-trial classification to the electroencephalography (EEG) data collected during reward anticipation. The LA group demonstrated significant valence discrimination in the early stages of reward anticipation within the cue-P3 time window (400-550 ms), whereas the HA group was insensitive to valence within this time window. Notably, the LA, but not the HA group demonstrated a relationship between single-trial variability in the early valence component and reaction times for gain and loss trials. This study evidences disrupted hypoactive valence sensitivity in the HA group, revealing potential neurophysiological markers for risky drinking behaviours which place individuals at-risk of adverse health events. [ABSTRACT FROM AUTHOR]

The challenges facing I Banksia i species conservation in the south-eastern state of Victoria were the focus of an online workshop in May 2020. Banksias are iconic Australian plants, with a Gondwanan origin. [Extracted from the article]

Background: Cognitive reserve (CR) enables individuals to maintain cognitive function despite the presence of pathology or atrophy. CR may be most directly measured using functional neuroimaging. Connectome‐based predictive modeling can develop measures of cognitive phenotypes using task‐fMRI that can be applied to resting‐state fMRI, which is easier to collect and unaffected by task‐related confounds. We aimed to develop and validate a CR measure that could be applied to resting‐state fMRI data. Method: Paper Folding task‐fMRI scans from 220 participants of the Cognitive Reserve/Reference Ability Neural Network studies formed a training set. Resting‐state fMRI scans from 294 participants from The Irish Longitudinal Study on Ageing formed a test set. fMRI data were preprocessed, motion‐corrected and parcellated into 205 nodes using the Shen atlas, excluding 63 brainstem and cerebellar nodes due to incomplete coverage. Functional connectivity matrices were calculated via Fisher z‐normalised correlations between the mean time series of each node‐pair. Connectome‐based predictive modeling with leave‐one‐out cross‐validation was used to predict a CR residual from task‐based functional connectivity in the training set (Fig. 1). This generated three network‐strength predicted CR measures. We established the validity of these measures via a positive correlation with a CR proxy (NART scores) and global cognition, independent of brain structure. We then applied the model to the test set and assessed the validity of the resulting network‐strength measures. Result: The three network‐strength measures accurately predicted the CR residuals of unseen participants (Fig. 2) and demonstrated validity as they were positively correlated with NART scores (Fig. 3) and global cognition, independent of brain structure. However, application of the model to the resting‐state data in the test set did not generate accurate predictions of the CR residual (Fig. 4) and the resulting measures did not correlate with NART scores nor global cognition (Fig. 5). Conclusion: Validated measures of CR were generated using task‐based fMRI data but these measures did not generalise to resting‐state fMRI from an independent dataset. The inability to generalise may be because CR involves a reorganisation of connectivity in response to task demands or that the data here excluded the cerebellum. [ABSTRACT FROM AUTHOR]

Previous studies suggest that individuals with substance use disorder have abnormally large responses to unexpected outcomes (reward prediction errors [RPEs]). However, there is much less information on RPE in individuals at risk of alcohol misuse, prior to neurobiological adaptations that might result from sustained alcohol use. Here, participants (mean age 23.77 years, range 18-32 years) performed the electrophysiological monetary incentive delay task. This task involved responding to a target stimulus following reward incentive cues to win, or avoid losing, the cued reward while brain activity was recorded under 64-channel EEG. The Alcohol Use Disorders Identification Test (AUDIT) was used to quantify at-risk alcohol use, with high (n = 22, mean AUDIT score: 13.82) and low (n = 22, mean AUDIT score: 5.77) alcohol use groups. Trial-by-trial RPEs were estimated using a Rescorla-Wagner reinforcement model based on behavioral data. A single-trial analysis revealed that the feedback-related negativity (FRN) and feedback P3 (fb-P3) event-related potential components were significantly modulated by RPEs. There was increased RPE-related fb-P3 amplitude for those in the high alcohol use group. Next, the mean amplitude of ERPs elicited by positive and negative RPEs were compared between groups. We found that high alcohol use participants had attenuated FRN amplitude in contrast with low alcohol use participants for both positive and negative RPEs but enhanced fb-P3 for both positive and negative RPE. These results, with differences in RPE in an at-risk group, suggest that RPE a potential vulnerability marker for alcohol use disorder. [ABSTRACT FROM AUTHOR]

It is often assumed that long‐lived woody perennials with canopy‐stored seed banks steadily accumulate seeds over time since fire. Trends in flowering and fruiting have usually been inferred from synchronic studies of sites of different post‐fire ages or counting stored seeds in apparent age classes, and mostly in obligate‐seeder species. Long‐term longitudinal studies on a broader range of species are needed to fully understand the dynamics of flower and fruit production and accumulation of viable seeds. Key questions are as follows: What is the annual trend in flowering and cone production? Is this matched by accumulation of cones and seeds? How is seed germinability related to cone age at the time of a fire?We counted inflorescences and tagged cones produced annually by the resprouting shrub Banksia spinulosa in 315 plants over 13 years at one site and in 46 plants over 20 years at another. At the end of the study, we harvested all accumulated cones, burned them and assessed seed viability using germination trials.We detected enormous inter‐plant variation in reproductive effort and output. 50% of inflorescences was produced by only 10%–15% of plants. There was a potential for accumulation of massive seed banks. However, (a) only 8%–10% of inflorescences became cones; (b) only 44%–50% of these were retained until harvest; (c) many retained cones suffered seed predation; and (d) viability of retained seeds declined with cone age. The result of these processes meant that the accumulated seed bank was only two to four seeds per plant, 82%–94% of the viable seeds had been produced in 6 years prior to harvest and only 12%–26% of plants contributed to this viable seed bank.Synthesis: Cone and seed losses and declining seed viability in B. spinulosa mean that almost all viable seeds come from the past few years of flowering even though apparently intact cones may be retained for decades. If this is typical for resprouting serotinous shrubs, it is important to understand trends in flowering and fruit set over time because the magnitude of recruitment will depend on fecundity in the few years prior to a fire. [ABSTRACT FROM AUTHOR]

Contralateral delay activity (CDA) has been proposed as a pre‐clinical neural marker for mild cognitive impairment (MCI). However, existing evidence is limited to one study with a small sample size (n = 24). Our aim was to extend previous work by investigating the relationship between the CDA and MCI risk in a large sample of older adults (n = 76). We used a regression approach to determine whether (and when) CDA amplitude predicted MCI risk, as indexed by the Montreal Cognitive Assessment (MoCA). CDA amplitude from ~300‐500 and ~800‐900 ms predicted MoCA performance. However, significant effects were only observed for specific electrodes (P5/P6 and CP3/CP4, but not PO7/PO8) and the nature of the relationship between the CDA and MoCA scores differed across time and according to set size. Bayesian regression analysis indicated partial evidence in favour of the null hypothesis (BF10 values = 4–1.18). Contrary to previous results, our findings suggest that the CDA may not a robust marker of MCI risk. More broadly, our results highlight the difficulty in identifying at‐risk individuals, particularly as MCI is a heterogeneous, unstable condition. Future research should prioritise longitudinal approaches in order to track the progression of the CDA and its association with cognitive decline in later life. [ABSTRACT FROM AUTHOR]

Adults with attention‐deficit/hyperactivity disorder (ADHD) have been described as having altered resting‐state electroencephalographic (EEG) spectral power and theta/beta ratio (TBR). However, a recent review (Pulini et al. 2018) identified methodological errors in neuroimaging, including EEG, ADHD classification studies. Therefore, the specific EEG neuromarkers of adult ADHD remain to be identified, as do the EEG characteristics that mediate between genes and behaviour (mediational endophenotypes). Resting‐state eyes‐open and eyes‐closed EEG was measured from 38 adults with ADHD, 45 first‐degree relatives of people with ADHD and 51 unrelated controls. A machine learning classification analysis using penalized logistic regression (Elastic Net) examined if EEG spectral power (1–45 Hz) and TBR could classify participants into ADHD, first‐degree relatives and/or control groups. Random‐label permutation was used to quantify any bias in the analysis. Eyes‐open absolute and relative EEG power distinguished ADHD from control participants (area under receiver operating characteristic = 0.71–0.77). The best predictors of ADHD status were increased power in delta, theta and low‐alpha over centro‐parietal regions, and in frontal low‐beta and parietal mid‐beta. TBR did not successfully classify ADHD status. Elevated eyes‐open power in delta, theta, low‐alpha and low‐beta distinguished first‐degree relatives from controls (area under receiver operating characteristic = 0.68–0.72), suggesting that these features may be a mediational endophenotype for adult ADHD. Resting‐state EEG spectral power may be a neuromarker and mediational endophenotype of adult ADHD. These results did not support TBR as a diagnostic neuromarker for ADHD. It is possible that TBR is a characteristic of childhood ADHD. [ABSTRACT FROM AUTHOR]

Cannabis use initiated during adolescence might precipitate negative consequences in adulthood. Thus, predicting adolescent cannabis use prior to any exposure will inform the aetiology of substance abuse by disentangling predictors from consequences of use. In this prediction study, data were drawn from the IMAGEN sample, a longitudinal study of adolescence. All selected participants (n = 1,581) were cannabis‐naïve at age 14. Those reporting any cannabis use (out of six ordinal use levels) by age 16 were included in the outcome group (N = 365, males n = 207). Cannabis‐naïve participants at age 14 and 16 were included in the comparison group (N = 1,216, males n = 538). Psychosocial, brain and genetic features were measured at age 14 prior to any exposure. Cross‐validated regularized logistic regressions for each use level by sex were used to perform feature selection and obtain prediction error statistics on independent observations. Predictors were probed for sex‐ and drug‐specificity using post‐hoc logistic regressions. Models reliably predicted use as indicated by satisfactory prediction error statistics, and contained psychosocial features common to both sexes. However, males and females exhibited distinct brain predictors that failed to predict use in the opposite sex or predict binge drinking in independent samples of same‐sex participants. Collapsed across sex, genetic variation on catecholamine and opioid receptors marginally predicted use. Using machine learning techniques applied to a large multimodal dataset, we identified a risk profile containing psychosocial and sex‐specific brain prognostic markers, which were likely to precede and influence cannabis initiation. [ABSTRACT FROM AUTHOR]

Background: The value of Electroencephalography (EEG) to unveil pathophysiological signatures in neurodegenerative diseases that cause dementia has been recently highlighted. To grant EEG tools the necessary validity, reliability, and scalability to support the diagnosis of dementia globally, efforts will need to integrate knowledge developed by EEG labs across diverse countries and develop protocols that can be swiftly implemented by such labs to harmonize research and clinical practices. These are the aims of EuroLaD‐EEG, a consortium that brings together five Latin American (LAC) and five European countries to develop a harmonised EEG database (Aim 1) that can help improve dementia phenotyping and diagnosis (Aim 2). Methods: EuroLaD‐EEG has developed a global EEG database that comprises 1234 EEG recordings from groups of healthy adults (n=1223), patients with mild cognitive impairment (n=199), and with familial and sporadic variants of neurodegenerative diseases (e.g., AD and FTD) (n=501). We have recently published the harmonization pipeline that will allow EuroLaD‐EEG meet its Aim 1 (Prado et al., 2022, Int J Psychophysiol, 172, 24–38). We have now developed a multi‐feature multimodal approach that combines demographic, neuropsychological, fMRI and EEG data as inputs for a gradient boosting machine‐learning classifier. Multicentric data including those from underrepresented samples will enter such a classification algorithm towards our Aim 2. Results: Preliminary results with a subsample from LAC (n=282) revealed high classification (AUC > 0.90 for all the classes) and robustness towards heterogeneity, sociodemographic variability, and missing data. We are now planning to combine data from European and LAC to explore sources of phenotypic variability linked to socio‐demographic and cultural factors. Conclusion: By broadening our understanding of dementia phenotypes, risk factors, and affordable diagnostic approaches, and adding new evidence on variability across developed and developing countries, the EEG will contribute unique evidence that will help enhance both dementia phenotyping and diagnostic strategies. [ABSTRACT FROM AUTHOR]

Background: Impulsivity, broadly characterized as the tendency to act prematurely without foresight, is linked to alcohol misuse in college students. However, impulsivity is a multidimensional construct and different subdomains likely underlie different patterns of alcohol misuse. Here, we quantified the association between alcohol intoxication frequency and alcohol consumption frequency and choice, action, cognitive, and trait domains of impulsivity. Methods: University student drinkers (n = 106) completed a battery of demographic and alcoholrelated items, as well as self-report and task-based measures indexing different facets of impulsivity. Two orthogonal latent factors, intoxication frequency and alcohol consumption frequency, were generated. Their validity was demonstrated with respect to adverse consequences of alcohol use. Machine learning with penalized regression and feature selection was then utilized to predict intoxication and alcohol consumption frequency using all impulsivity subdomains. Out-of-sample validation was used to quantify model performance. Results: Impulsivity measures alone were significant predictors of intoxication frequency, but not consumption frequency. Propensity for increased intoxication frequency was characterized by increased trait impulsivity, including the Disinhibition subscale of the Sensation Seeking Scale, Attentional and Non-planning subscales of the Barratt Impulsiveness Scale, increased task-based cognitive impulsivity (response time variability), and increased choice impulsivity (steeper delay discounting on a delay discounting questionnaire). A model combining impulsivity domains with other risk factors (gender; nicotine, cannabis, and other drug use; executive functioning; and learning processes) was also significant but did not outperform the model comprising of impulsivity alone. Conclusions: Intoxication frequency, but not consumption frequency, was characterized by a number of impulsivity subdomains. [ABSTRACT FROM AUTHOR]

Abstract: Many plant species have pollination and seed dispersal systems and evolutionary histories that have produced strong genetic structuring. These genetic patterns may be consistent with expectations following recent anthropogenic fragmentation, making it difficult to detect fragmentation effects if no prefragmentation genetic data are available. We used microsatellite markers to investigate whether severe habitat fragmentation may have affected the structure and diversity of populations of the endangered Australian bird‐pollinated shrub Grevillea caleyi R.Br., by comparing current patterns of genetic structure and diversity with those of the closely related G. longifolia R.Br. that has a similar life history but has not experienced anthropogenic fragmentation. Grevillea caleyi and G. longifolia showed similar and substantial population subdivision at all spatial levels (global F′ST = 0.615 and 0.454; Sp = 0.039 and 0.066), marked isolation by distance and large heterozygous deficiencies. These characteristics suggest long‐term effects of inbreeding in self‐compatible species that have poor seed dispersal, limited connectivity via pollen flow and undergo population bottlenecks because of periodic fires. Highly structured allele size distributions, most notably in G. caleyi, imply historical processes of drift and mutation were important in isolated subpopulations. Genetic diversity did not vary with population size but was lower in more isolated populations for both species. Through this comparison, we reject the hypothesis that anthropogenic fragmentation has impacted substantially on the genetic composition or structure of G. caleyi populations. Our results suggest that highly self‐compatible species with limited dispersal may be relatively resilient to the genetic changes predicted to follow habitat fragmentation. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to examine symptom profiles of people diagnosed with attention‐deficit/hyperactivity disorder (ADHD) and/or anxiety (ANX) in order to determine the validity of widely used ADHD and ANX rating scales for differential diagnostic use and to develop modified measures that take symptom overlap into account. Design: A cross‐sectional design was used to assess differences in rating scale scores between clinical (n = 52) and control (n = 74) samples as well as differences among subgroups of the clinical sample (22 ADHD; 16 ADHD + ANX; 14 ANX). Method: Participants completed an online questionnaire where they responded to the Conners Adult ADHD Rating Scale (CAARS; Conners, Erhardt, & Sparrow, ) and State Trait Anxiety Inventory scales (STAI; Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, ). Results: Results showed that the CAARS and STAI had limited sensitivity and specificity and may lack in ability to differentially diagnose ADHD and/or ANX. Cluster analysis was used to guide the proposal of modifications for the two scales, which were to use inattentive items only for the CAARS and to exclude state ANX‐present items on the STAI for use in differential diagnosis. Further parametric analysis supported these proposed modifications. Conclusions: Clinicians should be made aware of the limitations of the CAARS and STAI scales in terms of specificity, when used to inform differential diagnosis of ADHD and ANX. Further analysis on the psychometric properties of these modified scales is needed in order to confirm that they are valid and reliable scales. Practitioner points: Clinical implications It is possible that widely used self‐report rating scales are not valid for use in the context of assessing adult ADHD when ANX is present. Clinicians should take alternative approaches to measuring ADHD symptoms in the context of ANX. Findings of the present study suggest the use of inattentive items only for the CAARS and to exclude state ANX‐present items on the STAI for differential diagnostic use.Limitations of the study The sample sizes of the clinical subgroups were relatively small. Diagnoses were not confirmed using a semi‐structured clinical interview. Alternative cluster approaches (e.g., two‐step clustering using larger samples) would provide further insight. [ABSTRACT FROM AUTHOR]

Background and Aims Dysfunction in brain regions underlying impulse control, reward processing and executive function have been associated previously with adolescent alcohol misuse. However, identifying pre-existing neurobiological risk factors, as distinct from changes arising from early alcohol-use, is difficult. Here, we outline how neuroimaging data can identify the neural predictors of adolescent alcohol-use initiation and misuse by using prospective longitudinal studies to follow initially alcohol-naive individuals over time and by neuroimaging adolescents with inherited risk factors for alcohol misuse. Method A comprehensive narrative of the literature regarding neuroimaging studies published between 2010 and 2016 focusing on predictors of adolescent alcohol use initiation and misuse. Findings Prospective, longitudinal neuroimaging studies have identified pre-existing differences between adolescents who remained alcohol-naive and those who transitioned subsequently to alcohol use. Both functional and structural grey matter differences were observed in temporal and frontal regions, including reduced brain activity in the superior frontal gyrus and temporal lobe, and thinner temporal cortices of future alcohol users. Interactions between brain function and genetic predispositions have been identified, including significant association found between the Ras protein-specific guanine nucleotide releasing factor 2 ( RASGRF2) gene and reward-related striatal functioning. Conclusions Neuroimaging predictors of alcohol use have shown modest utility to date. Future research should use out-of-sample performance as a quantitative measure of a predictor's utility. Neuroimaging data should be combined across multiple modalities, including structural information such as volumetrics and cortical thickness, in conjunction with white-matter tractography. A number of relevant neurocognitive systems should be assayed; particularly, inhibitory control, reward processing and executive functioning. Combining a rich magnetic resonance imaging data set could permit the generation of neuroimaging risk scores, which could potentially yield targeted interventions. [ABSTRACT FROM AUTHOR]

Background: Despite calls for integration of neurobiological methods into research on youth resilience (high competence despite high adversity), we know little about structural brain correlates of resilient functioning. The aim of the current study was to test for brain regions uniquely associated with positive functioning in the context of adversity, using detailed phenotypic classification. Methods: 1,870 European adolescents (Mage = 14.56 years, SDage = 0.44 years, 51.5% female) underwent MRI scanning and completed behavioral and psychological measures of stressful life events, academic competence, social competence, rule-abiding conduct, personality, and alcohol use. Results: The interaction of competence and adversity identified two regions centered on the right middle and superior frontal gyri; grey matter volumes in these regions were larger in adolescents experiencing adversity who showed positive adaptation. Differences in these regions among competence/adversity subgroups were maintained after controlling for several covariates and were robust to alternative operationalization decisions for key constructs. Conclusions: We demonstrate structural brain correlates of adolescent resilience, and suggest that right prefrontal structures are implicated in adaptive functioning for youth who have experienced adversity. [ABSTRACT FROM AUTHOR]

The subject matter of neuroscience research is complex, and synthesising the wealth of data from this research to better understand mental processes is challenging. A useful strategy, therefore, may be to distinguish explicitly between the causal effects of the environment on behaviour (i.e. functional analyses) and the mental processes that mediate these effects (i.e. cognitive analyses). In this article, we describe how the functional-cognitive (F-C) framework can accelerate cognitive neuroscience and also advance a functional treatment of brain activity. We first highlight that cognitive neuroscience can particularly benefit from the F-C approach by providing an alternative to the problematic practice of reducing cognitive constructs to behavioural and/or neural proxies. Next, we outline how functional (behaviour-environment) relations can serve as a bridge between cognitive and neural processes by restoring mental constructs to their original role as heuristic tools. Finally, we give some examples of how both cognitive neuroscience and traditional functional approaches can mutually benefit from the F-C framework. [ABSTRACT FROM AUTHOR]

ABSTRACT The pathogenesis of adult-onset primary dystonia remains poorly understood. There is variable age-related and gender-related expression of the phenotype, the commonest of which is cervical dystonia. Endophenotypes may provide insight into underlying genetic and pathophysiological mechanisms of dystonia. The temporal discrimination threshold (TDT)-the shortest time interval at which two separate stimuli can be detected as being asynchronous-is abnormal both in patients with cervical dystonia and in their unaffected first-degree relatives. Functional magnetic resonance imaging (fMRI) studies have shown that putaminal activation positively correlates with the ease of temporal discrimination between two stimuli in healthy individuals. We hypothesized that abnormal temporal discrimination would exhibit similar age-related and gender-related penetrance as cervical dystonia and that unaffected relatives with an abnormal TDT would have reduced putaminal activation during a temporal discrimination task. TDTs were examined in a group of 192 healthy controls and in 158 unaffected first-degree relatives of 84 patients with cervical dystonia. In 24 unaffected first-degree relatives, fMRI scanning was performed during a temporal discrimination task. The prevalence of abnormal TDTs in unaffected female relatives reached 50% after age 48 years; whereas, in male relatives, penetrance of the endophenotype was reduced. By fMRI, relatives who had abnormal TDTs, compared with relatives who had normal TDTs, had significantly less activation in the putamina and in the middle frontal and precentral gyri. Only the degree of reduction of putaminal activity correlated significantly with worsening of temporal discrimination. These findings further support abnormal temporal discrimination as an endophenotype of cervical dystonia involving disordered basal ganglia circuits. © 2014 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

The Relational Completion Procedure is effective for establishing same, opposite and comparative derived relations in verbally able adults, but to date it has not been used to establish relational frames in young children or those with developmental delay. In Experiment 1, the Relational Completion Procedure was used with the goal of establishing two 3-member sameness networks in nine individuals with Autism Spectrum Disorder (eight with language delay). A multiple exemplar intervention was employed to facilitate derived relational responding when required. Seven of nine participants in Experiment 1 passed tests for derived relations. In Experiment 2, eight participants (all of whom, except one, had a verbal repertoire) were given training with the aim of establishing two 4-member sameness networks. Three of these participants were typically developing young children aged between 5 and 6 years old, all of whom demonstrated derived relations, as did four of the five participants with developmental delay. These data demonstrate that it is possible to reliably establish derived relations in young children and those with developmental delay using an automated procedure. [ABSTRACT FROM AUTHOR]

Background: Cognitive reserve (CR) enables individuals to maintain cognitive function despite the presence of brain pathology or atrophy [1]. CR is typically measured via proxy variables that reflect exposure to lifetime experiences, such as education [2]. Composite measures of multiple proxies combine contributions from several experiences and display consistent positive relationships with cognitive function [3]. However, the optimal set of proxies for inclusion in composite measures remains to be determined [2]. Here, we aimed to identify a combination of proxies that best reflects the ability to maintain cognitive function despite cortical thinning. Method: As part of a larger analysis, 277 healthy adult participants provided data for this study (mean age = 69.18, SD age = 6.66, 141 females). Global cognition was defined as average of z‐scores from the Animal Naming task, Colour Trails Test 1 and 2, Immediate and Delayed Recall. Mean cortical thickness was calculated using FreeSurfer using a previously reported method [4]. CR proxies were: educational attainment, occupational complexity, premorbid intelligence, social engagement, cognitively stimulating activity, leisure activity, and physical activity. For each composite, a three‐step hierarchical‐multiple regression was performed to predict global cognition. Independent variables in Step 1 were age, gender, cortical thickness, CR composite was added in Step 2, and an interaction term (cortical thickness*composite) was further added in Step 3. Positive associations between CR composites and global cognition – independent of age, gender and cortical thickness – were ranked on significant R‐squared change values from Step 1 to Step 2. Moderation effects were identified by significant R‐squared change values from Step 2 to Step 3. Result: Most CR composites had positive associations with global cognition, independent of age, gender, and cortical thickness (see Figure 1). A CR composite measuring cognitively stimulating activity, leisure activity, and physical activity had the biggest negative moderation effect (R2 change = 0.013, p = 0.0276) on the cortical thickness‐global cognition relationship. Conclusion: A composite measure of cognitively stimulating‐, leisure‐, and physical‐activity, displays construct validity as a measure of CR in addition to a wide range of composites which display positive, independent, associations with cognitive function. [ABSTRACT FROM AUTHOR]

ABSTRACT The pathogenesis and the genetic basis of adult-onset primary torsion dystonia remain poorly understood. Because of markedly reduced penetrance in this disorder, a number of endophenotypes have been proposed; many of these may be epiphenomena secondary to disease manifestation. Mediational endophenotypes represent gene expression; the study of trait (endophenotypic) rather than state (phenotypic) characteristics avoids the misattribution of secondary adaptive cerebral changes to pathogenesis. We argue that abnormal temporal discrimination is a mediational endophenotype; its use facilitates examination of the effects of age, gender, and environment on disease penetrance in adult-onset dystonia. Using abnormal temporal discrimination in unaffected first-degree relatives as a marker for gene mutation carriage may inform exome sequencing techniques in families with few affected individuals. We further hypothesize that abnormal temporal discrimination reflects dysfunction in an evolutionarily conserved subcortical-basal ganglia circuit for the detection of salient novel environmental change. The mechanisms of dysfunction in this pathway should be a focus for future research in the pathogenesis of adult-onset primary torsion dystonia. © 2013 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

The frequency of hybridization in plants is context dependent and can be influenced by the local mating environment. We used progeny arrays and admixture and pollen dispersal analyses to assess the relative importance of pre-mating reproductive barriers and the local demographic environment as explanations of variation in hybrid frequency in three mapped hybrid zones of Eucalyptus aggregata and E. rubida. A total of 731 open-pollinated progeny from 36 E. aggregata maternal parents were genotyped using six microsatellite markers. Admixture analysis identified substantial variation in hybrid frequency among progeny arrays (0-76.9%). In one hybrid zone, hybrid frequency was related to pre-mating barriers (degree of flowering synchrony) and demographic components of the local mating environment (decreasing population size, closer proximity to E. rubida and hybrid trees). At this site, average pollen dispersal distance was less and almost half (46%) of the hybrid progeny were sired by local E. rubida and hybrid trees. In contrast, at the other two sites, pre-mating and demographic factors were not related to hybrid frequency. Compared to the first hybrid zone where most of the E. rubida (76%) and all hybrids flowered, in the remaining sites fewer E. rubida (22-41%) and hybrid trees (0-50%) flowered and their reproductive success was lower (sired 0-23% of hybrids). As a result, most hybrids were sired by external E. rubida/hybrids located at least 2-3 km away. These results indicate that although pre-mating barriers and local demography can influence patterns of hybridization, their importance can depend upon the scale of pollen dispersal. [ABSTRACT FROM AUTHOR]

Adult-onset primary torsion dystonia (AOPTD) has an autosomal dominant pattern of inheritance with markedly reduced penetrance; the genetic causes of most forms of AOPTD remain unknown. Endophenotypes, markers of sub-clinical gene carriage, may be of use detecting non-manifesting gene carriers in relatives of AOPTD patients. The aim of this study was to compare the utility of the spatial discrimination threshold (SDT) and temporal discrimination threshold (TDT) as potential endophenotypes in AOPTD. Data on other published candidate endophenotypes are also considered. Both SDT and TDT testing were performed in 24 AOPTD patients and 34 of their unaffected first degree relatives; results were compared with normal values from a control population. Of the 24 AOPTD patients 5 (21%) had abnormal SDTs and 20 (83%) had abnormal TDTs. Of the 34 first degree relatives 17 (50%) had abnormal SDTs and 14 (41%) had abnormal TDTs. Discordant results on SDT and TDT testing were found in 16 (67%) AOPTD patients and 21 (62%) first degree relatives. TDT testing has superior sensitivity compared to SDT testing in AOPTD patients; although false positive TDTs are recognised, the specificity of TDT testing in unaffected relatives is not determinable. The high level of discordance between the two tests probably relates methodological difficulties with SDT testing. The SDT is an unreliable AOPTD endophenotype; TDT testing fulfils criteria for a reliable endophenotype with a high sensitivity. © 2009 Movement Disorder Society [ABSTRACT FROM AUTHOR]

1. Increased fire frequency is seen as a key threat to plant populations in Mediterranean-type ecosystems across the globe. Short inter-fire periods may exhaust soil-stored and fire-stimulated seed banks of fire-sensitive species, reducing actual and effective population sizes and eroding genetic diversity. 2. Here we used microsatellite genotyping to investigate the genetic impacts of repeated wildfires and, in particular, the contribution of above-ground genetic processes (seed and pollen dispersal) to the genetic structuring and composition of post-fire recruits in an isolated population of the fire-sensitive shrub Persoonia mollis ssp. nectens. 3. We tested the hypothesis that limited pollen and seed dispersal, in combination with the potentially patchy effects of fire at a fine scale within populations, would generate a highly structured population, a decline in genetic diversity after each fire and genetic heterogeneity between successive cohorts. 4. Wildfires killed all 25 adult plants in 1997 and, in 2001, killed all of the 476 seedlings remaining from the 1997 seedling cohort. Although there was no possibility of replenishment of the seed bank in the interval between fires, a second cohort of 381 seedlings emerged after the 2001 fire. 5. We found no evidence that successive fires produced either a decline in genetic diversity, as measured by allelic richness or expected heterozygosity, or the genetic differentiation of adult and successive seedling cohorts (Pairwise FST = −0.0125 to 0.0009). The seedling cohorts displayed less genetic structuring than anticipated. Spatial genetic structure was low, ranging from Sp = 0.02 in the 1997 seedlings to Sp = 0.06 in the 2001 seedlings, and using parentage analysis, we found that seedlings clustered under dead adults rarely reflected simple seed shadows. 6. Synthesis. Overall, we found that a numerically large seed bank with a bet-hedging strategy of staged seed germination, in combination with genetic mixing achieved by both pollen and seed dispersal, provides a powerful buffer against the negative impacts of frequent fire in P. mollis ssp. nectens. [ABSTRACT FROM AUTHOR]

Spatial patterns of fruit set within inflorescences may be controlled by pollination, nutrient allocation, or inflorescence architecture. Generally, flowers that have spatial and/or temporal precedence are more likely to set fruits. We sought to separate these factors by comparing patterns of fruit set on inflorescences of two species of Telopea (Proteaceae); one that flowers from the tip to the base of the rachis, the other from base to tip. In both species, most fruits were set at the top of the inflorescence (the last flowers to open for T. speciosissima) and this was extreme for T. mongaensis, where the top flowers open first. Fruit set was not generally limited by inadequate pollination for either T. mongaensis or T. speciosissima, as hand pollinations did not increase fruit set and many abscised flowers contained pollen tubes. In T. speciosissima, we tested whether removal of developing topmost fruits would ‘release’ those that had initiated but not yet aborted lower down. There was no significant effect. Plant hormones can increase the degree to which a developing fruit is a sink for nutrients, so we applied cytokinin to the developing lower fruits on some inflorescences. There was no significant effect of the hormone treatment. We conclude that temporal precedence may contribute to the skewed pattern of fruit set in T. mongaensis, because there was an extreme concentration of fruit set on the distal part of the inflorescences, but it cannot explain this pattern of fruit set in T. speciosissima, where the distal flowers are the last to open. Some other process must therefore constrain fruit set to the topmost flowers in an inflorescence. While cytokinin application had no significant effect, the power of this experiment was low and we consider that the hypothesis of hormonal control is worth further exploration. [ABSTRACT FROM AUTHOR]

1. Habitat fragmentation can alter the relative frequency of cross-compatible species within an area, which can affect the levels of interspecific hybrid production and reduce the viability of small populations through genetic and demographic swamping. For 18 populations of Eucalyptus aggregata, we examined the effects of absolute and relative population size (compared with its congeners E. rubida, E. viminalis and E. dalrympleana) on hybrid production, genetic diversity and subsequent seed production and seedling performance. 2. Relative population size was strongly negatively correlated with rates of hybrid seed production, suggesting increased hybridization when the potential sources of interspecific pollen outnumber the sources of intraspecific pollen for E. aggregata trees. 3. Genetic diversity was negatively correlated with relative population size which suggests that hybridization may maintain diversity lost through bottlenecks and drift following reductions in population size. However, the presence of fertile hybrid adults, and introgressed leaf traits within populations exhibiting high hybridization rates, suggests that small E. aggregata populations may be vulnerable to genetic swamping by common congeners. 4. Amongst an array of population parameters (population sizes, genetic diversity and inbreeding), seed production was only positively correlated with relative population size, whereby sites with low relative population sizes tended to produce fewer seed. This could be due to the action of pre-zygotic barriers which removes inviable hybrid genotypes as levels of interspecific pollen flow increase. 5. Germination and survivorship displayed a similar positive correlation with relative population size, suggesting post-zygotic hybrid breakdown may also contribute towards to demographic swamping of remnant populations. 6. Synthesis. Our results suggest that relative population size is an important parameter determining rates of hybrid production, seed production and seedling performance. Furthermore, relative population size has stronger effects on population fecundity than absolute population size, genetic diversity and levels of inbreeding. Relative population sizes > 0.5 (i.e. at least equal frequencies of parentals) may be required to avoid the deleterious effects of genetic and demographic swamping on the viability of rare species. [ABSTRACT FROM AUTHOR]

Housing for the poor was a thriving part of the voluntary sector in the nineteenth century, providing thousands of homes through hundreds of societies without subsidy. It was undermined by state action which has effectively driven other providers from the field. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Question: Is primary dormancy required for seed bank persistence of Leucopogon species? How does the distinction between dormancy and persistence affect our understanding of seed bank dynamics in fire-prone regions? Location: Sclerophyllous plant communities, Sydney region, southeastern Australia. Methods: Seed bank longevity of three morphophysiologically dormant species was ascertained using seed burial trials. Seeds of each species were buried in situ in replicate mesh bags and retrieved annually over three years. Laboratory germination trials and embryo growth measurements over time were used to establish in which order each component of dormancy was overcome, and whether seed banks persisted after the loss of primary dormancy. Results: All species had long-term persistent seed banks, with estimated half-lives between 3.5 and 5.5 years. Physiological dormancy was broken by stratification prior to embryo growth, during the first year of burial. Seeds were able to germinate after retrieval, in light and at warm temperatures. Only low levels of germination occurred in situ over three years of burial, and did not increase over time. During germination trials, embryos remained underdeveloped unless seeds germinated, indicating that seeds were committed to germination once embryo growth was initiated. Conclusions: Long-lived seed banks are an important trait of plants from fire-prone communities, but cues observed to promote germination in situ are not necessarily the ones that break dormancy. A failure to distinguish between these two factors can divert attention away from mechanisms actually controlling dormancy and seed bank dynamics. [ABSTRACT FROM AUTHOR]

Royal National Park, Australia's oldest national park, is a significant reserve for conservation of the flora and fauna that are characteristic of the Hawkesbury Sandstone in New South Wales. Since at least 1974, Phytophthora Root Rot (caused by Phytophthora cinnamomi) has been known to occur in the Park, but there is no knowledge of the extent of infestation or the potential impacts of the disease within the Park. This study investigated the distribution of the pathogen within Royal National Park at two scales: a systematic survey by vegetation type, and a targeted survey of populations of Waratah and Spear Grass-tree. These two species are known to be susceptible to Phytophthora Root Rot and are therefore potential indicators of the impact of the pathogen on vegetation in Royal National Park. Phytophthora cinnamomi was recovered from all vegetation types sampled but most commonly in heathland/open scrub vegetation. The pathogen was easily recovered from sites containing Spear Grass-tree, but was not isolated from any sites containing Waratah. Because of the widespread distribution of P. cinnamomi, we conclude that hygiene measures will be of little use to prevent the spread of the pathogen within Royal National Park. Monitoring of the occurrence and spread of disease symptoms in plants and applying phosphite to protect susceptible rare or threatened flora may be the most appropriate management options. [ABSTRACT FROM AUTHOR]

The current study aimed to test a Relational Frame Theory (RFT) model of analogical reasoning based on the relating of derived same and derived difference relations. Experiment 1 recorded reaction time measures of similar-similar (e.g., apple is to orange as dog is to cat") versus different-different (e.g., "he is to his brother as chalk is to cheese") derived relational responding, in both speed-contingent and speed-noncontingent conditions. Experiment 2 examined the event-related potentials (ERPs) associated with these two response patterns. Both experiments showed similar-similar responding to be significantly faster than different-different responding. Experiment 2 revealed significant differences between the waveforms of the two response patterns in the left-hemispheric prefrontal regions; different-different waveforms were significantly more negative than similar-similar waveforms. The behavioral and neurophysiological data support the RFT prediction that, all things being equal, similar-similar responding is relationally "simpler" than, and functionally distinct from, different- different analogical responding. The ERP data were fully consistent with findings in the neurocognitive literature on analogy. These findings strengthen the validity of the RFT model of analogical reasoning and supplement the behavior-analytic approach to analogy based on the relating of derived relations. [ABSTRACT FROM AUTHOR]

Although the literature on reinforcement in behavioral psychology is extensive, few studies have examined the derived transformation of reinforcing functions in accordance with equivalence classes, and no published research has yet examined the derived transformation of consequential functions in accordance with nonequivalence relations. In the present study, which consisted of four experiments, the basic preparation was as follows. First, an arbitrary stimulus, B2, was established as a conditioned punisher, using direct stimulus pairing. Following nonarbitrary relational training, designed to establish SAME and OPPOSITE contextual cues, subjects were exposed to arbitrary relational training using these contextual cues to establish A1 as the same as B1 and C1, and as opposite to B2 and C2. Subsequently, C2 (based on its Same relation with B2) functioned as a punisher and C1 (based on its Opposite relation with B2) functioned as a reinforcer in a simultaneous discrimination task. Critically, the C1 stimulus acquired reinforcing functions, based on the derived relation of Opposite, although no such function had actually been established for any member of the network. Furthermore, these effects were observed across ABA reversals in the baseline contingencies. [ABSTRACT FROM AUTHOR]

Abstract Seed germination is dependent on the interaction between the dormancy state of a seed and the presence of favourable environmental conditions. Thus, the spectacular pulse of seedling recruitment in many Australian vegetation communities following disturbances such as fire can be attributed to changes in microsite conditions and/or the dormancy-breaking effect of the disturbance on accumulated seed banks. Grevillea rivularis is a threatened species endemic to the area immediately above Carrington Falls in the NSW Southern Highlands. Most of the population is confined to the riparian vegetation zone in woodland and heath, and is therefore subject to periodic disturbance from fire and flood. For this species, a pulse of seedling recruitment has been recorded after fire, flood and mechanical soil disturbance. The aims of this study were to examine the density and vertical distribution of the soil-stored seed bank and to investigate the role of heat and scarification as cues for germination of fresh and soil-stored seed. There was a large seed bank under the canopies of established individuals (194 ± 73 seeds m-2 ) and most seeds were found in the 0–2 cm and leaf-litter layers of the soil profile. The germination response of soil-stored and fresh seed was examined using a hierarchical series of laboratory experiments. Seeds of G. rivularis showed marked dormancy polymorphism. Thirty-six percent of soil-stored seed germinated without treatment, whereas no untreated fresh seeds germinated. Scarification or heating caused significant germination of dormant soil-stored seed, but only scarification resulted in germination of dormant fresh seeds. These results highlight important differences in the dormancy state of soil-stored and fresh seed. Thus, being a riparian species in a fire-prone environment, the dormancy mechanisms in seeds of G. rivularis suit this species to disturbance by both fire and flood. [ABSTRACT FROM AUTHOR]

Ecotones have been considered as unique environments, and the concepts of edge effect and ecotonal species have been widely used, especially in avian community ecology. We studied the patterns of bird densities across heath-wood edges at replicated sites in three locations in southeastern Australia. Multivariate analysis showed that the bird community in the ecotone was intermediate between the heath and wood communities, indicating that the ecotone contained a mixing of species rather than a unique bird community. ANOVA showed a modest increase in bird density at the wood side of the ecotone, which may be partly due to sampling biases rather than to some inherent habitat value in the ecotone. The outstanding pattern was that bird density and species richness in the wood habitat were twice as high as in the heath habitat. Of a total of 86 species, 31 occurred in sufficient numbers to categorize according to their habitat association (generalist, or heath or wood specialist) and their density at the ecotone (ecotone neutral, ecotone shy, or ecotone conspicuous). Three of these were habitat-generalist-ecotone-neutral. Fourteen species were ecotone neutral but were habitat specialists on either the wood (13 spp.) or the heath (1 sp.). Three species were ecotone shy. Although 11 species were ecotone conspicuous, they also occurred in either heath or wood or both. Thus, no species could be categorized as entirely ecotonal. We conclude that there is little evidence from this or other studies of avian communities to support an edge effect of increased density and species richness, and no evidence of entirely ecotonal species. [ABSTRACT FROM AUTHOR]

Abstract Recent habitat loss and fragmentation superimposed upon ancient patterns of population subdivision are likely to have produced low levels of neutral genetic diversity and marked genetic structure in many plant species. The genetic effects of habitat fragmentation may be most pronounced in species that form small populations, are fully self-compatible and have limited seed dispersal. However, long-lived seed banks, mobile pollinators and long adult lifespans may prevent or delay the accumulation of genetic effects. We studied a rare Australian shrub species, Grevillea macleayana (Proteaceae), that occurs in many small populations, is self-compatible and has restricted seed dispersal. However, it has a relatively long adult lifespan (c . 30 years), a long-lived seed bank that germinates after fire and is pollinated by birds that are numerous and highly mobile. These latter characteristics raise the possibility that populations in the past may have been effectively large and genetically homogeneous. Using six microsatellites, we found that G. macleayana may have relatively low within-population diversity (3.2–4.2 alleles/locus; Hexp = 0.420–0.530), significant population differentiation and moderate genetic structure (F ST = 0.218) showing isolation by distance, consistent with historically low gene flow. The frequency distribution of allele sizes suggest that this geographical differentiation is being driven by mutation. We found a lack mutation-drift equilibrium in some populations that is indicative of population bottlenecks. Combined with evidence for large spatiotemporal variation of selfing rates, this suggests that fluctuating population sizes characterize the demography in this species, promoting genetic drift. We argue that natural patterns of pollen and seed dispersal, coupled with the patchy, fire-shaped distribution, may have restricted long-distance gene flow in the past. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Presents information on a study which investigated the effects of fires in different seasons on the availability and release of germinable seeds from a canopy-stored seed bank. Study area and species description; Materials and methods; Results and discussion.

Profiles social worker Bob Holman. His campaign against poverty; Views on government policy; Adverse consequences of state funding to the anti-poverty programs he implemented at several communities.

Describes a calcium alginate gel formula that was modified for use in feeding trials with slugs. Preparation of the gel; Acceptability of the gel as lettuce in standard choice experiments with Arion subfuscus; Slightly higher growth rate of slugs fed on a standard lettuce diet than on the medium.

Tests the hypothesis that relatively unacceptable plants will be more acceptable to slugs from the same habitat than to slugs from other populations that are not normally exposed to these plants. Reduced amount of feeding of unexposed slugs on the unacceptable plants in a second feeding trial; Tendency of unexposed slugs to feed more on the unacceptable plants in the initial trial.

Mammals are frequent visitors to flowers in some Australian plant communities. Nectar is usually considered to be the food sought, because pollen is thought to be of low digestibility. This study compared the abilities of four non-flying mammal species to extract the protoplasts from Banksia pollen grains and quantified the amount of pollen in the diets of the species over 16 months. All four species were capable of extracting the protoplast from a large proportion of the pollen grains that they ingested the mean percentage of empty Banksia pollen grains in the faeces ranged from 37% to 66%. Banksia pollen was a major component in the faecal samples from two species, Cercartetus nanus and Petaurus breviceps, between March and October. It occasionally comprised a large proportion of Antechinus stuartis faeces but was rare in the faeces of Rattus fuscipes. Other major components of faeces included invertebrates and plant material other than pollen and fungal spores. As the four mammal species tested were all from separate families and all capable of extracting the protoplast from a large proportion of the pollen grains, it is concluded that the extraction of pollen protoplasts by mammals may be widespread and may require no special adaptations. [ABSTRACT FROM AUTHOR]

The article provides information about a study, which demonstrated that seed-set does not occur by autogamy and that pollinators are indeed necessary. It affirmed that the consequences of observed variations in pollinator activity for plant reproduction depend on the breeding system of the plant and also on whether pollination is a resource in short supply. The study did experiments with Banksia paludosa in heath and B. spinulosa var. spinulosa in woodland. Experimental addition of outcrossed pollen to inflorescences failed to produce any increase in the mean number of seeds per inflorescence, measured for non-barren inflorescences, for either species.

Presents several letters to the editor on issues related to public administration. Problems faced by black elected administrators; Criticisms on an essay related to black administrators; Details of political pressures on black administrators.