Experimental evolution of dispersal: Unifying theory, experiments and natural systems.

Dispersal is a central life history trait that affects the ecological and evolutionary dynamics of populations and communities. The recent use of experimental evolution for the study of dispersal is a promising avenue for demonstrating valuable proofs of concept, bringing insight into alternative dispersal strategies and trade-offs, and testing the repeatability of evolutionary outcomes. Practical constraints restrict experimental evolution studies of dispersal to a set of typically small, short-lived organisms reared in artificial laboratory conditions. Here, we argue that despite these restrictions, inferences from these studies can reinforce links between theoretical predictions and empirical observations and advance our understanding of the eco-evolutionary consequences of dispersal. We illustrate how applying an integrative framework of theory, experimental evolution and natural systems can improve our understanding of dispersal evolution under more complex and realistic biological scenarios, such as the role of biotic interactions and complex dispersal syndromes.

Invasion and rapid adaptation of guppies (Poecilia reticulata) across the Hawaiian Archipelago.

How much does natural selection, as opposed to genetic drift, admixture, and gene flow, contribute to the evolution of invasive species following introduction to a new environment? Here we assess how evolution can shape biological invasions by examining population genomic variation in non-native guppies (Poecilia reticulata) introduced to the Hawaiian Islands approximately a century ago. By examining 18 invasive populations from four Hawaiian islands and four populations from the native range in northern South America, we reconstructed the history of introductions and evaluated population structure as well as the extent of ongoing gene flow across watersheds and among islands. Patterns of differentiation indicate that guppies have developed significant population structure, with little natural or human-mediated gene flow having occurred among populations following introduction. Demographic modeling and admixture graph analyses together suggest that guppies were initially introduced to O'ahu and Maui and then translocated to Hawai'i and Kaua'i. We detected evidence for only one introduction event from the native range, implying that any adaptive evolution in introduced populations likely utilized the genetic variation present in the founding population. Environmental association tests accounting for population structure identified loci exhibiting signatures of adaptive variation related to predators and landscape characteristics but not nutrient regimes. When paired with high estimates of effective population sizes and detectable population structure, the presence of environment-associated loci supports the role of natural selection in shaping contemporary evolution of Hawaiian guppy populations. Our findings indicate that local adaptation may engender invasion success, particularly in species with life histories that facilitate rapid evolution. Finally, evidence of low gene flow between populations suggests that removal could be an effective approach to control invasive guppies across the Hawaiian archipelago.

Exploring the Role of Executive Functioning Capacity in Patient Activation and Health Outcomes Among Medicaid Members With Multiple Comorbidities.

Patient activation, the perceived capacity to manage one's health, is positively associated with better health outcomes and lower costs. Underlying characteristics influencing patient activation are not completely understood leading to gaps in intervention strategies designed to improve patient activation. We suggest that variability in executive functioning influences patient activation and ultimately has an impact on health outcomes. To examine this hypothesis, 440 chronically ill Medicaid enrollees completed measures of executive functioning, patient activation, and health-related quality of life. Mediation analyses revealed that executive functioning: (a) directly affected patient activation and mental health-related quality of life, (b) indirectly affected mental health-related quality of life through patient activation, and (c) was unrelated to physical health-related quality of life. These data indicate that further study of the relationships among neurocognitive processes, patient activation, and health-related quality of life is needed and reinforces previous work demonstrating the association between patient activation and self-reported outcomes.

Development of a novel observer reported outcome tool as the primary efficacy outcome measure for a rare disease randomized controlled trial.

We developed an Observer-Reported Outcome (ObsRO) survey instrument to be applied in a multicenter, placebo-controlled, crossover randomized controlled trial of dichloroacetate in children with pyruvate dehydrogenase complex deficiency. The instrument quantifies a subject's at-home level of functionality, as reported by a parent/caregiver, who were instrumental in providing the clinical descriptors and domains that formed the instrument's content. Feasibility testing of the ObsRO tool showed it to be easy to use and comprehensive in capturing the major clinical functional limitations of affected children and requires less than 5min for a parent/caregiver to complete daily.

The Opportunity for Post-Copulatory Sexual Selection in the Ectoparasitic Pea Crab, Dissodactylus primitivus (Brachyura: Pinnotheridae).

Pea crabs, Dissodactylus primitivus, inhabit multiple echinoid (heart urchin) hosts. Male and female crabs move among hosts in search for mates, and both sexes mate multiple times, creating opportunities for post-copulatory sexual selection. For such selection to occur, only a fraction of the males who succeed in mating can also succeed in siring progeny. Jossart et al. 2014 used 4 microsatellite loci to document parentage and mating frequencies of both sexes in D. primitivus. From these data we identified the mean and variance in female offspring numbers, as well as the proportions of the female population that were gravid and not bearing offspring. We next identified the proportions of the male population who had (1) mated and sired offspring, (2) mated but failed to sire offspring, and (3) failed to mate altogether. We used these results to estimate the opportunity for selection on males and females in terms of mate numbers and offspring numbers, and estimated the sex difference in the opportunity for selection (i.e., the opportunity for sexual selection) using both forms of data. We then partitioned the total variance in male fitness into pre- and post-copulatory components and identified the fraction of the total opportunity for selection occurring in each context. Our results show that the opportunity for selection on each sex was of similar magnitude (0.69-0.98), consistent with this polyandrogynous mating system. We also found that 37% of the total opportunity for sexual selection on males occurred within the context of post-copulatory sexual selection. However, the fraction of the total opportunity for selection that was due to sexual selection, estimated using both mate numbers and offspring numbers, was 9% and 23% respectively. Thus, we further reduced our estimate of the opportunity for post-copulatory sexual selection in D. primitivus to less than 10% of the total opportunity for selection (0.37 of 0.09 and 0.23 = 0.03 and 0.09). Our results provide the first estimate of the maximum possible strength of post-copulatory sexual selection in crustaceans using this approach.

Sex differences in alcohol-related neurobehavioral consequences.

In this chapter, we review existing research regarding sex differences in alcohol's effects on neurobehavioral functions/processes. Drawn largely from laboratory studies, literature regarding acute alcohol administration and chronic alcohol misuse is explored focusing on commonly employed neuropsychologic domains (e.g., executive function, visuospatial skills, learning and memory, gait and balance), neurophysiologic measures (e.g., electroencephalography and event-related potentials), and structural and functional neuroimaging (e.g., magnetic resonance imaging (MRI), functional MRI, diffusion tensor imaging, positron emission tomography, and magnetic resonance spectroscopy). To provide a historical perspective on the development of these questions, we have included reference to early and more recent research. Additionally, specific biases, knowledge gaps, and continuing controversies are noted.

Acute effects of moderate alcohol on psychomotor, set shifting, and working memory function in older and younger social drinkers.

UNLABELLED: ABSTRACT. OBJECTIVE: Despite substantial attention being paid to the health benefits of moderate alcohol intake as a lifestyle, the acute effects of alcohol on psychomotor and working memory function in older adults are poorly understood. METHOD: The effects of low to moderate doses of alcohol on neurobehavioral function were investigated in 39 older (55-70 years; 15 men) and 51 younger (25-35 years; 31 men) social drinkers. Subjects received one of three randomly assigned doses (placebo, .04 g/dl, or .065 g/dl target breath alcohol concentration). After beverage consumption, they completed the Trail Making Test Parts A and B and a working memory task requiring participants to determine whether probe stimuli were novel or had been presented in a preceding set of cue stimuli. Efficiency of working memory task performance was derived from accuracy and reaction time measures. RESULTS: Alcohol was associated with poorer Trail Making Test Part B performance for older subjects. Working memory task results suggested an Age × Dose interaction for performance efficiency, with older but not younger adults demonstrating alcohol-related change. Directionality of change and whether effects on accuracy or reaction time drove the change depended on the novelty of probe stimuli. CONCLUSIONS: This study replicates previous research indicating increased susceptibility of older adults to moderate alcohol-induced psychomotor and set-shifting impairment and suggests such susceptibility extends to working memory performance. Further research using additional tasks and assessing other neuropsychological domains is needed. (J. Stud. Alcohol Drugs, 75, 870-879, 2014).

Neurophysiological correlates of moderate alcohol consumption in older and younger social drinkers.

BACKGROUND: Nearly 40% of adults aged 65 and older in the United States consume alcohol. Research in older adults has largely examined potential health effects of a moderate drinking lifestyle. Examination of acute effects in this population is generally lacking. To investigate alcohol-induced alteration of electrophysiological correlates of attention in this population, we employed a covert attentional task. We hypothesized that moderate alcohol administration as well as older age would reduce P3 amplitude and increase latency. We anticipated an interaction such that, relative to their age-matched controls, older adults receiving alcohol would be more affected than their younger counterparts. METHODS: Participants included healthy older (aged 50 to 67; n = 20; 9 men) and younger (aged 25 to 35; n = 12; 5 men) moderate drinkers. Participants received either a moderate dose of alcohol (breath alcohol concentration ~50 mg/dl) or a placebo beverage. Following absorption, the task was administered and neurophysiological measures were obtained. P3 amplitude and latency were separately subjected to ANOVA across cue conditions using age and dose as independent variables. RESULTS: As predicted, P3 amplitude in older adults was significantly lower than in younger adults across cue conditions. An age by alcohol interaction was detected, revealing that older adults receiving alcohol showed lower P3 amplitudes than any other group. An age effect for P3 latency was found, with older adults having longer latencies than their younger counterparts. A significant age by alcohol interaction for P3 latency was detected, revealing that older adults receiving alcohol displayed delayed P3 latencies relative to older adults receiving placebo. In contrast, younger adults receiving alcohol had reduced latency compared to those receiving placebo, although this effect did not reach significance. CONCLUSIONS: Results suggest that older adults demonstrated alcohol-related shifts in P3 characteristics during an intentional attention task, whereas younger adults failed to demonstrate this pattern.

Differential effects of moderate alcohol consumption on performance among older and younger adults.

BACKGROUND: Studies exploring differential effects of acute alcohol consumption on younger and older adults are lacking within the field of alcohol research, especially those using moderate doses. Previous studies addressing this question have tended to use complex behavioral tasks too broad to isolate specific neurocognitive processes affected by both alcohol and aging. Compromises in cognitive efficiency (i.e., the ability to respond both quickly and accurately) have previously been identified in both elderly and acutely intoxicated individuals. METHODS: The present study employed a visual-spatial, 2-choice reaction time (RT) task to evaluate the interactive effects of aging and alcohol on cognitive efficiency. Our primary outcome measure was an efficiency ratio derived from each participant's response accuracy (ACC) and mean RT (%correct/RT). Younger (25 to 35; n = 22) and older (55 to 74; n = 37) participants were randomly assigned to receive either a placebo or moderate alcohol dose intended to produce a peak breath alcohol concentration of 0.04%. Participants performed the task at peak alcohol levels. RESULTS: A significant interaction between age group and dose assignment was observed, F(3, 55) = 4.86, p = 0.03, for the efficiency ratio. Younger participants who received alcohol performed significantly better than did their older counterparts regardless of alcohol condition and despite no differences in performance between the 2 age groups in the placebo condition. Additional correlation analyses between ACC and RT suggested that moderately intoxicated older adults become more accurate as response times increase. This relationship was not observed in older adults in the placebo condition. CONCLUSIONS: These data suggest that healthy individuals exhibit a differential susceptibility to the effects of alcohol depending on their age. Unfortunately, because of the presumed safety of moderate alcohol doses and a lack of studies investigating the interactive effects of acute alcohol consumption and aging, most individuals are unlikely to be aware of this relationship between alcohol consumption and age.

Contrasting behavioral effects of acute nicotine and chronic smoking in detoxified alcoholics.

BACKGROUND: Current literature suggests that acute nicotine administration provides a compensatory mechanism by which alcoholics might alleviate attentional deficits. In contrast, chronic smoking is increasingly recognized as negatively affecting neurobehavioral integrity. These opposing effects have not been simultaneously examined. Thus, we sought to a) extend previous work by exploring the effects of acute nicotine effects on vigilance components of attention and replicate previous findings suggesting that treatment-seeking alcoholics experience benefit to a greater extent than do other groups; and b) to examine the impact of chronic smoking on these tasks and across subgroups. METHODS: Substance abusing participants (N=86) were recruited and subgrouped on the basis of dependency criteria as either alcoholics, alcoholics with co-morbid stimulant dependence, or stimulant dependent individuals. Groups of cigarette-smoking (N=17) and non-smoking (N=22) community controls were recruited as comparison groups. Smoking subjects were assigned a placebo, low, or high dose nicotine patch in a double-blind placebo controlled fashion. Non-smoking controls were administered either a placebo or low dose. Testing occurred after dose stabilization. RESULTS: General linear models indicated greater sensitivity to acute nicotine administration among alcoholics than other groups when controlling for the effect of intensity of smoking history, as reflected by pack-years. Pack-years correlated negatively with performance measures in alcoholics but not stimulant abusing subgroups or smoking controls. Finally, regression analyses demonstrated that pack-years predicted poorer performance only for the alcoholic subgroup. CONCLUSIONS: These results support previous work finding a compensatory effect of acute nicotine administration on attentional performance in alcoholics and reinforce the consideration of recent nicotine use as a confound in neurocognitive studies of alcoholics. Of particular interest is the finding that smoking history as reflected in pack-years predicted poorer performance, but only among alcoholics. Further systematic study of these opposing effects among alcoholics and other groups using a broader array of tasks is needed.

Nicotine effects on immediate and delayed verbal memory after substance use detoxification.

Decrements in verbal memory are commonly reported by detoxified treatment-seeking individuals. Although acute nicotine has been shown to improve attentional performance, its effects on verbal memory in substance abusers have not been addressed. Treatment-seeking alcohol-dependent (ALCs, n = 29; 14 male), illicit-stimulant-dependent (predominantly cocaine; STIMs, n = 25; 15 male), and alcohol- and illicit-stimulant-dependent (ALC/STIMs, n = 50; 35 male) participants with comorbid nicotine dependence were studied. Subjects had been abstinent from their drugs of choice for 41 (±18) days and were in short-term abstinence from tobacco (∼8-10 hours). Subjects received double-blind administration of either transdermal nicotine (high dose: 21/14 mg for men and women, respectively, or low dose: 7 mg) or placebo. The Logical Memory (LM) subtest from the Wechsler Memory Scale-Revised (WMS-R) was used to assess immediate and delayed verbal memory recall. Results indicated that STIMs receiving the high dose of nicotine recalled more words at immediate recall than STIMs who received placebo. Trend level differences were also noted at delayed recall between STIM nicotine and placebo doses. Nicotine failed to impact either recall in alcoholic subgroups. Although not the primary focus, results also revealed differences in the forgetting rates between the groups with the ALC/STIMs demonstrating the steepest forgetting slope. In summary, this study suggests that nicotine effects may be differentially experienced by substance-using subgroups; that nicotine may have a direct effect on memory; and that in considering neurocognitive processes (e.g., encoding vs. retrieval), underlying endpoint indicators (e.g., correct recall) may be critical in predicting outcomes.

Measurement of ethanol in gaseous breath using a miniature gas chromatograph.

We designed and built a novel, miniature gas chromatograph (mGC) to use exhaled breath to estimate blood ethanol concentrations that may offer GC quality sensitivity and specificity, but with portability, reduced size, and decreased cost. We hypothesized that the mGC would accurately estimate the serum ethanol concentration using exhaled breath. Human subjects (n = 8) were dosed with ethanol employing the Widmark criteria, targeting a blood concentration of 0.08 g/dL. Serum and breath samples were collected concurrently over an hour. Ethanol concentrations in serum were measured using a CLIA-approved laboratory. Ethanol concentrations in conventional breath were assayed using a calibrated mGC or Intoxilyzer 400PA. Data were analyzed using Bland-Altman analysis using serum concentrations as a "gold standard". For the mGC, the regression line (correlation coefficient), bias, and 95% limits of agreement were y = 1.013x - 0.009 (r = 0.91), -0.008 g/dL, and -0.031 to 0.016 g/dL, respectively, for 30 specimens. For the Intoxilyzer 400PA, the regression line (correlation coefficient), bias, and 95% limits of agreement were y = 0.599x + 0.008 (r = 0.86), -0.024 g/dL, and -0.049 to 0.002 g/dL, respectively, for 71 specimens with a large magnitude effect. We concluded that the mGC, using exhaled breath, performed well to estimate the serum ethanol concentrations.

Acute alcohol administration and placebo effectiveness in older moderate drinkers: influences on cognitive performance.

OBJECTIVE: Placebo effectiveness and subsequent influence on cognitive performance were investigated in older moderate drinkers (ages 50-69; N = 30; 15 men) following acute alcohol administration. METHOD: Double-blind, placebo-controlled alcohol administration techniques were designed to produce peak breath alcohol concentration levels consistent with an episode of social drinking (approximately 40 mg/100 ml). Cognitive performance, measured via a covert attentional processing task, was assessed. Participants were also asked to rate their perceived levels of intoxication and impairment. RESULTS: The placebo beverage was effective in older moderate drinkers, with 63% of participants who received placebo reporting that they received alcohol. Placebo beverage effectiveness influenced cognitive performance. Participants who received placebo, but reported they received alcohol, demonstrated slower reaction times on the covert attentional processing task, similar to those receiving alcohol. Placebo effects did not influence accuracy on the covert attentional processing task or self-reported measures of intoxication and impairment. As expected, participants who received alcohol had less accuracy on the covert attentional processing task and more self-reported impairment and intoxication than those who received placebo, regardless of placebo effectiveness. CONCLUSIONS: These results suggest that belief of having received a moderate dose of alcohol has an effect on reaction time similar to that of its pharmacological effect in older moderate drinkers. Although placebo effects are not novel, these findings suggest that cognitive processes are differentially affected. The study of moderate doses and more complex real-world tasks is an important next step.

Effects of acute alcohol consumption in older and younger adults: perceived impairment versus psychomotor performance.

OBJECTIVE: Perceived impairment and psychomotor performance following acute alcohol administration in older (ages 50-74, n=42; 22 male) and younger (ages 25-35, n=26; 12 male) adults were investigated in this study. METHOD: Double-blind, placebo-controlled alcohol administration techniques were designed to produce peak levels of breath alcohol concentration consistent with an episode of social drinking (40 mg/100 ml). Behavioral measures (Trail Making Test, Forms A and B), as well as measures of self-reported perceived intoxication and impairment, were administered on the ascending and descending limbs at common time points after beverage ingestion. RESULTS: Results indicated that psychomotor performance differences did not parallel self-reported levels of perceived impairment. Relative to younger adults, older adults exhibited performance deficits on the ascending limb while simultaneously reporting less perceived impairment. Conversely, on the descending limb, older adults who received alcohol reported more perceived impairment than did those who received placebo, although psychomotor performance between these two groups of older drinkers did not differ. For younger participants, a moderate dose of alcohol facilitated performance on the ascending limb; however, these differences were not reflected on the descending limb. CONCLUSIONS: These results reinforce the common knowledge that self-reported measures may not provide an accurate reflection of performance outcomes and, importantly, that older adults may be impaired even under a moderate dose of alcohol, although they may not be aware (i.e., report) of this impairment.

Transdermal nicotine administration and the electroencephalographic activity of substance abusers in treatment.

OBJECTIVES: It is widely recognized that individuals with alcohol or illicit substance abuse disorders often smoke cigarettes. However, few studies have examined the direct effects of nicotine among substance abuse subgroups. The current study examined patterns of electroencephalographic (EEG) activity in alcohol-dependent (AD), stimulant-dependent (StimD), alcohol- and stimulant-dependent (ASD) participants, as well as community controls (CC). All participants were regular smokers. METHODS: After overnight nicotine abstinence, subjects were administered either a high (14 or 21 mg) or low (7mg) dose transdermal nicotine patch. EEG data were collected during a 2 minute eyes open and 5 minute eyes closed baseline recording session, which occurred as part of a larger study of brain electrophysiology. RESULTS: The most interesting finding was a differential pattern of nicotine dose effects by group. EEGs of Controls and ASD participants did not distinguish between high and low nicotine doses; whereas, nicotine administration in the AD and StimD groups resulted in opposite findings across a range of spectral bands. CONCLUSIONS: Although further research is warranted, these results may have implications for the study of smoking cessation and attentional functioning among substance abusers in treatment. These data suggest that nicotine-related changes in neurophysiology may be associated with specific brain areas and/or specific drug histories and reinforce the need for caution in generalizing among such groups.

The role of selected factors in the development and consequences of alcohol dependence.

Gender, family history, comorbid psychiatric and substance use disorders, and age all influence a person's risk for alcoholism. In addition, these factors interact with alcoholism to influence neurocognitive functioning following detoxification. This article examines these factors and considers how they interact with each other. This complexity reinforces the need for both animal and human studies and suggests multiple factors that may be sensitive to differential prevention, intervention, and treatment efforts. Thus, it is imperative that hypothesis-driven research designs be directed to identifying the relative potency of these factors and their interactions.

Dose-dependent cocaine place conditioning and D1 dopamine antagonist effects in male Japanese quail.

The dopamine D1 receptor subtype has been implicated in drug reward processes in mammals. Two experiments investigated whether dose-dependent differences in cocaine conditioned place preference (CPP) would be obtained in an avian species and whether these cocaine effects were mediated by the dopamine D1 antagonist R(+/-)-SCH23390. In Experiment 1, male birds were given intraperitoneal injections of 1, 3, 10, or 30 mg/kg of cocaine hydrochloride, paired with a chamber that contained distinct visual cues. On alternate days, they received saline paired with a chamber containing different visual cues. A CPP test was given after four pairings of cocaine with the distinct chamber. In Experiment 2, 0.0025, 0.025, or 0.25 mg/kg of SCH 23390 or saline was administered 15 min prior to cocaine (3 mg/kg) and placement into the least preferred chamber. CPP was observed at 1, 3, and 10 mg/kg doses of cocaine but not at 30 mg/kg or saline. All doses of SCH 23390 attenuated cocaine-induced CPP. The findings suggest that cocaine administration results in a dose-dependent CPP, and that similar with mammals, it may be mediated by D1 receptors in an avian species. Thus, the avian species may be a beneficial comparative model for drug studies, especially those involving visual cue mechanisms of drug reward.