bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of male mating history on paternal investment, fecundity and female remating in the seed beetle Callosobruchus maculatus
Authors: SAVALLI U. M. , FOX C. W. 
Published: March 2003

1. In many organisms, males provide nutrients to females via ejaculates that can influence female fecundity, longevity and mating behaviour. The effect of male mating history on male ejaculate size, female fecundity, female longevity and female remating behaviour in the seed beetle Callosobruchus maculatus was determined. 2. The quantity of ejaculate passed to females declined dramatically with successive matings. Despite the decline, a male’s ability to fertilize a female fully did not appear to decline substantially until his fourth mating. 3. When females multiply mated with males of a particular mated status, the pattern of egg production was cyclic, with egg production increasing after mating. Females multiply mated to virgins had higher fecundity than females mated to non‐virgins, and females mated to twice‐mated males had disproportionately increased egg production late in their life. 4. Females that mated to multiple virgins, and consequently laid more eggs, experienced greater mortality than females mated only once or mated to non‐virgins, suggesting that egg production is costly, and rather than ameliorating these costs, male ejaculates may increase them by allowing or stimulating females to lay more eggs. 5. Females mating with non‐virgin males remated more readily than did females mated to virgins. Females given food supplements were less likely to remate than females that were nutritionally stressed, suggesting that females remate in part to obtain additional nutrients.
Photosynthetic pathway diversity in a seasonal pool community
Authors: Keeley J. E. 
Published: March 2003

1. Photosynthetic pathway diversity was evaluated for the dominant species in a seasonally aquatic community in the south‐western USA using 14C pulse‐chase techniques. 2. Under submerged conditions, only about half of the species were clearly C3, three of the 15 dominants were CAM, one species was C4 and three were potentially assimilating carbon with both C3 and C4 fixation. 3. During the brief terrestrial stage in the life history of these amphibious plants, both the CAM and the C3 + C4 species switched to C3, whereas the C4 species did not switch. 4. Numerous variations were apparent; for example, the C4 species, while exhibiting a biochemical pathway indistinguishable from terrestrial C4 plants, lacked Kranz anatomy in the aquatic foliage. Also, despite well‐developed CAM in several species, others exhibited low‐level diel changes in acidity, apparently not indicative of CAM. 5. Species with C4 or CAM CO2 concentrating mechanisms lacked the capacity for bicarbonate uptake, an alternative CO2 concentrating mechanism found in certain C3 species in this community. 6. Rubisco/PEPC in aquatic foliage was higher in C3 species than in C4, CAM or putative C3 + C4 species. In the terrestrial phase, as expected, the switch from CAM or C3 + C4 to strictly C3 assimilation was associated with a substantial increase in Rubisco/PEPC. Quite unexpected, however, was the substantial increase in this ratio in terrestrial C3 foliage. It is hypothesized that submerged C3 plants utilize PEPC for recycling of respiratory CO2 and/or C4 phototrophism under field conditions of limited CO2 and O2 saturation, and this is lost in the terrestrial foliage.
Contramensal interactions between two collembolan species: effects on population development and on soil processes
Authors: THEENHAUS A. , SCHEU S. , SCHAEFER M. 
Published: March 2003

1.In the laboratory, a microcosm experiment was set up to study (1) the interaction between two collembolan speciesOnychiurus furcifer(Börner) andHeteromurus nitidus(Templeton) during 24 weeks of incubation; (2) the influence of slug (Arion rufusL.) cast material on the outcome of this interaction; and (3) the influence of collembolan activity on microbial biomass, respiration and nutrient mobilization.2.The CO2production was monitored every other week and NH4+, NO3–and PO43–contents of leachates were determined every 4 weeks. After 12 and 24 weeks of incubation, the number of collembolans, basal respiration (O2consumption), microbial biomass (substrate‐induced respiration method), specific respiration (qO2) and the content of NH4+, NO3–and PO43–in soil were determined.3.Generally, the number of collembolans in microcosms with cast material exceeded that of microcosms without cast material considerably on average by factors of 20 and 26 forO.furciferandH. nitidus, respectively. This increase was attributed to the additional food supply provided with the cast material. Numbers of collembolans declined during the experiment.4.At both sampling dates, the presence ofH. nitidusled to a reduction in the number ofO.furcifer, whereasH. nitidusbenefited from the presence ofO.furcifer. Either trophic or non‐trophic mechanisms, or both, may have caused this interaction (contramensalism,sensuArthur & Mitchell 1989).5.Both collembola species caused a decrease in microbial respiration, decomposition rates and tentatively also microbial biomass at high densities, whereas at low densities microbial respiration was stimulated while decomposition rates and microbial biomass remained unaffected. These effects were more pronounced forO.furciferthan forH. nitidus.6.In treatments with cast material N‐mobilization was increased by collembolan activity.
Parental investment and egg yolk lipid composition in gulls
Authors: Royle N. J. , Surai P. F. , Mccartney R. J. , Speake B. K. 
Published: March 2003

1.Within‐clutch variation in parental investment of yolk lipid (including essential fatty acid composition and fat‐soluble vitamin content) was investigated in whole clutches of three eggs of Lesser Black‐backed Gulls,Larus fuscus.2.Although there were no significant differences between years in egg size or yolk mass among eggs of the same laying order, eggs collected in 1996 had significantly lower lipid content than those collected in 1997.3.In both years third‐laid c‐eggs were smaller, had a smaller mass of yolk and had significantly lower yolk lipid mass compared with earlier laid (a‐ and b‐) eggs.4.Despite this lower lipid mass of c‐eggs, of the different lipid fractions only cholesterol content of c‐eggs was significantly lower than that of a‐ or b‐eggs.5.Earlier laid eggs had greater amounts of arachidonic acid in the phospholipid and cholesterol ester fractions of yolk lipid, and considerably greater quantities of vitamin E and carotenoids.6.Conversely, levels of linoleic acid and vitamin A were equalized among eggs of different laying sequence as both these essential nutrients have primarily systemic roles.7.The probable effect of increased antioxidant (vitamin E and carotenoid) content of earlier‐laid eggs is to enhance embryonic and neonatal growth and development, reduce susceptibility to pathogens and increase the ability of the embryo to withstand the oxidative stress associated with hatching.8.The results suggest that there is maternal bias of essential nutrients to offspring with the highest reproductive value in order to maximize reproductive success.
Adjustments to nitrogen metabolism during wing moult in Greylag Geese, Anser anser
Authors: Fox A. D. , Kahlert J. 
Published: March 2003

1. This study examined the nitrogen balance of free‐living flightless moulting Greylag Geese, Anser anser, in relation to food quality, nitrogen absorption, food retention time and nitrogen excretion rates. 2. Food intake rates during moult were the same as those before and after the flightless period, but total daily time spent foraging fell by 58% from 9·45 h to 3·96 h. Dropping production during moult was 43%, and mean dropping mass 42% of that before and after moult, suggesting a considerable increase in food passage time through the gut during moult. Nitrogen absorption increased from 25% prior to moult to 47% during moult. 3. At the same time, excreted dry mass uric acid in faecal material fell by 68%, such that the proportion of nitrogen absorbed and retained in the body as a proportion of the nitrogen ingested in food rose from 16% prior to moult to 42% during moult. 4. Based on these significant increases in nitrogen absorption and decreases in nitrogen excretion, geese were able to compensate for reduced food intake and derive sufficient nitrogen from their diet to re‐grow flight feathers.
Reproductive significance of feeding on saprobic and arbuscular mycorrhizal fungi by the collembolan, Folsomia candida
Authors: Klironomos J. N. , Bednarczuk E. M. , Neville J. 
Published: March 2003

1. Collembolans have often been credited with negatively affecting arbuscular mycorrhizal (AM) symbioses, mainly by grazing and severing the associated external fungal network from host roots. However, most previous experiments were performed using relatively ‘clean’ systems where other, non‐mycorrhizal, fungi were largely excluded. Yet, plant rhizospheres harbour a wide variety of highly palatable non‐AM fungi, most of which have saprobic lifestyles. 2. In this study we isolated and cultured several rhizosphere fungi, and the collembolan, Folsomia candida, from the Long‐Term Mycorrhiza Research Site, University of Guelph, Canada, to test the hypothesis that, given a choice, collembolans would prefer to feed on saprobic fungi and that such a choice is of adaptive significance to the animals. 3. A laboratory food preference experiment revealed that F. candida favours common saprobic fungi over a variety of AM fungi. Coincidentally, fecundity levels across two Folsomia generations were higher when animals fed exclusively on the preferred fungus, Alternaria alternata. When fed less palatable fungi, fecundity was greatly reduced; in fact animals from the F1 generation were unable to produce any eggs when placed on an exclusive diet of one of the following three AM fungi, Acaulospora spinosa, Scutellospora calospora and Gigaspora gigantea. 4. These results indicate that a strict diet of AM fungi by collembolans has reproductive consequences. Therefore, we propose that under natural conditions these animals spend more time feeding on common saprobic fungi rather than their AM counterparts. This suggests that previous ‘clean’ studies that investigated the interactions between collembolans and AM fungi may have reported exaggerated effects of animal grazing. The influence of collembolans on the functioning of AM symbioses, under more natural conditions, remains not well understood.
Evapotranspiration from Eucalypt open‐forest savanna of Northern Australia
Authors: Hutley L. B. , O'Grady A. P. , Eamus D. 
Published: March 2003

Abstract1. Using three independent methods (eddy covariance, heat pulse and open‐top chambers), diurnal and seasonal measurements of evapotranspiration were made in a wet–dry Eucalypt savanna of the Northern Territory, Australia.2. Total annual dry‐canopy water loss was estimated to be 870 mm and understorey evapotranspiration contributed 557 mm to this flux. Understorey evapotranspiration occurred predominantly during the wet season as bare soil evaporation and transpiration of Sorghum spp., a C4 grass.3. Annual transpiration from trees was 313 mm, significantly less than the grassy understorey. Despite a very high degree of seasonality in distribution of rainfall and large changes to soil and atmospheric water content, water use by the trees did not differ between wet and dry seasons. This suggests that mature trees exploit a large soil volume and this may include extraction from the capillary fringe of the shallow water table (2–10 m below the ground surface).4. The open canopy created an aerodynamically rough surface well coupled to the atmosphere with the coupling coefficient, Ω, ranging from 0·40 to 0·11 over a wet–dry cycle.5. Leaf area index (LAI) of the overstorey was typically 1·0 in the wet season and 0·65 in the dry season. The decline in tree LAI occurred when evaporative demand showed a similar proportional increase. Consequently overstorey water use remained relatively unchanged throughout the year.6. Given the very high rainfall intensities of the monsoonal climate and low LAI of the site, canopy interception was set at 5% of rainfall. Including this amount gives an annual evapotranspiration of 958 mm for this savanna.
Trade‐offs in phenotypic traits: endurance at birth, growth, survival, predation and susceptibility to parasitism in a lizard,Lacerta vivipara
Authors: Clobert J. , Oppliger A. , Sorci G. , Ernande B. , Swallow J. G. , Garland T. 
Published: March 2003

AbstractConsiderable within‐population variability of locomotor performance traits has been shown to exist in several species of squamate reptiles. In general, high values for speed and endurance are thought to have positive effects on the ability to capture prey, escape from predators, compete with conspecifics and acquire mates. On the other hand, variation in performance might trade‐off with other components of fitness such that the net effect on Darwinian fitness is unpredictable.Gravid females of the common lizard (Lacerta vivipara) were captured and several phenotypic traits of their offspring measured immediately following birth. These were endurance, body length and body mass. Offspring were marked for individual identification, released into the field, and correlations between the phenotypic traits and their subsequent growth, activity and survival rate over the next months were then tested for. Parasitism by hematozoa was monitored and predation risk by tail losses estimated.It was found that individuals with a low endurance at birth tended to have reduced activity and growth rate, and higher parasite load; on the positive side, however, they experienced lower predation risk as assessed by tail losses. Conversely, individuals with a high endurance at birth had high activity and growth rates, low parasite load, but higher incidence of broken tails. Finally, endurance at birth was not correlated with survivorship up to the age of sexual maturity. Thus, individuals with varying locomotor endurance seem to exhibit behaviours that may result in the same level of Darwinian fitness.The possibility that our results reveal a trade‐off between the risk of becoming infected with parasites when lizards are less active (which is related to having lower endurance)vsthe risk of being predated when the lizards are more active (higher endurance) is discussed.
Does enemy‐free space for eggs contribute to a leaf beetle’s oviposition preference for a nutritionally inferior host plant?
Authors: Ballabeni P. , Wlodarczyk M. , Rahier M. 
Published: March 2003

Summary

Natural enemies are likely to influence the interactions between herbivorous insects and their host plants. In particular, selection exerted by natural enemies could favour host‐plant switches and cause, or maintain, oviposition preference for a host species that is nutritionally inferior to another acceptable host.
In a previous study, it was shown that larvae of the leaf beetle Oreina elongata perform better on Adenostyles alliariae (Asteraceae) than on Cirsium spinosissimum (Asteraceae). Moreover, A. alliariae provides larval and adult beetles with sequestrable chemical defences. However, in the field, egg densities are much higher on C. spinosissimum than on adjacent A. alliariae.
In this study, it was investigated whether this oviposition pattern could be maintained by C. spinosissimum, providing the eggs of O. elongata with better protection from natural enemies. In a field experiment, the survival of eggs was quantified on plants of each of the two species, with and without enemy exclusion.
Egg survival was equal for both host species when enemies were excluded from the plants, but it was higher on C. spinosissimum than on A. alliariae when enemies were allowed to the plants. It was also experimentally tested whether the higher egg densities observed in the field on C. spinosissimum are actually due to oviposition preference by the beetle. In a no‐choice test, females laid more eggs on C. spinosissimum than on A. alliariae.
It can thus be confirmed that C. spinosissimum is really preferred for oviposition and it is concluded that this preference is likely to be maintained, at least partly, by a higher egg survival on C. spinosissimum due to enemy‐free space provided by this host plant.
The energetics of Gentoo Penguins, Pygoscelis papua, during the breeding season
Authors: Bevan R. M. , Butler P. J. , Woakes A. J. , Boyd I. L. 
Published: March 2003

Summary

The food consumption of an animal, both at the individual and the population level, is an essential component for assessing the impact of that animal on its ecosystem. As such, measurements of the energy requirements of marine top‐predators are extremely valuable as they can be used to estimate these food requirements.
The present study used heart rate to estimate the rate of energy expenditure of gentoo penguins during the breeding season. The average daily metabolic rate (ADMR) of penguins when one adult was necessarily present at the nest (incubating eggs or guarding small chicks; IG; 4·76 W kg−1) was significantly lower than that when both parents forage concurrently during the major period of chick growth (CR; 6·88 W kg−1).
The ADMR of a bird was found to be dependent on a number of factors, including the day within the breeding season and the percentage time that the bird spent foraging during that day.
When they were ashore, the estimated metabolic rate of IG birds (3·94 W kg−1) was significantly lower than that of CR birds (5·93 W kg−1). However, the estimated metabolic rates when the birds were at sea during these periods were essentially the same (8·58 W kg−1).
The heart rate recorded when the penguins were submerged (128 beats min−1) was significantly higher than that recorded from resting animals when ashore (89 beats min−1). However, it was lower than that recorded from birds that were swimming in a water channel (177 beats min−1). This might indicate that, although primarily aerobic in nature, there was an anaerobic component to metabolism during diving. An alternative interpretation is that the metabolic requirement during diving was lower than when the birds were swimming with access to air.
There was a significant decline in abdominal temperature, from 38·8 °C at the start of a diving bout to 36·2 °C at the end, which may indicate a reduction in overall metabolic rate during submersion. This in turn may explain the lowered heart rate.
In the present study, we have shown that the metabolic rate of the gentoo penguin varies during the breeding season. The relatively constant metabolic rate of the birds when at sea could represent an upper physiological limit that the birds are unable to exceed. If so, it will only be possible for the birds to increase foraging effort by diving more frequently and/or for longer periods thus reducing their foraging efficiency (the energy gained during foraging vs. energy spent gaining that food). During years when food is scarce, this reduction in foraging efficiency may have a profound influence on the reproductive productivity of the gentoo penguin.
Ecological correlates of endozoochory by herbivores
Authors: Pakeman R. J. , Digneffe G. , Small J. L. 
Published: March 2003

Summary1. Many plant species germinate from herbivore dung. However, there has been little assessment of how widespread this dispersal mechanism is.2. A survey of the germinable seed in rabbit and sheep dung from 10 sites in the UK was used to identify the characteristics of species dispersed internally by animals.3. A wide range of species germinated; the commonest species being ‘weeds’ of grazed communities.4. Species that did germinate were characterized by small seed size and the capability of forming a persistent seedbank.5. A substantial quantity and range of seeds are dispersed by herbivores in grazed ecosystems, and this could have a significant effect on the dynamics and species richness of these systems.
Does pregnancy affect swimming performance of female Mosquitofish, Gambusia affinis?
Authors: Plaut I. 
Published: March 2003

Summary1. The cost of reproduction due to limiting of the reproductive female’s locomotion capability has been suggested many times, but has rarely been directly examined, especially in fishes. Here, the effect of pregnancy on swimming performance in the viviparous Mosquitofish, Gambusia affinis, was studied.2. Eight females of G. affinis were isolated, each in a separate aquarium, and critical swimming speed (Ucrit), body mass (BM) and cross‐section area were measured every 5 days from the beginning of the pregnancy until 2–4 days after parturition.3. Swimming kinematics (tail beat frequency and amplitude) was measured in non‐pregnant and pregnant females at different swimming speeds.4. BM increased during pregnancy from 0·47 ± 0·13 g to 0·72 ± 0·19 g, and the cross‐section area also increased during pregnancy from 0·21 ± 0·06 cm2 to 0·32 ± 0·07 cm2. Ucrit decreased from 25·0 ± 1·3 cm s−1 before pregnancy to 20·1 ± 1·5 cm s−1 just before parturition, and returned to 24·7 ± 1·4 cm s−1 2–4 days after parturition. Interindividual variation was repeatable and reflects real differences among individuals.5. Swimming kinematics was not affected by pregnancy.6. The results suggest that reductions in Ucrit are probably because of aerobic constraints and not necessarily due to hydrodynamic changes resulting from changing in body form or plasticity. Moreover, the reduction in Ucrit is, potentially, a ‘cost of reproduction’ owing to decrease in the ability to gain food during pregnancy in G. affinis females.
Patterns of yolk enrichment with dietary carotenoids in gulls: the roles of pigment acquisition and utilization
Authors: Blount J. D. , Surai P. F. , Houston D. C. , Møller A. P. 
Published: March 2003

Summary 1. Carotenoid pigments are deposited into egg yolk by female birds, but little is known of the ecological regulation of this process. In particular, the relative importance of pigment acquisition and utilization (i.e. physiological discrimination: differential uptake, transport, deposition or metabolic conversions) is poorly understood. 2. Carotenoids are antioxidants, capable of neutralizing reactive free radicals and thus preventing lipid peroxidation. But animals must ultimately obtain carotenoids in the diet, and metabolic conversion of carotenoids is inefficient and expends energy. It has therefore been suggested that carotenoid supply may be limiting to animals. 3. Prelaying, wild Lesser Black‐Backed Gulls (Larus fuscus L.) were given supplementary feed with a cocktail of four carotenoids, or a carotenoid‐free (control) supplement. The yolk carotenoid profile and susceptibility to lipid peroxidation were then compared in eggs that they laid. 4. In comparison with controls, there was an increase in the yolk concentrations of seven carotenoids, and also unidentified carotenoids in eggs produced by carotenoid‐supplemented females. However, the relative proportions of five classes of carotenoid did not differ significantly, and consequently the percentage profile of yolk carotenoids was positively correlated, between feeding treatments, possibly indicating metabolic transformations and differential transfer of carotenoids from maternal diet to yolk. 5. Moreover, in control eggs relatively few possible correlations between carotenoid concentrations were significantly positive, and some correlations between carotenoid proportions were significantly negative, suggesting physiological discrimination. 6. Egg yolk produced by carotenoid‐supplemented females was significantly less susceptible to lipid peroxidation in comparison with controls. 7. These results suggest that yolk enrichment with carotenoids involves physiological discrimination in gulls, highlighting a previously unstudied, potential cost of reproduction.