Trade-offs In Energy Allocation Research Articles

Specific dynamic action: the energy cost of digestion or growth?

The physiological processes underlying the post-prandial rise in metabolic rate, most commonly known as the 'specific dynamic action' (SDA), remain debated and controversial. This Commentary examines the SDA response from two opposing hypotheses: (i) the classic interpretation, where the SDA represents the energy cost of digestion, versus (ii) the alternative view that much of the SDA represents the energy cost of growth. The traditional viewpoint implies that individuals with a reduced SDA should grow faster given the same caloric intake, but experimental evidence for this effect remains scarce and inconclusive. Alternatively, we suggest that the SDA reflects an organism's efficacy in allocating the ingested food to growth, emphasising the role of post-absorptive processes, particularly protein synthesis. Although both viewpoints recognise the trade-offs in energy allocation and the dynamic nature of energy distribution among physiological processes, we argue that equating the SDA with 'the energy cost of digestion' oversimplifies the complexities of energy use in relation to the SDA and growth. In many instances, a reduced SDA may reflect diminished nutrient absorption (e.g. due to lower digestive efficiency) rather than increased 'free' energy available for somatic growth. Considering these perspectives, we summarise evidence both for and against the opposing hypotheses with a focus on ectothermic vertebrates. We conclude by presenting a number of future directions for experiments that may clarify what the SDA is, and what it is not.

Molecular fingerprint of gilthead seabream physiology in response to pollutant mixtures in the wild

The increase in trace element concentrations in the aquatic environment due to anthropogenic activities, urges the need for their monitoring and potential toxicity, persistence, bioaccumulation, and biomagnification at different trophic levels. Gilthead seabream is a species of commercial importance in the Mediterranean Sea, both for the aquaculture and fisheries sectors, however very little is known about their trace element contamination accumulation and the resulting effect on their health status. In the present study, 135 juveniles were collected from seven coastal lagoons known to be essential nursery areas for this species. We measured seventeen different inorganic contaminants at the individual level in fish muscle (namely Al, As, Be, Bi, Cd, Cr, Cu, Hg, Li, Ni, Pb, Rb, Sb, Sr, Ti, Tl and Zn). Our results revealed the accumulation of multiple trace elements in individuals and distinct contamination signatures between lagoons which might lead to contrasted quality as nurseries for juveniles of numerous ecologically and economically relevant fish species in addition to seabreams. We further evaluated the potential adverse effect of these complex contamination mixtures on the liver (the main organ implicated in the metabolism of xenobiotics) and red muscle (a highly metabolic organ) using a proteomic approach. Alterations in cellular organization pathways and protein transport were detected in both tissues (albeit they were not similarly regulated). Chromosome organization and telomere maintenance in the liver appeared to be affected by contaminant mixture which could increase mortality, age-related disease risk and shorter lifetime expectancy for these juveniles. Red muscle proteome also demonstrated an upregulation of pathways involved in metabolism in response to contamination which raises the issue of potential energy allocation trade-offs between the organisms’ main functions such as reproduction and growth. This study provides new insights into the cellular and molecular responses of seabreams to environmental pollution and proposed biomarkers of health effects of trace elements that could serve as a starting point for larger-scale biomonitoring programs.

Past energy allocation overwhelms current energy stresses in determining energy allocation trade-offs.

Regeneration of lost appendages is a gradual process in many species, spreading energetic costs of regeneration through time. Energy allocated to the regeneration of lost appendages cannot be used for other purposes and, therefore, commonly elicits energetic trade-offs in biological processes. We used limb loss in the Asian shore crab Hemigrapsus sanguineus to compare the strength of energetic trade-offs resulting from historic limb losses that have been partially regenerated versus current injuries that have not yet been repaired. Consistent with previous studies, we show that limb loss and regeneration results in trade-offs that reduce reproduction, energy storage, and growth. As may be expected, we show that trade-offs in these metrics from historic limb losses far outweigh trade-offs from current limb losses, and correlate directly with the degree of historic limb loss that has been regenerated. As regenerating limbs get closer to their normal size, these historical injuries get harder to detect, despite the continued allocation of additional resources to limb development. Our results demonstrate the importance of and a method for identifying historic appendage losses and of quantifying the amount of regeneration that has already occurred, as opposed to assessing only current injury, to accurately assess the strength of energetic trade-offs in animals recovering from nonlethal injury.

Unpacking the Lifelong Secrets of Little Penguins: Individual Quality, Energy Allocation, and Stochasticity in Defining Fitness.

While the heterogeneity among individuals of a population is more and more documented, questions on the paths through which it arises, particularly whether it is linked to fixed heterogeneity or chance alone, are still widely debated. Here, we tested how individual quality, energy allocation trade-offs and environmental stochasticity define individual fitness. To do so, we simultaneously investigated the contribution of 18 life-history traits to the fitness of breeding little penguins (Eudyptula minor), using a structural equation model. Fitness was highly variable amongst the 162 birds monitored over their entire lifespan. It increased with the individual penguin's ability to increase i) the number of breeding events (i.e. living longer, breeding younger, breeding more often and producing more second clutches), and ii) the breeding success per event through increased foraging performances (i.e. mass gained at sea). While all three processes (stochasticity, individual quality and allocation trade-offs) affected fitness, inter-individual variability in fitness was mainly driven by individual quality, birds consistently breeding earlier in the season and displaying higher foraging efficiency exhibiting higher fitness. Why some birds consistently can perform better at sea and breed earlier remains a question to investigate to understand how selection applies to these traits.

Interspecific insights into direct and indirect effects of acetochlor on interactions between daphnids and microalgae: Toxic, trophic, and grazer-infochemical responses

As the herbicide acetochlor (ACT) affects the plankton food web, this study investigated the effects of ACT and exocrine infochemicals from daphnids (after ACT exposure and/or starvation) on Scenedesmus obliquus growth, as well as the effects of ACT and starvation on life-history traits of Daphnia magna. Filtered secretions from daphnids increased algal ACT tolerance, dependent on different ACT exposure histories and food intake. Endogenous and secretory metabolite profiles of daphnids following ACT and/or starvation appear to be regulated by the fatty acid synthesis pathway and sulfotransferases and were related to energy allocation trade-offs. Oleic acid (OA) and octyl sulfate (OS), screened by secreted and somatic metabolomics, affected algal growth and ACT behavior in the algal culture in opposite ways. Trophic and non-trophic interspecific effects caused by ACT were observed in microalgae-daphnid microcosms, including algal growth inhibition, daphnid starvation, OA down-regulation, and OS up-regulation. Based on these findings, risk assessment of ACT on the freshwater plankton communities should take species interactions into account.

Patterns of energy allocation during energetic scarcity; evolutionary insights from ultra-endurance events

Exercise physiologists and evolutionary biologists share a research interest in determining patterns of energy allocation during times of acute or chronic energetic scarcity. Within sport and exercise science, this information has important implications for athlete health and performance. For evolutionary biologists, this would shed new light on our adaptive capabilities as a phenotypically plastic species.In recent years, evolutionary biologists have begun recruiting athletes as study participants and using contemporary sports as a model for studying evolution. This approach, known as human athletic palaeobiology, has identified ultra-endurance events as a valuable experimental model to investigate patterns of energy allocation during conditions of elevated energy demand, which are generally accompanied by an energy deficit. This energetic stress provokes detectable functional trade-offs in energy allocation between physiological processes. Early results from this modelsuggest thatlimited resources are preferentially allocated to processes which could be considered to confer the greatest immediate survival advantage (including immune and cognitive function). This aligns with evolutionary perspectives regarding energetic trade-offs during periods of acute and chronic energetic scarcity.Here, we discuss energy allocation patterns during periods of energetic stress as an area of shared interest between exercise physiology and evolutionary biology. We propose that, by addressing the ultimate “why” questions, namely why certain traits were selected for during the human evolutionary journey, an evolutionary perspective can complement the exercise physiology literature and provide a deeper insight of the reasons underpinning the body's physiological response to conditions of energetic stress.

Energy allocation shifts from sperm production to self-maintenance at low temperatures in male bats

The ability of animals to produce endogenous heat provides a buffer against environmental changes but also incurs high energetic costs. Especially small endothermic mammals have high energy demands. Some temperate-zone species (heterotherms) regularly use torpor, which slows down their entire metabolism but also potentially delays reproduction, to compensate for this. We used a unique experimental approach to test the consequences of extended low and high ambient temperatures on the trade-off in energy allocation to body mass maintenance, thermoregulation effort and seasonal sexual maturation in temperate zone male bats. We showed that long exposure to low ambient temperature shifts energy allocation away from sexual maturation to self-maintenance and results in a delay of sperm maturation by as much as an entire month. This effect was partially buffered by higher body mass. Heavier bats were able to afford more intensive thermoregulation and consequently speed up maturation. Interestingly, bats at constant high temperatures avoided deep torpor and matured faster than those at low temperatures, but sperm production was also slower than under natural conditions. Our results show that not only low, but also constant high ambient temperatures are detrimental during seasonal sexual maturation and the trade-off between investing into self-maintenance and fitness is a finely tuned compromise.

Energy allocation trade-offs between life-history traits in the Mediterranean sardine: an ecophysiological approach

Since 2008, there has been a major decrease in the numbers of old and large sardines in the Gulf of Lions, which has had a major effect on regional fisheries. A bottom-up process involving a shift in diet towards smaller planktonic prey has been suggested as the main driver of this development. Yet, the reproductive capacities of the sardines have not changed, suggesting potential modifications in energy allocation trade-offs. Whether this could also affect maintenance, in particular at the end of the winter reproductive period, and explain the lower adult survival and the disappearance of older individuals remains unclear. We therefore experimentally investigated the consequences of seasonal food availability (summer vs. winter) on life-history traits and energy allocation trade-offs at the individual and population levels. Our results indicate that food resources during summer had a major effect on energy reserves and growth, limiting the maximum size and body condition reached at the end of reproduction. In addition, food restrictions during growth and/or reproduction periods led to physiological costs mediated by increased oxidative damage. Mediterranean sardines did not show any ability for compensatory growth and did not appear to be capital breeders. Instead, they displayed individual differences in coping with physiological constraints and displayed various life-history strategies regardless of food availability. We highlighted 3 main individual energy allocation strategies: (1) preferential allocation to body condition or (2) to growth, or (3) simultaneous allocation to reproduction and growth. These issues are key, as climate change is expected to favour smaller phytoplankton, which might amplify the deterioration in the condition of pelagic fish.

The energy allocation trade-offs underlying life history traits in hypometabolic strepsirhines and other primates

Life history, brain size and energy expenditure scale with body mass in mammals but there is little conclusive evidence for a correlated evolution between life history and energy expenditure (either basal/resting or daily) independent of body mass. We addressed this question by examining the relationship between primate free-living daily energy expenditure (DEE) measured by doubly labeled water method (n = 18 species), life history variables (maximum lifespan, gestation and lactation duration, interbirth interval, litter mass, age at first reproduction), resting metabolic rate (RMR) and brain size. We also analyzed whether the hypometabolic primates of Madagascar (lemurs) make distinct energy allocation tradeoffs compared to other primates (monkeys and apes) with different life history traits and ecological constraints. None of the life-history traits correlated with DEE after controlling for body mass and phylogeny. In contrast, a regression model showed that DEE increased with increasing RMR and decreasing reproductive output (i.e., litter mass/interbirth interval) independent of body mass. Despite their low RMR and smaller brains, lemurs had an average DEE remarkably similar to that of haplorhines. The data suggest that lemurs have evolved energy strategies that maximize energy investment to survive in the unusually harsh and unpredictable environments of Madagascar at the expense of reproduction.

Mechanisms of possible self-limitation in the invasive Asian shore crab Hemigrapsus sanguineus

Population sizes of invasive species are commonly characterized by boom-bust dynamics, and self-limitation via resource depletion is posited as one factor leading to these boom-bust changes in population size. Yet, while this phenomenon is well-documented in plants, few studies have demonstrated that self-limitation is possible for invasive animal species, especially those that are mobile. Here we examined the invasive Asian shore crab Hemigrapsus sanguineus, a species that reached very high abundances throughout invaded regions of North America, but has recently declined in many of these same regions. We examined the relationship between diet, energy storage, reproduction, and growth in crabs collected from the New Hampshire coast. We show that energy storage and reproduction both increase with diet quality, while growth declines with diet quality. These results suggest that self-limitation may be a contributing factor to the recent declines of H. sanguineus at sites where this invader was once much more abundant. Further, these results suggest a diet-associated tradeoff in energy allocation to different vital rates, with a focus on reproduction when high quality resources are consumed, and a focus instead on growth when poor quality resources are consumed.

Within-host competition drives energy allocation trade-offs in an insect parasitoid.

Organismal body size is an important biological trait that has broad impacts across scales of biological organization, from cells to ecosystems. Size is also deeply embedded in life history theory, as the size of an individual is one factor that governs the amount of available resources an individual is able to allocate to different structures and systems. A large body of work examining resource allocation across body sizes (allometry) has demonstrated patterns of allocation to different organismal systems and morphologies, and extrapolated rules governing biological structure and organization. However, the full scope of evolutionary and ecological ramifications of these patterns have yet to be realized. Here, we show that density-dependent larval competition in a natural population of insect parasitoids (Drino rhoeo: Tachinidae) results in a wide range of body sizes (largest flies are more than six times larger (by mass) than the smallest flies). We describe strong patterns of trade-offs between different body structures linked to dispersal and reproduction that point to life history strategies that differ between both males and females and individuals of different sizes. By better understanding the mechanisms that generate natural variation in body size and subsequent effects on the evolution of life history strategies, we gain better insight into the evolutionary and ecological impacts of insect parasitoids in tri-trophic systems.

Cnaphalocrocis medinalis Moths Decide to Migrate when Suffering Nutrient Shortage on the First Day after Emergence.

Migration is a costly strategy in terms of reproduction output. Competition for limited internal resources leads to physiological management of migration-reproduction trade-offs in energy allocation. Migratory insects must choose to determine to allocate energy into reproduction or migration when confronted insufficient energy supply. Although nutrient shortage is known to stimulate insect migration to escape deteriorating habitat, little is known about when and how migratory insects make decisions when confronted by a nutritional shortage. Here Cnaphalocrocis medinalis (Lepidoptera: Pyralidae), a migratory rice pest in eastern Asia, was used to study the effects of starvation on reproductive traits, behavioral traits and energy allocation. The result showed that one or two days’ starvation before preoviposition did not significantly reduce the fertility (total egg per female laid) and flight capability (flight duration and distance) of both sexes C. medinalis. The preoviposition period was extended significantly only if moths were starved starting on the first day after emergence. Also, take-off percentage of moths starved since their first day increased significantly, and continued to increase even if supplemental nutrients were supplied as honey solution in later days. Moths starved on the first day appeared to allocate or transfer triglycerides into the thorax to maintain the migration process: the quantity of thoracic triglycerides did not differ with age, but abdominal triglycerides decreased with age if starvation continued. These results indicate that the first day post-emergence is a critical period for C. medinalis to decide to migrate or not in response to lack of food. This furthers our understanding of the population dynamics of migratory insects under natural conditions.

Differences in tail feather growth rate in storm-petrels breeding in the Northern and Southern hemisphere: a ptilochronological approach.

Moulting and breeding are costly stages in the avian annual cycle and may impose trade-offs in energy allocation between both stages or in their timing. Here, we compared feather growth rates (FGR) of rectrices in adults between two pairs of small pelagic Procellariiformes species differing in moult-breeding strategies: the European storm-petrel Hydrobates pelagicus and Leach’s storm-petrel Oceanodroma leucorhoa breeding in the Northern Hemisphere (Faroe Islands), showing moult-breeding overlap in tail feathers; and the Wilson’s storm-petrel Oceanites oceanicus and black-bellied storm-petrel Fregetta tropica, breeding in the Southern Hemisphere (South Shetlands), temporally separating moult and breeding. We used ptilochronology (i.e., feather growth bar width) to reconstruct FGR reflecting relative energy availability during moult. Based on previous research, we expected positive correlations between feather length (FL) and FGR. Additionally, we expected to find differences in FGR relative to FL between the moult-breeding strategies, where a relatively higher FGR to FL indicates a higher energy availability for moult. To investigate if energy availability during moult in the studied species is similar to species from other avian orders, we used FGR and FL found in literature (n = 164) and this study. We fitted a phylogenetic generalized least squares (PGLS) model to FGR with FL, group (i.e., Procellariiformes vs. non-Procellariiformes) and the interaction FL * group as predictors. As it has been suggested that Procellariiformes may form two growth bars per 24 h, we fitted the same model but with doubled FGR for Procellariiformes (PGLSadj). The group term was significant in the PGLS model, but was not in the PGLSadj model, confirming this suggestion. Individually predicted FGR by the PGLSadj model based on FL, showed that the Southern species have a significantly higher FGR relative to FL compared to the Northern species. Additionally, we found no correlation between FL and FGR in the Northern species, and a positive correlation between FL and FGR in the Southern species, suggesting differences in the trade-off between feather growth and size between species from both hemispheres. The observed differences between the Northern and Southern species may be caused by different moult-breeding strategies. The Southern species may have had more energy available for moult as they are free from breeding duties during moult, while the Northern species may have had less free energy due to a trade-off in energy allocation between breeding and moulting. Our study shows how different moult-breeding strategies may affect relative nutritional condition or energy allocation during moult of migratory pelagic seabirds.

Prolonged survival out of water is linked to a slow pace of life in a self-fertilizing amphibious fish.

Metabolic rate and life-history traits vary widely both among and within species, reflecting trade-offs in energy allocation, but the proximate and ultimate causes of variation are not well understood. We tested the hypothesis that these trade-offs are mediated by environmental heterogeneity, using isogenic strains of the amphibious fish Kryptolebias marmoratus that vary in the amount of time each can survive out of water. Consistent with pace of life theory, the strain that survived air exposure the longest generally exhibited a 'slow' phenotype, including the lowest metabolic rate, largest scope for metabolic depression, slowest consumption of energy stores and least investment in reproduction under standard conditions. Growth rates were fastest in the otherwise slow strain, however. We then tested for fitness trade-offs between 'fast' and 'slow' strains using microcosms where fish were held either with constant water availability or under fluctuating conditions where water was absent for half of the experiment. Under both conditions the slow strain grew larger and was in better condition, and under fluctuating conditions the slow strain produced more embryos. However, the fast strain had larger adult population sizes under both conditions, indicating that fecundity is not the sole determinant of population size in this species. We conclude that genetically based differences in the pace of life of amphibious fish determine survival duration out of water. Relatively slow fish tended to perform better under conditions of limited water availability, but there was no detectable cost under control conditions. Thus, pace of life differences may reflect a conditionally neutral instead of antagonistic trade-off.

The Energetic Cost of Reproduction and Its Effect on Optimal Life-History Strategies.

Trade-offs in energy allocation between growth, reproduction, and survival are at the core of life-history theory. While age-specific mortality is considered to be the main determinant of the optimal allocation, some life-history strategies, such as delayed or skipped reproduction, may be better understood when also accounting for reproduction costs. Here, we present a two-pool indeterminate grower model that includes survival and energetic costs of reproduction. The energetic cost sets a minimum reserve required for reproduction, while the survival cost reflects increased mortality from low postreproductive body condition. Three life-history parameters determining age-dependent energy allocation to soma, reserve, and reproduction are optimized, and we show that the optimal strategies can reproduce realistic emergent growth trajectories, maturation ages, and reproductive outputs for fish. The model predicts maturation phase shifts along the gradient of condition-related mortality and shows that increased harvesting will select for earlier maturation and higher energy allocation to reproduction. However, since the energetic reproduction cost sets limits on how early an individual can mature, an increase in fitness at high harvesting can only be achieved by diverting most reserves into reproduction. The model presented here can improve predictions of life-history responses to environmental change and human impacts because key life-history traits such as maturation age and size, maximum body size, and size-specific fecundity emerge dynamically.

Evidence for energetic tradeoffs between physical activity and childhood growth across the nutritional transition

Despite broad implications for understanding human life history, energetics, and health, the impact of physical activity on childhood growth remains unclear. Particularly understudied is the effect of secular changes in physical activity on child development. We address these shortcomings using data spanning the transition from traditional to semi-developed economy among Yucatec Maya agriculturalists. Anthropometric and behavioral observation data were collected from children living in a subsistence-based rural community in 1992 and again in 2012 following the introduction of a school and mechanized technologies but minimal overt dietary change. Multiple regression analyses demonstrate dramatic twenty-year transformations in how children spent their time. This behavioral change was associated with large declines in estimated physical activity level (PAL), associated activity energy expenditure savings of several hundred kilocalories/day, and sizable increases in mean height, weight, and triceps skinfold thickness. Controlling for observed frequency of market food consumption, PAL was inversely related to child body size and subcutaneous fat stores and significantly mediated the effects of data collection year on anthropometric indices. These findings indicate that physical activity can considerably influence childhood growth, highlighting the role of energy allocation tradeoffs between physical activity and competing life tasks in shaping patterns of human ontogeny and health.

Trade-offs in a high CO2 habitat on a subsea volcano: condition and reproductive features of a bathymodioline mussel

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 574:49-64 (2017) - DOI: https://doi.org/10.3354/meps12196 Trade-offs in a high CO2 habitat on a subsea volcano: condition and reproductive features of a bathymodioline mussel Giulia S. Rossi1,3,*, Verena Tunnicliffe1,2 1Department of Biology, University of Victoria, Victoria, BC V8W 2Y2, Canada 2School of Earth & Ocean Sciences, University of Victoria, Victoria, BC V8W 2Y2, Canada 3Present address: Department of Integrative Biology, University of Guelph, Guelph, ON N1G 2W1, Canada *Corresponding author: grossinetwork@gmail.com ABSTRACT: Northwest Eifuku submarine volcano (Mariana Volcanic Arc) emits very high concentrations of CO2 at a vent where the mussel Bathymodiolus septemdierum experiences pH as low as 5.2. We examined how this natural setting of high pCO2 influences shell, body, and reproductive condition. Calcification is highly compromised: at a given shell volume, shells from NW Eifuku weigh about half those from reference sites in the south Pacific, and dissolution of the inner shell is evident. However, the condition indices of some NW Eifuku mussels were equal to or higher than those from Lau back-arc basin and the New Hebrides Island Arc. NW Eifuku mussels in pH 5.2 fluids had the highest symbiont abundances in gill bacteriocytes, probably due to greater dissolved sulphide access. Excess energy demands imposed by high pCO2 conditions appears moderated by adequate food availability through symbiont chemosynthesis. In the sample with the lowest body condition, gametogenesis was lagging, although all mussels in high pCO2 had developing gonads and the complete gametogenic cycle was present in our samples. Gamete development is synchronous between sexes and is possibly periodic. While mussels are functionally dioecious, protogynous hermaphroditism can occur—a first record for the genus—which may be an adaptation to resource availability. B. septemdierum likely makes energy allocation trade-offs among calcification, body mass maintenance, reproduction and other processes to maximize fitness. We suggest that flexibility to divert energy from shell formation, combined with good food supply, can mitigate the manifestation of high CO2 stress on B. septemdierum. KEY WORDS: High pCO2 · Hydrothermal vent · Calcification · Condition · Gametogenesis · Protogyny · Acidification Full text in pdf format Supplementary material PreviousNextCite this article as: Rossi GS, Tunnicliffe V (2017) Trade-offs in a high CO2 habitat on a subsea volcano: condition and reproductive features of a bathymodioline mussel. Mar Ecol Prog Ser 574:49-64. https://doi.org/10.3354/meps12196 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 574. Online publication date: July 04, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Resources allocated to reproduction decrease at the range edge of an expanding population of an invasive amphibian

Predicting the magnitude and nature of changes in a species’ range is becoming ever more important as an increas- ing number of species are faced with habitat changes or are introduced to areas outside of the species’ native range. An organism’s investment in life-history traits is expected to change during range shifts or range expansion because populations encounter new ecological conditions. While simulation studies predict that dispersal and reproductive allocation should increase at the range edge, we suggest that reproductive allocation might decrease at the range edge due to energy allocation trade-offs. We studied the reproductive investment of an invasive amphibian, Xenopus laevis, and measured reproductive allocation in three clusters of populations distributed from the centre to the edge of the colonized range of X. laevis in France. Resource allocation was estimated with the scaled mass index of gonads of both sexes during the local period of reproduction of the species. The level of resources allocated to reproduction was lower at the periphery of the colonized range compared to the centre and may be the result of changes in trade- offs between life-history traits. Such a pattern could be explained by interspecific competition or enhanced invest- ment in dispersal capacity.

Physiological and histopathological impacts of increased carbon dioxide and temperature on the scallops Argopecten purpuratus cultured under upwelling influences in northern Chile

In addition to the increase in temperature occurring in the world's oceans, new evidences suggest a tendency for an increase in upwelling-favorable winds, bringing to surface cold and high pCO2 corrosive waters. Changing temperature and pCO2 conditions may have significant implications for the shellfish farming socio-ecological system. In order, to setup the basis for understand the impact of both environmental variables, in this study, we investigated the combined effects of changing temperature and pCO2 on the physiological rates and histopathology of scallops Argopecten purpuratus farmed in Tongoy Bay, an area permanently influenced by coastal upwelling. Juvenile scallops were reared at two pCO2 levels (400 and 1000μatm) and two temperatures (14 and 18°C). After 18d of experimental exposure, growth, metabolic and clearance rates increased significantly at high temperature but independent of pCO2 level, indicating a positive effect of warming on the physiological processes associated with energy acquisition. However, ingestion rates of scallops showed a synergistic interactive effect when exposed to both stressors. Increased pCO2 also impacts the health of A. purpuratus through atrophy in the digestive gland. These results suggest that, the presence of trade-offs in energy allocation during upwelling-induced stress (low temperature and high pCO2) can impact growth, metabolism, ingestion rates and health status of scallops cultured in Tongoy Bay. But, less severe response to high pCO2 levels, suggest that natural variability in upwelling areas may promote acclimation and adaptation potential in this farmed scallops.

Waist-to-hip ratio, body-mass index, age and number of children in seven traditional societies

It has been suggested that the preference for low WHRs evolved because low WHR provided a cue to female reproductive status and health, and therefore to her reproductive value. The present study aimed to test whether WHR might indeed be a reliable cue to female reproductive history (with lower WHRs indicating lower number of children). Previous studies showed such a relationship for modern and industrialized populations, but it has not been investigated in natural fertility, indigenous, more energy constrained populations facing greater trade-offs in energy allocation than do modern societies. Our sample comprised 925 women aged 13 to 95 years from seven non-industrial societies including tribes from Sub-Saharan Africa (Hadza, Datoga, and Isanzu), Western Siberia (Ob Ugric people: Khanty and Mansi), South America (Tsimane) and South Asia (Minahasans and Sangirese). We demonstrated a culturally stable, significant relationship between number of children and WHR among women, controlling for BMI and age. Based on these data, we suggest that WHR is a reliable cue to female reproductive history, and we discuss our results in the context of previous studies indicating usefulness of WHR as an indicator of health and fertility.