1. Resource acquisition and allocation are the physiological mechanisms integrating foraging and life-history traits. An understanding of the patterns of acquisition and allocation in different ...environments and organisms is critical to a predictive theory of life history. 2. Here I develop an allocation framework, which provides a template for conceptualizing the interactions among resource acquisition, allocation and life-history traits. The framework describes the process through which food is taken in by an organism at specific life stages, then allocated to growth, survival (including maintenance, defence, dispersal, etc), reproduction and further foraging. 3. I use the allocation framework to examine allocation to life-history traits in insects under both benign and stressful environments. Stressful environments result from resource scarcity or harsh environmental conditions. I consider effects of consistent stress or variable stress across time. 4. Several broad generalizations emerge from empirical studies, viewed in the allocation framework. First, resource congruence, or the requirement for specific nutrient ratios in, for example, eggs, results in different limiting nutrients for each life-history trait. Second, the timing of resource acquisition affects both allocation patterns and the identity of limiting nutrients for a given life-history trait. Third, physiological trade-offs may occur across, not just within, life stages. Fourth, apparent trade-offs may be driven by differences among traits in resource congruence constraints and deleterious effects of excess nutrients on a particular trait. Fifth, allocation response to environmental stress shows age-specific and sex-specific patterns. Sixth, physiological trade-offs are often more pronounced under environmental stress. Finally, even within insects, there is considerable variability in allocation response to environmental stress. We do not yet have sufficiently diverse and thorough case studies to understand why this is so. Studies in the wild, or relating laboratory conditions to wild environments, are also needed. 5. Senescence can also be understood in an allocation framework. The present approach provides a necessary functional basis for understanding patterns of senescence in diverse organisms and environments. 6. The allocation framework fosters a mechanistic understanding of life-history patterns, and the beginning of an understanding of the processes underlying those patterns.
Synthesizing papers from the last two years, I examined generalizations about the fingerprints of climate change on insects' population dynamics and phenology. Recent work shows that populations can ...differ in response to changes in climate means and variances. The part of the thermal niche occupied by an insect population, voltinism, plasticity and adaptation to weather perturbations, and interactions with other species can all exacerbate or mitigate responses to climate change. Likewise, land use change or agricultural practices can affect responses to climate change. Nonetheless, our knowledge of effects of climate change is still biased by organism and geographic region, and to some extent by scale of climate parameter.
Ecology Letters (2012) 15: 502–508 ABSTRACT: Weather drives population dynamics directly, through effects on vital rates, or indirectly, through effects on the population’s competitors, predators or ...prey and thence on vital rates. Indirect effects may include non‐additive interactions with density dependence. Detection of climate drivers is critical to predicting climate change effects, but identification of potential drivers may depend on knowing the underlying mechanisms. For the butterfly Speyeria mormonia, one climate driver, snow melt date, has multiple effects on population growth. Snow melt date in year t has density‐dependent indirect effects. Through frost effects, early snow melt decreases floral resources, thence per‐capita nectar availability, which determines fecundity in the lab. Snow melt date in year t + 1 has density‐independent direct effects. These effects explain 84% of the variation in population growth rate. One climate parameter thus has multiple effects on the dynamics of a species with non‐overlapping generations, with one effect not detectable without understanding the underlying mechanism.
In light of the large number of studies published since the 2004 update of Schizophrenia Patient Outcomes Research Team psychopharmacological treatment recommendations, we conducted an extensive ...literature review to determine whether the current psychopharmacological treatment recommendations required revision and whether there was sufficient evidence to warrant new treatment recommendations for prespecified outcomes of interest. We reviewed over 400 articles, which resulted in 16 treatment recommendations: the revision of 11 previous treatment recommendations and 5 new treatment recommendations. Three previous treatment recommendations were eliminated. There were 13 interventions and/or outcomes for which there was insufficient evidence for a treatment recommendation, and a statement was written to summarize the current level of evidence and identify important gaps in our knowledge that need to be addressed. In general, there was considerable consensus among the Psychopharmacology Evidence Review Group and the expert consultants. Two major areas of contention concerned whether there was sufficient evidence to recommend specific dosage ranges for the acute and maintenance treatment of first-episode and multi-episode schizophrenia and to endorse the practice of switching antipsychotics for the treatment of antipsychotic-related weight gain. Finally, there continue to be major gaps in our knowledge, including limited information on (1) the use of adjunctive pharmacological agents for the treatment of persistent positive symptoms or other symptom domains of psychopathology, including anxiety, cognitive impairments, depressive symptoms, and persistent negative symptoms and (2) the treatment of co-occurring substance or medical disorders that occur frequently in individuals with schizophrenia.
Roughly 90% of butterfly species live in the tropics. Despite this, we know very little about tropical butterfly ecology particularly when compared to temperate butterfly systems. The relative ...scarcity of data on tropical butterfly populations hampers our ability to effectively conserve them. In this review we summarize recurring themes from ecological research on tropical butterflies to serve as a framework for understanding their conservation. Key themes include: (1) the tropics represent the evolutionary origins of butterfly diversity, (2) while some tropical butterflies exhibit relatively stable population dynamics, longer-lived adult stages, and more continuous age-specific reproduction compared to temperate zone species, the generality of these patterns is debatable, and (3) complex species interactions (e.g. mimicry, parasitism and predation) can have significantly greater influences on ecological and evolutionary processes in tropical butterflies than in temperate ones. This state of ecological knowledge, combined with scarce resources, has traditionally constrained tropical butterfly conservation efforts to habitat level approaches, unlike the species- and population-specific approaches familiar in North America and Europe. Consequently, much conservation research on butterflies in the tropics has focused on the relationship between habitat quality (e.g. forest fragmentation) and butterfly diversity, though predictive patterns even in this regard remain elusive. We argue that with the increasing threats of habitat destruction, fragmentation and climate change, it is necessary to move beyond this diversity and habitat relationship if we are to improve predictive capabilities when evaluating anthropogenic impacts on tropical butterfly communities. Tropical butterflies are more than just useful indicator species. They represent some of the most spectacular and visually appealing organisms in the world and play many vital roles in tropical ecosystems. We hope that this synthesis will lay the groundwork for future ecological studies of tropical butterfly populations, species, communities and conservation.
Allocation of larval food resources affects adult morphology and fitness in holometabolous insects. Here we explore the effects on adult morphology and female fitness of larval semi-starvation in the ...butterfly Speyeria mormonia. Using a split-brood design, food intake was reduced by approximately half during the last half of the last larval instar. Body mass and forewing length of resulting adults were smaller than those of control animals. Feeding treatment significantly altered the allometric relationship between mass and wing length for females but not males, such that body mass increased more steeply with wing length in stressed insects as compared to control insects. This may result in changes in female flight performance and cost. With regard to adult life history traits, male feeding treatment or mating number had no effect on female fecundity or survival, in agreement with expectations for this species. Potential fecundity decreased with decreasing body mass and relative fat content, but there was no independent effect of larval feeding treatment. Realized fecundity decreased with decreasing adult survival, and was not affected by body mass or larval feeding treatment. Adult survival was lower in insects subjected to larval semi-starvation, with no effect of body mass. In contrast, previous laboratory studies on adult nectar restriction showed that adult survival was not affected by such stress, whereas fecundity was reduced in direct 11 proportion to the reduction of adult food. We thus see a direct impact of larval dietary restriction on survival, whereas fecundity is affected by adult dietary restriction, a pattern reminiscent of a survival/reproduction trade-off, but across a developmental boundary. The data, in combination with previous work, thus provide a picture of the intra-specific response of a suite of traits to ecological stress.
Movement uses resources that may otherwise be allocated to somatic maintenance or reproduction. How does increased energy expenditure affect resource allocation? Using the butterfly Speyeria ...mormonia, we tested whether experimentally increased flight affects fecundity, lifespan or flight capacity. We measured body mass (storage), resting metabolic rate and lifespan (repair and maintenance), flight metabolic rate (flight capacity), egg number and composition (reproduction), and food intake across the adult lifespan. The flight treatment did not affect body mass or lifespan. Food intake increased sufficiently to offset the increased energy expenditure. Total egg number did not change, but flown females had higher early-life fecundity and higher egg dry mass than control females. Egg dry mass decreased with age in both treatments. Egg protein, triglyceride or glycogen content did not change with flight or age, but some components tracked egg dry mass. Flight elevated resting metabolic rate, indicating increased maintenance costs. Flight metabolism decreased with age, with a steeper slope for flown females. This may reflect accelerated metabolic senescence from detrimental effects of flight. These effects of a drawdown of nutrients via flight contrast with studies restricting adult nutrient input. There, fecundity was reduced, but flight capacity and lifespan were unchanged. The current study showed that when food resources were abundant, wing-monomorphic butterflies living in a continuous meadow landscape resisted flight-induced stress, exhibiting no evidence of a flight-fecundity or flight-longevity trade-off. Instead, flight changed the dynamics of energy use and reproduction as butterflies adopted a faster lifestyle in early life. High investment in early reproduction may have positive fitness effects in the wild, as long as food is available. Our results help to predict the effect of stressful conditions on the life history of insects living in a changing world.
New interactions with non-native species can alter selection pressures on native species. Here, we examined the effect of the spatial distribution of a non-native species, a factor that determines ...ecological and evolutionary outcomes but that is poorly understood, particularly on a fine scale. Specifically, we explored a native butterfly population and a non-native plant on which the butterfly oviposits despite the plant's toxicity to larvae. We developed an individual-based model to describe movement and oviposition behaviors of each butterfly, which were determined by plant distribution and the butterfly's host preference genotype. We estimated the parameter values of the model from rich field data. We simulated various patterns of plant distributions and compared the rates of butterfly population growth and changes in the allele frequency of oviposition preference. Neither the number nor mean area of patches of non-native species affected the butterfly population, whereas plant abundance, patch shape, and distance to the nearest native and non-native patches altered both the population dynamics and genetics. Furthermore, we found a dramatic decrease in population growth rates when we reduced the distance to the nearest native patch from 147 m to 136 m. Thus changes in the non-native resource distribution that are critical to the fate of the native herbivore could only be detected at a fine-grained scale that matched the scale of a female butterfly's movement. In addition, we found that the native butterfly population was unlikely to be rescued by the exclusion of the allele for acceptance of the non-native plant as a host. This study thus highlights the importance of including both ecological and evolutionary dynamics in analyses of the outcome of species interactions and provides insights into habitat management for non-native species.
Cathinone derivatives (bath salts) have emerged as the latest drugs of abuse. 3,4‐methylenedioxypyrovalerone (MDPV) is the primary active ingredient in bath salts used in this country. This article ...presents the second reported cause of death by MDPV intoxication alone. In April 2011, a delusional man was emergently brought to a hospital, where he self‐reported bath salt usage. He became agitated, developed ventricular tachycardia, hyperthermia, and died. Comprehensive alcohol and drug testing was performed. Using the alkaline drug screen, heart blood contained 0.7 mg/L MDPV and peripheral blood contained 1.0 mg/L MDPV. His bizarre behavior with life‐threatening hyperthermia was consistent with an MDPV‐induced excited delirium state. MDPV is not yet found by routine immunoassay toxicology screens. Testing for MDPV should be considered in cases with a history of polysubstance abuse with stimulant type drugs, report of acute onset of psychogenic symptoms, excited delirium syndrome, or presentation in a hyperthermic state.
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