Evolution of foraging behaviour in response to chronic malnutrition in Drosophila melanogaster

Chronic exposure to food of low quality may exert conflicting selection pressures on foraging behaviour. On the one hand, more active search behaviour may allow the animal to find patches with slightly better, or more, food; on the other hand, such active foraging is energetically costly, and thus may be opposed by selection for energetic efficiency. Here, we test these alternative hypotheses in Drosophila larvae. We show that populations which experimentally evolved improved tolerance to larval chronic malnutrition have shorter foraging path length than unselected control populations. A behavioural polymorphism in foraging path length (the rover-sitter polymorphism) exists in nature and is attributed to the foraging locus (for). We show that a sitter strain (for(s2)) survives better on the poor food than the rover strain (for(R)), confirming that the sitter foraging strategy is advantageous under malnutrition. Larvae of the selected and control populations did not differ in global for expression. However, a quantitative complementation test suggests that the for locus may have contributed to the adaptation to poor food in one of the selected populations, either through a change in for allele frequencies, or by interacting epistatically with alleles at other loci. Irrespective of its genetic basis, our results provide two independent lines of evidence that sitter-like foraging behaviour is favoured under chronic larval malnutrition.     

Short‐Term Nutritional Limitation Affects Mating Behaviour and Reproductive Output in Dwarf Spiders

Mating decisions can vary considerably depending on individual experience, mate availability and nutritional status. Here, we applied short‐term dietary restrictions to adult female spiders that were well fed during the juvenile stage in an effort to understand whether and how brief periods of food shortage can influence male and female mating decisions and mating behaviour. To assess whether responses vary between closely related species, we conducted the same experiment on the dwarf spiders Oedothorax retusus and O. apicatus. During courtship and mating, males of both species offer secretion to females from glandular tissue in their prosoma. Females were subject to food shortage over a period of 3 wks (‘low‐diet’ treatment, LD) or fed regularly (‘high‐diet’ treatment, HD). We compared courtship probability, mating probability/behaviour, and reproductive output between dietary groups and species. In both Oedothorax species, females in the LD treatment were less likely to mate and more aggressive towards males. Furthermore, LD females produced egg sacs that were significantly lighter than were those of the HD females. Effects of food deprivation on copulation duration, gustatory behaviour and oviposition latency differed between species. Our study shows that short periods of dietary restriction during the adult stage can strongly affect mating behaviour and reproductive output with differences between closely related species.     

Diet and size influence sexual advertisement and copulatory success of males in Mediterranean fruit fly leks

1. The objective of the work reported here was to test the hypothesis that in insects that invest considerable energy in sexual displays and courtship, foraging successfully for food affects their subsequent performance and copulatory success in leks. Accordingly, the interactions between body size and diet on initiation of lekking behaviour and copulatory success in male Mediterranean fruit flies Ceratitis capitata (Diptera: Tephritidae) were investigated. 2. Protein‐fed males were heavier and contained more protein and less lipid reserves than protein‐deprived males. Protein‐fed males were more likely to emit pheromone in leks and, consequently, were more likely to copulate than protein‐deprived males. Furthermore, protein‐fed males tended to start calling earlier than their nutritionally deprived competitors. 3. Though size was not related to initiation of lek behaviour, large males were more likely to copulate than small males. Among protein‐fed males, large individuals tended to mate earlier than smaller individuals. 4. Generally, in lek mating systems where a considerable investment of time and energy is required by males, foraging successfully for nutritional resources prior to engaging in territorial or courtship behaviour is essential for reproductive success.     

The nutritional value of feeding on crops: Diets of vervet monkeys in a humanized landscape

Anthropogenic influences have dramatically altered the environments with which primates interact. In particular, the introduction of anthropogenic food sources to primate groups has implications for feeding behaviour, social behaviour, activity budgets, demography and life history. While the incorporation of anthropogenic foods can be beneficial to primates in a variety of nutritional ways including increased energetic return, they also carry risks associated with proximity to humans, such as risk of being hunted, disease risk and risk of conflict. Given such risks, we initiated a 3‐year study where we sought to understand the underlying nutritional motivations for anthropogenic food resource use by vervet monkeys (Cercopithecus aethiops) in the humanized matrix surrounding the Nabugabo Field Station in central Uganda. Feeding effort, defined as proportion of feeding scans spent on anthropogenic food, was not associated with ripe fruit availability nor with crop availability as determined by phenological monitoring. Likewise, there was no difference in the protein, fibre, or lipid composition of crop food items compared to wild food items. Individuals spent less time feeding overall in months over the 3 years with a higher proportion of time spent feeding on crop foods, suggesting a potential benefit in terms of accessibility (reduction in the proportion of activity budget devoted to feeding).     

Nucleolar variation in response to nutritional condition in juvenile pejerrey Odontesthes bonariensis (Valenciennes)

The variations of the nucleolar characteristics size and number were studied in the gill and liver of Odontesthes bonariensis under different feeding regimes in order to test the hypothesis that functional genomes at the nucleolus, which determine variation of size (heterogeneity) in juvenile fishes, are modulated by environmental factors such as food availability. The programme that controls genetic changes of the nucleolar characteristics of the diploid cells of O. bonariensis was different from that described in the diploid cells of cyprinid fishes. No variations of the mean nucleolar number per nucleus were observed in liver or gill cells in relation to the feeding regime. Conversely, significant reduction of the mean nucleolar volume per nucleus ( V _MN) and change in the shape of the frequency distribution of the total nucleolar volume per cell was evident in both cell types in response to starvation or food restriction. Tissue specificity was observed in relation to the absolute values of the nucleolar characteristics; however, the relative behaviour was comparable in digestive and non-digestive tissues. The time-course reduction of V _MN in gill and liver cells of restrictively fed fish followed a negative exponential. A good correlation between V _MN and the condition index of the fish ( K ) was observed after long-term food restriction; however, a faster response of V _MN was observed after short-term fasting events. Results supported the stated hypothesis and showed nucleolar activity as a direct, rapid and sensitive indicator of the nutritional status of the fish.     

Dietary generalists and nutritional specialists: Feeding strategies of adult female blue monkeys (Cercopithecus mitis) in the Kakamega Forest,Kenya

Generalist primates eat many food types and shift their diet with changes in food availability. Variation in foods eaten may not, however, match variation in nutrient intake. We examined dietary variation in a generalist‐feeder, the blue monkey (Cercopithecus mitis), to see how dietary food intake related to variation in available food and nutrient intake. We used 371 all‐day focal follows from 24 adult females (three groups) in a wild rainforest population to quantify daily diet over 9 months. We measured food availability using vegetation surveys and phenology monitoring. We analyzed >700 food and fecal samples for macronutrient content. Subjects included 445 food items (species‐specific plant parts and insect morphotypes) in their diet. Variation in fruit consumption (percentage of diet and total kcal) tracked variation in availability, suggesting fruit was a preferred food type. Fruits also constituted the majority of the diet (by calories) and some fruit species were eaten more than expected based on relative availability. In contrast, few species of young leaves were eaten more than expected. Also, subjects ate fewer young leaves (based on calories consumed) when fruit or young leaves were more available, suggesting that young leaves served as fallback foods. Despite the broad range of foods in the diet, group differences in fiber digestibility, and variation that reflected food availability, subjects and groups converged on similar nutrient intakes (grand mean ± SD: 637.1 ± 104.7 kcal overall energy intake, 293.3 ± 46.9 kcal nonstructural carbohydrate, 147.8 ± 72.4 kcal lipid, 107.8 ± 12.9 kcal available protein, and 88.1 ± 17.5 kcal structural carbohydrate; N = 24 subjects). Thus, blue monkeys appear to be food composition generalists and nutrient intake specialists, using flexible feeding strategies to regulate nutrient intake. Findings highlight the importance of simultaneously examining dietary composition at both levels of foods and nutrients to understand primate feeding ecology.     

Major urinary protein 5, a scent communication protein,is regulated by dietary restriction and subsequent re-feeding in mice

Major urinary proteins (Mups) are important for rodent scent communication and sexual behaviour. Recent evidence suggests that Mup1 may be regulated by fasting and re-feeding (RF). However, other Mup isoforms are poorly investigated, and data on the impact of long-term dietary restriction (DR) and ad libitum RF on Mup expression are missing. We investigated the effects of long-term 25 per cent DR and subsequent RF on Mup expression in male C57BL6 mice. DR significantly decreased Mup gene expression, hepatic and urinary protein levels compared with ad libitum (AL) fed control mice, with the greatest downregulation found for Mup5 expression. The decline in Mup expression was inverted by six months of RF. Because of inhibitory glucocorticoid response elements in the genomic sequence of the Mup5 gene, the observed inverse correlation of nuclear glucocorticoid receptor levels with Mup expression in response to DR and subsequent RF is a possible regulatory mechanism. Additionally, gene-expression-inhibiting histone deacetylation (H3K9) occurred in the region of the Mup5 gene in response to DR. We assume that Mup may act as a molecular switch linking nutritional status to sexual behaviour of mice, and thereby regulating male fertility and reproduction in response to food supply.     

Feeding strategy of the Tana mangabey (Cercocebus galeritus galeritus) (Mammalia: Primates)

Systematic data on the feeding behaviour and ecology of the Tana mangabey ( Cercocebus g. galeritus ) were collected over a period of 13 months in a riverine forest study site on the Tana River in Kenya. A total of 1151 hours of observation was conducted on two study groups, containing 36 and 17 animals respectively. Both spatial and temporal aspects of vegetation were studied. Particular emphasis was placed on quantification of foraging behaviour , which has not been treated as a distinct category in previous primate studies. (Feeding behaviour = foraging + eating.)
Dietary composition varied according to season, but there was also evidence that the diversity of the diet increased as food availability decreased. In addition, foraging increased when food was scarce, as did total distance moved and area searched for food. Results of analysis of major food items indicated that the mangabeys were possibly selecting such items in association with their metabolisable energy values. The conspicuous foraging behaviour and locomotor versatility of the mangabeys, combined with these quantitative observations, support the interpretation that this primate is a "generalist" in terms of feeding strategy, compared with "specialist" folivores exhibiting minimal searching and manipulation of food items. It is suggested that as "generalists" the mangabeys are particularly suited to forests lining meandering river systems, with their fluctuating mosaic of vegetation and food availability.     

Food and water economy and its relation to growth in fifth-instar larvae of the tobacco hornworm, Manduca sexta

Fifth-instar larvae of Manduca sexta were reared on artificial diet at 25°C. Daily measurement of the wet and dry weights of insects, food eaten and faeces produced, allowed the construction of detailed budgets for food and water economy.Approximate digestibility (AD) was about 60% both in dry weight and energetic terms. This did not change significantly on successive days of the instar, despite the very considerable changes that occur in the size of the insect and the amount of food eaten during the same period. Two indices of conversion efficiency (ECI and ECD) also showed only insignificant changes during this time. ECI and ECD were both very high: at their maximal values, ECI was 43% (51% in energy terms) and ECD was 72% (81% in energy terms).Correction of the nutritional indices for the presence of food in the gut reduced their value slightly in all cases.Most of the water requirements of the larva were provided by the diet. The estimated gain from metabolic water was between 3.5 and 10% of the total water input. Faeces accounted for most of the water lost from the body; under our conditions transpirational losses were very small. Almost half of the water taken up with the food was retained in the body.The gut contents are more hydrated than the food. The faeces contain less water than the gut contents. It is suggested that the caterpillars recycle water by absorbing it from the faeces and returning it to the contents of the midgut. A quantitative model of such water movement within the body is presented. The data provide indirect evidence that caterpillars may optimise the retention time of food in the gut (and thus the AD) in order to maximise the absolute rate of nutrient uptake from it.     

Carbohydrate scarcity increases foraging activities and aggressiveness in the ant Prolasius advenus (Hymenoptera: Formicidae)

1. Behavioural responses to varying macronutrient availability are increasingly studied in highly invasive ant species to better understand their ecological success. However, such work is lacking in relation to native ant species confronted with biological invaders. 2. Here the link between diet and behaviour was examined in Prolasius advenus, a native ant from New Zealand facing intense competition for food with invasive insects, including social wasps. A long‐term laboratory experiment was conducted to assess the impact of protein and carbohydrate restriction on several behavioural parameters. 3. Ants shifted their food‐collecting activity towards the least available macronutrient in both protein‐limited and carbohydrate‐limited colonies. But when lacking carbohydrate, they also strongly increased their efforts to discover resources. After 10 weeks, the proportion of the colony patrolling outside of the nest was eight times higher than at the initiation of the experiment. This high patrolling activity was then maintained for several weeks and resulted in a higher efficiency to explore a novel territory. Moreover, ants fed a carbohydrate‐limited diet engaged in longer aggressive acts towards conspecifics. 4. These behavioural responses to carbohydrate scarcity may, in part, enhance the ability of P. advenus to resist a competing invader under natural conditions. While much of the previous research has linked diet and behavioural dominance in invasive ants, the present study shows that conducting similar investigations in the native species to which they are confronted may shed light on the mechanisms behind biotic resistance and the ability of some native species to coexist with highly abundant invaders.     

A system for the quantitative study of the learning capacity of rainbow trout and its application to the study of food preferences and behaviour

A system for the quantitative study of the learning capacity of rainbow trout and its application to the study of food preferences and of behaviour. Groups of trout were self-trained in about 10 days to actuate a trigger and feed themselves. This capacity was retained for 3 months without the stimulus of continuous reinforcement. Presented with a choice, conditioned populations showed a high degree of discriminatory ability towards a trigger that supplies food and one that does not. The choice system was used to examine preferences for the taste of pelleted foods. A trained population, under continuous illumination developed a feeding rhythm that occurred about every 8 h.     

在不同营养状态下东方田鼠对陌生食物选择学习的研究

通过不同饥饿处理 ,研究了东方田鼠在不同营养状态下 ,对陌生食物尝试和选择的行为模式。结果表明 ,初次遇到陌生食物时 ,各处理组对陌生食物的采食量分别为饱食 6.9± 1 .8g,饥饿组为 4.8± 1 .6g,饥饿 食物短缺组为 3.4± 1 .4g。各处理组动物对陌生食物的摄入量间差异极为显著 ( P=0 .0 0 4 3)。饱食组、饥饿组及饥饿 食物短缺组动物初次遇到陌生食物时 ,所摄入的陌生食物量占总摄入量的百分比分别为72 %、38%与 1 2 %。说明 ,在实验室条件下饱食动物较饥饿和饥饿 食物短缺的动物学习选择摄食陌生食物的倾向较强。     

Copepod post-embryonic durations: pattern,conformity, and predictability. The realities of isochronal and equiproportional development,and trends in the opepodid-naupliar duration ratio

A collation of post-embryonic durations for freshwater and marine calanoid, cyclopoid and harpacticoid copepods is provided, and examined for patterns and conformities which may be of predictive value. Most of the analysis concerns calanoids. Only the genus Acartia exhibits evidence of equal stage duration (isochronality). Accordingly, isochronal development must be rejected as a general pattern in copepods — with various implications to the study of their production. Conversely, relative stage durations are surprisingly comparable in a wide range of copepods across a broad range of temperatures and food levels. A loose consistency is evident among copepod species generally, (interspecific equiproportionality), but within given genera, a striking regularity, here termed intergeneric equiproportionality (IGE) is evident. Patterns of IGE are consistent with selectively adaptive life-history traits, and IGE thus offers predictive prospects which are of both quantitative and qualitative (heuristic) value. Empirical support which exists for IGE among marine calanoids suggests that in contrast to isochronality and interspecific equiproportionality, IGE is indeed a real, and ultimately quantifiable feature of copepod development. Within calanoids, the ratio of total copepodid to total naupliar duration (Dc/Dn) appears independent of temperature, shows little relationship to adult body mass, but is inversely related to food supply, markedly so in freshwater forms. In this context, changes in the ratio are attributable largely to influences of food supply upon copepodid development times: naupliar durations appear relatively independent of food concentrations during development. Considerably higher Dc/Dn ratios in freshwater than in marine calanoids conceivably arise from selective influences of different nutritional conditions and size-selective predation pressures in freshwater and marine environments. In the generally high predation environment of freshwaters, acceleration of naupliar development potentially reduces the vulnerability of these smaller stages to size-selective tactile predation, while larger copepodid instars are able to reduce the opposing size-selective influences of visual planktivores by virtue of their escape responses to suction attack. Within the spectrum of copepod life histories and development schedules, ecologically consistent trends of this nature await formal recognition. The present recognition of IGE is a modest initiative in this quest. Both naupliar and copepodid durations are inverse monotonic functions of temperature. Several mathematical expressions which account for this temperature-duration response are provided. The response envelope is much tighter for naupliar than copepodid durations. Predictability of temperature-duration responses accordingly declines ontogenetically from egg to naupliar to copepodid stages.     

Energetic constraints and steroid hormone correlates of male calling behaviour in the túngara frog

We investigated physiological constraints on calling behaviour in the túgara frog, Physalaemus pustulosus. First, we examined the hypothesis that energetic factors limit calling. Time spent in chorus activity is the best predictor of male mating success (Ryan, 1985). Manipulation of food availability demonstrated that males given supplemental food were more likely to call than males without supplemental food. Males without supplemental food were less likely to call even though their lipid reserves were only slightly less than males given the supplemental food, suggesting that part of the increased energy obtained from the supplemental food may have been channelled into calling to attract females. Secondly, we examined the role of steroid hormones in switching between reproductive and non-reproductive behaviours. Calling males had higher levels of plasma testosterone than silent males. Experimental elevation of corticosterone decreased testosterone levels and the likelihood of calling, thus linking both of these steroid hormones to calling behaviour. Males who responded to supplemental food by increasing calling had higher levels of testosterone than those without supplemental food, but there was no difference in plasma corticosterone levels. Overall, the results suggest that energetic factors affect calling behaviour and that one potential mechanism for this affect is through plasma testosterone levels. Corticosterone can decrease calling behaviour, however, corticosterone does not appear to mediate the effect of energetic factors on calling behaviour. These data are consistent with the hypothesis that energetic factors ultimately constrain sexual selection for calling behaviour.     

Physiological mechanisms for food-hoarding motivation in animals

The study of ingestive behaviour has an extensive history, starting as early as 1918 when Wallace Craig, an animal behaviourist, coined the terms ‘appetitive’ and ‘consummatory’ for the two-part sequence of eating, drinking and sexual behaviours. Since then, most ingestive behaviour research has focused on the neuroendocrine control of food ingestion (consummatory behaviour). The quantity of food eaten, however, is also influenced by the drive both to acquire and to store food (appetitive behaviour). For example, hamster species have a natural proclivity to hoard food and preferentially alter appetitive ingestive behaviours in response to environmental changes and/or metabolic hormones and neuropeptides, whereas other species would instead primarily increase their food intake. Therefore, with the strong appetitive component to their ingestive behaviour that is relatively separate from their consummatory behaviour, they seem an ideal model for elucidating the neuroendocrine mechanisms underlying the control of food hoarding and foraging. This review focuses on the appetitive side of ingestive behaviour, in particular food hoarding, attempting to integrate what is known about the neuroendocrine mechanisms regulating this relatively poorly studied behaviour. An hypothesis is formed stating that the direction of ‘energy flux’ is a unifying factor for the control of food hoarding.     

On the evolutionary and ontogenetic origins of tool‐oriented behaviour in New Caledonian crows (Corvus moneduloides)

New Caledonian crows (Corvus moneduloides) are prolific tool users in captivity and in the wild, and have an inherited predisposition to express tool‐oriented behaviours. To further understand the evolution and development of tool use, we compared the development of object manipulation in New Caledonian crows and common ravens (Corvus corax), which do not routinely use tools. We found striking qualitative similarities in the ontogeny of tool‐oriented behaviour in New Caledonian crows and food‐caching behaviour in ravens. Given that the common ancestor of New Caledonian crows and ravens was almost certainly a caching species, we therefore propose that the basic action patterns for tool use in New Caledonian crows may have their evolutionary origins in caching behaviour. Noncombinatorial object manipulations had similar frequencies in the two species. However, frequencies of object combinations that are precursors to functional behaviour increased in New Caledonian crows and decreased in ravens throughout the study period, ending 6 weeks post‐fledging. These quantitative observations are consistent with the hypothesis that New Caledonian crows develop tool‐oriented behaviour because of an increased motivation to perform object combinations that facilitate the necessary learning. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 870–877.     

The physiological control of feeding in corals: a review

Little is known about the factors that control food capture by the coral polyp and the way that internal physiological events may coordinate, or even modify, this behaviour. A total understanding of the nutritional dynamics of corals demands detailed study of their feeding behaviour, and recent advances in behavioural and electrophysiological techniques are starting to provide some insights into how polyps control this behaviour. This review describes our present understanding of the physiological control of feeding behaviour in corals and suggests new studies on food recognition, food capture, and ingestion.     

Dietary protein supplementation and its consequences for intake,digestion, and physical activity of a carnivorous marsupial,Sminthopsis crassicaudata

Diet regulation behavior can mediate the consequences of imbalanced diets for animal well‐being, particularly for captive species that have little dietary choice. Dasyurids (carnivorous marsupials) are of conservation concern in Australia, and many species are in captive breeding programmes. However, their nutrient targets and dietary regulation behaviors are poorly understood, a limitation that may decrease the breeding success and well‐being of captive animals. We tested how dietary protein content influenced the intake and utilization of nutrients, physical activity, and body mass of fat‐tailed dunnarts Sminthopsis crassicaudata. Twelve adult dunnarts from six sibling pairs (one female and one male per pair) were provided ad libitum access to three diets in a repeated measures design: cat food, cat food supplemented with raw lean beef (1:1), and cat food supplemented with cooked lean beef (1:1). Food intake, activity level, and fecal output were measured daily. Dunnarts significantly decreased food intake, increased protein digestion, and physical activity, but body mass was unchanged when on the high‐protein diet compared to the normal cat food diet. These observations suggest a capacity of dunnarts to maintain constant body mass using a dynamic balance of feeding, digestion, and activity. We also found a significant effect of family, with differences between families as large as the difference between the diet treatments, suggesting a genetic component to diet selection. The nutrient regulation responses of dunnarts to high‐protein diets and the strong family effects provide important messages for the management of populations of small carnivores, including the aspects of dietary manipulation and conservation of genetic diversity.     

Effects of stochastic food deprivation on energy budget,body mass and activity in Swiss mice

When small animals are faced with an unpredictable food supply,they can adapt by altering different components of their energy budget such as energy intake,metabolic rate,rate of non-shivering thermogenesis(NST)or behaviour.The present study examined the effect of stochastic food deprivation(FD)on body mass,food intake,resting metabolic rate(RMR),NST and behaviour in male Swiss mice.During a period of 4 weeks' FD,animals were fed ad libitum for a randomly assigned 4 days each week,but were deprived of food ...