Marsupial position on life-history continua and the potential contribution of life-history traits to population growth.

Previous studies have suggested that mammal life history varies along the fast-slow continuum and that, in eutherians, this continuum is linked to variation in the potential contribution of survival and reproduction to population growth rate (λ). Fast eutherians mature early, have large litters and short lifespans, and exhibit high potential contribution of age at first reproduction and fertility to λ, while slow eutherians show high potential contribution of survival to λ. However, marsupials have typically been overlooked in comparative tests of mammalian life-history evolution. Here, we tested whether the eutherian life-history pattern extends to marsupials, and show that marsupial life-history trade-offs are organized along two major axes: (i) the reproductive output and dispersion axis, and (ii) the fast-slow continuum, with an additional association between adult survival and body mass. Life-history traits that potentially drive changes in λ are similar in eutherians and marsupials with slow life histories, but differ in fast marsupials; age at first reproduction is the most important trait contributing to λ and fertility contributes little. Marsupials have slower life histories than eutherians, and differences between these clades may derive from their contrasting reproductive modes; marsupials have slower development, growth and metabolism than eutherians of equivalent size.

Modeling mammal response to fire based on species' traits.

Fire has shaped ecological communities worldwide for millennia, but impacts of fire on individual species are often poorly understood. We performed a meta-analysis to predict which traits, habitat, or study variables and fire characteristics affect how mammal species respond to fire. We modeled effect sizes of measures of population abundance or occupancy as a function of various combinations of these traits and variables with phylogenetic least squares regression. Nine of 115 modeled species (7.83%) returned statistically significant effect sizes, suggesting most mammals are resilient to fire. The top-ranked model predicted a negative impact of fire on species with lower reproductive rates, regardless of fire type (estimate = -0.68), a positive impact of burrowing in prescribed fires (estimate = 1.46) but not wildfires, and a positive impact of average fire return interval for wildfires (estimate = 0.93) but not prescribed fires. If a species' International Union for Conservation of Nature Red List assessment includes fire as a known or possible threat, the species was predicted to respond negatively to wildfire relative to prescribed fire (estimate = -2.84). These findings provide evidence of experts' abilities to predict whether fire is a threat to a mammal species and the ability of managers to meet the needs of fire-threatened species through prescribed fire. Where empirical data are lacking, our methods provide a basis for predicting mammal responses to fire and thus can guide conservation actions or interventions in species or communities.

Modelos de las respuestas de los mamíferos a los incendios basados en las características de la especie Resumen Durante milenios, los incendios han moldeado a las comunidades ecológicas en todo el mundo y aun así conocemos muy poco sobre el impacto que tienen sobre cada especie. Realizamos un metaanálisis para predecir cuáles características, hábitat o variable de estudio en conjunto con las características del incendio afectan la respuesta de los mamíferos ante este fenómeno. Usamos para modelar los tamaños del efecto de las medidas de la abundancia poblacional o la ocupación como función de varias combinaciones de estas características y variables mediante una regresión filogenética por mínimos cuadrados. Nueve de las 115 especies modeladas (7.83%) devolvieron tamaños del efecto con importancia estadística, lo que sugiere que la mayoría de los mamíferos son resilientes a los incendios. El modelo mejor clasificado pronosticó un impacto negativo de los incendios sobre las especies con tasas reproductivas más bajas, sin importar el tipo de incendio (estimado = -0.68); un impacto positivo de las madrigueras durante las quemas prescritas (estimado = 1.46) pero no durante los incendios forestales; y un impacto positivo del intervalo promedio de rendimiento del incendio para los incendios forestales (estimado = 0.93) pero no para las quemas prescritas. Si la valoración de una especie en la Lista Roja de la Unión Internacional para la Conservación de la Naturaleza incluye a los incendios como una amenaza conocida o posible, pronosticamos que la especie respondería negativamente a los incendios forestales con relación a la quema prescrita (estimado = -2.84). Estos hallazgos proporcionan evidencia de la habilidad que tienen los expertos para predecir si los incendios son una amenaza para los mamíferos y la habilidad de los gestores para cumplir con las necesidades de las especies amenazadas por incendios por medio de las quemas prescritas. En caso de que falte información empírica, nuestros métodos proporcionan una base para predecir las respuestas de los mamíferos a los incendios y así orientar a las acciones o intervenciones de conservación para una especie o comunidad.

Population genomics of a predatory mammal reveals patterns of decline and impacts of exposure to toxic toads.

Mammal declines across northern Australia are one of the major biodiversity loss events occurring globally. There has been no regional assessment of the implications of these species declines for genomic diversity. To address this, we conducted a species-wide assessment of genomic diversity in the northern quoll (Dasyurus hallucatus), an Endangered marsupial carnivore. We used next generation sequencing methods to genotype 10,191 single nucleotide polymorphisms (SNPs) in 352 individuals from across a 3220-km length of the continent, investigating patterns of population genomic structure and diversity, and identifying loci showing signals of putative selection. We found strong heterogeneity in the distribution of genomic diversity across the continent, characterized by (i) biogeographical barriers driving hierarchical population structure through long-term isolation, and (ii) severe reductions in diversity resulting from population declines, exacerbated by the spread of introduced toxic cane toads (Rhinella marina). These results warn of a large ongoing loss of genomic diversity and associated adaptive capacity as mammals decline across northern Australia. Encouragingly, populations of the northern quoll established on toad-free islands by translocations appear to have maintained most of the initial genomic diversity after 16 years. By mapping patterns of genomic diversity within and among populations, and investigating these patterns in the context of population declines, we can provide conservation managers with data critical to informed decision-making. This includes the identification of populations that are candidates for genetic management, the importance of remnant island and insurance/translocated populations for the conservation of genetic diversity, and the characterization of putative evolutionarily significant units.

Creativity, leisure activities, social engagement and cognitive impairment: the AGES-Reykjavík study.

BACKGROUND: Participation in leisure activities and extensive social network have been associated with lower risk of cognitive impairment (CI) and dementia. AIMS: We examined whether leisure activities (cognitive solitary, cognitive group, social, physical, or creative activities) and social involvement are associated with less incidence of CI or dementia. METHODS: Analyses were performed from data of 2933 cognitively intact individuals at baseline included in the AGES-REYKJAVIK study. Odds ratios (OR) were calculated for incident CI and dementia in relation to cognitive individual, cognitive group, social, physical, and creative leisure activities as well as social networks. Models were adjusted for a number of known risk factors for cognitive decline. RESULTS: In 5 years, 12% of the cohort were diagnosed with CI or dementia. All leisure activities were associated with reduced likelihood of cognitive decline in the raw model, but in adjusted models, cognitive solitary [OR 0.49 (Confidence Interval (CI) 0.38-0.64)], cognitive group [OR 0.50 (CI 0.30-0.82)], and creative activities [OR 0.53 (CI 0.35-0.83)] were significantly associated with less cognitive decline. Analyses examining creative leisure activities independently, controlling for all other activities, suggested individuals participating in creative activities exhibited less CI [OR 0.64 (CI 0.41-0.98)]. Among social networks variables, frequency of meeting with friends and relatives was associated with reduced likelihood of CI [OR 0.49 (CI 0.31-0.75)]. DISCUSSION: Cognitive and creative leisure activities and frequent gatherings with friends and relatives are associated with reduced incidence of CI in this older cohort. CONCLUSION: Creative leisure activities might have special benefit for cognitive ability.

Ecological generalism and resilience of tropical island mammals to logging: A 23 year test.

Tropical forest disturbance is a key driver of global biodiversity decline. On continents, the effects of logging are greatest on endemic species, presumably because disturbance is more likely to cover narrower distributions (the "cookie cutter" model). Islands hold disproportionate biodiversity, and are subject to accelerating biotic homogenization, where specialist endemics are lost while generalists persist. We tested responses of tropical island mammals to logging at multiple spatial scales, using a long-term experimental test in a Pacific archipelago. The most widely distributed ecological generalists did not decline after logging, and we detected no overall changes in relative abundance or species diversity. However, endemics with small ranges did decline in response to logging. The least mobile and most range-restricted species declined even at the smallest spatial scale, supporting the cookie cutter model for sedentary species, and suggesting that habitat change due to selective logging is contributing to biotic homogenization on islands.

Range-wide genetic structure of a cooperative mouse in a semi-arid zone: Evidence for panmixia.

Landscape topography and the mobility of individuals will have fundamental impacts on a species' population structure, for example by enhancing or reducing gene flow and therefore influencing the effective size and genetic diversity of the population. However, social organization will also influence population genetic structure. For example, species that live and breed in cooperative groups may experience high levels of inbreeding and strong genetic drift. The western pebble-mound mouse (Pseudomys chapmani), which occupies a highly heterogeneous, semi-arid landscape in Australia, is an enigmatic social mammal that has the intriguing behaviour of working cooperatively in groups to build permanent pebble mounds above a subterranean burrow system. Here, we used both nuclear (microsatellite) and mitochondrial (mtDNA) markers to analyse the range-wide population structure of western pebble-mound mice sourced from multiple social groups. We observed high levels of genetic diversity at the broad scale, very weak genetic differentiation at a finer scale and low levels of inbreeding. Our genetic analyses suggest that the western pebble-mound mouse population is both panmictic and highly viable. We conclude that high genetic connectivity across the complex landscape is a consequence of the species' ability to permeate their environment, which may be enhanced by "boom-bust" population dynamics driven by the semi-arid climate. More broadly, our results highlight the importance of sampling strategies to infer social structure and demonstrate that sociality is an important component of population genetic structure.

Hand and knee osteoarthritis are associated with reduced diameters in retinal vessels: the AGES-Reykjavik study.

To investigate the association between osteoarthritis (OA) and microvascular pathology, we examined the relationship between retinal microvascular caliber and osteoarthritis of the hand and knee in an elderly population. The AGES-Reykjavik is a population-based, multidisciplinary longitudinal cohort study of aging. Retinal vessel caliber, hand osteoarthritis and total knee joint replacements due to OA were examined in 4757 individuals (mean age 76 ± 5 years; 57% female). Incident knee joint replacements during 5-year follow-up (n = 2961, mean age 75 ± 5 years; 58% female) were also assessed. Logistic regression analysis, adjusting for age, sex, and body mass index, showed an association between narrow arteriolar caliber and hand OA, as well as knee replacement. After adjustment for other covariates, including statin therapy, this association was significant for both hand OA in men and women [OR 1.10(1.03-1.17), p < 0.01] (per unit standard deviation decrease in CRAE) and TKR prevalence [OR 1.15 (1.01-1.32), p = 0.04], especially for men [OR 1.22 (1.00-1.51) p = 0.04] and also for incident TKRs in men [OR 1.50 (1.07-2.10), p = 0.04]. Narrow venular caliber was associated with hand OA in women [OR 1.10 (1.01-1.21), p = 0.03]. Retinal arterial narrowing in hand and knee OA is present in males as well as females. Venular narrowing in hand OA in women was an unexpected finding and is in contrast with the venular widening usually observed in cardiovascular diseases.

Prey productivity and predictability drive different axes of life-history variation in carnivorous marsupials.

Variation in life-history strategies has usually been characterized as a single fast-slow continuum of life-history variation, in which mean lifespan increases with age at maturity as reproductive output at each breeding event declines. Analyses of plants and animals suggest that strategies of reproductive timing can vary on an independent axis, with iteroparous species at one extreme and semelparous species at the other. Insectivorous marsupials in the Family Dasyuridae have an unusually wide range of life-history strategies on both purported axes. We test and confirm that reproductive output and degree of iteroparity are independent in females across species. Variation in reproductive output per episode is associated with mean annual rainfall, which predicts food availability. Position on the iteroparity-semelparity axis is not associated with annual rainfall, but species in regions of unpredictable rainfall have longer maximum lifespans, more potential reproductive events per year, and longer breeding seasons. We suggest that these two axes of life-history variation arise because reproductive output is limited by overall food availability, and selection for high offspring survival favours concentrated breeding in seasonal environments. Longer lifespans are favoured when reproductive opportunities are dispersed over longer periods in environments with less predictable food schedules.

Surface friction alters the agility of a small Australian marsupial.

Movement speed can underpin an animal's probability of success in ecological tasks. Prey often use agility to outmanoeuvre predators; however, faster speeds increase inertia and reduce agility. Agility is also constrained by grip, as the foot must have sufficient friction with the ground to apply the forces required for turning. Consequently, ground surface should affect optimum turning speed. We tested the speed-agility trade-off in buff-footed antechinus (Antechinus mysticus) on two different surfaces. Antechinus used slower turning speeds over smaller turning radii on both surfaces, as predicted by the speed-agility trade-off. Slipping was 64% more likely on the low-friction surface, and had a higher probability of occurring the faster the antechinus were running before the turn. However, antechinus compensated for differences in surface friction by using slower pre-turn speeds as their amount of experience on the low-friction surface increased, which consequently reduced their probability of slipping. Conversely, on the high-friction surface, antechinus used faster pre-turn speeds in later trials, which had no effect on their probability of slipping. Overall, antechinus used larger turning radii (0.733±0.062 versus 0.576±0.051 m) and slower pre-turn (1.595±0.058 versus 2.174±0.050 m s-1) and turning speeds (1.649±0.061 versus 2.01±0.054 m s-1) on the low-friction surface. Our results demonstrate the interactive effect of surface friction and the speed-agility trade-off on speed choice. To predict wild animals' movement speeds, future studies should examine the interactions between biomechanical trade-offs and terrain, and quantify the costs of motor mistakes in different ecological activities.

Extinct or still out there? Disentangling influences on extinction and rediscovery helps to clarify the fate of species on the edge.

Each year, two or three species that had been considered to be extinct are rediscovered. Uncertainty about whether or not a species is extinct is common, because rare and highly threatened species are difficult to detect. Biological traits such as body size and range size are expected to be associated with extinction. However, these traits, together with the intensity of search effort, might influence the probability of detection and extinction differently. This makes statistical analysis of extinction and rediscovery challenging. Here, we use a variant of survival analysis known as cure rate modelling to differentiate factors that influence rediscovery from those that influence extinction. We analyse a global data set of 99 mammals that have been categorized as extinct or possibly extinct. We estimate the probability that each of these mammals is still extant and thus estimate the proportion of missing (presumed extinct) mammals that are incorrectly assigned extinction. We find that body mass and population density are predictors of extinction, and body mass and search effort predict rediscovery. In mammals, extinction rate increases with body mass and population density, and these traits act synergistically to greatly elevate extinction rate in large species that also occurred in formerly dense populations. However, when they remain extant, larger-bodied missing species are rediscovered sooner than smaller species. Greater search effort increases the probability of rediscovery in larger species of missing mammals, but has a minimal effect on small species, which take longer to be rediscovered, if extant. By separating the effects of species characteristics on extinction and detection, and using models with the assumption that a proportion of missing species will never be rediscovered, our new approach provides estimates of extinction probability in species with few observation records and scant ecological information.

Minimizing species extinctions through strategic planning for conservation fencing.

Conservation fences are an increasingly common management action, particularly for species threatened by invasive predators. However, unlike many conservation actions, fence networks are expanding in an unsystematic manner, generally as a reaction to local funding opportunities or threats. We conducted a gap analysis of Australia's large predator-exclusion fence network by examining translocation of Australian mammals relative to their extinction risk. To address gaps identified in species representation, we devised a systematic prioritization method for expanding the conservation fence network that explicitly incorporated population viability analysis and minimized expected species' extinctions. The approach was applied to New South Wales, Australia, where the state government intends to expand the existing conservation fence network. Existing protection of species in fenced areas was highly uneven; 67% of predator-sensitive species were unrepresented in the fence network. Our systematic prioritization yielded substantial efficiencies in that it reduced expected number of species extinctions up to 17 times more effectively than ad hoc approaches. The outcome illustrates the importance of governance in coordinating management action when multiple projects have similar objectives and rely on systematic methods rather than expanding networks opportunistically.

Mortality in Older Persons with Retinopathy and Concomitant Health Conditions: The Age, Gene/Environment Susceptibility-Reykjavik Study.

PURPOSE: To assess the impact of retinopathy on mortality in older persons with concomitant health conditions. DESIGN: Population-based prospective cohort study. PARTICIPANTS: A total of 4966 individuals aged 67 to 96 years (43.2% were male) from the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-RS). METHODS: Retinopathy was evaluated from digital fundus images (2002-2006) using the modified Airlie House adaptation of the Early Treatment Diabetic Retinopathy Study protocol. Mortality was assessed through September 2013 (cause of death assigned through 2009). Cox proportional hazards regression models, with age as the time scale, estimated the association between retinopathy and death while controlling for risk factors and the presence of concomitant health conditions. MAIN OUTCOME MEASURES: Mortality from all causes and cardiovascular disease (CVD). RESULTS: Among the 4966 participants, 503 (10.1%) had diabetes and 614 (12.4%) had retinopathy at baseline. A subset of these (136 [2.7%]) had both diabetes and retinopathy. After a median follow-up of 8.6 years, 1763 persons died, 276 (45.0%) with retinopathy and 1487 (34.2%) without retinopathy, of whom 76 and 162 persons, respectively, also had diabetes. There were 366 deaths from CVD through 2009, 72 (11.7%) in persons with retinopathy and 294 (6.8%) in those without retinopathy. In multivariable analyses, retinopathy was significantly associated with all-cause mortality (hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.10-1.43; P < 0.01) and CVD-related mortality (HR, 1.57; 95% CI, 1.20-2.06; P < 0.01). Findings were more striking in men: all-cause HR, 1.33 (95% CI, 1.11-1.60) and CVD HR, 1.81 (95% CI, 1.25-2.63). Risk of mortality was further increased among those with retinopathy concomitant with microalbuminuria (all-cause HR, 1.70; 95% CI, 1.03-2.23, and CVD HR, 2.04; 95% CI, 1.27-3.28) and those with retinopathy, microalbuminuria, and diabetes (all-cause HR, 2.01; 95% CI, 1.22-3.31, and CVD HR, 5.24; 95% CI, 1.91-14.42). History of clinical stroke increased the risk of CVD-related mortality among persons with retinopathy (HR, 3.30; 95% CI, 2.05-5.32), particularly those with retinopathy and diabetes (HR, 5.38; 95% CI, 1.80-16.06). CONCLUSIONS: Even minimal retinopathy was a significant predictor of increased mortality in older persons, particularly men, irrespective of diabetes status. Persons with retinopathy may warrant closer clinical management of general health.

Incidence of Age-Related Macular Degeneration in a Multi-Ethnic United States Population: The Multi-Ethnic Study of Atherosclerosis.

PURPOSE: To describe the incidence of age-related macular degeneration (AMD) and associated risk factors in 4 racial/ethnic groups (white, black, Hispanic, and Chinese) residing in the United States. DESIGN: Prospective cohort study. PARTICIPANTS: A total of 3811 participants, aged 46 to 86 years, from the Multi-Ethnic Study of Atherosclerosis (MESA) cohort, with retinal data collected twice, on average, 8 years apart. METHODS: Fundus images, taken using a digital camera through dark-adapted pupils using a standard protocol and the same equipment at both study visits, were graded centrally for early and late AMD on the basis of drusen size, type and area, increased retinal pigment, retinal pigment epithelial depigmentation, neovascular lesions, and geographic atrophy using the modified Wisconsin Age-Related Maculopathy Grading System. Demographic, clinical, and laboratory measures were included in multivariable regression models to determine their impact on the variation in AMD incidence among racial/ethnic groups. MAIN OUTCOME MEASURES: Incident early and late AMD. RESULTS: The overall 8-year age- and sex-standardized incidence of early and late AMD were 4.1% and 2.3%, respectively, with incidence of early and late AMD highest in whites (5.3% and 4.1%, respectively), intermediate in Chinese (4.5% and 2.2%, respectively) and Hispanics (3.3% and 0.8%, respectively), and lowest in blacks (1.6% and 0.4%, respectively). By adjusting for age and sex, blacks had a 70% lower risk of developing early AMD than whites, and this decreased only slightly to a 67% lower risk after multivariable adjustment. By adjusting for age, sex, and race/ethnicity, hyperopia was associated with early AMD (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.04-2.20), as was astigmatism (OR, 1.47; 95% CI, 1.00-2.16), but not myopia (P = 0.29). Age, race/ethnicity, current smoking, hyperopia, and AMD-susceptibility genotypes Complement Factor H (CFH) RS1061170 and Age Related Maculopathy Susceptibility 2 (ARMS2) RS3793917 were independently associated with incident early AMD in multivariable models for the combined sample. However, the only statistically significant factor consistently associated with incident early AMD across the 4 racial/ethnic groups was increasing age. Risk factors for late AMD were not assessed because of its low incidence, particularly across racial/ethnic groups. CONCLUSIONS: Variation in the incidence of early AMD exists among racial/ethnic groups in the United States and is not explained by the clinical, genetic, and environmental factors included in this study.

Sperm competition drives the evolution of suicidal reproduction in mammals.

Suicidal reproduction (semelparity) has evolved in only four genera of mammals. In these insectivorous marsupials, all males die after mating, when failure of the corticosteroid feedback mechanism elevates stress hormone levels during the mating season and causes lethal immune system collapse (die-off). We quantitatively test and resolve the evolutionary causes of this surprising and extreme life history strategy. We show that as marsupial predators in Australia, South America, and Papua New Guinea diversified into higher latitudes, seasonal predictability in abundance of their arthropod prey increased in multiple habitats. More-predictable prey peaks were associated with shorter annual breeding seasons, consistent with the suggestion that females accrue fitness benefits by timing peak energy demands of reproduction to coincide with maximum food abundance. We demonstrate that short mating seasons intensified reproductive competition between males, increasing male energy investment in copulations and reducing male postmating survival. However, predictability of annual prey cycles alone does not explain suicidal reproduction, because unlike insect abundance, peak ovulation dates in semelparous species are often synchronized to the day among years, triggered by a species-specific rate of change of photoperiod. Among species with low postmating male survival, we show that those with suicidal reproduction have shorter mating seasons and larger testes relative to body size. This indicates that lethal effort is adaptive in males because females escalate sperm competition by further shortening and synchronizing the annual mating period and mating promiscuously. We conclude that precopulatory sexual selection by females favored the evolution of suicidal reproduction in mammals.

Age-related macular degeneration and mortality in community-dwelling elders: the age, gene/environment susceptibility Reykjavik study.

OBJECTIVE: To investigate the association between age-related macular degeneration (AMD) and mortality in older persons. DESIGN: Population-based prospective cohort study. PARTICIPANTS: Participants 67 to 96 years of age (43.1% male) enrolled between 2002 and 2006 in the Age, Gene/Environment Susceptibility-Reykjavik Study. METHODS: Retinal photographs of the macula were acquired digitally and evaluated for the presence of AMD lesions using the Wisconsin Age-Related Maculopathy grading scheme. Mortality was assessed prospectively through 2013 with cause of death available through 2009. The association between AMD and death, resulting from any cause and specifically cardiovascular disease (CVD), was examined using Cox proportional hazards regression with age as the time scale, adjusted for significant risk factors and comorbid conditions. To address a violation in the proportional hazards assumption, analyses were stratified into 2 groups based on the mean age at death (83 years). MAIN OUTCOME MEASURES: Mortality resulting from all causes and CVD. RESULTS: Among 4910 participants, after a median follow-up of 8.6 years, 1742 died (35.5%), of whom 614 (35.2%) had signs of AMD at baseline. Cardiovascular disease was the cause of death for 357 people who died before the end of 2009, of whom 144 (40%) had AMD (101 with early disease and 43 with late disease). After considering covariates, including comorbid conditions, having early AMD at any age or having late AMD in individuals younger than 83 years (n = 4179) were not associated with all-cause or CVD mortality. In individuals 83 years of age and older (n = 731), late AMD was associated significantly with increased risk of all-cause mortality (hazard ratio [HR], 1.76; 95% confidence interval [CI], 1.20-2.57) and CVD-related mortality (HR, 2.37; 95% CI, 1.41-3.98). In addition to having AMD, older individuals who died were more likely to be male and to have low body mass index, impaired cognition, and microalbuminuria. CONCLUSIONS: Competing risk factors and concomitant conditions are important in determining mortality risk resulting from AMD. Individuals with early AMD are not more likely to die than peers of comparable age. Late AMD becomes a predictor of mortality by the mid-octogenarian years.

Eastern equine encephalitis virus in mice I: clinical course and outcome are dependent on route of exposure.

BACKGROUND: Eastern equine encephalitis virus (EEEV), an arbovirus, is an important human and veterinary pathogen belonging to one of seven antigenic complexes in the genus Alphavirus, family Togaviridae. EEEV is considered the most deadly of the mosquito-borne alphaviruses due to the high case fatality rate associated with clinical infections, reaching up to 75 % in humans and 90 % in horses. In patients that survive acute infection, neurologic sequelae are often devastating. Although natural infections are acquired by mosquito bite, EEEV is also highly infectious by aerosol. This fact, along with the relative ease of production and stability of this virus, has led it to being identified as a potential agent of bioterrorism. METHODS: To characterize the clinical course and outcome of EEEV strain FL93-939 infection, we compared clinical parameters, cytokine expression, viremia, and viral titers in numerous tissues of mice exposed by various routes. Twelve-week-old female BALB/c mice were infected by the intranasal, aerosol, or subcutaneous route. Mice were monitored for clinical signs of disease and euthanized at specified time points (6 hpi through 8 dpi). Blood and tissues were harvested for cytokine analysis and/or viral titer determination. RESULTS: Although all groups of animals exhibited similar clinical signs after inoculation, the onset and severity differed. The majority of those animals exposed by the aerosol route developed severe clinical signs by 4 dpi. Significant differences were also observed in the viral titers of target tissues, with virus being detected in the brain at 6 hpi in the aerosol study. CONCLUSION: The clinical course and outcome of EEEV infection in mice is dependent on route of exposure. Aerosol exposure to EEEV results in acute onset of clinical signs, rapid neuroinvasion, and 100 % mortality.

The evolution of relative brain size in marsupials is energetically constrained but not driven by behavioral complexity.

Evolutionary increases in mammalian brain size relative to body size are energetically costly but are also thought to confer selective advantages by permitting the evolution of cognitively complex behaviors. However, many suggested associations between brain size and specific behaviors - particularly related to social complexity - are possibly confounded by the reproductive diversity of placental mammals, whose brain size evolution is the most frequently studied. Based on a phylogenetic generalized least squares analysis of a data set on the reproductively homogenous clade of marsupials, we provide the first quantitative comparison of two hypotheses based on energetic constraints (maternal investment and seasonality) with two hypotheses that posit behavioral selection on relative brain size (social complexity and environmental interactions). We show that the two behavioral hypotheses have far less support than the constraint hypotheses. The only unambiguous associates of brain size are the constraint variables of litter size and seasonality. We also found no association between brain size and specific behavioral complexity categories within kangaroos, dasyurids, and possums. The largest-brained marsupials after phylogenetic correction are from low-seasonality New Guinea, supporting the notion that low seasonality represents greater nutrition safety for brain maintenance. Alternatively, low seasonality might improve the maternal support of offspring brain growth. The lack of behavioral brain size associates, found here and elsewhere, supports the general 'cognitive buffer hypothesis' as the best explanatory framework of mammalian brain size evolution. However, it is possible that brain size alone simply does not provide sufficient resolution on the question of how brain morphology and cognitive capacities coevolve.

Sex-specific predictors of hearing-aid use in older persons: The age, gene/environment susceptibility - Reykjavik study.

OBJECTIVE: We estimate the prevalence of hearing-aid use in Iceland and identify sex-specific factors associated with use. DESIGN: Population-based cohort study. STUDY SAMPLE: A total of 5172 age, gene/environment susceptibility - Reykjavik study (AGES-RS) participants, aged 67 to 96 years (mean age 76.5 years), who completed air-conduction and pure-tone audiometry. RESULTS: Hearing-aid use was reported by 23.0% of men and 15.9% of women in the cohort, although among participants with at least moderate hearing loss in the better ear (pure-tone average [PTA] of thresholds at 0.5, 1, 2, and 4 kHz ≥ 35 dB hearing level [HL]) it was 49.9% and did not differ by sex. Self-reported hearing loss was the strongest predictor of hearing-aid use in men [OR: 2.68 (95% CI: 1.77, 4.08)] and women [OR: 3.07 (95% CI: 1.94, 4.86)], followed by hearing loss severity based on audiometry. Having diabetes or osteoarthritis were significant positive predictors of use in men, whereas greater physical activity and unimpaired cognitive status were important in women. CONCLUSIONS: Hearing-aid use was comparable in Icelandic men and women with moderate or greater hearing loss. Self-recognition of hearing loss was the factor most predictive of hearing-aid use; other influential factors differed for men and women.

Five-year incidence, progression, and risk factors for age-related macular degeneration: the age, gene/environment susceptibility study.

OBJECTIVE: To investigate the incidence and progression of age-related macular degeneration (AMD) and associated risk factors. DESIGN: Population-based, prospective, cohort study. PARTICIPANTS: We included 2868 participants from the Age Gene/Environment Susceptibility-Reykjavik Study with retinal data at baseline and 5-year follow-up. METHODS: Digital macular photographs were graded for presence of AMD. Participants completed a questionnaire and extensive clinical battery. Biomarkers were assessed. Risk factors for AMD were analyzed using multivariate regression analysis with odds ratios (ORs) and 95% CIs. MAIN OUTCOME MEASURES: We assessed AMD, defined as early or late. RESULTS: Among 2196 participants free of AMD at baseline, 14.9% developed incident AMD. In multivariate models, incident AMD was significantly associated with age (OR per year, 1.14; 95% CI, 1.11-1.17), current smoking (OR, 2.07; 95% CI, 1.38-3.11), former smoking (OR, 1.36; 95% CI, 1.04-1.79), plasma high-density lipoprotein (HDL) cholesterol level (OR, 1.62 per mmol/L; 95% CI, 1.19-2.22), and body mass index (BMI; OR, 1.04 per kg/m(2); 95% CI, 1.01-1.07). Among 563 participants with early AMD at baseline, 22.7% progressed to late AMD (11.0% pure geographic atrophy [GA] and 11.7% exudative AMD). On multivariate analyses, age was significantly associated with progression to GA (OR 1.14; 95% CI, 1.07-1.21) and exudative AMD (OR, 1.08; 95% CI, 1.01-1.14). Adjusting for age, female sex was associated with exudative AMD (OR, 2.10; 95% CI, 1.10-3.98) and plasma HDL cholesterol with GA (OR, 2.03 per mmol/L; 95% CI, 1.02-4.05). CONCLUSIONS: By age 85, 57.4% of participants had signs of AMD. Age, smoking, plasma HDL cholesterol, BMI, and female sex are associated with AMD. Elevated HDL cholesterol is associated with GA development.

Impairments in hearing and vision impact on mortality in older people: the AGES-Reykjavik Study.

OBJECTIVE: to examine the relationships between impairments in hearing and vision and mortality from all-causes and cardiovascular disease (CVD) among older people. DESIGN: population-based cohort study. PARTICIPANTS: the study population included 4,926 Icelandic individuals, aged ≥67 years, 43.4% male, who completed vision and hearing examinations between 2002 and 2006 in the Age, Gene/Environment Susceptibility-Reykjavik Study (AGES-RS) and were followed prospectively for mortality through 2009. METHODS: participants were classified as having 'moderate or greater' degree of impairment for vision only (VI), hearing only (HI), and both vision and hearing (dual sensory impairment, DSI). Cox proportional hazard regression, with age as the time scale, was used to calculate hazard ratios (HR) associated with impairment and mortality due to all-causes and specifically CVD after a median follow-up of 5.3 years. RESULTS: the prevalence of HI, VI and DSI were 25.4, 9.2 and 7.0%, respectively. After adjusting for age, significantly (P < 0.01) increased mortality from all causes, and CVD was observed for HI and DSI, especially among men. After further adjustment for established mortality risk factors, people with HI remained at higher risk for CVD mortality [HR: 1.70 (1.27-2.27)], whereas people with DSI remained at higher risk of all-cause mortality [HR: 1.43 (1.11-1.85)] and CVD mortality [HR: 1.78 (1.18-2.69)]. Mortality rates were significantly higher in men with HI and DSI and were elevated, although not significantly, among women with HI. CONCLUSIONS: older men with HI or DSI had a greater risk of dying from any cause and particularly cardiovascular causes within a median 5-year follow-up. Women with hearing impairment had a non-significantly elevated risk. Vision impairment alone was not associated with increased mortality.