Stored Energy Reserves Research Articles

Allocating Ecological Space

Liberals have long been committed to two axiomatic claims about freedom: that the exercise of control within one’s private space epitomizes individual liberty, and that each person must be free to define and pursue the good life for themselves. Together, these claims form a conception of freedom as autonomy (from the Greek Auto-Nomos, giving law to oneself), conceptualized as a personal space in which each can act according to one’s own view of the good, free from external constraint. Liberal theories of justice have embraced such claims about autonomy, defining justice in terms that recognize sovereignty within one’s personal space and protect individuality. John Rawls’s primary goods, 1 Ronald Dworkin’s resources, 2 and Amartya Sen’s capabilities approach 3 all focus on instrumental goods within a metric of egalitarian justice, allowing individuals full control over their personal spaces of autonomy while maintaining the bases for interpersonal comparison that distributive justice requires. This spatial conception of liberty has dominated liberal thought at least since J. S. Mill’s observation that “the only freedom which deserves the name, is that of pursuing our own good in our own way, so long as we do not attempt to deprive others of theirs, or impede their efforts to attain it.” 4 Here, Mill not only defines individual liberty in terms of autonomy, but he also specifies its limits: each of us should be free to pursue our own ideas about the good within our own space, bounded only by the space of others, where our acts infringe upon their autonomy. 5 If this autonomous space is to play the role that Mill and other liberals have long assumed, it must be sufficiently large to allow for a wide range of actions and choices, allowing each to express their individuality without encountering the limits that Mill mentions and the constraints on action that they entail. If almost everything that I do impedes others from pursuing the good in their way—harming them directly, limiting their opportunities, or otherwise infringing upon their space—then my personal space becomes vanishingly small, and my liberty but a trivial abstraction. This spatial conception of freedom is challenged by analyses emerging from the ecological crisis, which offer competing accounts of personal space with quite different implications for the exercise of individual autonomy. 6 Given ecological limits, aggregate ecological space 7 (i.e., life-supporting natural resource-based goods and services, conceived in spatial terms) is finite and threatened by current patterns of over-appropriation, yielding imperatives to fairly allocate that space among various claimants, present and future. Uninhibited autonomy, as construed above, is not sustainable, justifying significant limits on both personal space and

Lipid, fatty acid and protein content of late larval to early juvenile stages of the western rock lobster, Panulirus cygnus

Lipid, fatty acid and protein content were determined individually on 7 phyllosomata, 69 clear pueruli, 286 pre-moult pueruli, and 86 juvenile western rock lobster (WRL) collected from four locations between the settlement seasons 2000 to 2006 to evaluate compositional changes during the non-feeding puerulus stage. Only the lipid content, particularly the phospholipids, decreased significantly with development. Protein declined sharply following moult to the juvenile. PL comprised between 86-94% of total lipid in all animals, and declined most between phyllosomata and clear pueruli (238.5 to 121.4 mg g(-1) DW) (p<0.001). Triacylglycerols were the only lipid to increase in absolute amounts with development, but declined 53% on average following moult to juvenile. This increase in TAG is likely due to the conversion of phospholipids to triacylglycerols. Monounsaturated fatty acids were the main energy form utilised during benthic development while polyunsaturated fatty acids showed a high degree of sparing. The n-3:n-6 fatty acid ratio of juveniles indicates that they may be approaching critically low levels of stored lipid energy reserves. Both protein, and lipid, declined sharply from the final puerulus phase to the juvenile confirming that a high energetic demand is required to fuel the moulting process.

Spiny lobster development: where does successful metamorphosis to the puerulus occur?: a review

This review re-addresses the question: Where does metamorphosis to the puerulus mainly take place among the shallow-water palinurids? A decade ago we reviewed this ecological question in a paper that focused on phyllosomal development of the western rock lobster, Panulirus cygnus. The main region of occurrence of its metamorphosis was found to be in the slope region beyond the shelf break. Because the puerulus of P. cygnus is a non-feeding stage, it was hypothesised that metamorphosis will not occur until the final phyllosoma has reached some critical, and specific, level of stored energy reserves. For late larval development and successful metamorphosis of P. cygnus, the richest food resources seem to be located in the slope waters adjoining the shelf break off Western Australia. This, like most shelf break areas, is a region of higher zooplankton and micronekton biomass than is usually found further offshore, and is dominated (in winter-spring months) by the warm south-flowing Leeuwin Current. In this new review, distribution and abundance data of final phyllosomas and pueruli are examined from, Panulirus argus, Panulirus cygnus, Panulirus japonicus, Panulirus ornatus and Jasus edwardsii, and where possible, related to features of the satellite imagery of the areas in which they occur. We hypothesise that metamorphosis will occur where the final stages have partaken of sufficient, appropriate nutrition to provide them with a reserve of bioenergetic resources, and this can occur where oceanographic fronts effect greater planktonic productivity and concentrations of food organisms. This may be near the shelf-break, or out to large distances offshore, because of large-scale oceanographic events such as the prevailing current system, its off-shoots, mesoscale eddy fronts, counter-currents, etc. However, we contend that, in terms of population recruitment, metamorphosis in most shallow-water palinurid species occurs mainly in the slope waters adjoining the shelf break of the region to which the species is endemic. Although some final phyllosomas may metamorphose much further offshore, it is unlikely that these pueruli will reach the shore, let alone settle and successfully moult to the juvenile stage. All of the data indicate that successful metamorphosis from the final-stage phyllosoma to the puerulus stage in all species occurs offshore but close to the continental shelf.

Combined effects of abiotic and biotic variables on the energy metabolism and metallothionein level of Mytilus galloprovincialis

Estuaries represent particularly variable environments characterised by large temporal and spatial fluctuations in abiotic factors such as salinity, temperature and dissolved oxygen (natural stress). Mussels (Mytilus galloprovincialis) living in these areas are generally able to cope with these changes owing to their ability to adapt to a wide range of salinities and their efficient respiratory physiology. The cellular energy allocation (CEA) methodology was applied as a physiological research tool to assess the effects of abiotic stress and the reproductive cycle on the energy metabolism of the mussels. The CEA value is calculated as a ratio between available energy (sum of total sugars, proteins and lipids) and energy consumption (based on the activity of mitochondrial electron transport system). Present study was performed at 4 stations of different salinities in the Krka River estuary (Adriatic coast, Croatia). To evaluate the influence of reproductive stage and sex on the measured parameters, mussels were sampled in summer and autumn season and the sex determination was performed. The hepatopancreas was selected as a target organ since it serves as storage of energy reserves and represents a central detoxification site of the organism. Differential allocation of cellular energy as a result of stress and/or reproductive cycle will be discussed. The energy metabolism results will be related to the data on metallothionein level.

Life History and the Costs of Reproduction in Northern Great Plains Paddlefish ( Polyodon spathula ) as a Potential Framework for Other Acipenseriform Fishes

A 14-year investigation of a North American Acipenseriform fish, the paddlefish Polyodon spathula in the Yellowstone River, Montana, and North Dakota, USA has provided a detailed empirical framework of the life history in relation to the costs of reproduction for that species and potentially for closely related sturgeons. Nearly all aspects of life histories of males and females differed from each other after the immature period. The five periods in the juvenile and adult life histories for males and females, which occur at different ages for each sex, were (1) immature, (2) maturing, (3) somatic growth and reproduction, (4) prime reproduction, and (5) senescence to death. During the first period (immature), fishes exhibit rapid somatic growth as well as accumulation of energy reserves in the form of gonadal fat bodies (GFBs) and other fat deposits. During the second period (maturing), somatic growth slows as production and stored energy reserves are diverted into reproduction. In the third period, fish are allocating energy to both somatic growth and reproduction. Reproductive periodicity is typically close to two years for males and three years for females; gonadal recrudescence is slower than in older fish. The gonadosomatic index (GSI) is increasing, and GFBs are depleted over 2–3 spawns in females and reduced more gradually in males. Fish make longer pre-spawning migrations upriver. In the fourth period (prime reproduction), somatic growth is slow or negative, as energy is routed more strongly into reproduction. GSI is at a maximum; GFBs are completely depleted in females. Reproductive periodicity is typically one year for males and two years for females; the rate of gonadal recrudescence is at its maximum. Fish make shorter pre-spawning migrations upriver. In the fifth period (senescence to death), GSI of some of the oldest females decreases; the oldest males have few energy reserves and are long and lean. Distinct male-female differences in life histories were consistent with theoretical models and with empirical observations of the lack of direct male competition for females. The framework outlined for this paddlefish stock may exist among other Acipenseriform fishes and is potentially useful for evaluating their life histories.

Effects of in vitro oocyte maturation and embryo culture on the expression of glucose transporters, glucose metabolism and insulin signaling genes in rhesus monkey oocytes and preimplantation embryos

Glucose plays a fundamental role during oogenesis and embryogenesis, satisfying the metabolic demands of oocytes and embryos, providing for stored energy reserves in the form of glycogen and supporting nucleotide biosynthesis via the pentose phosphate pathway. Glucose also contributes to the production of amino acids, glycosylated proteins and extracellular components. A detailed understanding of the molecular mechanisms that mediate and regulate glucose uptake and metabolism at different stages of oogenesis and preimplantation embryogenesis could greatly benefit the development of improved methods for in vitro oocyte maturation and in vitro embryo production. Although these processes have been examined in a variety of rodent and agricultural species, detailed information has not yet been described for non-human primates. In this study, we examined the expression of the genes encoding glucose transporters, glucose metabolism enzymes and potential regulators of glucose metabolism in rhesus monkey oocytes and embryos. The data reveal stage-specific regulation of expression of specific types of glucose transporters, stage-specific changes in expression of genes related to different pathways of glucose metabolism and temporal changes in the expression of mRNAs related to insulin signaling. Additionally, the data reveal significant differences in expression of some of these genes in cultured embryos as compared with flushed embryos and between oocytes and embryos obtained following different hormonal stimulation and oocyte maturation protocols.

Utilization of stored energy reserves during fasting varies by age and season in Steller sea lions

Nine captive Steller sea lions ( Eumetopias jubatus (Schreber, 1776), 1.75–6 years of age) were fasted for 7–14 d to test the effect of short-term fasting on changes in body mass and body condition. Trials were repeated during both the summer breeding season and the nonbreeding season in seven animals to elucidate whether there was a seasonal component to the ability of Steller sea lions to adapt to limited food resources. Mean percent mass loss per day was higher during the breeding season in juveniles (1.8% ± 0.2%·d–1) than in subadults (1.2% ± 0.1%·d–1), but there were no significant age-related differences during the nonbreeding season (juveniles, 1.5% ± 0.3%·d–1; subadults, 1.7% ± 0.3%·d–1). A decrease in the rate of mass loss occurred after the first 3 d of fasting only in subadults during the breeding season. Percent total body lipid ranged from 11% to 28% of total body mass at the initiation of fasting trials. Animals with lower initial percent total body lipid exhibited higher subsequent rates of mass loss and a lower percentage of tissue catabolism derived from lipid reserves. There was no evidence of metabolic adaptation to fasting in juveniles, which suggests that juvenile sea lions would be more negatively impacted by food limitation during the breeding season than would subadults.

Survival, starvation, and activity in Heterorhabditis megidis (Nematoda: Heterorhabditidae)

Infective juveniles (IJs) of entomopathogenic nematodes do not feed but have ample stored energy reserves and can survive for several months in soil or in water. Intraspecific variation in survival of Heterorhabditis megidis has been observed for eight isolates of H. megidis stored in water at 20 °C for up to 14 weeks with the 50% survival time (ST 50 ) ranging from 5.6 to 12.5 weeks. How important physical and behavioral attributes were in explaining this variation in survival was explored using stepwise regression. Included in the analysis were: initial energy reserves (measured by image analysis densitometry), size (area and length) the time at which 50% of energy reserves were depleted (ET 50 ), and motility (head movements/min in week 0). Energy depletion rate, ET 50 , is an important predictor of survival, explaining 93.8% of the variation in ST 50 among isolates. Energy depletion rate was highest in the first week, a time at which H. megidis IJs were spontaneously active during storage. By week 5, when IJs had begun to die, some individuals had completely depleted their energy reserves, supporting the hypothesis that death was a result of starvation. In a second stepwise regression, performed to explore what factors contribute to variation in rate of energy depletion, motility accounted for 60.1% of the variation in ET 50 . With the inclusion of initial energy reserves, length, and area, 88.5% of the variation was accounted for. We conclude that intraspecific variation in survival of H. megidis in water is due largely to variation in rates of depletion of energy reserves, which in turn is strongly associated with levels of locomotory activity.

Seasonal Response of Juvenile Atlantic Salmon to Experimental Hydropeaking Power Generation in Newfoundland, Canada

AbstractVariable hydropower production leads to hydropeaking, which causes discharge fluctuations that are potentially harmful to aquatic organisms. In this study, an experimental approach was used to investigate hydropeaking effects and associated hydraulic and habitat conditions on the home range and movement of juvenile Atlantic salmon Salmo salar. Prior studies examined the responses of Atlantic salmon and brook trout Salvelinus fontinalis to experimental hydropeaking during summer and autumn. The present study focused on Atlantic salmon, involved more rapid and extreme discharge manipulation, and included winter experiments to reflect influences of reduced temperature, ice conditions, and seasonal differences in behavior and habitat selection. Experiments were conducted over a range in discharge (0.5–5.0 m3/s) that resulted in dramatic habitat changes in the wide, shallow, boulder‐strewn study reach. Experiments were repeated in summer and winter; however, the winter range in discharge was narrower due to constraints on water release. Fish response was monitored using manual telemetry in both seasons, and fixed telemetry was used to monitor fine‐scale diel winter movements. Atlantic salmon had larger home ranges and were more mobile during all flow conditions and over diel cycles in summer than in winter, and there was anecdotal evidence of stranding in isolated pools in summer. Stream morphology, in addition to the magnitude of discharge change, was an important determinant of the propensity to move. In our study, there were considerable refugia from increased velocity and dewatering, which may have reduced the need to move. In winter, fish remained relatively sedentary in comparison with the summer foraging period, and this behavior may increase the likelihood for dewatering, stranding, and freezing. A secondary concern with hydropeaking regimes is the energetic cost to fish of moving to find suitable habitats, and during summer this cost could affect stored energy reserves, which could, in turn, affect overwinter survival.

Nocturnal activity and energetic condition of spring landbird migrants at Braddock Bay, Lake Ontario

Abstract We investigated the relationship between migratory restlessness and stored energy reserves in two species of landbird migrants at Braddock Bay, Lake Ontario during spring 1999 and spring 2000. There was no significant difference in the amount of nighttime locomotor activity between lean and fat Swainson's Thrushes (Catharus ustulatus) or White-throated Sparrows (Zonotrichia albicollis) held overnight in activity cages. We found no significant relationships between nocturnal activity level and energetic condition (mass/wing chord) or date of capture. In addition, there were no significant differences in nocturnal activity levels between age groups in Swainson's Thrushes. These results suggest that the migratory restlessness of spring migrants stopping at this site is not strongly influenced by their energetic condition upon arrival, regardless of age or date of passage. Birds nearing the end of their spring migratory route that are very close to their breeding grounds may show decreased levels of ...

Deriving condition indices from standard fisheries databases and evaluating their sensitivity to variation in stored energy reserves

To evaluate interstock differences in condition, it would be advantageous to develop stock-level condition indices from standardized databases on weight and length. This study describes a method for estimating stock-level condition when individual-level observations on length and weight are not easily accessible. For each year in a 56-year time series (1946–2001) for Northeast Arctic cod (Gadus morhua), pseudo-observations of weight and length were generated by pairing the Norwegian and Russian values for weight-at-age provided annually to the assessment working group with estimates of length-at-age derived from the same databases. A weight–length relationship fit to each year was then used to predict weight-at-length, i.e., girth, for a range of standard lengths (30–120 cm). This index was uncorrelated with both the liver condition index and the abundance of Barents Sea capelin (Mallotus villosus), suggesting that at the stock level, the girth of cod is not necessarily indicative of the magnitude of stored energy reserves. Partitioning body size into length-at-age and girth revealed long-term trends in body size. In particular, large/old cod showed substantially higher values of both length-at-age and girth that could be the result of long-term increases in fishing mortality.

The influence of body condition and prey availability on female breeding success in the smooth snake (Coronella austriaca Laurenti)

AbstractA study of individually marked smooth snakes Coronella austriaca was carried out in Wareham Forest, southern England between 1992 and 2001. On average, approximately one‐third of potential breeding females reproduced each year and within this group, the proportion breeding was positively correlated with snout–vent length (SVL). Successful breeders had a higher than average body condition at the start of the breeding year compared with unsuccessful breeders. The density of gravid females was positively correlated with prey density in the breeding year but not in the year preceding it. No significant relationships were found between the density of non‐breeding females and prey density in either the breeding year or the preceding year. Although most breeding females did not produce young in consecutive years, a small proportion did. There was a weak positive relationship between clutch size and female SVL. This study suggests that the potential for female smooth snakes to breed is provided by stored energy reserves but that this potential is regulated by prey availability in the breeding year.

Complementary (secondary) metabolites in an octocoral competing with a scleractinian coral: effects of varying nutrient regimes

Competitive interactions between two sessile, epibenthic species were investigated on the Great Barrier Reef (GBR) in the presence and absence of added nutrients, as part of the Enrichment of Nutrients on Coral Reefs Experiment (ENCORE). Sarcophyton ehrenbergi Marenzeller (Octocorallia: Alcyonacea), an alcyonacean soft coral, and Pocillopora damicornis (Linnaeus), a scleractinian coral, were relocated and placed in contact with each other on large plastic grids on each of 12 micro-atolls within the One Tree Island (OTI) lagoon (23°30′S, 152°96′E, GBR). These micro-atolls were allocated in equal-sized groups to three enrichment treatments (addition of nitrogen, N; addition of phosphorus, P; addition of both nitrogen and phosphorus, N+P) and one control. Non-relocated (NR) and relocated colonies were also monitored as controls. After relocation and 1 year of nutrient enrichment, concentrations of a terpenoid complementary metabolite—sarcophytoxide—and wax esters were analyzed in colonies of S. ehrenbergi that had been exposed to elevated concentrations of N, P, N+P and compared with colonies on the non-nutrient-enriched control. Non-relocated control colonies from the natural environment were monitored over a period of 1 year and compared to colonies relocated to the control micro-atolls to assess handling effects. Analyses were performed on non-interacting S. ehrenbergi colonies, S. ehrenbergi colonies in experimental contact with P. damicornis colonies, and on non-interacting S. ehrenbergi colonies from the site of initial collection. Significant differences were found between sarcophytoxide levels in colonies of S. ehrenbergi in contact with P. damicornis vs. control/non-contact colonies; contact colonies had higher levels of this metabolite. Non-relocated control colonies of S. ehrenbergi exhibited significantly higher levels of sarcophytoxide than relocated control colonies. Augmentation of nutrient levels in micro-atolls significantly increased sarcophytoxide levels in S. ehrenbergi colonies relative to colonies on the control micro-atolls, although this response was not strong. Concentrations of fatty esters increased significantly through time in S. ehrenbergi colonies in their natural setting (non-relocated controls). This variability was not observed in relocated colonies in the treatment and control micro-atolls, irrespective of contact with P. damicornis. Concentrations of fatty esters in colonies of S. ehrenbergi in contact with P. damicornis were significantly lower than control/non-contact colonies, indicating that there is a cost in terms of stored energy reserves for the production of additional complementary metabolites when involved in competition for space. Augmentation of P levels in micro-atolls induced significant increases in fatty ester levels within S. ehrenbergi colonies vs. colonies in control micro-atolls, or in micro-atolls treated with added N or N+P together. These findings indicate that interspecific competition for space between a scleractinian coral and an alcyonacean soft coral and/or changes in the environmental nutrient regime can influence concentrations of complementary/secondary metabolites in the alcyonacean coral and the organism's stored energy reserves.

Seasonal variation in starvation resistance of early larval North Sea shrimp Crangon crangon (Decapoda: Crangonidae)

The North Sea shrimp Crangon crangon (Linnaeus, 1758) has seasonal dimorphism in egg size, with larger winter eggs and smaller summer eggs. In the laboratory, we compared the tol- erance of nutritional stress in Zoea I larvae hatching from the different types of eggs (referred to as 'winter larvae', WL, and 'summer larvae', SL, respectively). Starvation tolerance was quantified as median point-of-no-return (PNR50) and point-of-reserve-saturation (PRS50). PNR50 is defined as the time when 50% of starved larvae have lost the capability to recover (after subsequent feeding); PRS50 is the time when 50% of fed larvae attain the capability to develop through the rest of the moulting cycle using internally stored energy reserves. These critical points in the moulting cycle were esti- mated by fitting sigmoidal dose-response curves of cumulative mortality to the time of initial starva- tion or feeding, respectively. Significant seasonal variation was observed in the initial biomass at hatching (16.2 vs 14.7 µg dry mass in WL and SL, respectively) as well as in the development dura- tion of continuously fed larvae (fed controls, FC; average Zoea I stage durations: 4.4 vs 5.0 d). Like- wise, WL showed a consistently shorter development duration after 1 to 4 d initial starvation and sub- sequent feeding (PNR treatments). In treatments with 3 to 5 d initial starvation, mortality was also significantly lower in WL than in SL. Both larval groups showed an increasingly delayed moult to the Zoea II stage with increasing time of initial starvation, but this effect was significantly weaker in WL than in SL. As a consequence, the mean PNR50 value was higher in WL than in SL (4.8 vs 3.5). When zoeae were continuously starved from hatching onwards (starved controls, SC), WL were able to sur- vive significantly longer than SL (8.8 vs 6.4 d). In experiments with differential periods of initial feed- ing and subsequent starvation (PRS experiments), 50% of the WL exceeded their PRS after only 1 d of food availability, while SL required at least 2 d of feeding to become independent of further food supply. PSR50 values of WL and SL differed significantly (1.0 vs 1.6 d). Our results indicate a shorter development and stronger starvation resistance in WL compared to SL. Seasonal variation in egg size and initial biomass and physiological condition of early larvae allow for an extended period of repro- duction, including larval hatching under conditions of low or unpredictable planktonic food avail- ability in winter and early spring.

The concept of allostasis in biology and biomedicine

Living organisms have regular patterns and routines that involve obtaining food and carrying out life history stages such as breeding, migrating, molting, and hibernating. The acquisition, utilization, and storage of energy reserves (and other resources) are critical to lifetime reproductive success. There are also responses to predictable changes, e.g., seasonal, and unpredictable challenges, i.e., storms and natural disasters. Social organization in many populations provides advantages through cooperation in providing basic necessities and beneficial social support. But there are disadvantages owing to conflict in social hierarchies and competition for resources. Here we discuss the concept of allostasis, maintaining stability through change, as a fundamental process through which organisms actively adjust to both predictable and unpredictable events. Allostatic load refers to the cumulative cost to the body of allostasis, with allostatic overload being a state in which serious pathophysiology can occur. Using the balance between energy input and expenditure as the basis for applying the concept of allostasis, we propose two types of allostatic overload. Type 1 allostatic overload occurs when energy demand exceeds supply, resulting in activation of the emergency life history stage. This serves to direct the animal away from normal life history stages into a survival mode that decreases allostatic load and regains positive energy balance. The normal life cycle can be resumed when the perturbation passes. Type 2 allostatic overload begins when there is sufficient or even excess energy consumption accompanied by social conflict and other types of social dysfunction. The latter is the case in human society and certain situations affecting animals in captivity. In all cases, secretion of glucocorticosteroids and activity of other mediators of allostasis such as the autonomic nervous system, CNS neurotransmitters, and inflammatory cytokines wax and wane with allostatic load. If allostatic load is chronically high, then pathologies develop. Type 2 allostatic overload does not trigger an escape response, and can only be counteracted through learning and changes in the social structure.

A comparison of the colony-founding potential of queens from single- and multiple-queen colonies of the fire antSolenopsis invicta

Newly mated queens from the polygyne (multiple-queen) form of S. invicta show a weight polymorphism that correlates with their genotype at the protein locus Gp-9. Although this variation in weight might be expected to translate into variation in the ability of queens to initiate new colonies using stored energy reserves, a systematic examination of the colony-founding ability of newly mated polygyne-derived queens of different weights has never been reported. Here I compare the ability of monogyne-derived queens (Gp-9BB M), heavy polygyne-derived queens (Gp-9BB P), and light polygyne-derived queens (Gp-9Bb P) to initiate their own colonies using only stored energy reserves. Most measurements of the ants' abilities yielded the following scale of competency:Gp-9BB M>Gp-9BB P>Gp-9Bb P. Surprisingly, most mated polygyne-derived queens of even the lighter genotype were capable of rearing considerable numbers of workers in isolation. This ability may be enhanced substantially in the field if such queens cooperate in initiating new nests (pleometrosis). These results are concordant with the growing body of work that implicates a simply inherited genetic polymorphism for the control of a complex social trait in this ant, and they indicate that the modes of reproduction in polygyne fire ants may show considerable diversity.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .

Moulting fast and time constraint for reproduction in the king penguin

King penguins (Aptenodytes patagonicus) replace their complete plumage during a 3- to 4-week moulting fast on shore. After moulting, birds forage at sea for 2–3 weeks to store energy reserves for reproduction. Using an automatic identification and weighing system coupled with visual observations, we investigated the trade-off between the moulting fast and the following breeding attempt, in terms of body condition and in relation to time constraints, in free-living king penguins. King penguins reached their lowest body mass of the yearly cycle at the end of the moulting fast; this was lower than that at the end of the incubation fasts and not different from the body mass at egg desertion. Later in the season, the duration of the moulting fast became shorter and old feather loss occurred earlier after arrival ashore. Postmoulting foraging trips were shorter, but at the expense of body condition at the beginning of courtship. These results are discussed in relation to the synchronisation of the breeding cycle with food availability and mate choice.

Individual Recognition of Amphibians: Effects of Toe Clipping and Fluorescent Tagging on the Salamander Plethodon vehiculum

-Recognition of individual animals is essential for a wide variety of research and monitoring studies involving amphibians, but little information exists on the effects that marking methods have on survivorship, life history, and behavior. We evaluated toe clipping and subcutaneous injections of a fluorescent-elastomer for individual identification of the western red-backed salamander, Plethodon vehiculum, on Vancouver Island, British Columbia. In the laboratory, no confirmed mortality of marked or unmarked (control) salamanders occurred over 64 weeks. The number of toe clips lost as the result of regeneration increased steadily after 35 weeks postmarking, but few fluorescent marks were lost or misidentified. In the field, we recaptured more fluorescent-marked (60%) than toe-clipped (40%) salamanders from September 1997 to May 1998 but detected no differences in growth or spatial movements. In a second field experiment (27 April to 31 May 1999), toe-clipped salamanders gained less weight in relation to their initial body size than did fluorescent-marked and control salamanders. These data suggest that toe clipping affects the ability of individuals to take full advantage of optimal foraging conditions that prevail in May, which, in turn, might affect the quantity of stored energy reserves required for survival over adverse, dry periods in sum-

Limited use of stored energy reserves for reproduction by the tropical loliginid squid Photololigo sp.

AbstractThis study sought to determine if the tropical loliginid squid Photololigo sp. stores energy in the form of lipid, carbohydrate or protein for reproductive investment. Individuals were examined for changes in morphometry, mantle muscle structure and concentrations of water, lipid, carbohydrate and protein in muscle tissue and the digestive gland, associated with the stage of reproductive maturation. Muscle mass was affected by reproductive maturation in females. Mature individuals were lighter for their length compared with females in the early stages of maturation. Concentrations of lipid and carbohydrate in the muscle tissue were very low, and female Photololigo sp. showed equivocal evidence of declining lipid and carbohydrate levels with egg production. There was no evidence of dramatic changes in protein concentration in the mantle muscle with reproductive maturation. Male Photololigo sp. showed a change in the digestive gland with maturation, with water content increasing and protein concentrations decreasing. The digestive gland of both male and female Photololigo sp. increased in size and contained less water with growth. There was little evidence that the storage and transfer of energy for reproduction occurred in Photololigo sp. Instead, it is probable that energy for reproduction is predominantly sourced directly from consumed food.

Limited use of stored energy reserves for reproduction by the tropical loliginid squid Photololigo sp.

This study sought to determine if the tropical loliginid squid Photololigo sp. stores energy in the form of lipid, carbohydrate or protein for reproductive investment. Individuals were examined for changes in morphometry, mantle muscle structure and concentrations of water, lipid, carbohydrate and protein in muscle tissue and the digestive gland, associated with the stage of reproductive maturation. Muscle mass was affected by reproductive maturation in females. Mature individuals were lighter for their length compared with females in the early stages of maturation. Concentrations of lipid and carbohydrate in the muscle tissue were very low, and female Photololigo sp. showed equivocal evidence of declining lipid and carbohydrate levels with egg production. There was no evidence of dramatic changes in protein concentration in the mantle muscle with reproductive maturation. Male Photololigo sp. showed a change in the digestive gland with maturation, with water content increasing and protein concentrations decreasing. The digestive gland of both male and female Photololigo sp. increased in size and contained less water with growth. There was little evidence that the storage and transfer of energy for reproduction occurred in Photololigo sp. Instead, it is probable that energy for reproduction is predominantly sourced directly from consumed food.