Poor Nutritional Conditions During the Early Larval Stage Reduce Risk‐Taking Activities of Fire Salamander Larvae (Salamandra salamandra)

Environmental conditions experienced early in life have been shown to significantly affect growth trajectories at later stages in many vertebrate species. Amphibians typically have a biphasic life history, with an aquatic larval phase during early development and a subsequent terrestrial adult phase after completed metamorphosis. Thus, the early conditions have an especially strong impact on the future survival and fitness of amphibians. We studied whether early nutritional conditions affect the behavioural reaction of fire salamander larvae (Salamandra salamandra) before completion of metamorphosis. Fire salamander larvae reared under rich nutritional conditions were heavier and larger, displayed better body condition overall throughout the first three month of life and metamorphosed earlier compared with larvae raised under poor nutritional conditions. Specifically, we tested whether larvae reared under these different conditions differed with respect to their risk‐taking behaviour and activity. We found no differences in the activity of larvae with respect to their experienced early food conditions. However, larvae reared under poor nutritional conditions hid significantly more often in a risk‐taking test than larvae reared under rich food conditions. This increase in shelter‐seeking behaviour might be an adaptation to reduce the risk of larval drift or an adaptation to compensate for physiological deficits in part by appropriate behavioural reactions. Our results indicate that environmental conditions, such as food availability, may lead to different behavioural strategies.     

The thrifty phenotype hypothesis: thrifty offspring or thrifty mother?

Medical research is increasingly focusing on the contribution of nutritional programming to disease in later life. Programming is a process whereby a stimulus during a critical window of time permanently affects subsequent structure, function or developmental schedule of the organism. The thrifty phenotype hypothesis is widely used to interpret such studies, with early growth restriction seen as adaptation to environmental deprivation. However, such permanent adjustment is less beneficial than maintaining flexibility so as to recover from early growth deficits if the environment improves. Thus, the existing thrifty phenotype hypothesis fails to explain why plasticity is lost so early in development in species with extended growth. One explanation is that the developing organism simply cannot maintain phenotypic plasticity throughout the period of organ growth. This article adds a life history perspective, arguing that programming of the offspring may in some species benefit maternal fitness more than it does that of individual offspring. Closing the critical window early in development allows the preservation of maternal strategy in offspring phenotype, which in humans benefits the mother by constraining offspring demand after weaning. The offspring gains by being buffered against environmental fluctuations during the most sensitive period of development, allowing coherent adaptation of organ growth to the state of the environment. The critical window is predicted to close when offspring physiology becomes independent of maternal physiology, the timing of which depends on offspring trait. Because placental nutrition and lactation buffer against short-term environmental fluctuations, maternal strategy is predicted to derive from long-term experience, encapsulated in maternal size and nutritional status. Such an approach implies that public health programmes for improving birth weight may be more effective if they target maternal development rather than nutrition during pregnancy. Equally, aggressive nutritional management of infants born small or pre-term may induce the very environmental fluctuations that are naturally softened by maternal nutrition.     

Life histories have a history: effects of past and present conditions on adult somatic growth rates in wild Trinidadian guppies

1.?Environmental conditions in the present, more recent past and during the juvenile stage can have significant effects on adult performance and population dynamics, but their relative importance and potential interactions remain unexplored. 2.?We examined the influence of food availability at the time of sampling, 2?months prior and during the juvenile stage on adult somatic growth rates in wild Trinidadian guppies (Poecilia reticulata). 3.?We found that food availability during both the early and later parts of an individual's ontogeny had important consequences for adult growth strategies, but the direction of these effects differed among life stages and their magnitude, in some cases, depended on food levels experienced during other life stages. Current food levels and those 2?months prior to growth measurements had positive effects on adult growth rate; though, food levels 2?months prior had a greater effect on growth than current food levels. In contrast, the effects of food availability during the juvenile stage were higher in magnitude but opposite in direction to current food levels and those 2?months prior to growth rate measurements. Individuals recruiting under low food levels grew faster as adults than individuals recruiting during periods of high food availability. There was also a positive interaction between food levels experienced during the juvenile stage and 2?months prior such that the effects of juvenile food level diminished as the food level experienced 2?months prior increased. 4.?These results suggest that the similar conditions occurring at different life stages can have different effects on short- and long-term growth strategies of individuals within a population. They also demonstrate that, while juvenile conditions can have lasting effects on adult performance, the strength of that effect can be dampened by environmental conditions experienced as an adult. 5.?A simultaneous consideration of past events in both the adult and juvenile stage may therefore improve predictions for individual- and population-level responses to environmental change.     

Larval development and poor trophic resource availability: Local adaptations and plasticity in a widespread amphibian species

Theory predicts that, in organisms with complex life cycles, if the earlier-stage limiting factor induces weak later-stage phenotypes, the development of the later-stage trait should evolve to reduce carry-over effects. Local adaptations could thus favour decoupling of later stages. However, decoupling is not always possible. In this study, we used a widespread amphibian, the European fire salamander (Salamandra salamandra), to assess the role of local adaptations to environmental stressful conditions experienced at the larval stage. We exposed 150 larvae from different altitudes to two conditions: rich food and poor food condition. Conditions in early life stages can affect an individual's traits, either as a direct effect or mediated through outcomes in successive life stages. To distinguish between effects of rearing conditions and local adaptation, we searched for a causal model. The causal model detected effects of both food treatment and population origin (altitude) on all life stages. Larvae reared under rich food condition metamorphosed earlier, had higher growth rates and reached smaller size at metamorphosis. Significant differences occurred between larvae of different origin: low-altitude individuals performed poorly under the poor food treatment. Moreover, larvae from higher altitudes were slower with rich food and faster with poor food compared to those from lower altitudes. Our results underline that environmental conditions and local adaptation can interplay in determining the plasticity of larval stages, still adaptations can maximize the growth efficiency of early stages in oligotrophic environments, leading to divergent pathways across populations and environmental conditions.     

Carry-over effects of food supplementation on recruitment and breeding performance of long-lived seabirds

Supplementation of food to wild animals is extensively applied as a conservation tool to increase local production of young. However, in long-lived migratory animals, the carry-over effects of food supplementation early in life on the subsequent recruitment of individuals into natal populations and their lifetime reproductive success are largely unknown. We examine how experimental food supplementation early in life affects: (i) recruitment as breeders of kittiwakes Rissa tridactyla born in a colony on Middleton Island (Alaska) between 1996 and 2006 (n = 1629) that bred in the same colony through 2013 (n = 235); and (ii) breeding success of individuals that have completed their life cycle at the colony (n = 56). Birds were raised in nests that were either supplemented with food (Fed) or unsupplemented (Unfed). Fledging success was higher in Fed compared with Unfed nests. After accounting for hatching rank, growth and oceanic conditions at fledging, Fed fledglings had a lower probability of recruiting as breeders in the Middleton colony than Unfed birds. The per-nest contribution of breeders was still significantly higher for Fed nests because of their higher productivity. Lifetime reproductive success of a subset of kittiwakes that thus far had completed their life cycle was not affected by the food supplementation during development. Our results cast light on the carry-over effects of early food conditions on the vital rates of long-lived animals and support food supplementation as an effective conservation strategy for long-lived seabirds.     

Disappearance of opioidergic tone on LH secretion in underfed prepubertal sheep

A study was conducted to determine whether an opioid tonus inhibitory of LH secretion is present in underfed prepubertal sheep. Ten Suffolk ewe lambs were subjected to food restriction during 60 days. During this period they were allowed to pasture only 2 hours per day while control ewe lambs were allowed for 10 hours. Body weight and plasma blood levels of glucose, urea and total proteins were measured weekly. At the end of this period, an intravenous injection of Naloxone (NAL, 1.5 mg/kg BW) was given to control and underfed animals followed 60 min later by an intravenous injection of LHRH to test the pituitary responsiveness. Underfed animals did not show an increase in plasma LH while control animals presented a rise from 0.28 +/- 0.08 to 2.02 +/- 0.6 ng/ml after the NAL stimulus (P less than 0.05). The response to LHRH was similar in both group of animals. Basal plasma levels of insulin were lower in underfed ewe lambs than in control animals (P less than 0.05). Underfed animals were placed on plain feeding with a schedule similar to control lambs for 30 days and the same experiment was repeated. During this occasion, NAL increased plasma LH concentration in both group of lambs. Levels of plasma insulin were not different in both groups. The lack of effect of NAL on LH secretion in food restricted ewe lambs suggests that the opioid modulation of LH secretion is absent by underfeeding in female prepubertal sheep.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of prenatal malnutrition on later body-weight gain in guinea pigs]

In prenatally underfed guinea pigs the following data were obtained: 1. On the 1st day of life the mean body weight of 18 underfed animals was significantly reduced as compared to that of 18 control animals. This difference was not compensated by postnatal feeding ad libitum but persisted up to the 36th week of life (day of sacrificing). 2. The mean food intake per day estimated over 10 days during the 5th month of life was also significantly diminished in the prenatally underfed animals. 3. A significant positive correlation was found between the body weight at birth and the adult body weight, adult body length and adult body weight/body length, when the parameters of the experimental plus control animals were evaluated together. These findings suggest that in guinea pigs, which are born in a relatively mature stage, the prenatal nutrition can influence body weight, body length and body weight/body length ratio as well as food intake in adulthood.     

Growth to death in lizards

Abstract.— Negative relationships between growth rate and survival have been demonstrated in many organisms, often reflecting risks associated with increased foraging rates. More puzzling, however, are recent reports that rapid growth early in life may lower survival rates much later in life, presumably because fast-growing animals allocate resources among different body components in ways that later compromise their survival. If widespread, such delayed effects may modify our interpretation of the evolution of life histories and phenotypic plasticity. Previous reports of this phenomenon are derived mostly from laboratory studies, generally on rodents or humans. We provide the first evidence from an experimental study in the field: neonatal lizards were exposed to different thermal conditions in seminatural enclosures at two different elevations (within their natural thermal regime). This arrangement allowed relatively higher and lower levels of food intake, which modified the neonates' growth rates (because lizards at more benign thermal conditions could forage more frequently). When later released into the wild, the individuals that grew more rapidly as neonates experienced much higher mortality than did slower-growing conspecifics, regardless of the elevation at which they had been kept.     

Living with the past: nutritional stress in juvenile males has immediate effects on their plumage ornaments and on adult attractiveness in zebra finches

The environmental conditions individuals experience during early development are well known to have fundamental effects on a variety of fitness-relevant traits. Although it is evident that the earliest developmental stages have large effects on fitness, other developmental stages, such as the period when secondary sexual characters develop, might also exert a profound effect on fitness components. Here we show experimentally in male zebra finches, Taeniopygia guttata, that nutritional conditions during this later period have immediate effects on male plumage ornaments and on their attractiveness as adults. Males that had received high quality food during the second month of life, a period when secondary sexual characteristics develop, were significantly more attractive as adults in mate choice tests than siblings supplied with standard food during this period. Preferred males that had experienced better nutritional conditions had larger orange cheek patches when nutritional treatments ended than did unpreferred males. Sexual plumage ornaments of young males thus are honest indicators of nutritional conditions during this period. The mate choice tests with adult birds indicate that nutritional conditions during the period of song learning, brain and gonad development, and moult into adult plumage have persisting effects on male attractiveness. This suggests that the developmental period following nutritional dependence from the parents is just as important in affecting adult attractiveness as are much earlier developmental periods. These findings thus contribute to understanding the origin and consequences of environmentally determined fitness components.     

Costs of compensation: effect of early life conditions and reproduction on flight performance in zebra finches

Conditions experienced in early life have been shown to affect the development or programming of physiological processes. While animals may recover from earlier periods of adversity, this process can carry long-term costs. Such long-term effects are likely to be most evident when individuals are placed in demanding situations that require high performance. Escape flight speed in passerine birds is crucial to predator evasion and requires very rapid take-off. Here, we examine whether the ability to maintain escape flight performance during the immediate post-breeding period is influenced by conditions in early life. We manipulated the early life conditions experienced by zebra finches (Taeniopygia guttata) by rearing them on either low or high quality food through the growth period, or by changing conditions halfway through the nestling period, moving from high to low or vice versa. While there was no difference amongst the treatment groups in body size attained by adulthood, amongst the birds that experienced low quality food, the body size of those that were switched to a high quality diet halfway through the nestling growth period recovered faster than those that had low quality food until fledging. We found no differences amongst the dietary groups in flight performance at adulthood prior to breeding, and all groups showed a decline in average escape flight performance over the breeding period. However, the magnitude of the post-breeding decline in flight performance for a given level of reproductive output was significantly greater for those females that had experienced a switch from a low to a high quality diet during the nestling phase. These results suggest that this diet-induced rapid recovery of body size, which may have immediate competitive advantages, nonetheless carries locomotory costs in later life manifest in the capacity to sustain the high performance escape response during the post-reproductive recovery phase.     

Pheasant sexual ornaments reflect nutritional conditions during early growth.

Differences in growth conditions during early life have been suggested to cause long-lasting effects on morphology and quality of adult birds. We experimentally investigated the effect of early growth conditions on the expression of sexual ornaments later in life in male ring-necked pheasants (Phasianus colchicus). We also investigated the effects on immune function, as it could be a functional link between early nutrition and ornament expression. We manipulated the dietary protein intake during the first eight weeks post hatching. Males receiving fodder with 27% protein during the first three weeks of life grew larger and more colourful wattles when sexually mature than males receiving a low-protein diet (20.5% protein). Spur length was unaffected by diet treatment. Manipulation of food protein levels during weeks 4-8 after hatching had no effect on the development of ornaments. The different protein treatments had no long-term effect on either humoral or cell-mediated immune responses. There was, however, a positive relationship between spur length and cell-mediated immune responsiveness. Our study shows that expression of a sexual ornament in adult pheasants reflects nutritional conditions early in life. Because the expression of secondary sexual ornaments is affected by conditions during early growth, by selecting more ornamented males, females would choose mates that are superior at handling early nutritional stress. If the susceptibility to early nutritional stress also has a hereditary basis, females may benefit by obtaining 'good genes'.     

Functional changes of the small intestine in over- and undernourished suckling rats support the development of obesity risk on a high-energy diet in later life

To investigate the relationship between early nutritional experience, ontogeny of the small intestinal functions and predisposition to obesity development, the following experimental models of male Sprague-Dawley rats were used: 1) rats in which the quantity of nutrition was manipulated from birth to weaning (day 30) by adjusting the number of pups in the nest to 4 (SL), 10 (NL) and 16 pups (LL) and 2) littermates of SL, NL and LL rats fed either a standard or a hypercaloric diet from days 80 to 135 of age. The overfed SL pups were overweight after day 15 and became permanently obese, whereas the underfed smaller LL pups, due to accelerated growth and enhanced food intake from day 30 to day 35, attained a body fat level that did not differ from normally fed NL rats. Moreover, a significantly increased duodenal and jejunal alkaline phosphatase (AP) activity was found in SL and LL rats and these acquired somatic and intestinal characteristics persisted from weaning throughout life. Eight weeks of high-energy diet feeding elicited a similar pattern of intestinal response in SL and LL rats that was clearly different from NL rats. Despite energy over-consumption in these three groups, both SL and LL rats still displayed enhanced AP activity and showed a significant increase in protein/DNA ratio accompanied with a significant body fat accretion. These results indicate that the postnatally acquired small intestinal changes induced by over- and undernutrition could be involved in the similar predisposition to obesity risk in later life when caloric density of the diet is raised.     

Otolith microstructure reveals consequences for juvenile growth of fractional spawning in an invasive goldfish Carassius auratus (Linnaeus, 1758) population

The consequences of fractional spawning on the early‐life growth rates of invasive goldfish (Carassius auratus) from the Qinghai‐Tibet Plateau were studied using the otolith microstructure of samples collected in June 2011. The effect of the estimated hatching date on the subsequent growth of individual fish was determined by back‐calculating their number of growth days, daily growth rates and the onset of their second growth season. The number of growth days in the first growth season ranged from 93 to 186 days. Following hatching, daily growth rates increased rapidly to a maximum of 0.55 mm days^?1 before declining to 0.09 mm days^?1. The effect of the duration of the first growth season on individuals was significant (P < 0.01), with later spawned fish having faster growth rates. These later spawned fish were, however, still significantly smaller in body length at the end of the first growth season (37 ± 4 mm in late hatched fish vs 55 ± 9 mm in early hatched fish). However, the smaller, later hatched fish started growing earlier in their second growth season than all other fish (P < 0.01) and subsequently achieved larger growth increments (P < 0.01), suggesting that the larger, early‐hatched fish were investing more resources in gonadal growth than somatic growth in their second growth year. Thus, this invasive population revealed considerable plasticity in their early‐life growth rates that were associated with the hatching date, potentially having substantial effects on their development in their second year of life.     

Compensation for a bad start: grow now, pay later?

Nutritional conditions during key periods of development, when the architecture and modus operandi of the body become established, are of profound importance in determining the subsequent life-history trajectory of an organism. If developing individuals experience a period of nutritional deficit, they can subsequently show accelerated growth should conditions improve, apparently compensating for the initial setback. However, recent research suggests that, although compensatory growth can bring quick benefits, it is also associated with a surprising variety of costs that are often not evident until much later in adult life. Clearly, the nature of these costs, the timescale over which they are incurred and the mechanisms underlying them will play a crucial role in determining compensatory strategies. Nonetheless, such effects remain poorly understood and largely neglected by ecologists and evolutionary biologists.     

Lactational performance, consummatory behavior, and suppression of estrous cyclicity in rats suckling underfed pups

The role of pups' appetite in the regulation of maternal consummatory behavior (food intake of nursing mothers), lactational performance and postpartum diestrus was studied over a period of 45 days postpartum in rats chronically exposed to either underfed or normally fed pups. Experimental rats (n = 10) daily received 5 pups, 4-10-days-old, that had been deprived of food for the preceding 24 h while under the care of nonlactating foster mothers. Control rats (n = 10) received normally fed pups obtained daily from lactating foster mothers. Throughout the experimental period, the daily milk yield (estimated by litter weight gain), the intake of food and water by the mother, as well as the ratio of litter weight gain to mother's intake of food and water were all markedly higher in rats nursing underfed pups than in rats nursing normally fed pups. After a peak in lactation around Day 15 postpartum, experimental rats produced the same amount of milk during extended lactation as they did in the beginning of lactation, while control rats produced only half the amount of milk during extended lactation as they did in early lactation. Regardless of the nutritional state of the suckling pups, maternal body weight increased progressively over the first four weeks of lactation and remained unchanged during the time of extended lactation. The postpartum diestrus and the subsequent diestrous phase in the time of extended lactation were considerably longer in duration in rats that nursed underfed pups. On Day 45 of lactation, prolactin levels were higher and the adrenal glands were larger in experimental rats than in controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Season of birth affects short- and long-term survival

Recent research findings have highlighted the importance of early life conditions as risk factors for adult diseases and therefore determinants of subsequent survival. Given that individuals born during different seasons in seasonal environments experience different early-developmental conditions, an analysis of the effects of the season of birth on survival is considered an effective approach in clarifying the influence of early life conditions on survival in later life. In the present study, we analyzed the long-term effects of early developmental conditions in a historical population in which both nutritional levels and the burden of infectious diseases showed a seasonal variation. Using a semi-computerized linkage process, we were able to match birth and death data for 4,646 individuals born between 1634 and 1870 in the village of Es Mercadal (Minorca Island, Spain). To determine ecological differences associated with the season of birth, we first evaluated the association between season of birth and early life survival. This analysis helped us to determine seasonal variations in early life conditions such as infectious burden and nutritional levels. The season of birth had a significant effect on long-term survival in the birth cohort 1800-1870: summer births had a lower risk of death after age 15. We explain these results in terms of lower susceptibility to degenerative diseases in adult years due to superior in utero nutrition for summer births. These findings support the fetal origin hypothesis which states that the early life environment plays a key role in shaping the subsequent phenotype and risk of adult disease.     

Benefits and costs of increased levels of corticosterone in seabird chicks

Seabird chicks respond to food shortages by increasing corticosterone (cort) secretion, which is probably associated with fitness benefits and costs. To examine this, we experimentally increased levels of circulating cort in captive black-legged kittiwake chicks fed ad libitum. We found that cort-implanted chicks begged more frequently and were more aggressive compared to controls. These behavioral modifications must be beneficial to chicks as they facilitate acquisition of food from the parents and might trigger brood reduction and reduced competition for food. Cort-implanted chicks also increased food intake; however, their growth rates were similar to controls. To examine the costs of chronically increased circulating levels of cort, we removed cort implants and, after a 10-day recovery period, tested cognitive abilities of young kittiwakes. We found that the ability of kittiwakes to associate a visual cue with the presence of food in a choice situation was compromised by the experimental elevation of cort during development. To examine the long-term costs of increased levels of cort, 8 months later we tested the performance of the same individuals in a spatial task requiring them to make a detour around a barrier in order to escape from an enclosure. Individuals treated with cort during development took significantly more time to solve this task compared to controls. The results of this study suggest that the adrenocortical response of a developing bird to environmental stressors is associated with both benefits (increased food intake, foraging behavior, and aggression) and costs (low growth efficiency and compromised cognitive abilities later in life). This provides an evolutionary framework for relating juvenile physiological traits to fitness of birds in subsequent life-history stages.     

Prenatal and pre-weaning growth and nutrition of cattle: long-term consequences for beef production

Severe, chronic growth retardation of cattle early in life reduces growth potential, resulting in smaller animals at any given age. Capacity for long-term compensatory growth diminishes as the age of onset of nutritional restriction resulting in prolonged growth retardation declines. Hence, more extreme intrauterine growth retardation can result in slower growth throughout postnatal life. However, within the limits of beef production systems, neither severely restricted growth in utero nor from birth to weaning influences efficiency of nutrient utilisation later in life. Retail yield from cattle severely restricted in growth during pregnancy or from birth to weaning is reduced compared with cattle well grown early in life, when compared at the same age later in life. However, retail yield and carcass composition of low- and high-birth-weight calves are similar at the same carcass weight. At equivalent carcass weights, cattle grown slowly from birth to weaning have carcasses of similar or leaner composition than those grown rapidly. However, if high energy, concentrate feed is provided following severe growth restriction from birth to weaning, then at equivalent weights post-weaning the slowly-grown, small weaners may be fatter than their well-grown counterparts. Restricted prenatal and pre-weaning nutrition and growth do not adversely affect measures of beef quality. Similarly, bovine myofibre characteristics are little affected in the long term by growth in utero or from birth to weaning. Interactions were not evident between prenatal and pre-weaning growth for subsequent growth, efficiency, carcass, yield and beef-quality characteristics, within our pasture-based production systems. Furthermore, interactions between genotype and nutrition early in life, studied using offspring of Piedmontese and Wagyu sired cattle, were not evident for any growth, efficiency, carcass, yield and beef-quality parameters. We propose that within pasture-based production systems for beef cattle, the plasticity of the carcass tissues, particularly of muscle, allows animals that are growth-retarded early in life to attain normal composition at equivalent weights in the long term, albeit at older ages. However, the quality of nutrition during recovery from early life growth retardation may be important in determining the subsequent composition of young, light-weight cattle relative to their heavier counterparts. Finally, it should be emphasised that long-term consequences of more specific and/or acute environmental influences during specific stages of embryonic, foetal and neonatal calf development remain to be determined. This need for further research extends to consequences of nutrition and growth early in life for reproductive capacity.     

Food quantity and quality shapes reproductive strategies of Daphnia

In freshwater environments, one of the challenges aquatic grazers face are periods of suboptimal food quantity and quality. In a life table experiment, the effects of food quantity (a gradient of algae concentration) and quality (a diet of cyanobacteria) on the life histories and resource allocation strategy in Daphnia magna were tested. Growth‐related traits were similarly affected under different food regimes while the reproductive strategies differed in animals exposed to low food quantity and quality. The per‐clutch investment (clutch volume) did not differ between Daphnia fed with cyanobacteria and underfed mothers, but resources were differently allocated; underfed mothers increased their per‐offspring investment by producing fewer, but larger eggs, whereas cyanobacteria‐fed mothers invested in a greater number of eggs of smaller size. I argue that both strategies of resource allocation (number vs. size of eggs) may be adaptive under the given food regime. The results of the study show that the cyanobacteria diet‐driven fitness losses are comparable to losses caused by food quantity, which is only slightly above the growth capability threshold for Daphnia.